part.py

#!/usr/bin/env python3
from pathlib import Path
import os
from typing import List
from typing import TypedDict

src = Path("/home/mschulte/Videos/39th-gate-music-video")
dst = Path("/tmp/nix-shell.i4wVnT/tmp.0BRU2RIDOa/overlays")

max_size_mb = 10_000

class Overlay(TypedDict):
    files: List[Path]
    size: int

def main():
    dst.mkdir(exist_ok=True)

    overlays: List[Overlay]  = []
    for file in src.rglob("*"):
        if not file.is_file():
            continue

        size = file.stat().st_size
        if size >= max_size_mb * 1e6:
            raise ValueError(f"file size {size} exceeds {max_size_mb}mb size limit")

        if len(overlays) == 0:
            overlays = [{"files": [file], "size": size}]
        elif overlays[-1]["size"] + size >= max_size_mb * 1e6:
            overlays.append({"files": [file], "size": size})
        else:
            overlays[-1]["files"].append(file)
            overlays[-1]["size"] += size

    for i, overlay in enumerate(overlays):
        for file in overlay["files"]:
            overlay_dst = dst / f"{src.name}-{i:03d}.part" / file.relative_to(src)
            overlay_dst.parent.mkdir(exist_ok=True, parents=True)
            overlay_dst.symlink_to(file)


if __name__ == "__main__":
    main()