from __future__ import annotations

import re
import sys
from pathlib import Path


LINK_PATTERN = re.compile(r"\[[^\]]*\]\(([^)]+)\)")
IGNORED_PREFIXES = ("http://", "https://", "mailto:", "#")


def markdown_files() -> list[Path]:
    return [Path("README.md"), *sorted(Path("docs").rglob("*.md"))]


def main() -> int:
    missing: list[tuple[Path, str]] = []
    for document in markdown_files():
        for target in LINK_PATTERN.findall(document.read_text(encoding="utf-8")):
            if target.startswith(IGNORED_PREFIXES):
                continue
            path_part = target.split("#", 1)[0]
            if not (document.parent / path_part).exists():
                missing.append((document, target))

    if missing:
        for document, target in missing:
            print(f"Broken relative link: {document}: {target}", file=sys.stderr)
        return 1

    print("Markdown relative links passed.")
    return 0


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