#!/usr/bin/env python3
"""Create a checksummed regional YOLO view without copying protected data."""

from __future__ import annotations

import argparse
import hashlib
import json
from pathlib import Path
from typing import Any


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


def select_paths(summary: dict[str, Any], manifest: dict[str, Any], region: str) -> tuple[list[str], list[str]]:
    samples = {item["sample_slug"]: item for item in manifest["samples"]}
    train: list[str] = []
    val: list[str] = []
    for tile in summary["tiles"]:
        sample = samples[tile["sample_slug"]]
        if sample["region"] != region or not tile.get("kept", True):
            continue
        if sample["split"] == "train" and tile["split"] == "train":
            train.append(tile["image_path"])
        elif sample["split"] == "val" and tile["split"] == "val":
            val.append(tile["image_path"])
    if not train or not val:
        raise ValueError(f"Region {region!r} must contain train and validation images")
    return sorted(train), sorted(val)


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument("--summary", type=Path, required=True)
    parser.add_argument("--corpus-manifest", type=Path, required=True)
    parser.add_argument("--region", required=True)
    parser.add_argument("--output-dir", type=Path, required=True)
    args = parser.parse_args()
    summary = json.loads(args.summary.read_text(encoding="utf-8"))
    manifest = json.loads(args.corpus_manifest.read_text(encoding="utf-8"))
    train, val = select_paths(summary, manifest, args.region)
    args.output_dir.mkdir(parents=True, exist_ok=True)
    train_list = args.output_dir / "train.txt"
    val_list = args.output_dir / "val.txt"
    train_list.write_text("\n".join(train) + "\n", encoding="utf-8")
    val_list.write_text("\n".join(val) + "\n", encoding="utf-8")
    dataset_yaml = args.output_dir / "dataset.yaml"
    dataset_yaml.write_text(
        f"path: {args.output_dir}\ntrain: {train_list}\nval: {val_list}\nnames:\n  0: building\n",
        encoding="utf-8",
    )
    evidence = {
        "schema_version": 1,
        "status": "ok",
        "region": args.region,
        "train_image_count": len(train),
        "validation_image_count": len(val),
        "summary": str(args.summary),
        "summary_sha256": sha256(args.summary),
        "corpus_manifest": str(args.corpus_manifest),
        "corpus_manifest_sha256": sha256(args.corpus_manifest),
        "dataset_yaml": str(dataset_yaml),
        "protected_splits_in_training": [],
    }
    (args.output_dir / "regional-dataset.json").write_text(json.dumps(evidence, indent=2), encoding="utf-8")
    print(json.dumps(evidence, indent=2))
    return 0


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