Support reorganizing an archive, begin playlist

Also add more fields to the DB representation of a song.

archiver/archive.py

@@ -76,7 +76,8 @@ class Archive (models.Model):
 						self.songs.add(new_song)
 
 	def _update_song_metadata(self, use_echonest = False, progress_callback = lambda x, y: None):
-		"Scan every song in this archive (database only) and make sure all songs are correct"
+		"""Scan every song in this archive (database only) and make sure all songs are correct
+		The progress_callback function is called with the current song being operated on first, and the total songs second."""
 		#This method operates only on the songs that are in the database - if you need to make
 		#sure that new songs are added, use the _scan_filesystem() method in addition
 		total_songs  = self.songs.count()
@@ -127,3 +128,68 @@ class Archive (models.Model):
 		if force_backup or self._needs_backup():
 			import subprocess
 			subprocess.call(['rsync', '-av', self.root_folder, self.backup_location])
+
+	def reorganize(self, format_string, progress_function = lambda x, y: None, song_status_function = lambda x, y: None, dry_run = False):
+		"""Reorganize a music archive using a specified format string.
+		Recognized escape characters:
+		%a - Artist Name                     %A - Album Name
+		%d - Disc Number                     %e - Number of discs
+		%f - Current Filename (no extension) %g - Current Filename (with extension)
+		%n - Track Number                    %o - Number of tracks on disc
+		%y - Album year
+
+		Note that all organization takes place relative to the archive's root folder.
+		The progress_function is called with the current song number as its first argument, and total songs as its second.
+		The song_status_function is called with the current song url as its first argument, and new url as its second."""
+		import os, shutil, errno
+
+		for song in self.songs.all():
+			_current_filename              = os.path.basename(song.url)
+			_current_filename_no_extension = os.path.splitext(_current_filename)[0]
+
+			_release_year = song.release_date.year
+
+			new_location = format_string.replace("%a", song.artist)\
+										.replace("%A", song.album)\
+										.replace("%d", song.disc_number)\
+										.replace("%e", song.disc_total)\
+										.replace("%f", _current_filename)\
+										.replace("%g", _current_filename_no_extension)\
+										.replace("%n", song.track_number)\
+										.replace("%o", song.track_total)\
+										.replace("%y", _release_year)
+
+			new_url = os.path.join(self.root_folder, new_location)
+
+			song_status_function(song.url, new_url)
+
+			if not dry_run:
+				new_folder = os.path.dirname(new_url)
+				try:
+					#`mkdir -p` functionality
+					if not os.path.isdir(new_folder):
+						os.makedirs(new_folder)
+
+					#Safely copy the file - don't 'move' it, but do a full 'copy' 'rm'
+					#This way if the process is ever interrupted, we have an unaltered copy
+					#of the file.
+					shutil.copyfile(song.url, new_url)
+					shutil.copystat(song.url, new_url)
+
+					#Notify the database about the new URL
+					old_url  = song.url
+					song.url = new_url
+					song.save()
+
+					#Actually remove the file since all references to the original location have been removed
+					os.remove(old_url)
+
+				except OSError as exc:
+					if exc.errno == errno.EEXIST and os.path.isdir(new_folder):
+						#This is safe to skip - makedirs() is complaining about a folder already existing
+						pass
+					else: raise
+
+				except IOError as exc:
+					#shutil error - likely that folders weren't specified correctly
+					raise

archiver/listfield.py

@@ -0,0 +1,48 @@
+from django.db import models
+import re, itertools
+
+class IntegerListField(models.TextField):
+	"""Store a list of integers in a database string.
+	Format is: 
+	[<int_1>, <int_2>, <int_3>, ... , <int_n>]"""
+
+	description = "Field type for storing lists of integers."
+
+	__metaclass__ = models.SubfieldBase
+
+	def __init__(self, *args, **kwargs):
+		super(IntegerListField, self).__init__(*args, **kwargs)
+
+
+	#Convert database to python
+	def to_python(self, value):
+		if isinstance(value, list):
+			return value
+
+		#Process a database string
+		
+		#Validation first
+		if value[0] != '[' or value[-1] != ']':
+			raise ValidationError("Invalid input to parse a list of integers!")
+
+		#Note that any non-digit string is a valid separator
+		_csv_regex = "[0-9]"
+		csv_regex  = re.compile(_csv_regex)
+
+		#Synonymous to:
+		#string_list = filter(None, csv_regex.findall(value))
+		string_list  = itertools.ifilter(None, csv_regex.findall(value))
+		value_list   = [int(i) for i in string_list]
+
+		return value_list
+
+	#Convert python to database
+	def get_prep_value(self, value):
+		if not isinstance(value, list):
+			raise ValidationError("Invalid list given to put in database!")
+
+		separator_string = ", "
+
+		list_elements = separator_string.join(value)
+
+		return "[" + list_elements + "]"

archiver/playlist.py

@@ -0,0 +1,98 @@
+from django.db import models
+
+from song import Song
+from listfield import IntegerListField
+
+"""
+Playlist model
+Each playlist is a high-level ordering of songs. That's really it...
+"""
+
+class Playlist (models.Model):
+	"The Playlist class defines the playlist model and its operations"
+
+	name       = models.CharField(max_length = 255)
+	song_order = IntegerListField()
+
+	#This is a bit of a backup field, since technically the song PK's are in
+	#the song_order field. However, it might be useful to just get a reference
+	#to the songs in this playlist. Additionally, it's kind of hackish to reference
+	#the global Song manager, rather than something that is specific for this playlist.
+	songs      = models.ManyToManyField(Song)
+
+	def _populate_songs(self):
+		"""Make sure that the 'songs' relation is up-to-date."""
+		#This operation works by getting the ID's for all songs currently in the playlist,
+		#calculates what we need to add, what we need to remove, and then does it.
+		#As much work as is possible is done on the python side to avoid the DB
+		current_song_ids     = [song.id for song in self.songs.all()]
+		current_song_ids_set = set(current_song_ids)
+
+		new_song_ids_set = set(song_order)
+
+		remove_set = current_song_ids_set.difference(new_song_ids_set)
+		add_set    = new_song_ids_set.difference(current_song_ids_set)
+
+		for song_id in remove_set:
+			song = self.songs.get(id = song_id)
+			song.remove()
+
+		for song_id in add_set:
+			song = Song.objects.get(id = song_id) #Using the global Songs manager is unavoidable for this one
+			self.songs.add(song)
+
+	def insert(self, position, new_song):
+		"""Insert a new song into the playlist at a specific position."""
+
+		if not isinstance(new_song, Song):
+			#Not given a song reference, raise an error
+			raise ValidationError("Not given a song reference to insert.")
+			
+		self.songs.add(new_song)
+
+		self.song_order.insert(position, new_song.id)
+
+		_populate_songs()
+
+	def append(self, new_song):
+		"""Add a new song to the end of the playlist."""
+		if not isinstance(new_song, Song):
+			#Not given a song reference, raise an error
+			raise ValidationError("Not given a song reference to insert.")
+
+		self.songs.add(new_song)
+
+		self.song_order.append(new_song.id)
+
+	def move(self, original_position, new_position):
+		"""Move a song from one position to another"""
+		if original_position == new_position:
+			return
+
+		song_id = self.song_order[original_position]
+
+		#This is actually a bit more complicated than it first appears, since the index we're moving to may actually change
+		#when we remove an item.
+		if new_position < original_position:
+			del self.song_order[original_position]
+			self.song_order.insert(new_position, song_id)
+
+		else:
+			del self.song_order[original_position]
+			self.song_order.insert(new_position - 1, song_id) #Account for the list indices shifting down.
+
+	def remove(self, position):
+		if position > len(self.song_order):
+			return False
+
+		del self.song_order[position]
+
+	def export(self, playlist_type = "m3u"):
+		"""Export this internal playlist to a file format."""
+		#Default m3u playlist type, support others as I build them.
+
+		if playlist_type = "pls":
+			pass
+
+		else:
+			#Export m3u, default option

archiver/song.py

@@ -9,12 +9,16 @@ This database model is used for storing the metadata information about a song,
 and helps in doing sorting etc.
 """
 
-_default_title        = "<UNAVAILABLE>"
+_default_title        = "_UNAVAILABLE_"
-_default_artist       = "<UNAVAILABLE>"
+_default_artist       = "_UNAVAILABLE_"
-_default_album        = "<UNAVAILABLE>"
+_default_album        = "_UNAVAILABLE_"
 _default_release_date = datetime.datetime.now #Function will be called per new song, rather than once at loading the file
-_default_genre        = "<UNAVAILABLE>"
+_default_genre        = "_UNAVAILABLE_"
 _default_bpm          = -1
+_default_disc_number  = -1
+_default_disc_total   = -1
+_default_track_number = -1
+_default_track_total  = -1
 
 _default_bit_rate         = -1
 _default_duration         = -1
@@ -34,6 +38,10 @@ class Song (models.Model):
 	release_date = models.DateField(default    = _default_release_date)
 	genre        = models.CharField(max_length = 64, default            = _default_genre)
 	bpm          = models.IntegerField(default = _default_bpm)
+	disc_number  = models.IntegerField(default = _default_disc_number)
+	disc_total   = models.IntegerField(default = _default_disc_total)
+	track_number = models.IntegerField(default = _default_track_number)
+	track_total  = models.IntegerField(default = _default_track_total)
 
 	#File metadata
 	bit_rate         = models.IntegerField(default = _default_bit_rate)
@@ -77,6 +85,10 @@ class Song (models.Model):
 				self.artist       = track_metadata.artist_name or _default_artist
 				self.album        = track_metadata.album_name  or _default_album
 				self.release_date = datetime.date(int(track_metadata.year or 1), 1, 1)
+				self.track_number = track_metadata.track_number or _default_track_number
+				self.track_total  = track_metadata.track_total  or _default_track_total
+				self.disc_number  = track_metadata.album_number or _default_disc_number
+				self.disc_total   = track_metadata.album_total  or _default_disc_total
 				self.bpm          = _default_bpm
 
 				self.bit_rate         = track.bits_per_sample() or _default_bit_rate