#!/usr/bin/env python3

from __future__ import annotations

import argparse
import re
from pathlib import Path


CAMEL_CASE_RE = re.compile(r'(?<=[a-z])(?=[A-Z])')


def read_title(markdown_path: Path) -> str:
    for line in markdown_path.read_text(encoding='utf-8').splitlines():
        if line.startswith('# '):
            return line[2:].strip()
    return markdown_path.stem


def humanize_token(token: str) -> str:
    return CAMEL_CASE_RE.sub(' ', token).strip()


def display_section_name(directory_name: str) -> str:
    parts = [humanize_token(part) for part in directory_name.split('_') if part]
    if not parts:
        return directory_name
    if len(parts) == 1:
        return parts[0]
    if len(parts) == 2:
        return f'{parts[0]} & {parts[1]}'
    return f"{', '.join(parts[:-1])} & {parts[-1]}"


def build_index(workshops_dir: Path) -> str:
    sections: list[str] = ['# Workshops Index']

    for subdir in sorted(path for path in workshops_dir.iterdir() if path.is_dir()):
        sections.append(f'## {display_section_name(subdir.name)}')

        markdown_files = sorted(subdir.glob('*.md'))
        if not markdown_files:
            sections.append('_No Markdown files found._')
            continue

        for markdown_file in markdown_files:
            title = read_title(markdown_file)
            relative_path = markdown_file.relative_to(workshops_dir)
            sections.append(f'- [{title}]({relative_path.as_posix()})')

        sections.append('')

    return '\n'.join(sections).rstrip() + '\n'


def main() -> None:
    parser = argparse.ArgumentParser(description='Generate a Markdown index for workshop subdirectories.')
    parser.add_argument('directory', type=Path, help='Workshops directory containing topic subdirectories')
    args = parser.parse_args()

    index_path = args.directory / 'index.md'
    index_path.write_text(build_index(args.directory), encoding='utf-8')
    print(index_path)


if __name__ == '__main__':
    main()