#!/usr/bin/env python3
"""Build the isolated L54 native-caves fixture from the canonical owner input."""
from __future__ import annotations

import argparse
import hashlib
import json
from pathlib import Path


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


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--owner", type=Path, required=True)
    parser.add_argument("--out", type=Path, required=True)
    args = parser.parse_args()
    root = json.loads(args.owner.read_text(encoding="utf-8"))
    strates = root.get("strates")
    if not isinstance(strates, list):
        raise ValueError("owner input has no strates array")
    cave_candidates = [item for item in strates
        if isinstance(item, dict) and int(item.get("index", -1)) == 1
        and int(item.get("asset", {}).get("GeneratorType", -1)) == 4]
    if len(cave_candidates) != 1:
        raise ValueError("fixture requires exactly one SurfaceWorld cave strate at index 1")
    upper_candidates = [item for item in strates
        if isinstance(item, dict) and int(item.get("index", -1)) == 0]
    if len(upper_candidates) != 1:
        raise ValueError("fixture requires one adjacent upper strate at index 0")
    passage = upper_candidates[0].get("passage_config")
    asset_passage = upper_candidates[0].get("asset", {}).get("PassageConfig")
    if (not isinstance(passage, dict) or not isinstance(asset_passage, dict)
            or int(passage.get("Connections", -1)) != 1
            or int(asset_passage.get("Connections", -1)) != 1):
        raise ValueError("upper-strate passage config differs from the reviewed owner fixture")
    passage["Connections"] = 2
    asset_passage["Connections"] = 2
    args.out.parent.mkdir(parents=True, exist_ok=True)
    args.out.write_text(json.dumps(root, indent=2, sort_keys=True) + "\n",
                        encoding="utf-8")
    print(f"[CavesFixtureBuild] source={args.owner} source_sha256={sha256(args.owner)} "
          f"fixture={args.out} fixture_sha256={sha256(args.out)} changed=upper-strate-0-connections:1->2 "
          "owner_input_untouched=true status=PASS")
    return 0


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