Added database support

- Database keeps a record of already processed songs.
- Successfully downloaded songs are not processed again, this behavior allows
  the download to be interrupted and resumed several times.
- Failure to download songs is recorded as well, these cases should be inspected
  manually for now.

.gitignore

@@ -0,0 +1,2 @@
+songs.db
+

README.md

@@ -0,0 +1,37 @@
+Google Play Music Library Download
+=
+
+This script will download your whole google play music library. Each downloaded song is saved into a database, so if the script fails while running, you won't be downloading songs twice. If a song fails downloading, it will be saved to database with downloaded equals to 0: you should try downloading this again manually.
+
+The generated directory structure is of the format:
+
+`[album_artist | artist]/album_name`
+
+And inside each album, you will get:
+
+`track_id - track_name`
+
+Usage
+-
+
+- In a terminal run:
+
+`python download_library.py`
+
+- You will get a link to login with the google account where all the music is, google will give you a string that you have to copy and then paste it back into the terminal and hit enter.
+
+- Let it r(b)u(r)n.
+
+
+Dependencies
+-
+
+- Python >= v3.6
+
+### Packages
+
+For this program to work you will need to (virtual environment recommended) install:
+
+- (pip install) sqlite3
+- (pip install) gmusicapi
+

download_library.py

@@ -6,80 +6,108 @@ from gmusicapi import Musicmanager
 from os import path
 
 
-logger = logging.getLogger(__name__)
-
-
-def save_log(text):
-	log_file = open("log", "a")
-	log_file.write(text)
-	log_file.close()
-
-
-def create_db():
+def start_db():
 	try:
 		sqliteConnection = sqlite3.connect('songs.db')
-		sqlite_create_table_query = '''CREATE TABLE success_ids (
+		sqlite_create_table_query = '''CREATE TABLE IF NOT EXISTS song (
 					id INTEGER PRIMARY KEY,
-					google_id TEXT NOT NULL;'''
+					google_id TEXT NOT NULL,
+					downloaded INTEGER);'''
 
 		cursor = sqliteConnection.cursor()
 		cursor.execute(sqlite_create_table_query)
 
-		sqlite_create_table_query = '''CREATE TABLE failure_ids (
-					id INTEGER PRIMARY KEY,
-					google_id TEXT NOT NULL;'''
-		cursor.execute(sqlite_create_table_query)
-
 		sqliteConnection.commit()
 
 		cursor.close()
 
 	except sqlite3.Error as exc:
-		logger.error(f'Error creating the database: {exc}')
+		return
+
+	return sqliteConnection
+
+
+def insert_song(connection, song_id, failure=False):
+	sql = ''' INSERT INTO song (google_id, downloaded)
+	      VALUES(?,?) '''
+
+	cursor = connection.cursor()
+	cursor.execute(sql, (song_id, int(not failure)))
+	connection.commit()
+	lastrowid = cursor.lastrowid
+	cursor.close()
+
+	return lastrowid
+
 
+def get_all_song_ids(connection):
+	sql = ''' SELECT google_id from song WHERE downloaded = 1;'''
 
+	cursor = connection.cursor()
+	cursor.execute(sql)
+	results = cursor.fetchall()
+	return {r[0] for r in results}
 
+
+def main():
 	mm = Musicmanager()
 	mm.perform_oauth()
 	mm.login()
 	songs = mm.get_uploaded_songs(incremental=False)
 
-
-logger.info(f'There\'s {len(songs)} songs to download . . .')
+	db_connection = start_db()
+	already_downloaded = get_all_song_ids(db_connection)
 
 
 	for song in songs:
+		song_id = song['id']
+
+		if song_id in already_downloaded:
+			continue
+
 		if song['album_artist']:
 			level_one = song['album_artist']
 		elif song['artist']:
 			level_one = song['artist']
 		else:
 			level_one = 'Unknown Artist'
+
 		if song['album']:
 			level_two = song['album']
 		else:
 			level_two =  'Unknown Album'
+
 		full_path = f'{level_one}/{level_two}'
+
 		try:
 			os.mkdir(level_one)
 		except FileExistsError:
 			pass
 		except Exception as exc:
-		save_log(f"\n\n{song} \n {exc} \n\n")
+			insert_song(db_connection, song_id, True)
 			continue
+
 		try:
 			os.mkdir(full_path)
 		except FileExistsError:
 			pass
 		except Exception as exc:
-		save_log(f"\n\n{song} \n {exc} \n\n")
+			insert_song(db_connection, song_id, True)
 			continue
+
 		try:
-		downloaded_song = mm.download_song(song['id'])
+			downloaded_song = mm.download_song(song_id)
 		except Exception as exc:
-		save_log(f"\n\n{song} \n {exc} \n\n")
+			insert_song(db_connection, song_id, True)
+
 		full_path += f"/{downloaded_song[0]}"
 		file_path = path.relpath(full_path)
+	
 		file_to_write = open(file_path, "wb")
 		file_to_write.write(downloaded_song[1])
 		file_to_write.close()
+		insert_song(db_connection, song_id)
+
+
+if __name__ == "__main__":
+    main()