v0.0.1 first commit

app/venv_manager.py

@@ -0,0 +1,35 @@
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+
+class VirtualEnvManager:
+    def __init__(self, venv_dir: Path, entry_script: Path) -> None:
+        self.venv_dir = venv_dir
+        self.entry_script = entry_script
+
+    @staticmethod
+    def in_virtualenv() -> bool:
+        return (
+            hasattr(sys, "real_prefix")
+            or sys.prefix != getattr(sys, "base_prefix", sys.prefix)
+        )
+
+    def _venv_python(self) -> Path:
+        if os.name == "nt":
+            return self.venv_dir / "Scripts" / "python.exe"
+        return self.venv_dir / "bin" / "python"
+
+    def ensure_and_reexec_if_needed(self) -> None:
+        if self.in_virtualenv():
+            return
+
+        venv_python = self._venv_python()
+        if not venv_python.exists():
+            subprocess.check_call([sys.executable, "-m", "venv", str(self.venv_dir)])
+
+        os.execv(
+            str(venv_python),
+            [str(venv_python), str(self.entry_script.resolve()), *sys.argv[1:]],
+        )