import os
import posixpath
import secrets
import shutil
import tarfile
import tempfile
import threading
import traceback
from datetime import datetime
from functools import wraps
from pathlib import Path
import zipfile

from flask import Flask, flash, g, got_request_exception, jsonify, redirect, render_template, request, session, url_for
import smbclient

try:
    import py7zr
except Exception:  # noqa: BLE001
    py7zr = None

from app.config_model import AppConfig, BackupExecutionJob, BackupJob
from app.config_store import ConfigStore
from app.log_store import LogStore
from app.remote_targets import (
    TargetConnection,
    browse_ftp_directories,
    browse_sftp_directories,
    browse_smb_directories,
    create_smb_directory,
    list_smb_shares,
    normalize_subpath,
    test_connection,
)
from app.security import hash_password, verify_password


COMPRESSION_METHODS = [
    "none",
    "zip",
    "tar.gz",
    "tar.bz2",
    "tar.xz",
    "7z",
]

TARGET_PROTOCOLS = ["SMB", "LOCAL", "FTP", "SFTP"]
ENCRYPTION_MODES = ["none", "password-aes256"]
BACKUP_MODES = ["full", "sync", "clone"]


class FlaskServer:
    def __init__(self, config: AppConfig, store: ConfigStore, log_store: LogStore) -> None:
        self.config = config
        self.store = store
        self.log_store = log_store
        self._run_lock = threading.Lock()
        self._active_runs: dict[int, dict] = {}

    def _log(
        self,
        *,
        level: str,
        category: str,
        event: str,
        message: str,
        username: str | None = None,
        backup_id: int | None = None,
        details: dict | None = None,
        status_code: int | None = None,
    ) -> None:
        try:
            request_path = request.path if request else None
            request_method = request.method if request else None
        except RuntimeError:
            request_path = None
            request_method = None

        resolved_user = username
        if not resolved_user:
            try:
                resolved_user = session.get("adminuser")
            except RuntimeError:
                resolved_user = None

        self.log_store.write(
            level=level,
            category=category,
            event=event,
            message=message,
            username=resolved_user,
            backup_id=backup_id,
            request_path=request_path,
            request_method=request_method,
            status_code=status_code,
            details=details,
        )

    def _get_run_status(self, backup_id: int) -> dict:
        with self._run_lock:
            state = self._active_runs.get(backup_id)
            if not state:
                return {
                    "is_running": False,
                    "progress_percent": 0,
                    "progress_text": "Bereit",
                    "status_message": "Kein Lauf aktiv",
                }
            return {
                "is_running": bool(state.get("is_running", False)),
                "progress_percent": int(state.get("progress_percent", 0)),
                "progress_text": str(state.get("progress_text", "")),
                "status_message": str(state.get("status_message", "")),
            }

    def _set_run_state(self, backup_id: int, **values) -> None:
        with self._run_lock:
            state = self._active_runs.get(backup_id, {})
            state.update(values)
            self._active_runs[backup_id] = state

    def _build_runtime_meta(self, backup_id: int) -> dict:
        meta = self.store.get_backup_runtime_meta(backup_id)
        if meta is None:
            return {
                "last_run_at": None,
                "last_size_bytes": None,
            }
        return meta

    def _start_backup_run(self, backup_id: int, trigger: str = "manual") -> tuple[bool, str]:
        with self._run_lock:
            existing = self._active_runs.get(backup_id)
            if existing and bool(existing.get("is_running", False)):
                self._log(
                    level="WARNING",
                    category="backup",
                    event="run_start_rejected",
                    backup_id=backup_id,
                    message="Backup-Lauf konnte nicht gestartet werden, da bereits ein Lauf aktiv ist.",
                )
                return False, "Backup-Lauf ist bereits aktiv."

        job = self.store.get_backup_execution_job(backup_id)
        if job is None:
            self._log(
                level="ERROR",
                category="backup",
                event="run_start_failed",
                backup_id=backup_id,
                message="Backup-Lauf konnte nicht gestartet werden, da das Backup nicht gefunden wurde.",
            )
            return False, "Backup nicht gefunden."

        stop_event = threading.Event()
        thread = threading.Thread(
            target=self._run_backup_job,
            args=(job, stop_event),
            daemon=True,
            name=f"backup-run-{backup_id}",
        )

        trigger_normalized = (trigger or "manual").strip().lower()
        is_scheduled = trigger_normalized == "scheduled"
        start_label = "Geplanter Lauf" if is_scheduled else "Manueller Lauf"

        self._set_run_state(
            backup_id,
            is_running=True,
            progress_percent=2,
            progress_text="Startet...",
            status_message=f"{start_label} wird gestartet...",
            stop_event=stop_event,
            thread=thread,
        )
        thread.start()
        self._log(
            level="INFO",
            category="backup",
            event="run_started",
            backup_id=backup_id,
            message=f"{start_label} wurde gestartet: {job.name}",
            details={"trigger": trigger_normalized},
        )
        return True, f"{start_label} für '{job.name}' wurde gestartet."

    def _stop_backup_run(self, backup_id: int) -> tuple[bool, str]:
        with self._run_lock:
            state = self._active_runs.get(backup_id)
            if not state or not bool(state.get("is_running", False)):
                self._log(
                    level="WARNING",
                    category="backup",
                    event="run_stop_rejected",
                    backup_id=backup_id,
                    message="Backup-Abbruch angefordert, aber kein Lauf war aktiv.",
                )
                return False, "Kein aktiver Lauf zum Abbrechen."

            stop_event = state.get("stop_event")
            if stop_event is None or not hasattr(stop_event, "set"):
                self._log(
                    level="ERROR",
                    category="backup",
                    event="run_stop_failed",
                    backup_id=backup_id,
                    message="Backup-Abbruch konnte nicht angefordert werden (fehlendes stop_event).",
                )
                return False, "Abbruch konnte nicht angefordert werden."

            stop_event.set()
            state["progress_text"] = "Stoppt..."
            state["status_message"] = "Abbruch wurde angefordert..."
            self._active_runs[backup_id] = state

        self._log(
            level="INFO",
            category="backup",
            event="run_stop_requested",
            backup_id=backup_id,
            message="Abbruch eines laufenden Backups wurde angefordert.",
        )
        return True, "Abbruch wurde angefordert."

    @staticmethod
    def _replace_target_tokens(pattern: str) -> str:
        now = datetime.now()
        value = pattern
        value = value.replace("{date}",         now.strftime("%Y-%m-%d"))
        value = value.replace("{date_de}",       now.strftime("%d.%m.%Y"))
        value = value.replace("{date_compact}",  now.strftime("%Y%m%d"))
        value = value.replace("{time}",          now.strftime("%H-%M-%S"))
        value = value.replace("{time_short}",    now.strftime("%H%M"))
        value = value.replace("{datetime}",      now.strftime("%Y-%m-%d_%H-%M-%S"))
        return value

    @staticmethod
    def _join_subpath(base: str, child: str) -> str:
        normalized_base = normalize_subpath(base).rstrip("/")
        clean_child = child.strip("/")
        if not clean_child:
            return normalize_subpath(base)
        if normalized_base in {"", "/"}:
            return f"/{clean_child}"
        return f"{normalized_base}/{clean_child}"

    @staticmethod
    def _smb_unc_path(host: str, share: str, subpath: str) -> str:
        clean_share = share.strip().strip("\\/")
        clean_subpath = normalize_subpath(subpath).strip("/")
        if clean_subpath:
            return f"\\\\{host}\\{clean_share}\\{clean_subpath.replace('/', '\\\\')}"
        return f"\\\\{host}\\{clean_share}"

    def _ensure_smb_dir(self, host: str, share: str, subpath: str) -> None:
        parts = [p for p in normalize_subpath(subpath).strip("/").split("/") if p]
        current = "/"
        for part in parts:
            current = self._join_subpath(current, part)
            unc = self._smb_unc_path(host, share, current)
            try:
                smbclient.mkdir(unc)
            except Exception:  # noqa: BLE001
                # Zielordner kann bereits existieren.
                pass

    def _collect_source_files(self, job: BackupExecutionJob) -> list[tuple[str, str]]:
        source_protocol = job.source_protocol.upper()
        files: list[tuple[str, str]] = []

        if source_protocol == "LOCAL":
            source_path = Path(job.source_subpath).expanduser()
            # Auto-detect file vs directory regardless of source_entry_type
            if source_path.is_file():
                files.append((source_path.name, str(source_path)))
                return files
            if not source_path.is_dir():
                raise RuntimeError(f"Source-Pfad nicht gefunden: {source_path}")

            for entry in source_path.rglob("*"):
                if entry.is_file():
                    rel = entry.relative_to(source_path).as_posix()
                    files.append((rel, str(entry)))
            return files

        if source_protocol == "SMB":
            smbclient.register_session(
                server=job.source_host,
                username=job.source_username,
                password=job.source_password,
                port=job.source_port or 445,
            )

            source_subpath = normalize_subpath(job.source_subpath)
            if job.source_entry_type == "file":
                basename = posixpath.basename(source_subpath.rstrip("/"))
                if not basename:
                    raise RuntimeError("SMB Source-Datei ist ungültig.")
                files.append((basename, source_subpath))
                return files

            def walk(current_subpath: str, prefix: str = "") -> None:
                unc = self._smb_unc_path(job.source_host, job.source_share, current_subpath)
                for item in smbclient.scandir(unc):
                    if item.name in {".", ".."}:
                        continue
                    child_subpath = self._join_subpath(current_subpath, item.name)
                    child_rel = f"{prefix}/{item.name}" if prefix else item.name
                    if item.is_dir():
                        walk(child_subpath, child_rel)
                    else:
                        files.append((child_rel, child_subpath))

            walk(source_subpath)
            return files

        if source_protocol in {"FTP", "SFTP"}:
            return self._collect_source_files_ftp(job)

    def _collect_source_files_ftp(self, job: BackupExecutionJob) -> list[tuple[str, str]]:
        """Returns list of (relative_path, ftp_path) pairs from an FTP source."""
        from ftplib import FTP as _FTP
        ftp = _FTP()
        files: list[tuple[str, str]] = []
        try:
            ftp.connect(job.source_host, job.source_port or 21, timeout=30)
            ftp.login(job.source_username, job.source_password)
            subpath = normalize_subpath(job.source_subpath)
            if job.source_entry_type == "file":
                basename = posixpath.basename(subpath.rstrip("/")) or posixpath.basename(subpath)
                if not basename:
                    raise RuntimeError("FTP Source-Datei ist ungültig.")
                files.append((basename, subpath))
                return files

            def ftp_walk(path: str, prefix: str = "") -> None:
                raw: list[str] = []
                try:
                    ftp.retrlines(f"LIST {path}", raw.append)
                except Exception:  # noqa: BLE001
                    return
                for line in raw:
                    parts = line.split(None, 8)
                    if len(parts) < 9:
                        continue
                    name = parts[8].strip()
                    if name in (".", ".."):
                        continue
                    is_dir = parts[0].startswith("d")
                    child_path = f"{path.rstrip('/')}/{name}"
                    child_rel = f"{prefix}/{name}" if prefix else name
                    if is_dir:
                        ftp_walk(child_path, child_rel)
                    else:
                        files.append((child_rel, child_path))

            ftp_walk(subpath)
        finally:
            try:
                ftp.quit()
            except Exception:  # noqa: BLE001
                pass
        return files

    def _build_destination_spec(self, job: BackupExecutionJob, file_path: str, destination_protocol: str) -> str:
        if destination_protocol == "LOCAL":
            return file_path
        if destination_protocol in {"FTP", "SFTP"}:
            host_port = f"{job.destination_host}:{job.destination_port}" if job.destination_port else job.destination_host
            return f"{host_port}|{job.destination_username}|{job.destination_password}|{file_path}"
        return "|".join([job.destination_host, job.destination_share, file_path])

    def _build_source_spec(self, job: BackupExecutionJob, file_path: str, source_protocol: str) -> str:
        if source_protocol == "LOCAL":
            return file_path
        if source_protocol in {"FTP", "SFTP"}:
            host_port = f"{job.source_host}:{job.source_port}" if job.source_port else job.source_host
            return f"{host_port}|{job.source_username}|{job.source_password}|{file_path}"
        # SMB
        return "|".join([job.source_host, job.source_share, file_path])

    def _copy_file_stream(
        self,
        source_protocol: str,
        source_location: str,
        destination_protocol: str,
        destination_location: str,
        stop_event: threading.Event,
    ) -> int:
        # Fast path: SMB server-side copy when source and destination are on the same host.
        if source_protocol == "SMB" and destination_protocol == "SMB":
            src_parts = source_location.split("|", 2)
            dst_parts = destination_location.split("|", 2)
            if len(src_parts) == 3 and len(dst_parts) == 3:
                src_host, src_share, src_subpath = src_parts
                dst_host, dst_share, dst_subpath = dst_parts
                if src_host.strip().lower() == dst_host.strip().lower():
                    if stop_event.is_set():
                        raise RuntimeError("Lauf wurde abgebrochen.")
                    src_unc = self._smb_unc_path(src_host, src_share, src_subpath)
                    dst_unc = self._smb_unc_path(dst_host, dst_share, dst_subpath)
                    try:
                        smbclient.copyfile(src_unc, dst_unc)
                        try:
                            return int(smbclient.stat(dst_unc).st_size or 0)
                        except Exception:  # noqa: BLE001
                            return int(smbclient.stat(src_unc).st_size or 0)
                    except Exception:  # noqa: BLE001
                        # Fallback to streamed copy for incompatible servers or share policies.
                        pass

        total_bytes = 0
        source_handle = None
        destination_handle = None
        cleanup_callbacks: list = []

        class _StopAwareReader:
            def __init__(self, wrapped, stopper: threading.Event):
                self._wrapped = wrapped
                self._stopper = stopper

            def read(self, size: int = -1):
                if self._stopper.is_set():
                    raise RuntimeError("Lauf wurde abgebrochen.")
                return self._wrapped.read(size)

        def _parse_endpoint(endpoint: str, default_port: int) -> tuple[str, int, str, str, str]:
            parts = endpoint.split("|", 3)
            if len(parts) != 4:
                raise RuntimeError(f"Ungültiger Verbindungs-String: {endpoint}")
            host_port, user, password, remote_path = parts
            host, port_text = (host_port.rsplit(":", 1) + [None])[:2]
            port = int(port_text) if port_text else default_port
            return host, port, user, password, remote_path

        try:
            if source_protocol == "LOCAL":
                source_handle = open(source_location, "rb")
            elif source_protocol == "FTP":
                from ftplib import FTP as _FTP

                host, port, user, password, remote_path = _parse_endpoint(source_location, 21)
                ftp_dl = _FTP()
                spool = tempfile.SpooledTemporaryFile(max_size=32 * 1024 * 1024, mode="w+b")
                cleanup_callbacks.append(spool.close)
                try:
                    ftp_dl.connect(host, port, timeout=60)
                    ftp_dl.login(user, password)
                    ftp_dl.retrbinary(f"RETR {remote_path}", spool.write, blocksize=4 * 1024 * 1024)
                finally:
                    try:
                        ftp_dl.quit()
                    except Exception:  # noqa: BLE001
                        pass
                spool.seek(0)
                source_handle = spool
            elif source_protocol == "SFTP":
                import paramiko

                host, port, user, password, remote_path = _parse_endpoint(source_location, 22)
                transport = paramiko.Transport((host, port))
                transport.connect(username=user, password=password)
                sftp_client = paramiko.SFTPClient.from_transport(transport)
                cleanup_callbacks.append(sftp_client.close)
                cleanup_callbacks.append(transport.close)
                source_handle = sftp_client.open(remote_path, mode="rb")
            else:
                source_handle = smbclient.open_file(
                    self._smb_unc_path(*source_location.split("|", 2)),
                    mode="rb",
                )

            if destination_protocol == "LOCAL":
                destination_handle = open(destination_location, "wb")
            elif destination_protocol == "FTP":
                from ftplib import FTP as _FTP

                host, port, user, password, remote_path = _parse_endpoint(destination_location, 21)
                ftp_dest = _FTP()
                try:
                    ftp_dest.connect(host, port, timeout=60)
                    ftp_dest.login(user, password)
                    parent_dirs = [d for d in (remote_path.rsplit("/", 1)[0] if "/" in remote_path else "").split("/") if d]
                    current = ""
                    for directory in parent_dirs:
                        current = f"{current}/{directory}"
                        try:
                            ftp_dest.mkd(current)
                        except Exception:  # noqa: BLE001
                            pass

                    stream = _StopAwareReader(source_handle, stop_event)
                    ftp_dest.storbinary(f"STOR {remote_path}", stream, blocksize=4 * 1024 * 1024)
                    try:
                        total_bytes = int(ftp_dest.size(remote_path) or 0)
                    except Exception:  # noqa: BLE001
                        total_bytes = 0
                    if total_bytes <= 0:
                        source_handle.seek(0)
                        while True:
                            chunk = source_handle.read(4 * 1024 * 1024)
                            if not chunk:
                                break
                            total_bytes += len(chunk)
                    return total_bytes
                except Exception as exc:
                    raise RuntimeError(f"FTP-Upload fehlgeschlagen: {exc}") from exc
                finally:
                    try:
                        ftp_dest.quit()
                    except Exception:  # noqa: BLE001
                        pass
            elif destination_protocol == "SFTP":
                import paramiko

                host, port, user, password, remote_path = _parse_endpoint(destination_location, 22)
                transport = paramiko.Transport((host, port))
                transport.connect(username=user, password=password)
                sftp_client = paramiko.SFTPClient.from_transport(transport)
                cleanup_callbacks.append(sftp_client.close)
                cleanup_callbacks.append(transport.close)

                parent_dir = posixpath.dirname(remote_path)
                if parent_dir:
                    parts = [p for p in parent_dir.split("/") if p]
                    current = ""
                    for part in parts:
                        current = f"{current}/{part}"
                        try:
                            sftp_client.mkdir(current)
                        except Exception:  # noqa: BLE001
                            pass

                destination_handle = sftp_client.open(remote_path, mode="wb")
            else:
                destination_handle = smbclient.open_file(
                    self._smb_unc_path(*destination_location.split("|", 2)),
                    mode="wb",
                )

            while True:
                if stop_event.is_set():
                    raise RuntimeError("Lauf wurde abgebrochen.")
                chunk = source_handle.read(4 * 1024 * 1024)
                if not chunk:
                    break
                destination_handle.write(chunk)
                total_bytes += len(chunk)
        finally:
            if source_handle is not None:
                try:
                    source_handle.close()
                except Exception:  # noqa: BLE001
                    pass
            if destination_handle is not None:
                try:
                    destination_handle.close()
                except Exception:  # noqa: BLE001
                    pass
            for cb in reversed(cleanup_callbacks):
                try:
                    cb()
                except Exception:  # noqa: BLE001
                    pass

        return total_bytes

    @staticmethod
    def _compression_extension(compression_method: str) -> str:
        mapping = {
            "zip": ".zip",
            "tar.gz": ".tar.gz",
            "tar.bz2": ".tar.bz2",
            "tar.xz": ".tar.xz",
            "7z": ".7z",
        }
        return mapping.get(compression_method, "")

    @staticmethod
    def _ensure_archive_suffix(filename: str, compression_method: str) -> str:
        ext = FlaskServer._compression_extension(compression_method)
        if not ext:
            return filename
        lower_name = filename.lower()
        if lower_name.endswith(ext):
            return filename
        return f"{filename}{ext}"

    def _build_archive_file(
        self,
        job: BackupExecutionJob,
        source_files: list[tuple[str, str]],
        source_protocol: str,
        stop_event: threading.Event,
    ) -> tuple[Path, str, int]:
        method = job.compression_method
        if method not in {"zip", "tar.gz", "tar.bz2", "tar.xz", "7z"}:
            raise RuntimeError(f"Kompressionsmethode '{method}' wird nicht unterstützt.")

        if method == "7z" and py7zr is None:
            raise RuntimeError(
                "7z-Unterstützung ist nicht verfügbar. Bitte py7zr installieren und App neu starten."
            )

        target_base = self._replace_target_tokens(job.target_pattern).strip()
        if not target_base:
            target_base = f"backup_{datetime.now().strftime('%Y-%m-%d_%H-%M-%S')}"
        archive_name = self._ensure_archive_suffix(target_base, method)

        work_dir = Path(tempfile.mkdtemp(prefix="backitup-"))
        staging_dir = work_dir / "staging"
        staging_dir.mkdir(parents=True, exist_ok=True)

        total_count = len(source_files)
        for index, (relative_path, source_path) in enumerate(source_files, start=1):
            if stop_event.is_set():
                raise RuntimeError("Lauf wurde abgebrochen.")

            local_target = staging_dir / relative_path
            local_target.parent.mkdir(parents=True, exist_ok=True)

            source_spec = self._build_source_spec(job, source_path, source_protocol)
            self._copy_file_stream(
                source_protocol=source_protocol,
                source_location=source_spec,
                destination_protocol="LOCAL",
                destination_location=str(local_target),
                stop_event=stop_event,
            )

            progress = 52 + int((index / max(1, total_count)) * 18)
            self._set_run_state(
                job.backup_id,
                is_running=True,
                progress_percent=min(progress, 70),
                progress_text="Sammle Dateien...",
                status_message=f"Datei {index}/{total_count} für Archiv vorbereitet.",
            )

        archive_path = work_dir / archive_name

        self._set_run_state(
            job.backup_id,
            is_running=True,
            progress_percent=74,
            progress_text="Komprimiere...",
            status_message=f"Erzeuge {method}-Archiv...",
        )

        if method == "zip":
            with zipfile.ZipFile(archive_path, mode="w", compression=zipfile.ZIP_DEFLATED) as zf:
                for file_path in staging_dir.rglob("*"):
                    if file_path.is_file():
                        arcname = file_path.relative_to(staging_dir).as_posix()
                        zf.write(file_path, arcname=arcname)
        elif method in {"tar.gz", "tar.bz2", "tar.xz"}:
            mode_map = {
                "tar.gz": "w:gz",
                "tar.bz2": "w:bz2",
                "tar.xz": "w:xz",
            }
            with tarfile.open(archive_path, mode=mode_map[method]) as tf:
                for file_path in staging_dir.rglob("*"):
                    if file_path.is_file():
                        arcname = file_path.relative_to(staging_dir).as_posix()
                        tf.add(file_path, arcname=arcname)
        else:
            assert py7zr is not None
            with py7zr.SevenZipFile(archive_path, mode="w") as sz:
                for file_path in staging_dir.rglob("*"):
                    if file_path.is_file():
                        arcname = file_path.relative_to(staging_dir).as_posix()
                        sz.write(file_path, arcname=arcname)

        archive_bytes = archive_path.stat().st_size
        return archive_path, archive_name, archive_bytes

    def _list_destination_top_entries(self, job: BackupExecutionJob) -> list[tuple[str, float]]:
        """Returns [(name, mtime)] for direct children of destination_subpath."""
        protocol = job.destination_protocol.upper()
        subpath = normalize_subpath(job.destination_subpath)

        if protocol == "LOCAL":
            result: list[tuple[str, float]] = []
            root = Path(job.destination_subpath).expanduser()
            if not root.exists():
                return result
            for entry in root.iterdir():
                try:
                    result.append((entry.name, entry.stat().st_mtime))
                except Exception:
                    pass
            return result

        if protocol == "SMB":
            result = []
            unc = self._smb_unc_path(job.destination_host, job.destination_share, subpath)
            try:
                for item in smbclient.scandir(unc):
                    if item.name in {".", ".."}:
                        continue
                    try:
                        result.append((item.name, float(item.stat().st_mtime or 0)))
                    except Exception:
                        result.append((item.name, 0.0))
            except Exception:
                pass
            return result

        if protocol == "FTP":
            from ftplib import FTP as _FTP
            from datetime import datetime as _dt
            result = []
            ftp = _FTP()
            try:
                ftp.connect(job.destination_host, job.destination_port or 21, timeout=30)
                ftp.login(job.destination_username, job.destination_password)
                try:
                    for name, facts in ftp.mlsd(subpath):
                        if name in (".", ".."):
                            continue
                        mtime = 0.0
                        mts = facts.get("modify", "")
                        if mts:
                            try:
                                mtime = _dt.strptime(mts[:14], "%Y%m%d%H%M%S").timestamp()
                            except Exception:
                                pass
                        result.append((name, mtime))
                except Exception:
                    raw: list[str] = []
                    ftp.retrlines(f"LIST {subpath}", raw.append)
                    for line in raw:
                        parts = line.split(None, 8)
                        if len(parts) >= 9 and parts[8].strip() not in (".", ".."):
                            result.append((parts[8].strip(), 0.0))
                ftp.quit()
            except Exception:
                pass
            return result

        if protocol == "SFTP":
            import paramiko
            result = []
            client = paramiko.SSHClient()
            client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
            try:
                client.connect(
                    job.destination_host, port=job.destination_port or 22,
                    username=job.destination_username, password=job.destination_password,
                    timeout=30,
                )
                sftp = client.open_sftp()
                for attr in sftp.listdir_attr(subpath):
                    if attr.filename not in (".", ".."):
                        result.append((attr.filename, float(attr.st_mtime or 0)))
                sftp.close()
            except Exception:
                pass
            finally:
                client.close()
            return result

        return []

    def _smb_rmdir_recursive(self, host: str, share: str, subpath: str) -> None:
        unc = self._smb_unc_path(host, share, subpath)
        try:
            for item in smbclient.scandir(unc):
                if item.name in {".", ".."}:
                    continue
                child = self._join_subpath(subpath, item.name)
                if item.is_dir():
                    self._smb_rmdir_recursive(host, share, child)
                else:
                    try:
                        smbclient.remove(self._smb_unc_path(host, share, child))
                    except Exception:
                        pass
            smbclient.rmdir(unc)
        except Exception:
            pass

    @staticmethod
    def _ftp_delete_recursive(ftp, path: str) -> None:
        try:
            ftp.delete(path)
            return
        except Exception:
            pass
        raw: list[str] = []
        try:
            ftp.retrlines(f"LIST {path}", raw.append)
        except Exception:
            return
        for line in raw:
            parts = line.split(None, 8)
            if len(parts) < 9:
                continue
            name = parts[8].strip()
            if name in (".", ".."):
                continue
            child = f"{path.rstrip('/')}/{name}"
            if parts[0].startswith("d"):
                FlaskServer._ftp_delete_recursive(ftp, child)
            else:
                try:
                    ftp.delete(child)
                except Exception:
                    pass
        try:
            ftp.rmd(path)
        except Exception:
            pass

    @staticmethod
    def _sftp_delete_recursive(sftp, path: str) -> None:
        import stat as _stat
        try:
            attrs = sftp.listdir_attr(path)
        except Exception:
            try:
                sftp.remove(path)
            except Exception:
                pass
            return
        for attr in attrs:
            child = f"{path.rstrip('/')}/{attr.filename}"
            if _stat.S_ISDIR(attr.st_mode or 0):
                FlaskServer._sftp_delete_recursive(sftp, child)
            else:
                try:
                    sftp.remove(child)
                except Exception:
                    pass
        try:
            sftp.rmdir(path)
        except Exception:
            pass

    def _delete_destination_entry(self, job: BackupExecutionJob, entry_name: str) -> None:
        protocol = job.destination_protocol.upper()
        child_subpath = normalize_subpath(self._join_subpath(job.destination_subpath, entry_name))
        try:
            if protocol == "LOCAL":
                target = Path(job.destination_subpath).expanduser() / entry_name
                if target.is_dir():
                    shutil.rmtree(target, ignore_errors=True)
                else:
                    target.unlink(missing_ok=True)
            elif protocol == "SMB":
                unc = self._smb_unc_path(job.destination_host, job.destination_share, child_subpath)
                try:
                    smbclient.remove(unc)
                except Exception:
                    self._smb_rmdir_recursive(job.destination_host, job.destination_share, child_subpath)
            elif protocol == "FTP":
                from ftplib import FTP as _FTP
                ftp = _FTP()
                try:
                    ftp.connect(job.destination_host, job.destination_port or 21, timeout=30)
                    ftp.login(job.destination_username, job.destination_password)
                    self._ftp_delete_recursive(ftp, child_subpath)
                    ftp.quit()
                except Exception:
                    pass
            elif protocol == "SFTP":
                import paramiko
                client = paramiko.SSHClient()
                client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
                try:
                    client.connect(
                        job.destination_host, port=job.destination_port or 22,
                        username=job.destination_username, password=job.destination_password,
                        timeout=30,
                    )
                    sftp = client.open_sftp()
                    self._sftp_delete_recursive(sftp, child_subpath)
                    sftp.close()
                except Exception:
                    pass
                finally:
                    client.close()
        except Exception:
            pass

    def _apply_rotation(self, job: BackupExecutionJob) -> None:
        """Delete oldest destination entries if count exceeds rotation_keep."""
        if job.rotation_keep <= 0 or job.backup_mode in {"sync", "clone"}:
            return
        entries = self._list_destination_top_entries(job)
        if len(entries) <= job.rotation_keep:
            return
        entries.sort(key=lambda x: x[1])  # oldest first
        for name, _ in entries[:len(entries) - job.rotation_keep]:
            self._delete_destination_entry(job, name)

    # ------------------------------------------------------------------ #
    # Sync / Clone helpers                                                 #
    # ------------------------------------------------------------------ #

    def _build_file_tree_local(self, subpath: str) -> dict[str, tuple[int, float]]:
        result: dict[str, tuple[int, float]] = {}
        root = Path(subpath).expanduser()
        if not root.is_dir():
            return result
        for entry in root.rglob("*"):
            if entry.is_file():
                st = entry.stat()
                result[entry.relative_to(root).as_posix()] = (st.st_size, st.st_mtime)
        return result

    def _build_file_tree_smb(self, host: str, share: str, subpath: str) -> dict[str, tuple[int, float]]:
        result: dict[str, tuple[int, float]] = {}

        def walk(current: str, prefix: str) -> None:
            unc = self._smb_unc_path(host, share, current)
            try:
                entries = list(smbclient.scandir(unc))
            except Exception:
                return
            for item in entries:
                if item.name in {".", ".."}:
                    continue
                child = self._join_subpath(current, item.name)
                rel = f"{prefix}/{item.name}" if prefix else item.name
                if item.is_dir():
                    walk(child, rel)
                else:
                    try:
                        st = item.stat()
                        result[rel] = (st.st_size, float(st.st_mtime or 0))
                    except Exception:
                        result[rel] = (0, 0.0)

        walk(normalize_subpath(subpath), "")
        return result

    def _build_file_tree_ftp(
        self, host: str, port: int | None, username: str, password: str, subpath: str
    ) -> dict[str, tuple[int, float]]:
        from ftplib import FTP as _FTP
        from datetime import datetime as _dt
        result: dict[str, tuple[int, float]] = {}
        ftp = _FTP()
        try:
            ftp.connect(host, port or 21, timeout=30)
            ftp.login(username, password)

            def walk(path: str, prefix: str) -> None:
                # Prefer MLSD (reliable size + mtime) over LIST
                try:
                    entries = list(ftp.mlsd(path))
                    for name, facts in entries:
                        if name in (".", ".."):
                            continue
                        child = f"{path.rstrip('/')}/{name}"
                        rel = f"{prefix}/{name}" if prefix else name
                        if facts.get("type") == "dir":
                            walk(child, rel)
                        else:
                            size = int(facts.get("size", 0))
                            mtime = 0.0
                            mts = facts.get("modify", "")
                            if mts:
                                try:
                                    mtime = _dt.strptime(mts[:14], "%Y%m%d%H%M%S").timestamp()
                                except Exception:
                                    pass
                            result[rel] = (size, mtime)
                    return
                except Exception:
                    pass
                # Fallback: LIST
                raw: list[str] = []
                try:
                    ftp.retrlines(f"LIST {path}", raw.append)
                except Exception:
                    return
                for line in raw:
                    parts = line.split(None, 8)
                    if len(parts) < 9:
                        continue
                    name = parts[8].strip()
                    if name in (".", ".."):
                        continue
                    is_dir = parts[0].startswith("d")
                    child = f"{path.rstrip('/')}/{name}"
                    rel = f"{prefix}/{name}" if prefix else name
                    if is_dir:
                        walk(child, rel)
                    else:
                        size = int(parts[4]) if parts[4].isdigit() else 0
                        result[rel] = (size, 0.0)

            walk(normalize_subpath(subpath), "")
        finally:
            try:
                ftp.quit()
            except Exception:
                pass
        return result

    def _build_file_tree_sftp(
        self, host: str, port: int | None, username: str, password: str, subpath: str
    ) -> dict[str, tuple[int, float]]:
        import stat as _stat
        import paramiko
        result: dict[str, tuple[int, float]] = {}
        client = paramiko.SSHClient()
        client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        try:
            client.connect(host, port=port or 22, username=username, password=password, timeout=30)
            sftp = client.open_sftp()

            def walk(path: str, prefix: str) -> None:
                try:
                    attrs = sftp.listdir_attr(path)
                except Exception:
                    return
                for attr in attrs:
                    if attr.filename in (".", ".."):
                        continue
                    child = f"{path.rstrip('/')}/{attr.filename}"
                    rel = f"{prefix}/{attr.filename}" if prefix else attr.filename
                    if _stat.S_ISDIR(attr.st_mode or 0):
                        walk(child, rel)
                    else:
                        result[rel] = (attr.st_size or 0, float(attr.st_mtime or 0))

            walk(normalize_subpath(subpath), "")
            sftp.close()
        finally:
            client.close()
        return result

    def _build_file_tree(self, job: BackupExecutionJob, side: str) -> dict[str, tuple[int, float]]:
        if side == "source":
            protocol = job.source_protocol.upper()
            host, port, share = job.source_host, job.source_port, job.source_share
            subpath, username, password = job.source_subpath, job.source_username, job.source_password
        else:
            protocol = job.destination_protocol.upper()
            host, port, share = job.destination_host, job.destination_port, job.destination_share
            subpath, username, password = job.destination_subpath, job.destination_username, job.destination_password

        if protocol == "LOCAL":
            return self._build_file_tree_local(subpath)
        if protocol == "SMB":
            return self._build_file_tree_smb(host, share, subpath)
        if protocol == "FTP":
            return self._build_file_tree_ftp(host, port, username, password, subpath)
        if protocol == "SFTP":
            return self._build_file_tree_sftp(host, port, username, password, subpath)
        return {}

    def _delete_destination_file(
        self, protocol: str, job: BackupExecutionJob, rel_path: str
    ) -> None:
        subpath = self._join_subpath(job.destination_subpath, rel_path)
        try:
            if protocol == "LOCAL":
                Path(job.destination_subpath).expanduser().joinpath(rel_path).unlink(missing_ok=True)
            elif protocol == "SMB":
                unc = self._smb_unc_path(job.destination_host, job.destination_share, subpath)
                smbclient.remove(unc)
            elif protocol == "FTP":
                from ftplib import FTP as _FTP
                ftp = _FTP()
                ftp.connect(job.destination_host, job.destination_port or 21, timeout=30)
                ftp.login(job.destination_username, job.destination_password)
                ftp.delete(subpath)
                ftp.quit()
            elif protocol == "SFTP":
                import paramiko
                client = paramiko.SSHClient()
                client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
                client.connect(
                    job.destination_host, port=job.destination_port or 22,
                    username=job.destination_username, password=job.destination_password,
                    timeout=30,
                )
                client.open_sftp().remove(subpath)
                client.close()
        except Exception:
            pass

    def _sync_backup_payload(self, job: BackupExecutionJob, stop_event: threading.Event) -> tuple[int, int]:
        src_proto = job.source_protocol.upper()
        dst_proto = job.destination_protocol.upper()

        if src_proto == "SMB":
            smbclient.register_session(
                server=job.source_host, username=job.source_username,
                password=job.source_password, port=job.source_port or 445,
            )
        if dst_proto == "SMB":
            smbclient.register_session(
                server=job.destination_host, username=job.destination_username,
                password=job.destination_password, port=job.destination_port or 445,
            )

        self._set_run_state(
            job.backup_id, is_running=True, progress_percent=10,
            progress_text="Scanne Quelle...", status_message="Dateibaum der Quelle wird gelesen...",
        )
        source_tree = self._build_file_tree(job, "source")

        self._set_run_state(
            job.backup_id, is_running=True, progress_percent=25,
            progress_text="Scanne Ziel...", status_message="Dateibaum des Ziels wird gelesen...",
        )
        dest_tree = self._build_file_tree(job, "destination")

        # Determine changed/new files
        to_transfer = [
            rel for rel, (src_sz, src_mt) in source_tree.items()
            if rel not in dest_tree
            or dest_tree[rel][0] != src_sz
            or abs(dest_tree[rel][1] - src_mt) > 2
        ]

        # Clone only: files on destination that no longer exist on source
        to_delete = (
            [rel for rel in dest_tree if rel not in source_tree]
            if job.backup_mode == "clone" else []
        )

        total_ops = len(to_transfer) + len(to_delete)
        if total_ops == 0:
            return 0, 0

        copied_files = 0
        total_bytes = 0

        for index, rel_path in enumerate(to_transfer, start=1):
            if stop_event.is_set():
                raise RuntimeError("Lauf wurde abgebrochen.")

            src_subpath = self._join_subpath(job.source_subpath, rel_path)
            dst_subpath = self._join_subpath(job.destination_subpath, rel_path)

            if dst_proto == "LOCAL":
                dst_abs = Path(job.destination_subpath).expanduser() / rel_path
                dst_abs.parent.mkdir(parents=True, exist_ok=True)
                dest_spec = str(dst_abs)
            elif dst_proto == "SMB":
                dst_parent = normalize_subpath(posixpath.dirname(dst_subpath))
                self._ensure_smb_dir(job.destination_host, job.destination_share, dst_parent)
                dest_spec = self._build_destination_spec(job, dst_subpath, dst_proto)
            else:
                dest_spec = self._build_destination_spec(job, dst_subpath, dst_proto)

            src_spec = self._build_source_spec(job, src_subpath, src_proto)

            total_bytes += self._copy_file_stream(
                source_protocol=src_proto,
                source_location=src_spec,
                destination_protocol=dst_proto,
                destination_location=dest_spec,
                stop_event=stop_event,
            )
            copied_files += 1

            progress = 30 + int((index / max(1, total_ops)) * 60)
            self._set_run_state(
                job.backup_id, is_running=True,
                progress_percent=min(progress, 90),
                progress_text="Synchronisiere...",
                status_message=f"{index}/{len(to_transfer)} Dateien übertragen.",
            )

        for rel_path in to_delete:
            if stop_event.is_set():
                raise RuntimeError("Lauf wurde abgebrochen.")
            self._delete_destination_file(dst_proto, job, rel_path)

        return copied_files, total_bytes

    def _transfer_backup_payload(self, job: BackupExecutionJob, stop_event: threading.Event) -> tuple[int, int]:
        source_protocol = job.source_protocol.upper()
        destination_protocol = job.destination_protocol.upper()
        if source_protocol not in {"LOCAL", "SMB", "FTP", "SFTP"}:
            raise RuntimeError(f"Source-Protokoll '{source_protocol}' ist nicht unterstützt.")
        if destination_protocol not in {"LOCAL", "SMB", "FTP", "SFTP"}:
            raise RuntimeError(f"Destination-Protokoll '{destination_protocol}' ist nicht unterstützt.")

        if job.backup_mode in {"sync", "clone"}:
            return self._sync_backup_payload(job, stop_event)

        if destination_protocol == "SMB":
            smbclient.register_session(
                server=job.destination_host,
                username=job.destination_username,
                password=job.destination_password,
                port=job.destination_port or 445,
            )

        source_files = self._collect_source_files(job)
        if not source_files:
            raise RuntimeError("Keine Dateien in der Quelle gefunden.")

        if job.compression_method != "none":
            archive_path, archive_name, archive_bytes = self._build_archive_file(
                job=job,
                source_files=source_files,
                source_protocol=source_protocol,
                stop_event=stop_event,
            )

            destination_base = normalize_subpath(job.destination_subpath)
            # archive_name already encodes the target_pattern with resolved tokens + extension
            archive_rel = archive_name

            try:
                if destination_protocol == "LOCAL":
                    destination_abs = (Path(job.destination_subpath).expanduser() / archive_rel).resolve()
                    destination_abs.parent.mkdir(parents=True, exist_ok=True)
                    destination_spec = str(destination_abs)
                elif destination_protocol in {"FTP", "SFTP"}:
                    destination_subpath = self._join_subpath(destination_base, archive_rel)
                    destination_spec = self._build_destination_spec(job, destination_subpath, destination_protocol)
                else:
                    destination_subpath = self._join_subpath(destination_base, archive_rel)
                    destination_parent = normalize_subpath(posixpath.dirname(destination_subpath))
                    self._ensure_smb_dir(job.destination_host, job.destination_share, destination_parent)
                    destination_spec = "|".join([job.destination_host, job.destination_share, destination_subpath])

                self._set_run_state(
                    job.backup_id,
                    is_running=True,
                    progress_percent=90,
                    progress_text="Übertrage Archiv...",
                    status_message=f"Schreibe Archiv {archive_name} ins Ziel...",
                )

                transferred = self._copy_file_stream(
                    source_protocol="LOCAL",
                    source_location=str(archive_path),
                    destination_protocol=destination_protocol,
                    destination_location=destination_spec,
                    stop_event=stop_event,
                )
                return 1, max(transferred, archive_bytes)
            finally:
                shutil.rmtree(archive_path.parent, ignore_errors=True)

        target_pattern = self._replace_target_tokens(job.target_pattern)
        destination_base = normalize_subpath(job.destination_subpath)

        if job.target_kind == "file" and len(source_files) != 1:
            raise RuntimeError("Target ist Datei, aber die Quelle enthält mehrere Dateien.")

        copied_files = 0
        total_bytes = 0
        total_count = len(source_files)

        for index, (relative_path, source_path) in enumerate(source_files, start=1):
            if stop_event.is_set():
                raise RuntimeError("Lauf wurde abgebrochen.")

            if job.target_kind == "file":
                destination_rel = target_pattern
            else:
                destination_rel = f"{target_pattern}/{relative_path}" if target_pattern else relative_path

            if destination_protocol == "LOCAL":
                destination_abs = (Path(job.destination_subpath).expanduser() / destination_rel).resolve()
                destination_abs.parent.mkdir(parents=True, exist_ok=True)
                destination_spec = str(destination_abs)
            elif destination_protocol in {"FTP", "SFTP"}:
                destination_subpath = self._join_subpath(destination_base, destination_rel)
                destination_spec = self._build_destination_spec(job, destination_subpath, destination_protocol)
            else:
                destination_subpath = self._join_subpath(destination_base, destination_rel)
                destination_parent = normalize_subpath(posixpath.dirname(destination_subpath))
                self._ensure_smb_dir(job.destination_host, job.destination_share, destination_parent)
                destination_spec = "|".join([job.destination_host, job.destination_share, destination_subpath])

            source_spec = self._build_source_spec(job, source_path, source_protocol)

            total_bytes += self._copy_file_stream(
                source_protocol=source_protocol,
                source_location=source_spec,
                destination_protocol=destination_protocol,
                destination_location=destination_spec,
                stop_event=stop_event,
            )
            copied_files += 1

            progress = 50 + int((index / max(1, total_count)) * 45)
            self._set_run_state(
                job.backup_id,
                is_running=True,
                progress_percent=min(progress, 95),
                progress_text="Übertrage Daten...",
                status_message=f"Datei {index}/{total_count} wurde übertragen.",
            )

        return copied_files, total_bytes

    def _run_backup_job(self, job: BackupExecutionJob, stop_event: threading.Event) -> None:
        backup_id = job.backup_id
        try:
            self._set_run_state(
                backup_id,
                is_running=True,
                progress_percent=8,
                progress_text="Initialisiere Lauf...",
                status_message="Initialisiere Lauf...",
            )

            source = TargetConnection(
                protocol=job.source_protocol,
                host=job.source_host,
                port=job.source_port,
                share=job.source_share,
                subpath=job.source_subpath,
                username=job.source_username,
                password=job.source_password,
            )
            self._set_run_state(
                backup_id,
                is_running=True,
                progress_percent=22,
                progress_text="Prüfe Quelle...",
                status_message="Prüfe Quelle...",
            )
            ok, msg = test_connection(source)
            if not ok:
                self._log(
                    level="ERROR",
                    category="backup",
                    event="source_check_failed",
                    backup_id=backup_id,
                    message=f"Quelle nicht erreichbar: {msg}",
                )
                self._set_run_state(
                    backup_id,
                    is_running=False,
                    progress_percent=0,
                    progress_text="Fehler",
                    status_message=f"Quelle nicht erreichbar: {msg}",
                )
                return

            destination = TargetConnection(
                protocol=job.destination_protocol,
                host=job.destination_host,
                port=job.destination_port,
                share=job.destination_share,
                subpath=job.destination_subpath,
                username=job.destination_username,
                password=job.destination_password,
            )
            self._set_run_state(
                backup_id,
                is_running=True,
                progress_percent=45,
                progress_text="Prüfe Ziel...",
                status_message="Prüfe Ziel...",
            )
            ok, msg = test_connection(destination)
            if not ok:
                self._log(
                    level="ERROR",
                    category="backup",
                    event="destination_check_failed",
                    backup_id=backup_id,
                    message=f"Ziel nicht erreichbar: {msg}",
                )
                self._set_run_state(
                    backup_id,
                    is_running=False,
                    progress_percent=0,
                    progress_text="Fehler",
                    status_message=f"Ziel nicht erreichbar: {msg}",
                )
                return

            self._set_run_state(
                backup_id,
                is_running=True,
                progress_percent=50,
                progress_text="Übertrage Daten...",
                status_message="Datenübertragung läuft...",
            )

            copied_files, copied_bytes = self._transfer_backup_payload(job, stop_event)

            if stop_event.is_set():
                self._log(
                    level="INFO",
                    category="backup",
                    event="run_stopped",
                    backup_id=backup_id,
                    message="Backup-Lauf wurde manuell gestoppt.",
                )
                self._set_run_state(
                    backup_id,
                    is_running=False,
                    progress_percent=0,
                    progress_text="Gestoppt",
                    status_message="Lauf wurde manuell gestoppt.",
                )
                return

            self.store.mark_backup_run(backup_id, copied_bytes)
            self._apply_rotation(job)
            self._log(
                level="INFO",
                category="backup",
                event="run_finished",
                backup_id=backup_id,
                message=(
                    f"Backup erfolgreich abgeschlossen: {copied_files} Dateien, {copied_bytes} Bytes."
                ),
                details={"copied_files": copied_files, "copied_bytes": copied_bytes},
            )
            self._set_run_state(
                backup_id,
                is_running=False,
                progress_percent=100,
                progress_text="Fertig",
                status_message=(
                    f"Backup erfolgreich abgeschlossen: {copied_files} Dateien, "
                    f"{copied_bytes} Bytes übertragen."
                ),
            )
        except Exception as exc:  # noqa: BLE001
            self._set_run_state(
                backup_id,
                is_running=False,
                progress_percent=0,
                progress_text="Fehler",
                status_message=f"Lauf fehlgeschlagen: {exc}",
            )
            self._log(
                level="ERROR",
                category="backup",
                event="run_failed",
                backup_id=backup_id,
                message=f"Lauf fehlgeschlagen: {exc}",
                details={"traceback": traceback.format_exc()},
            )

    @staticmethod
    def _parse_port(value: str) -> int | None:
        try:
            port = int(value)
        except ValueError:
            return None
        if 1 <= port <= 65535:
            return port
        return None

    @staticmethod
    def _parse_optional_port(value: str) -> int | None:
        raw = value.strip()
        if not raw:
            return None
        return FlaskServer._parse_port(raw)

    @staticmethod
    def _split_host_and_port(host_input: str) -> tuple[str, int | None, str | None]:
        raw = host_input.strip()
        if not raw:
            return "", None, "Host/IP darf nicht leer sein."

        # IPv6 in Klammern: [fe80::1]:445
        if raw.startswith("["):
            end = raw.find("]")
            if end == -1:
                return "", None, "IPv6-Host muss in [ ] geklammert sein."
            host = raw[1:end].strip()
            rest = raw[end + 1 :].strip()
            if not rest:
                return host, None, None
            if not rest.startswith(":"):
                return "", None, "Nach IPv6-Host ist nur optional :Port erlaubt."
            port = FlaskServer._parse_port(rest[1:])
            if port is None:
                return "", None, "Port muss zwischen 1 und 65535 liegen."
            return host, port, None

        # IPv4/FQDN optional mit :port
        if raw.count(":") == 1:
            host_part, port_part = raw.rsplit(":", 1)
            host_part = host_part.strip()
            port_part = port_part.strip()
            if port_part:
                port = FlaskServer._parse_port(port_part)
                if port is None:
                    return "", None, "Port muss zwischen 1 und 65535 liegen."
                return host_part, port, None

        return raw, None, None

    @staticmethod
    def _target_from_payload(payload: dict, prefix: str) -> tuple[TargetConnection | None, str | None]:
        protocol = payload.get(f"{prefix}_protocol", "").strip().upper()
        host_input = payload.get(f"{prefix}_host", "").strip()
        host, parsed_port, host_error = FlaskServer._split_host_and_port(host_input)
        share = payload.get(f"{prefix}_share", "").strip()
        raw_subpath = payload.get(f"{prefix}_subpath", "")
        subpath = normalize_subpath(raw_subpath)
        username = payload.get(f"{prefix}_username", "").strip()
        password = payload.get(f"{prefix}_password", "")

        if protocol not in TARGET_PROTOCOLS:
            return None, "Bitte ein gueltiges Protokoll auswaehlen."
        if protocol != "LOCAL" and host_error:
            return None, host_error

        if protocol == "LOCAL":
            if not raw_subpath.strip():
                return None, "Fuer LOCAL muss ein gueltiger lokaler Pfad angegeben werden."
            return (
                TargetConnection(
                    protocol=protocol,
                    host="local",
                    port=None,
                    share="",
                    subpath=subpath,
                    username="",
                    password="",
                ),
                None,
            )

        if protocol == "SMB":
            if not all([host, share, username, password]):
                return None, "SMB benoetigt Host, Share, Benutzer und Passwort."
            return (
                TargetConnection(
                    protocol=protocol,
                    host=host,
                    port=parsed_port,
                    share=share,
                    subpath=subpath,
                    username=username,
                    password=password,
                ),
                None,
            )

        if protocol in {"FTP", "SFTP"}:
            if not all([host, username, password]):
                return None, f"{protocol} benoetigt Host, Benutzer und Passwort."
            return (
                TargetConnection(
                    protocol=protocol,
                    host=host,
                    port=parsed_port,
                    share=share,
                    subpath=subpath,
                    username=username,
                    password=password,
                ),
                None,
            )

        return None, "Unbekanntes Protokoll."

    def create_app(self) -> Flask:
        app = Flask(__name__, template_folder="templates")
        app.secret_key = os.getenv("APP_SECRET_KEY", secrets.token_hex(32))
        app.config.update(
            SESSION_COOKIE_HTTPONLY=True,
            SESSION_COOKIE_SAMESITE="Lax",
        )

        @app.before_request
        def _capture_request_start() -> None:
            g._request_started_at = datetime.now()

        @app.after_request
        def _log_problematic_requests(response):
            status = int(response.status_code)
            if status >= 400:
                elapsed_ms = None
                started = getattr(g, "_request_started_at", None)
                if isinstance(started, datetime):
                    elapsed_ms = int((datetime.now() - started).total_seconds() * 1000)
                self._log(
                    level="WARNING" if status < 500 else "ERROR",
                    category="http",
                    event="request_completed",
                    message=f"HTTP {status} für {request.method} {request.path}",
                    details={"elapsed_ms": elapsed_ms},
                    status_code=status,
                )
            return response

        def _handle_exception(sender, exception, **extra):
            self._log(
                level="ERROR",
                category="http",
                event="unhandled_exception",
                message=f"Unhandled Exception: {exception}",
                details={"traceback": traceback.format_exc()},
                status_code=500,
            )

        got_request_exception.connect(_handle_exception, app)

        @app.template_filter("fmt_bytes")
        def fmt_bytes(value):
            if value is None:
                return "Noch kein Lauf"
            try:
                size = float(value)
            except (TypeError, ValueError):
                return "Unbekannt"

            units = ["B", "KB", "MB", "GB", "TB"]
            unit_idx = 0
            while size >= 1024 and unit_idx < len(units) - 1:
                size /= 1024
                unit_idx += 1
            return f"{size:.2f} {units[unit_idx]}"

        @app.template_filter("fmt_dt")
        def fmt_dt(value):
            if not value:
                return "Noch kein Lauf"
            return str(value)

        def parse_schedule_fields(form_data):
            schedule_cron = form_data.get("schedule_cron", "").strip()
            return {"schedule_mode": "custom", "schedule_cron": schedule_cron}, None

        def login_required(view_func):
            @wraps(view_func)
            def wrapped(*args, **kwargs):
                if session.get("is_authenticated") is not True:
                    return redirect(url_for("login"))
                return view_func(*args, **kwargs)

            return wrapped

        def admin_required(view_func):
            @wraps(view_func)
            def wrapped(*args, **kwargs):
                if session.get("is_admin") is not True:
                    return redirect(url_for("dashboard"))
                return view_func(*args, **kwargs)

            return wrapped

        @app.get("/")
        def index():
            if session.get("is_authenticated") is True:
                return redirect(url_for("dashboard"))
            return redirect(url_for("login"))

        @app.route("/login", methods=["GET", "POST"])
        def login():
            error_message = ""
            if request.method == "POST":
                username = request.form.get("username", "")
                password = request.form.get("password", "")

                user = self.store.get_user(username)
                if user and verify_password(password, user.password_hash):
                    session["is_authenticated"] = True
                    session["is_admin"] = user.is_admin
                    session["adminuser"] = user.username
                    self._log(
                        level="INFO",
                        category="auth",
                        event="login_success",
                        message="Benutzer hat sich erfolgreich angemeldet.",
                        username=user.username,
                    )
                    return redirect(url_for("dashboard"))
                self._log(
                    level="WARNING",
                    category="auth",
                    event="login_failed",
                    message="Anmeldung fehlgeschlagen.",
                    username=username.strip() or None,
                )
                error_message = "Anmeldung fehlgeschlagen."

            return render_template("login.html", error_message=error_message)

        @app.get("/dashboard")
        @login_required
        def dashboard():
            return render_template(
                "dashboard.html",
                adminuser=session.get("adminuser", "admin"),
                backups=self.store.list_backups(),
                active_menu="dashboard",
            )

        @app.get("/logs")
        @login_required
        @admin_required
        def logs_view():
            level = request.args.get("level", "").strip().upper()
            category = request.args.get("category", "").strip()
            search = request.args.get("q", "").strip()
            try:
                limit = int(request.args.get("limit", "200") or "200")
            except ValueError:
                limit = 200

            entries = self.log_store.query_logs(
                level=level or None,
                category=category or None,
                search=search or None,
                limit=limit,
            )
            level_stats = self.log_store.count_by_level_last_hours(24)
            categories = self.log_store.list_categories()
            return render_template(
                "logs.html",
                adminuser=session.get("adminuser", "admin"),
                logs=entries,
                level_stats=level_stats,
                categories=categories,
                filters={
                    "level": level,
                    "category": category,
                    "q": search,
                    "limit": str(limit),
                },
                active_menu="logs",
                detail_compactor=self.log_store.compact_details,
            )

        @app.get("/api/logs")
        @login_required
        @admin_required
        def logs_api():
            level = request.args.get("level", "").strip().upper()
            category = request.args.get("category", "").strip()
            search = request.args.get("q", "").strip()
            try:
                limit = int(request.args.get("limit", "200") or "200")
            except ValueError:
                limit = 200
            entries = self.log_store.query_logs(
                level=level or None,
                category=category or None,
                search=search or None,
                limit=limit,
            )
            return jsonify({"ok": True, "entries": entries, "count": len(entries)})

        @app.post("/logs/clear")
        @login_required
        @admin_required
        def logs_clear():
            removed = self.log_store.clear()
            self._log(
                level="WARNING",
                category="audit",
                event="logs_cleared",
                message=f"Logdaten wurden bereinigt. Geloeschte Eintraege: {removed}",
            )
            flash(f"Logdaten wurden bereinigt ({removed} Einträge).", "success")
            return redirect(url_for("logs_view"))

        @app.post("/backups/<int:backup_id>/run")
        @login_required
        @admin_required
        def backup_run(backup_id: int):
            ok, message = self._start_backup_run(backup_id)
            flash(message, "success" if ok else "error")
            return redirect(url_for("dashboard"))

        @app.post("/api/backups/<int:backup_id>/run")
        @login_required
        @admin_required
        def backup_run_api(backup_id: int):
            ok, message = self._start_backup_run(backup_id)
            status_code = 200
            if not ok:
                status_code = 404 if "nicht gefunden" in message.lower() else 409
            return jsonify(
                {
                    "ok": ok,
                    "message": message,
                    "status": self._get_run_status(backup_id),
                    "runtime": self._build_runtime_meta(backup_id),
                }
            ), status_code

        @app.post("/api/backups/<int:backup_id>/stop")
        @login_required
        @admin_required
        def backup_stop_api(backup_id: int):
            ok, message = self._stop_backup_run(backup_id)
            status_code = 200 if ok else 409
            return jsonify(
                {
                    "ok": ok,
                    "message": message,
                    "status": self._get_run_status(backup_id),
                    "runtime": self._build_runtime_meta(backup_id),
                }
            ), status_code

        @app.get("/api/backups/<int:backup_id>/status")
        @login_required
        @admin_required
        def backup_status_api(backup_id: int):
            return jsonify(
                {
                    "ok": True,
                    "status": self._get_run_status(backup_id),
                    "runtime": self._build_runtime_meta(backup_id),
                }
            )

        @app.route("/backups/<int:backup_id>/edit", methods=["GET", "POST"])
        @login_required
        @admin_required
        def backup_edit(backup_id: int):
            backup = self.store.get_full_backup_for_edit(backup_id)
            if backup is None:
                self._log(
                    level="WARNING",
                    category="backup",
                    event="edit_not_found",
                    backup_id=backup_id,
                    message="Backup konnte nicht bearbeitet werden, da es nicht gefunden wurde.",
                )
                flash("Backup nicht gefunden.", "error")
                return redirect(url_for("dashboard"))

            if request.method == "POST":
                payload = request.form.to_dict(flat=True)
                name = payload.get("name", "").strip()
                target_pattern = payload.get("target_pattern", "").strip()
                compression_method = payload.get("compression_method", "zip")
                encryption_mode = payload.get("encryption_mode", "none")
                source_entry_type = payload.get("source_entry_type", "directory").strip().lower()
                target_kind = payload.get("target_kind", "folder").strip().lower()

                # Source connection
                source_protocol = payload.get("source_protocol", "").strip().upper()
                if source_protocol == "LOCAL":
                    source_host, source_port = "local", None
                else:
                    source_host, source_port, h_err = self._split_host_and_port(payload.get("source_host", ""))
                    if h_err:
                        flash(f"Source: {h_err}", "error")
                        return redirect(url_for("backup_edit", backup_id=backup_id))
                source_share = payload.get("source_share", "").strip()
                source_subpath = normalize_subpath(payload.get("source_subpath", "/"))
                source_username = payload.get("source_username", "").strip()
                src_pwd_raw = payload.get("source_password", "")
                source_password: str | None = None if src_pwd_raw == "***" else src_pwd_raw

                # Destination connection
                destination_protocol = payload.get("destination_protocol", "").strip().upper()
                if destination_protocol == "LOCAL":
                    destination_host, destination_port = "local", None
                else:
                    destination_host, destination_port, d_err = self._split_host_and_port(payload.get("destination_host", ""))
                    if d_err:
                        flash(f"Destination: {d_err}", "error")
                        return redirect(url_for("backup_edit", backup_id=backup_id))
                destination_share = payload.get("destination_share", "").strip()
                destination_subpath = normalize_subpath(payload.get("destination_subpath", "/"))
                destination_username = payload.get("destination_username", "").strip()
                dst_pwd_raw = payload.get("destination_password", "")
                destination_password: str | None = None if dst_pwd_raw == "***" else dst_pwd_raw

                # Archive password
                arc_pwd_raw = payload.get("archive_password", "")
                arc_pwd_confirm = payload.get("archive_password_confirm", "")
                archive_password: str | None = None if arc_pwd_raw == "***" else arc_pwd_raw

                schedule, _ = parse_schedule_fields(request.form)
                backup_mode = payload.get("backup_mode", "full").strip().lower()
                try:
                    rotation_keep = max(0, int(payload.get("rotation_keep", "0") or "0"))
                except ValueError:
                    rotation_keep = 0

                if not name or not target_pattern:
                    flash("Bitte Name und Ziel ausfüllen.", "error")
                    return redirect(url_for("backup_edit", backup_id=backup_id))
                if compression_method not in COMPRESSION_METHODS:
                    flash("Ungültige Kompressionsmethode.", "error")
                    return redirect(url_for("backup_edit", backup_id=backup_id))
                if backup_mode not in BACKUP_MODES:
                    flash("Ungültiger Backup-Modus.", "error")
                    return redirect(url_for("backup_edit", backup_id=backup_id))
                if encryption_mode not in ENCRYPTION_MODES:
                    flash("Ungültiger Verschlüsselungsmodus.", "error")
                    return redirect(url_for("backup_edit", backup_id=backup_id))
                if archive_password and archive_password != arc_pwd_confirm:
                    flash("Archiv-Passwort und Bestätigung stimmen nicht überein.", "error")
                    return redirect(url_for("backup_edit", backup_id=backup_id))

                updated = self.store.update_full_backup(
                    backup_id=backup_id,
                    name=name,
                    source_protocol=source_protocol,
                    source_host=source_host,
                    source_port=source_port,
                    source_share=source_share,
                    source_subpath=source_subpath,
                    source_username=source_username,
                    source_password=source_password,
                    destination_protocol=destination_protocol,
                    destination_host=destination_host,
                    destination_port=destination_port,
                    destination_share=destination_share,
                    destination_subpath=destination_subpath,
                    destination_username=destination_username,
                    destination_password=destination_password,
                    source_entry_type=source_entry_type,
                    target_kind=target_kind,
                    target_pattern=target_pattern,
                    compression_method=compression_method,
                    encryption_mode=encryption_mode,
                    archive_password=archive_password,
                    schedule_mode=schedule["schedule_mode"],
                    schedule_cron=schedule["schedule_cron"],
                    backup_mode=backup_mode,
                    rotation_keep=rotation_keep,
                )

                if not updated:
                    self._log(
                        level="ERROR",
                        category="backup",
                        event="edit_failed",
                        backup_id=backup_id,
                        message="Backup-Update konnte nicht gespeichert werden.",
                    )
                    flash("Backup konnte nicht gespeichert werden.", "error")
                    return redirect(url_for("backup_edit", backup_id=backup_id))

                self._log(
                    level="INFO",
                    category="backup",
                    event="edit_saved",
                    backup_id=backup_id,
                    message=f"Backup wurde aktualisiert: {name}",
                    details={"backup_mode": backup_mode, "compression_method": compression_method},
                )
                flash("Backup wurde aktualisiert.", "success")
                return redirect(url_for("dashboard"))

            return render_template(
                "backup_edit.html",
                adminuser=session.get("adminuser", "admin"),
                backup=backup,
                target_protocols=TARGET_PROTOCOLS,
                compression_methods=COMPRESSION_METHODS,
                encryption_modes=ENCRYPTION_MODES,
                backup_modes=BACKUP_MODES,
                active_menu="dashboard",
            )

        @app.post("/backups/<int:backup_id>/delete")
        @login_required
        @admin_required
        def backup_delete(backup_id: int):
            deleted = self.store.delete_backup(backup_id)
            if not deleted:
                self._log(
                    level="WARNING",
                    category="backup",
                    event="delete_not_found",
                    backup_id=backup_id,
                    message="Backup-Loeschung angefordert, aber Backup nicht gefunden.",
                )
                flash("Backup nicht gefunden.", "error")
            else:
                self._log(
                    level="WARNING",
                    category="backup",
                    event="deleted",
                    backup_id=backup_id,
                    message="Backup wurde geloescht.",
                )
                flash("Backup wurde gelöscht.", "success")
            return redirect(url_for("dashboard"))

        @app.post("/api/local/mkdir")
        @login_required
        def api_local_mkdir():
            import os
            payload = request.get_json(silent=True) or {}
            parent_path = payload.get("path", "").strip()
            folder_name = payload.get("folder_name", "").strip()

            if not parent_path or not folder_name:
                return jsonify({"ok": False, "message": "Pfad und Ordnername erforderlich."})
            if "/" in folder_name or "\\" in folder_name or folder_name in (".", ".."):
                return jsonify({"ok": False, "message": "Ung\u00fcltiger Ordnername."})

            new_path = os.path.join(os.path.abspath(parent_path), folder_name)
            try:
                os.makedirs(new_path, exist_ok=False)
                return jsonify({"ok": True, "path": new_path})
            except FileExistsError:
                return jsonify({"ok": False, "message": "Ordner existiert bereits."})
            except PermissionError:
                return jsonify({"ok": False, "message": "Kein Schreibrecht."})
            except OSError as e:
                return jsonify({"ok": False, "message": str(e)})

        @app.get("/api/local/browse")
        @login_required
        def api_local_browse():
            import os
            raw_path = request.args.get("path", "/").strip()
            path = os.path.abspath(raw_path) if raw_path else "/"

            if not os.path.exists(path):
                return jsonify({"ok": False, "message": f"Pfad nicht gefunden: {path}"})

            try:
                entries = []
                parent = os.path.dirname(path) if path != "/" else "/"
                if path != parent:
                    entries.append({"name": "..", "path": parent, "entry_type": "up"})

                for item in sorted(os.scandir(path), key=lambda e: (not e.is_dir(), e.name.lower())):
                    try:
                        entries.append({
                            "name": item.name,
                            "path": item.path,
                            "entry_type": "directory" if item.is_dir() else "file",
                        })
                    except (PermissionError, OSError):
                        continue

                return jsonify({"ok": True, "path": path, "entries": entries})
            except PermissionError:
                return jsonify({"ok": False, "message": "Kein Zugriff auf diesen Pfad."})
            except OSError as e:
                return jsonify({"ok": False, "message": str(e)})

        @app.post("/api/cron/preview")
        @login_required
        def api_cron_preview():
            try:
                from croniter import croniter
            except ImportError:
                return jsonify({"ok": False, "message": "croniter nicht installiert."}), 500

            payload = request.get_json(silent=True) or {}
            expr = payload.get("cron", "").strip()
            if not expr:
                return jsonify({"ok": False, "message": "Kein Ausdruck."})

            try:
                it = croniter(expr, datetime.now())
                next_dt = it.get_next(datetime)
            except Exception:
                return jsonify({"ok": False, "message": "Ungültiger CRON-Ausdruck."})

            DE_DAYS = ["Montag", "Dienstag", "Mittwoch", "Donnerstag", "Freitag", "Samstag", "Sonntag"]
            DE_MONTHS = ["Januar", "Februar", "März", "April", "Mai", "Juni",
                         "Juli", "August", "September", "Oktober", "November", "Dezember"]
            next_run = (
                f"{DE_DAYS[next_dt.weekday()]}, {next_dt.day:02d}. "
                f"{DE_MONTHS[next_dt.month - 1]} {next_dt.year} "
                f"um {next_dt.hour:02d}:{next_dt.minute:02d} Uhr"
            )

            parts = expr.split()
            description = "Benutzerdefinierter Zeitplan"

            def _format_weekday_text(value: str) -> str | None:
                de_dow = ["Sonntag", "Montag", "Dienstag", "Mittwoch", "Donnerstag", "Freitag", "Samstag"]
                short = ["So", "Mo", "Di", "Mi", "Do", "Fr", "Sa"]
                token = value.strip()
                if not token or token == "*":
                    return "jeden Tag"
                if "/" in token:
                    return None

                if "-" in token and "," not in token:
                    try:
                        start_raw, end_raw = token.split("-", 1)
                        start = int(start_raw) % 7
                        end = int(end_raw) % 7
                    except ValueError:
                        return None
                    if start == end:
                        return de_dow[start]
                    return f"{short[start]}-{short[end]}"

                if "," in token:
                    labels: list[str] = []
                    for part in token.split(","):
                        part = part.strip()
                        if not part:
                            return None
                        try:
                            idx = int(part) % 7
                        except ValueError:
                            return None
                        labels.append(short[idx])
                    return ", ".join(labels)

                try:
                    idx = int(token) % 7
                except ValueError:
                    return None
                return de_dow[idx]

            if len(parts) == 5:
                minute, hour, dom, month, dow = parts
                t = f"{int(hour):02d}:{int(minute):02d} Uhr" if hour.isdigit() and minute.isdigit() else ""
                dow_text = _format_weekday_text(dow)
                if all(p in ("*", "*/1") for p in parts):
                    description = "Jede Minute"
                elif hour == "*" and dom == "*" and month == "*" and dow == "*" and minute.isdigit():
                    description = f"Jede Stunde um :{int(minute):02d} Uhr"
                elif dom == "*" and month == "*" and dow == "*" and t:
                    description = f"Täglich um {t}"
                elif dom == "*" and month == "*" and dow_text and t and dow != "*":
                    if "-" in dow_text or "," in dow_text:
                        description = f"Wochentags {dow_text} um {t}"
                    else:
                        description = f"Wöchentlich am {dow_text} um {t}"
                elif month == "*" and dow == "*" and dom.isdigit() and t:
                    description = f"Monatlich am {dom}. um {t}"

            return jsonify({"ok": True, "description": description, "next_run": next_run})

        @app.post("/api/target/test")
        @login_required
        @admin_required
        def api_target_test():
            payload = request.get_json(silent=True) or {}
            prefix = payload.get("prefix", "")
            if prefix not in {"source", "destination"}:
                return jsonify({"ok": False, "message": "Ungueltiger Bereich."}), 400

            target, error = self._target_from_payload(payload, prefix)
            if error:
                return jsonify({"ok": False, "message": error}), 400

            assert target is not None
            ok, message = test_connection(target)
            status = 200 if ok else 400
            return jsonify({"ok": ok, "message": message}), status

        @app.post("/api/target/browse")
        @login_required
        @admin_required
        def api_target_browse():
            payload = request.get_json(silent=True) or {}
            prefix = payload.get("prefix", "")
            if prefix not in {"source", "destination"}:
                return jsonify({"ok": False, "message": "Ungueltiger Bereich."}), 400

            target, error = self._target_from_payload(payload, prefix)
            if error:
                return jsonify({"ok": False, "message": error}), 400
            assert target is not None

            protocol = target.protocol.upper()
            if protocol == "SMB":
                if not target.share:
                    return jsonify({"ok": False, "message": "Bitte zuerst eine SMB-Freigabe (Share) angeben."}), 400
                ok, path_or_err, entries = browse_smb_directories(target)
            elif protocol == "FTP":
                ok, path_or_err, entries = browse_ftp_directories(target)
            elif protocol == "SFTP":
                ok, path_or_err, entries = browse_sftp_directories(target)
            else:
                return jsonify({"ok": False, "message": f"Browser nicht verfügbar für: {protocol}"}), 400

            if not ok:
                return jsonify({"ok": False, "message": path_or_err}), 400
            return jsonify({"ok": True, "path": path_or_err, "entries": entries})

        @app.post("/api/target/browse-smb")
        @login_required
        @admin_required
        def api_target_browse_smb():
            payload = request.get_json(silent=True) or {}
            prefix = payload.get("prefix", "")
            if prefix not in {"source", "destination"}:
                return jsonify({"ok": False, "message": "Ungueltiger Bereich."}), 400

            target, error = self._target_from_payload(payload, prefix)
            if error:
                return jsonify({"ok": False, "message": error}), 400
            if target is None or target.protocol != "SMB":
                return jsonify({"ok": False, "message": "SMB-Browser nur mit SMB moeglich."}), 400

            if not target.share:
                return (
                    jsonify(
                        {
                            "ok": False,
                            "message": "Bitte zuerst eine SMB-Freigabe (Share) waehlen oder Shares laden.",
                        }
                    ),
                    400,
                )

            ok, path_or_error, directories = browse_smb_directories(target)
            if not ok:
                return jsonify({"ok": False, "message": path_or_error}), 400

            return jsonify(
                {
                    "ok": True,
                    "path": path_or_error,
                    "entries": directories,
                }
            )

        @app.post("/api/target/smb-mkdir")
        @login_required
        @admin_required
        def api_target_smb_mkdir():
            payload = request.get_json(silent=True) or {}
            prefix = payload.get("prefix", "")
            if prefix != "destination":
                return jsonify({"ok": False, "message": "Ordnererstellung ist nur fuer Destination erlaubt."}), 400

            target, error = self._target_from_payload(payload, prefix)
            if error:
                return jsonify({"ok": False, "message": error}), 400
            if target is None or target.protocol != "SMB":
                return jsonify({"ok": False, "message": "Ordnererstellung nur mit SMB moeglich."}), 400

            folder_name = payload.get("folder_name", "")
            base_path = payload.get(f"{prefix}_subpath", "/")
            ok, result = create_smb_directory(target, base_path, folder_name)
            if not ok:
                return jsonify({"ok": False, "message": result}), 400
            return jsonify({"ok": True, "path": result, "message": "Ordner wurde erstellt."})

        @app.post("/api/target/smb-shares")
        @login_required
        @admin_required
        def api_target_smb_shares():
            payload = request.get_json(silent=True) or {}
            prefix = payload.get("prefix", "")
            if prefix not in {"source", "destination"}:
                return jsonify({"ok": False, "message": "Ungueltiger Bereich."}), 400

            protocol = payload.get(f"{prefix}_protocol", "").strip().upper()
            if protocol != "SMB":
                return jsonify({"ok": False, "message": "Share-Liste nur mit SMB moeglich."}), 400

            host_input = payload.get(f"{prefix}_host", "").strip()
            host, parsed_port, host_error = self._split_host_and_port(host_input)
            if host_error:
                return jsonify({"ok": False, "message": host_error}), 400

            username = payload.get(f"{prefix}_username", "").strip()
            password = payload.get(f"{prefix}_password", "")
            if not all([host, username, password]):
                return (
                    jsonify(
                        {
                            "ok": False,
                            "message": "Host, Benutzer und Passwort sind zum Laden der Shares erforderlich.",
                        }
                    ),
                    400,
                )

            target = TargetConnection(
                protocol="SMB",
                host=host,
                port=parsed_port,
                share="",
                subpath="/",
                username=username,
                password=password,
            )
            ok, message, shares = list_smb_shares(target)
            if not ok:
                return jsonify({"ok": False, "message": message}), 400
            return jsonify({"ok": True, "message": message, "shares": shares})

        @app.route("/backups/new", methods=["GET", "POST"])
        @login_required
        @admin_required
        def backup_new():
            if request.method == "POST":
                payload = request.form.to_dict(flat=True)
                name = request.form.get("name", "").strip()
                source_target, source_error = self._target_from_payload(payload, "source")
                destination_target, destination_error = self._target_from_payload(payload, "destination")

                source_entry_type = request.form.get("source_entry_type", "directory").strip().lower()
                target_kind = request.form.get("target_kind", "folder").strip().lower()
                target_pattern = request.form.get("target_pattern", "").strip()
                compression_method = request.form.get("compression_method", "zip")
                encryption_mode = request.form.get("encryption_mode", "none")
                archive_password = request.form.get("archive_password", "")
                archive_password_confirm = request.form.get("archive_password_confirm", "")
                backup_mode = request.form.get("backup_mode", "full").strip().lower()
                try:
                    rotation_keep = max(0, int(request.form.get("rotation_keep", "0") or "0"))
                except ValueError:
                    rotation_keep = 0

                schedule, schedule_error = parse_schedule_fields(request.form)
                if schedule_error:
                    flash(schedule_error, "error")
                    return redirect(url_for("backup_new"))
                assert schedule is not None

                required_values = [name, target_pattern]
                if any(not item for item in required_values):
                    flash("Bitte alle Pflichtfelder ausfuellen.", "error")
                    return redirect(url_for("backup_new"))

                if source_error:
                    flash(f"Source: {source_error}", "error")
                    return redirect(url_for("backup_new"))
                if destination_error:
                    flash(f"Destination: {destination_error}", "error")
                    return redirect(url_for("backup_new"))

                if compression_method not in COMPRESSION_METHODS:
                    flash("Ungueltige Kompressionsmethode.", "error")
                    return redirect(url_for("backup_new"))
                if backup_mode not in BACKUP_MODES:
                    flash("Ungueltiger Backup-Modus.", "error")
                    return redirect(url_for("backup_new"))

                if source_entry_type not in {"directory", "file"}:
                    flash("Ungueltiger Source-Typ (Datei/Ordner).", "error")
                    return redirect(url_for("backup_new"))
                if target_kind not in {"folder", "file"}:
                    flash("Ungueltiger Target-Typ.", "error")
                    return redirect(url_for("backup_new"))

                if encryption_mode not in ENCRYPTION_MODES:
                    flash("Ungueltiger Verschluesselungsmodus.", "error")
                    return redirect(url_for("backup_new"))
                if encryption_mode == "none":
                    archive_password = ""
                    archive_password_confirm = ""
                else:
                    if not archive_password:
                        flash("Bitte ein Archiv-Passwort setzen.", "error")
                        return redirect(url_for("backup_new"))
                    if archive_password != archive_password_confirm:
                        flash("Archiv-Passwort und Bestaetigung stimmen nicht ueberein.", "error")
                        return redirect(url_for("backup_new"))

                assert source_target is not None
                assert destination_target is not None

                backup = BackupJob(
                    name=name,
                    source_protocol=source_target.protocol,
                    source_host=source_target.host,
                    source_port=source_target.port,
                    source_share=source_target.share,
                    source_subpath=source_target.subpath,
                    source_username=source_target.username,
                    source_password=source_target.password,
                    destination_protocol=destination_target.protocol,
                    destination_host=destination_target.host,
                    destination_port=destination_target.port,
                    destination_share=destination_target.share,
                    destination_subpath=destination_target.subpath,
                    destination_username=destination_target.username,
                    destination_password=destination_target.password,
                    source_entry_type=source_entry_type,
                    target_kind=target_kind,
                    target_pattern=target_pattern,
                    compression_method=compression_method,
                    encryption_mode=encryption_mode,
                    archive_password=archive_password,
                    schedule_mode=schedule["schedule_mode"],
                    schedule_cron=schedule["schedule_cron"],
                    backup_mode=backup_mode,
                    rotation_keep=rotation_keep,
                )

                created = self.store.create_backup(backup)
                if not created:
                    self._log(
                        level="ERROR",
                        category="backup",
                        event="create_failed",
                        message=f"Backup konnte nicht erstellt werden, Name existiert bereits: {name}",
                    )
                    flash("Backup-Name existiert bereits.", "error")
                    return redirect(url_for("backup_new"))

                self._log(
                    level="INFO",
                    category="backup",
                    event="created",
                    message=f"Backup wurde erstellt: {name}",
                    details={
                        "source_protocol": source_target.protocol,
                        "destination_protocol": destination_target.protocol,
                        "backup_mode": backup_mode,
                    },
                )
                flash("Backup wurde gespeichert.", "success")
                return redirect(url_for("dashboard"))

            return render_template(
                "backup_new.html",
                adminuser=session.get("adminuser", "admin"),
                compression_methods=COMPRESSION_METHODS,
                encryption_modes=ENCRYPTION_MODES,
                backup_modes=BACKUP_MODES,
                target_protocols=TARGET_PROTOCOLS,
                active_menu="backups",
            )

        @app.route("/settings/server", methods=["GET", "POST"])
        @login_required
        @admin_required
        def server_settings():
            if request.method == "POST":
                ip = request.form.get("ip", "").strip()
                port = self._parse_port(request.form.get("port", ""))
                debug = request.form.get("debug", "false").lower() == "true"

                if not ip:
                    flash("IP darf nicht leer sein.", "error")
                    return redirect(url_for("server_settings"))
                if port is None:
                    flash("Port muss zwischen 1 und 65535 liegen.", "error")
                    return redirect(url_for("server_settings"))

                self.config = AppConfig(ip=ip, port=port, debug=debug)
                self.store.save_config(self.config)
                self._log(
                    level="INFO",
                    category="config",
                    event="server_settings_saved",
                    message="Server-Einstellungen wurden aktualisiert.",
                    details={"ip": ip, "port": port, "debug": debug},
                )
                flash("Server-Settings gespeichert. Neustart des Services erforderlich.", "success")
                return redirect(url_for("server_settings"))

            return render_template(
                "server_settings.html",
                adminuser=session.get("adminuser", "admin"),
                config=self.config,
                active_menu="server",
            )

        @app.route("/settings/account", methods=["GET", "POST"])
        @login_required
        def account_settings():
            current_username = session.get("adminuser", "")
            if request.method == "POST":
                new_username = request.form.get("new_username", "").strip()
                current_password = request.form.get("current_password", "")
                new_password = request.form.get("new_password", "")
                confirm_password = request.form.get("confirm_password", "")

                user = self.store.get_user(current_username)
                if user is None:
                    flash("Benutzer wurde nicht gefunden.", "error")
                    return redirect(url_for("logout"))

                if not verify_password(current_password, user.password_hash):
                    flash("Aktuelles Passwort ist falsch.", "error")
                    return redirect(url_for("account_settings"))
                if not new_username:
                    flash("Neuer Benutzername darf nicht leer sein.", "error")
                    return redirect(url_for("account_settings"))
                if not new_password:
                    flash("Neues Passwort darf nicht leer sein.", "error")
                    return redirect(url_for("account_settings"))
                if new_password != confirm_password:
                    flash("Passwort-Bestaetigung stimmt nicht ueberein.", "error")
                    return redirect(url_for("account_settings"))

                updated = self.store.update_user_credentials(
                    current_username=current_username,
                    new_username=new_username,
                    new_password_hash=hash_password(new_password),
                )
                if not updated:
                    flash("Benutzername existiert bereits.", "error")
                    return redirect(url_for("account_settings"))

                self._log(
                    level="INFO",
                    category="auth",
                    event="account_updated",
                    message="Account-Zugangsdaten wurden aktualisiert.",
                    username=new_username,
                )
                session["adminuser"] = new_username
                flash("Deine Zugangsdaten wurden aktualisiert.", "success")
                return redirect(url_for("account_settings"))

            return render_template(
                "account_settings.html",
                adminuser=current_username,
                active_menu="account",
            )

        @app.route("/users", methods=["GET", "POST"])
        @login_required
        @admin_required
        def users():
            if request.method == "POST":
                username = request.form.get("username", "").strip()
                password = request.form.get("password", "")
                password_confirm = request.form.get("password_confirm", "")
                is_admin = request.form.get("is_admin") == "on"

                if not username:
                    flash("Benutzername darf nicht leer sein.", "error")
                    return redirect(url_for("users"))
                if not password:
                    flash("Passwort darf nicht leer sein.", "error")
                    return redirect(url_for("users"))
                if password != password_confirm:
                    flash("Passwort-Bestaetigung stimmt nicht ueberein.", "error")
                    return redirect(url_for("users"))

                created = self.store.create_user(
                    username=username,
                    password_hash=hash_password(password),
                    is_admin=is_admin,
                )
                if not created:
                    flash("Benutzername existiert bereits.", "error")
                    return redirect(url_for("users"))

                self._log(
                    level="INFO",
                    category="auth",
                    event="user_created",
                    message=f"Neuer Benutzer wurde erstellt: {username}",
                    details={"is_admin": is_admin},
                )
                flash("Neuer Benutzer wurde angelegt.", "success")
                return redirect(url_for("users"))

            return render_template(
                "users.html",
                adminuser=session.get("adminuser", "admin"),
                users=self.store.list_users(),
                active_menu="users",
            )

        @app.post("/logout")
        def logout():
            self._log(
                level="INFO",
                category="auth",
                event="logout",
                message="Benutzer wurde abgemeldet.",
            )
            session.clear()
            return redirect(url_for("login"))

        return app

    def _run_scheduler(self) -> None:
        from datetime import timedelta
        try:
            from croniter import croniter as CronIter
        except ImportError:
            return

        fired: dict[int, str] = {}  # backup_id → YYYYMMDDHHmm of the scheduled slot
        while not self._scheduler_stop.is_set():
            now = datetime.now()
            # Sleep until the next minute boundary
            sleep_secs = 61 - now.second - now.microsecond / 1_000_000
            if self._scheduler_stop.wait(sleep_secs):
                break

            fire_time = datetime.now()
            try:
                backups = self.store.list_backups()
            except Exception as exc:
                self._log(
                    level="ERROR",
                    category="scheduler",
                    event="list_backups_failed",
                    message=f"Scheduler konnte Backup-Liste nicht laden: {exc}",
                )
                continue

            for b in backups:
                if not b.schedule_cron:
                    continue
                try:
                    it = CronIter(b.schedule_cron, fire_time - timedelta(seconds=65))
                    next_dt = it.get_next(datetime)
                    diff = (fire_time - next_dt).total_seconds()
                    if not (0 <= diff <= 65):
                        continue
                    # Key by scheduled slot to prevent double-firing across minute boundaries
                    sched_key = next_dt.strftime("%Y%m%d%H%M")
                    if fired.get(b.backup_id) == sched_key:
                        continue
                    fired[b.backup_id] = sched_key
                    ok, start_message = self._start_backup_run(b.backup_id, trigger="scheduled")
                    self._log(
                        level="INFO" if ok else "WARNING",
                        category="scheduler",
                        event="scheduled_run_triggered" if ok else "scheduled_run_not_started",
                        backup_id=b.backup_id,
                        message=(
                            f"Geplanter Lauf ausgeloest fuer Backup: {b.name}"
                            if ok
                            else f"Geplanter Lauf konnte nicht gestartet werden: {b.name} ({start_message})"
                        ),
                        details={"scheduled_slot": sched_key, "cron": b.schedule_cron, "start_message": start_message},
                    )
                except Exception as exc:
                    self._log(
                        level="ERROR",
                        category="scheduler",
                        event="cron_evaluation_failed",
                        backup_id=b.backup_id,
                        message=f"CRON-Auswertung fehlgeschlagen fuer Backup '{b.name}': {exc}",
                        details={"cron": b.schedule_cron},
                    )
                    continue

    def run(self) -> None:
        import os
        app = self.create_app()
        # Start scheduler only in the actual serving process (not Werkzeug reloader watcher)
        if os.environ.get("WERKZEUG_RUN_MAIN") == "true" or not self.config.debug:
            self._scheduler_stop = threading.Event()
            threading.Thread(
                target=self._run_scheduler, daemon=True, name="backup-scheduler"
            ).start()
            self._log(
                level="INFO",
                category="scheduler",
                event="started",
                message="Backup-Scheduler wurde gestartet.",
            )
        self._log(
            level="INFO",
            category="app",
            event="startup",
            message=f"Webserver startet auf {self.config.ip}:{self.config.port} (debug={self.config.debug}).",
            details={"ip": self.config.ip, "port": self.config.port, "debug": self.config.debug},
        )
        app.run(host=self.config.ip, port=self.config.port, debug=self.config.debug)