#!/usr/bin/env python3
import argparse
import hashlib
import json
import os
from pathlib import Path


def sha256_file(path: Path) -> str:
    h = hashlib.sha256()
    with path.open("rb") as f:
        for chunk in iter(lambda: f.read(1024 * 1024), b""):
            h.update(chunk)
    return h.hexdigest()


def build_asl_manifest(root: Path) -> dict:
    artifacts_dir = root / "artifacts"
    fixtures = []
    for entry in sorted(artifacts_dir.iterdir()):
        if not entry.is_file() or entry.suffix != ".bin":
            continue
        artifact_rel = f"artifacts/{entry.name}"
        fixtures.append(
            {
                "id": entry.stem,
                "artifact": artifact_rel,
                "size": str(entry.stat().st_size),
                "sha256": sha256_file(entry),
            }
        )
    return {"schema": "amduat.conformance.fixtures.v0", "fixtures": fixtures}


def main() -> int:
    parser = argparse.ArgumentParser(
        description="Generate conformance fixture manifests."
    )
    parser.add_argument(
        "root",
        type=Path,
        help="Fixture directory containing artifacts/",
    )
    parser.add_argument(
        "--out",
        type=Path,
        default=None,
        help="Output manifest path (defaults to <root>/manifest.json)",
    )
    args = parser.parse_args()

    manifest = build_asl_manifest(args.root)
    out_path = args.out or (args.root / "manifest.json")
    out_path.parent.mkdir(parents=True, exist_ok=True)
    with out_path.open("w", encoding="utf-8") as f:
        json.dump(manifest, f, indent=2, sort_keys=False)
        f.write("\n")
    return 0


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