#!/usr/bin/env python3
"""Enforce per-file coverage thresholds from SlipCover JSON output."""

from __future__ import annotations

import argparse
import json
from pathlib import Path


def _normalize_report_path(path: str, cwd: Path) -> str:
    """Return a stable repository-relative path for a coverage report entry."""

    candidate = Path(path)
    if candidate.is_absolute():
        try:
            return candidate.relative_to(cwd).as_posix()
        except ValueError:
            return candidate.as_posix()
    return candidate.as_posix()


def _production_files(root: Path, cwd: Path) -> set[str]:
    """List production Python files that must appear in the coverage report."""

    required: set[str] = set()
    for path in root.rglob("*.py"):
        if path.name == "__init__.py" or "__pycache__" in path.parts:
            continue
        try:
            required.add(path.relative_to(cwd).as_posix())
        except ValueError:
            required.add(path.as_posix())
    return required


def main() -> int:
    """Check each production file against a minimum coverage percentage."""

    parser = argparse.ArgumentParser()
    parser.add_argument("coverage_json")
    parser.add_argument("--root", default="atlasbot")
    parser.add_argument("--threshold", type=float, default=95.0)
    args = parser.parse_args()

    data = json.loads(Path(args.coverage_json).read_text(encoding="utf-8"))
    files = data.get("files") if isinstance(data, dict) else {}
    cwd = Path.cwd().resolve()
    root = Path(args.root)
    root_path = (root if root.is_absolute() else cwd / root).resolve()
    root_prefix = root_path.relative_to(cwd).as_posix() if root_path.is_relative_to(cwd) else root_path.as_posix()
    covered_paths: set[str] = set()
    violations: list[str] = []

    for path, payload in sorted(files.items()):
        normalized_path = _normalize_report_path(path, cwd)
        if not normalized_path.startswith(f"{root_prefix}/"):
            continue
        summary = payload.get("summary") if isinstance(payload, dict) else {}
        percent = summary.get("percent_covered") if isinstance(summary, dict) else None
        if not isinstance(percent, (int, float)):
            violations.append(f"{normalized_path}: coverage percent missing")
            continue
        covered_paths.add(normalized_path)
        if float(percent) < args.threshold:
            violations.append(f"{normalized_path}: {float(percent):.2f}% < {args.threshold:.2f}%")

    for path in sorted(_production_files(root_path, cwd) - covered_paths):
        violations.append(f"{path}: missing from coverage report")

    if violations:
        for violation in sorted(violations):
            print(violation)
        return 1
    return 0


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