#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
collatz_compare_verifiers.py

Compare two verification outputs (MD files from verifiers).
Reports differences.

Usage: python collatz_compare_verifiers.py --verif1 MD --verif2 MD --output MD
"""

from __future__ import annotations

import argparse
from pathlib import Path


def parse_verification_output(path: str) -> tuple[str, list[str]]:
    """Parse verification MD: status (OK/failed) and list of error lines."""
    p = Path(path)
    if not p.exists():
        return "missing", [f"File not found: {path}"]

    text = p.read_text(encoding="utf-8")
    lines = text.strip().splitlines()
    status = "OK" if "Verification OK" in text else "failed"

    errors: list[str] = []
    for ln in lines:
        if ln.strip().startswith("- "):
            errors.append(ln.strip()[2:])

    return status, errors


def compare(verif1: str, verif2: str) -> list[str]:
    """Compare two verification outputs. Returns list of difference descriptions."""
    diffs: list[str] = []

    s1, e1 = parse_verification_output(verif1)
    s2, e2 = parse_verification_output(verif2)

    if s1 != s2:
        diffs.append(f"Status mismatch: verif1={s1}, verif2={s2}")

    set1 = set(e1)
    set2 = set(e2)
    only_in_1 = set1 - set2
    only_in_2 = set2 - set1

    if only_in_1:
        diffs.append(f"Only in verif1 ({len(only_in_1)}):")
        for x in sorted(only_in_1)[:10]:
            diffs.append(f"  - {x}")
        if len(only_in_1) > 10:
            diffs.append(f"  ... and {len(only_in_1) - 10} more")

    if only_in_2:
        diffs.append(f"Only in verif2 ({len(only_in_2)}):")
        for x in sorted(only_in_2)[:10]:
            diffs.append(f"  - {x}")
        if len(only_in_2) > 10:
            diffs.append(f"  ... and {len(only_in_2) - 10} more")

    return diffs


def run(verif1_path: str, verif2_path: str, output_path: str) -> None:
    """Compare and write output."""
    diffs = compare(verif1_path, verif2_path)

    if diffs:
        content = "# Verification comparison: differences\n\n" + "\n".join(diffs)
    else:
        content = "# Verification comparison: identical\n\n"

    Path(output_path).write_text(content, encoding="utf-8")


def main() -> None:
    parser = argparse.ArgumentParser(description="Compare two verification outputs")
    parser.add_argument("--verif1", required=True, help="Path to first verification MD")
    parser.add_argument("--verif2", required=True, help="Path to second verification MD")
    parser.add_argument("--output", required=True, help="Path to output MD file")
    args = parser.parse_args()
    run(args.verif1, args.verif2, args.output)


if __name__ == "__main__":
    main()