Initial commit

Backend/Preview.py

@@ -0,0 +1,44 @@
+from __future__ import annotations
+
+from pathlib import Path
+
+
+TextFileTypes = {"markdown", "text", "config", "html"}
+
+MimeTypeMap = {
+    ".png": "image/png",
+    ".jpg": "image/jpeg",
+    ".jpeg": "image/jpeg",
+    ".gif": "image/gif",
+    ".webp": "image/webp",
+    ".svg": "image/svg+xml",
+    ".mp4": "video/mp4",
+    ".webm": "video/webm",
+    ".mov": "video/quicktime",
+    ".mkv": "video/x-matroska",
+}
+
+
+def ReadTextFile(FilePath: Path) -> str:
+    """Read a text-classified file as UTF-8."""
+    return FilePath.read_text(encoding="utf-8")
+
+
+def GetFileSize(FilePath: Path) -> int:
+    return FilePath.stat().st_size
+
+
+def GetMimeType(FilePath: Path) -> str:
+    return MimeTypeMap.get(FilePath.suffix.lower(), "application/octet-stream")
+
+
+def ParseRangeHeader(RangeHeader: str, FileSize: int) -> tuple[int, int]:
+    """Parse a single-range HTTP Range header into an inclusive (Start, End)."""
+    RangeValue = RangeHeader.replace("bytes=", "").strip()
+    StartText, _, EndText = RangeValue.partition("-")
+
+    Start = int(StartText) if StartText else 0
+    End = int(EndText) if EndText else FileSize - 1
+    End = min(End, FileSize - 1)
+
+    return Start, End