#!/usr/bin/env python3

from argparse import ArgumentParser
from os import path
from subprocess import run

from git import Repo

from helpers import compute_directories


def parse_arguments():
    parser = ArgumentParser()
    parser.add_argument(
        'extensions', type=str.split,
        help='File extensions to consider when recording pages.'
    )
    parser.add_argument(
        'target', help='Folder to generate an index for.'
    )
    parser.add_argument(
        'output', help='Path to the output file.'
    )
    return parser.parse_args()


def list_files(extensions, folder, repo):
    directories = compute_directories(extensions, repo)
    return directories[folder].subfolders, directories[folder].files


def generate_index_page(title, directories, files, intro_file):
    intro_text = ''
    if intro_file is not None:
        with open(intro_file) as intro:
            intro_text = intro.read()

    dir_list = '\n'.join(
        f'- [{d}/]({d}/index.html)' for d in directories
    )

    file_list = '\n'.join(
        f'- [{f}]({f}.html)' for f in files
    )

    return f'''\
% {title}

{intro_text}

{dir_list}
{file_list}
'''

def convert_page(content, output):
    run(
        ('pandoc', '-s', '-o', output), input=content, check=True, text=True
    )


def main(arguments):
    repo = Repo(search_parent_directories=True)

    target_path = arguments.target
    extensions = arguments.extensions

    target = path.relpath(target_path, repo.working_dir)
    if target == '.':
        target =''

    folders, files = list_files(extensions, target, repo)

    names = []
    intro = None

    for f in files:
        name, _ = path.splitext(f)
        if name == 'README':
            intro = path.join(repo.working_dir, target, f)
        else:
            names.append(name)

    title = path.basename(target) if target else 'index'

    convert_page(
        generate_index_page(title, folders, names, intro),
        arguments.output
    )


if __name__ == '__main__':
    main(parse_arguments())