#!/usr/bin/env python3
"""Generate the wasm lazy-asset manifest.

The wasm build runs the engine on a worker, where synchronous XHR is legal, so
assets are registered with ``FS.createLazyFile`` instead of being preloaded: the
browser fetches each file only when the engine first opens it. This script lists
every file under the assets root (as POSIX-relative paths) as
``{"files": [...]}``; CMake preloads the manifest to ``/assets.manifest.json``.

    scripts/make_web_manifest.py --root /path/to/assets --out assets.manifest.json

Serve the tree at ``<wasm-root>/assets`` (or use ``serve.py --assets``).
"""

import argparse
import json
import os
import sys


def main() -> int:
    parser = argparse.ArgumentParser(description="Generate the OpenRA3 wasm asset manifest")
    parser.add_argument("--root", required=True, help="assets root to enumerate")
    parser.add_argument("--out", required=True, help="manifest JSON to write")
    args = parser.parse_args()

    if not os.path.isdir(args.root):
        print(f"root not found: {args.root}", file=sys.stderr)
        return 1

    files = []
    for dirpath, dirnames, filenames in os.walk(args.root):
        dirnames.sort()
        for name in sorted(filenames):
            rel = os.path.relpath(os.path.join(dirpath, name), args.root).replace(os.sep, "/")
            files.append(rel)

    with open(args.out, "w", encoding="utf-8") as handle:
        json.dump({"files": files}, handle, separators=(",", ":"))
        handle.write("\n")
    print(f"wrote {args.out} ({len(files)} files)")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())