#!/usr/bin/env python3
# Copyright © 2017 Kristof Toth <mrtoth@strongds.hu>
# This program is free software. It comes without any warranty, to the extent
# permitted by applicable law. You can redistribute it and/or modify it under the
# terms of the Do What The Fuck You Want To Public License, Version 2,
# as published by Sam Hocevar. See http://www.wtfpl.net/ for more details.

from subprocess import call, Popen, PIPE, DEVNULL
from os import listdir, remove
from os.path import splitext, exists, join
from re import match
from enum import Enum
from datetime import timedelta
from math import floor
from argparse import ArgumentParser
from signal import signal, SIGINT
from sys import exit
from copy import deepcopy
import utility
from utility import call_verbose, print_opt, get_output, temporary_directory, yes_no_question, check_dependencies


class Stream(Enum):
    AUDIO = 1
    VIDEO = 2

class File(Enum):
    LIST = 1
    LOOP = 2
    FRACTION = 3
    OUTPUT = 4


class DownloadFailure(RuntimeError):
    pass


class coub_dl:
    default_files = {Stream.AUDIO: 'audio', Stream.VIDEO: 'video',
                     File.LIST: 'list.txt', File.LOOP: 'loop', File.FRACTION: 'fraction',
                     File.OUTPUT: 'out'}
    output_files = {File.OUTPUT}


    def __init__(self, url, files_dict, directory):
        self._url = url
        self._files_dict = files_dict
        self._directory = directory


    def __call__(self):
        # download streams and update FILE dict with extensions
        self.download_audio_stream()
        self.download_video_stream()
        self.read_extensions()
        self.check_downloads()
        self.fix_video_stream()

        # get stream lengths via ffprobe
        audioLen = coub_dl.get_length(self._files_dict[Stream.AUDIO])
        videoLen = coub_dl.get_length(self._files_dict[Stream.VIDEO])

        # decide which stream needs some looping
        longer = audioLen if audioLen > videoLen else videoLen
        shorter = audioLen if audioLen < videoLen else videoLen
        shorterFile = self._files_dict[Stream.AUDIO] if audioLen < videoLen else self._files_dict[Stream.VIDEO]
        self._files_dict[File.LOOP] += splitext(shorterFile)[1]
        self._files_dict[File.FRACTION] += splitext(shorterFile)[1]

        # calculate how many times to loop
        times = longer.total_seconds() / shorter.total_seconds()
        timesLoop_base = int(floor(times))
        timesLoop_fraction = times % 1

        # write concat helper file for ffmpeg
        with open(self._files_dict[File.LIST], 'w') as f:
            for i in range(timesLoop_base):
                print("file '{}'".format(shorterFile), file=f)
            print("file '{}'".format(self._files_dict[File.FRACTION]), file=f)

        # loop & mux streams
        self.loop_shorter_stream(shorter, shorterFile, timesLoop_fraction)
        self.mux_streams()


    def download_audio_stream(self):
        call(('youtube-dl', '--ignore-config',
              '--extract-audio',
              '--output', '{}.%(ext)s'.format(self._files_dict[Stream.AUDIO]),
              self._url),
             stdout=DEVNULL, stderr=DEVNULL)


    def download_video_stream(self):
        call(('youtube-dl', '--ignore-config',
              '--output', '{}.%(ext)s'.format(self._files_dict[Stream.VIDEO]),
              self._url),
             stdout=DEVNULL, stderr=DEVNULL)


    def read_extensions(self):
        for file in listdir(self._directory):
            for filename in self._files_dict:
                fullname = join(self._directory, file)
                if match('^{}\..+$'.format(self._files_dict[filename]), fullname):
                    self._files_dict[filename] = fullname


    def check_downloads(self):
        check = {Stream.VIDEO, Stream.AUDIO}
        if not all({exists(self._files_dict[item]) for item in check}):
            raise DownloadFailure()


    def fix_video_stream(self):
        """ magic fix for videos served by coub. see https://github.com/rg3/youtube-dl/issues/13754 """
        with open(self._files_dict[Stream.VIDEO], 'r+b') as f:
            f.seek(0)
            f.write(bytes(2))


    def loop_shorter_stream(self, shorter, shorter_file, loop_fraction):
        # prepare last fractional loop
        call(('ffmpeg', '-i', shorter_file, '-t', str(loop_fraction * shorter.total_seconds()),
              self._files_dict[File.FRACTION]),
             stdout=DEVNULL, stderr=DEVNULL)

        # concat them
        call(('ffmpeg', '-f', 'concat', '-safe', '0', '-i', self._files_dict[File.LIST],
              '-c', 'copy', self._files_dict[File.LOOP]),
             stdout=DEVNULL, stderr=DEVNULL)


    def mux_streams(self):
        call(('ffmpeg', '-i', self._files_dict[File.LOOP],
              '-i', self._files_dict[Stream.AUDIO],
              '-map', '0:v:0', '-map', '1:a:0',
              '-c', 'copy', self._files_dict[File.OUTPUT]),
             stdout=DEVNULL, stderr=DEVNULL)


    @staticmethod
    def get_length(file):
        data = coub_dl.get_duration(coub_dl.get_command_stderr(('ffprobe', file))).split(':')
        return timedelta(hours=float(data[0]), minutes=float(data[1]), seconds=float(data[2]))


    @staticmethod
    def get_command_stderr(command):
        process = Popen(command, stderr=PIPE, stdout=PIPE)
        out, err = process.communicate()
        return err


    @staticmethod
    def get_duration(ffprobe_output):
        durationPattern = r'.*Duration:\s(.+),\sstart.*'
        regex = match(durationPattern, str(ffprobe_output))
        duration = regex.groups()[0] if regex else None
        if not duration:
            raise ValueError('Cannot process ffprobe output!')
        return duration


    @staticmethod
    def get_title(url):
        return get_output(('youtube-dl', '--get-title', url))


def run(URL, output, extension):
    # create dict that contains files used
    FILES = deepcopy(coub_dl.default_files)
    determine_output_filename(URL, output, extension, FILES)

    # ask what to do if output exists
    if exists(FILES[File.OUTPUT]):
        answer = yes_no_question('A file named "{}" already exists! Overwrite?'.format(FILES[File.OUTPUT]),
                                 default='no')
        if not answer:
            print_opt('Exiting!')
            exit()
        else:
            remove(FILES[File.OUTPUT])

    # create temporary directory to work in
    with temporary_directory() as dir:
        # update temporary file locations in FILES dict
        for key in {key: FILES[key] for key in FILES if key not in coub_dl.output_files}:
            FILES[key] = join(dir, FILES[key])

        coub_dl(URL, FILES, dir)()


def determine_output_filename(url, user_supplied, extension, files_dict):
    if user_supplied is None:
        files_dict[File.OUTPUT] = coub_dl.get_title(url)
    else:
        files_dict[File.OUTPUT] = user_supplied
    files_dict[File.OUTPUT] += extension


def parse_cmd_arguments():
    parser = ArgumentParser(description='Download player-looped videos with youtube-dl & ffmpeg.')
    parser.add_argument('-nv', '--nonverbose', action='store_true', help='Turn off non-critical messages to user')
    parser.add_argument('-o', '--output', default=None, help='Specify name of the output file (use -e for extension)')
    parser.add_argument('-e', '--extension', default='mp4', help='Set the container to use for the output')
    parser.add_argument('URLs', type=str, nargs='+', help='The URLs of the sites containing the videos to download')

    args = parser.parse_args()
    args.extension = '.' + args.extension

    return args


def decorate_coubdl_uimsgs(*args):
    for item in args:
        setattr(coub_dl, item[0],
                call_verbose(**item[1])(getattr(coub_dl, item[0])))


if __name__ == '__main__':
    signal(SIGINT, lambda a, b: exit('\nExiting!'))
    args = parse_cmd_arguments()
    utility.VERBOSE = False if args.nonverbose else True
    decorate_coubdl_uimsgs(('download_audio_stream', {'before_message': 'Downloading audio stream... '}),
                           ('download_video_stream', {'before_message': 'Downloading video stream... '}),
                           ('loop_shorter_stream',   {'before_message': 'Looping shorter stream... '}),
                           ('mux_streams',           {'before_message': 'Muxing streams... '}))

    check_dependencies((('youtube-dl', '--version'), ('ffmpeg', '-version')))

    for url in set(args.URLs):
        print_opt('\nCreating video from {}'.format(url))
        try: run(url, args.output, args.extension)
        except DownloadFailure: exit('Failed to download streams! This usually happens when Coub changes something.')