# This program will download artists from a queue file.
# Multiple instances of this program can run simultaniously.
# Previously downloaded albums and singles are skipped, newly found albums and singles are downloaded.

# Use this program with flag --test to see what it will download.

from ytmusicapi import YTMusic
import sys
import argparse
import os
import subprocess 
from subprocess import Popen, PIPE, STDOUT

try:
    from subprocess import DEVNULL # py3k
except ImportError:
    import os
    DEVNULL = open(os.devnull, 'wb')

parser = argparse.ArgumentParser(description='Music downloader.')
parser.add_argument('--test', action='store_true', help='Test script without downloading anything.')
parser.add_argument('--update', action='store_true', help='Retrieve artists from output directory and download missing albums and singles. Overwrites queue file.')
parser.add_argument('--out', type=str, default='download', 
                    help='Output directory. (default: folder /download/ will be created in active directory.)')
parser.add_argument('--queue', type=str, default='queue.txt', 
                    help='Input queue file. .txt file with artists separated by newline. When testing with --test, test_ is prepended to queue file. e.g. test_queue.txt')
args = parser.parse_args()

ytmusic = YTMusic()
queue_test_file = 'test_' + args.queue
queue_file = args.queue
output_dir = args.out
do_download = True

if args.test:
	do_download = False
	queue_file = queue_test_file

# Write out own queue file if updating existing library.
if args.update:
	print('Updating existing library: getting artist list...')
	filenames = [f for f in os.listdir(output_dir) if os.path.isdir(os.path.join(output_dir, f))]
	filenames.sort()
	print(f'Found {len(filenames)} artists to check.')
	with open(queue_file, 'w') as file:
		for line in filenames:
			file.write(line + '\n')


def artist_is_external(name, complete_albums):
	directory_path = output_dir+'/'+name
	if not os.path.exists(directory_path):
		return False

	album_titles = [album['title'] for album in complete_albums]
	album_titles = album_titles.copy()
	album_titles.append('Singles')

	filenames = [f for f in os.listdir(directory_path) if os.path.isdir(os.path.join(directory_path, f))]

	# Find albums that are on disk, but are not is discography list.
	unknown_albums = [elem for elem in filenames if elem not in album_titles]

	if len(unknown_albums) > 0:
		return True

	return False


try:
	while True:
		print('')
		## Pop item from top of list and write back file.
		with open(queue_file, 'r') as file:
			lines = file.readlines()

		lines = [line.strip() for line in lines if line.strip()]
		artist_to_download = lines.pop(0)

		with open(queue_file, 'w') as file:
			for line in lines:
				file.write(line + '\n')

		artist_id_to_download = 0
		
		## Find artist id by name.
		search_results = ytmusic.search(artist_to_download, filter='artists')
		if search_results:
			for artist in search_results:
				artist_id_to_download = artist['browseId']
				print(f"Found artist: {artist['artist']}, ID: {artist['browseId']} ({len(lines)} left in queue)")
				break
		else:
			print(f"No artists found for {artist_to_download}")
			continue


		artist_result = ytmusic.get_artist(artist_id_to_download)
		artist_name = artist_to_download #artist_result['name']

		## Collect albums and singles to download.
		albums = []
		singles = []
		if 'albums' in artist_result:
			albums = artist_result['albums']['results']
			if artist_result['albums']['browseId'] != None:
				albums = ytmusic.get_artist_albums(artist_result["albums"]["browseId"], artist_result["albums"]["params"], 9999)

		if 'singles' in artist_result:
			singles = artist_result['singles']['results']
			if artist_result['singles']['browseId'] != None:
				singles = ytmusic.get_artist_albums(artist_result["singles"]["browseId"], artist_result["singles"]["params"], 9999)

		if artist_is_external(artist_name, albums):
			print(f'Artist {artist_name} was downloaded externally and has been skipped.')
			continue

		# Check if artist albums and singles are downloaded already by counting.
		#directory_path = output_dir+'/'+artist_name+'/Singles'
		#existing_single_count = sum(1 for entry in os.listdir(directory_path) if os.path.isfile(os.path.join(directory_path, entry)))
		directory_path = output_dir+'/'+artist_name.replace('/', r'\/')
		existing_album_count = sum(1 for entry in os.listdir(directory_path) if os.path.isdir(os.path.join(directory_path, entry)))
		if existing_album_count == len(albums)+1: # Ideally we check single count here too but we have no way to find out how many singles the artist actually has.
			print(f'Artist {artist_name} is complete.')
			continue

		# 1. Download albums
		print('Artist "' + artist_name + '" has ' + str(len(albums)) + ' albums...')
		for index, album in enumerate(albums):
			albumdata = ytmusic.get_album(album['browseId'])
			album_name = albumdata['title']

			# Skip existing albums.
			directory_path = output_dir+'/'+artist_name+'/'+album_name
			if os.path.exists(directory_path) and os.path.isdir(directory_path):
				print(f'Skipping existing album "{album_name}"')
				continue
			
			print(f'Downloading "{album_name}"', end='\r')

			# Construct the command as a list
			command = [
				'./yt-dlp_linux',
				f"https://music.youtube.com/playlist?list={albumdata['audioPlaylistId']}",
				'-o',
				output_dir+'/'+artist_name+'/'+album_name+'/%(title)s.%(ext)s',  # Adjust the path as needed
				'-x',
				'--audio-format',
				'mp3',
				'--embed-thumbnail',
				'--add-metadata',
				'--no-overwrites'
			]

			if not do_download:
				print(f'Skipped download of album {album_name}')
				continue

			p = subprocess.Popen(command, stdin=PIPE, stdout=DEVNULL, stderr=STDOUT)
			(output, err) = p.communicate()  
			p_status = p.wait()

			directory_path = output_dir+'/'+artist_name+'/'+album_name
			if os.path.exists(directory_path) and os.path.isdir(directory_path):
				print(f'Downloaded "{album_name} ({index+1}/{len(albums)})"')
			else:
				print('Download failed')
				exit()

		# 2. Download singles
		print('Artist "' + artist_name + '" has ' + str(len(singles)) + ' singles...')
		for index, single in enumerate(singles):
			singledata = ytmusic.get_album(single['browseId'])
			single_name = singledata['title']

			# Skip existing albums.
			directory_path = output_dir+'/'+artist_name+'/Singles/'+single_name+'.mp3'
			if os.path.exists(directory_path):
				print(f'Skipping existing single "{single_name}"')
				continue
			
			print(f'Downloading "{single_name}"', end='\r')

			# Construct the command as a list
			command = [
				'./yt-dlp_linux',
				f"https://music.youtube.com/playlist?list={singledata['audioPlaylistId']}",
				'-o',
				output_dir+'/'+artist_name+'/Singles/%(title)s.%(ext)s',  # Adjust the path as needed
				'-x',
				'--audio-format',
				'mp3',
				'--embed-thumbnail',
				'--add-metadata',
				'--no-overwrites'
			]

			if not do_download:
				print(f'Skipped download of single {single_name}')
				continue

			p = subprocess.Popen(command, stdin=PIPE, stdout=DEVNULL, stderr=STDOUT)
			(output, err) = p.communicate()  
			p_status = p.wait()

			if os.path.exists(directory_path):
				print(f'Downloaded "{single_name} ({index+1}/{len(singles)})"')
			else:
				print('Download failed')
				exit()
except KeyboardInterrupt:
    print('Download cancelled')

print('Download finished')