from __future__ import unicode_literals
import youtube_dl
from os import path, listdir, rename, mkdir
import sys
# sudo apt-get install ffmpeg ## Also required

# RUN:
# Python3 mp3_downloader.py (assumes songs.txt in the same dir with links)
# Python3 mp3_downloader.py <file_with_links_relative_to_script>


def get_all_links(this_dir, file_name):
    with open(path.join(this_dir, './%s' % file_name)) as f:
        return [w.rstrip() for w in f.readlines() if w.strip()]


def all_links_valid(links):
    ydl_opts = {
        'quiet': True,
        'skip_download': True,
        'format': 'bestaudio/best',
        'postprocessors': [{
            'key': 'FFmpegExtractAudio',
            'preferredcodec': 'mp3',
            'preferredquality': '320',
        }],
    }
    with youtube_dl.YoutubeDL(ydl_opts) as ydl:
        try:
            ydl.download(links)
        except:
            return False
    return True


def download_all(links):
    ydl_opts = {
        'format': 'bestaudio/best',
        'postprocessors': [{
            'key': 'FFmpegExtractAudio',
            'preferredcodec': 'mp3',
            'preferredquality': '320',
        }],
    }
    with youtube_dl.YoutubeDL(ydl_opts) as ydl:
        ydl.download(links)


def get_all_file_names(this_dir, script_files):
    return {x for x in listdir(this_dir) if path.isfile(path.join(this_dir, x))} - script_files


def new_name(old_name):
    return '-'.join(old_name.split('-')[:-1]) + '.mp3'


def move_all_files(this_dir, script_files):
    for name in get_all_file_names(this_dir, script_files):
        rename(path.join(this_dir, name), path.join(path.join(this_dir, './output/'), new_name(name)))


def check_folder(this_dir):
    folder = path.join(this_dir, './output/')
    if not path.exists(folder):
        mkdir(folder)


def main(args):
    file_name = args[0] if args else 'songs.txt'
    script_files = {file_name, 'downloader.py'}
    this_dir = path.abspath(path.dirname(__file__))
    links = get_all_links(this_dir, file_name)
    if not all_links_valid(links):
        print('At least one link is invalid')
        return
    download_all(links)
    check_folder(this_dir)
    move_all_files(this_dir, script_files)


if __name__ == '__main__':
    main(sys.argv[1:])