#!/usr/bin/env python3
"""Enforce Ariadne's per-file source coverage contract."""

from __future__ import annotations

import argparse
import json
from pathlib import Path


def _source_files(root: Path) -> list[str]:
    files: list[str] = []
    for path in sorted(root.rglob("*.py")):
        if "__pycache__" in path.parts:
            continue
        files.append(path.as_posix())
    return files


def _coverage_percent(file_payload: object) -> float | None:
    if not isinstance(file_payload, dict):
        return None
    summary = file_payload.get("summary")
    if not isinstance(summary, dict):
        return None
    value = summary.get("percent_covered")
    if isinstance(value, (int, float)):
        return float(value)
    return None


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("coverage_json")
    parser.add_argument("--source-root", default="ariadne")
    parser.add_argument("--threshold", type=float, default=95.0)
    args = parser.parse_args()

    coverage_path = Path(args.coverage_json)
    source_root = Path(args.source_root)
    payload = json.loads(coverage_path.read_text(encoding="utf-8"))
    files = payload.get("files") if isinstance(payload, dict) else None
    if not isinstance(files, dict):
        print(f"{coverage_path}: missing files coverage map")
        return 1

    failures: list[str] = []
    for source_file in _source_files(source_root):
        percent = _coverage_percent(files.get(source_file))
        if percent is None:
            failures.append(f"{source_file}: missing from coverage report")
        elif percent < args.threshold:
            failures.append(f"{source_file}: {percent:.2f}% below {args.threshold:.2f}%")

    if failures:
        print("coverage contract failed:")
        for failure in failures:
            print(f" - {failure}")
        return 1

    print(f"coverage contract passed: {len(_source_files(source_root))} files >= {args.threshold:.2f}%")
    return 0


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