#!/usr/bin/env python3
"""Merge completed per-video prediction shards in inventory order."""

from __future__ import annotations

import argparse
import hashlib
import json
from pathlib import Path


def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--inventory", type=Path, required=True)
    parser.add_argument("--inference-dir", type=Path, required=True)
    parser.add_argument("--output", type=Path, required=True)
    parser.add_argument("--allow-incomplete", action="store_true")
    args = parser.parse_args()

    inventory = [json.loads(line) for line in args.inventory.read_text(encoding="utf-8").splitlines() if line.strip()]
    missing = []
    total_frames = 0
    temporary = args.output.with_suffix(args.output.suffix + ".part")
    args.output.parent.mkdir(parents=True, exist_ok=True)
    with temporary.open("w", encoding="utf-8") as output:
        for row in inventory:
            if row.get("decode_status") != "ok":
                continue
            relative = str(row["relative_video_path"])
            digest = hashlib.sha1(relative.encode("utf-8")).hexdigest()
            shard = args.inference_dir / "video_shards" / f"{digest}.jsonl"
            done = args.inference_dir / "done" / f"{digest}.json"
            if not shard.is_file() or not done.is_file():
                missing.append(relative)
                continue
            for line in shard.read_text(encoding="utf-8").splitlines():
                if line.strip():
                    output.write(line + "\n")
                    total_frames += 1
    if missing and not args.allow_incomplete:
        temporary.unlink(missing_ok=True)
        raise SystemExit(f"missing {len(missing)} completed videos; first examples: {missing[:5]}")
    temporary.replace(args.output)
    summary = {"videos_in_inventory": len(inventory), "missing_videos": len(missing), "merged_frames": total_frames, "output": str(args.output.resolve())}
    (args.output.parent / f"{args.output.name}.summary.json").write_text(json.dumps(summary, ensure_ascii=False, indent=2) + "\n", encoding="utf-8")
    print(json.dumps(summary, ensure_ascii=False, indent=2))


if __name__ == "__main__":
    main()