design: Rework playlists, add filtering

Signed-off-by: Bryan Schumaker <bjschuma@gmail.com>

design.txt

@@ -21,6 +21,7 @@ Files:
 		database.h
 		database.hpp
 		file.h
+		filter.h
 		group.h
 		index.h
 		library.h
@@ -43,6 +44,7 @@ Files:
 		genre.db
 		groups.idx
 		library.db
+		playlists.lst
 		track.db
 
 
@@ -208,7 +210,8 @@ Database: (lib/database.cpp)
 
 - API:
 	Database.Database(filename);
-		Initializes database to use ~/.ocarina{-debug}/filename
+		Initializes database to use ~/.ocarina{-debug}/filename.  Pass
+		an empty string if you do not want this database to be saved.
 	Database.load();
 		Reads data from file.  Call after static initialization of
 		Ocarina to ensure idle tasks are configured.
@@ -249,7 +252,8 @@ Index: (lib/index.cpp)
 
 - API:
 	Index.Index(filename);
-		Initializes an index using ~/.ocarina{-debug}/filename
+		Initializes an index using ~/.ocarina{-debug}K/filename.  Pass
+		an empty string if you do not want this index to be saved.
 	Index.load();
 		Reads data from a file.  Call after static initialization of
 		Ocarina to ensure idle tasks are configured
@@ -361,8 +365,8 @@ Library: (lib/library.cpp)
 	2) For each file in the scan directory, check if (lib_id, track_path)
 	   exists in the known_tracks map.
 	   2a) If the file is in the map, do nothing.
-	   2b) Else, add track to the library and to the "All Music" and
-	       "Library" and "Unplayed Tracks" groups
+	   2b) Else, add track to the library, to the groups "All Music" and
+	       "Library", and then to the filter index.
 	3) Save all databases
 
 	The taglib library should be used for finding artist, album, etc. tags
@@ -404,8 +408,6 @@ Groups: (lib/group.cpp)
 	Banned Songs
 		These groups are mutually exclusive.  A track is either
 		in the Library or the Banned Songs group
-	Unplayed tracks
-		Tracks with a play count of 0
 
 - API
 	group :: init();
@@ -437,26 +439,97 @@ Preferences: (lib/prefs.cpp)
 
 
 Playlist: (lib/playlist.cpp)
-	A playlist is a simple list of songs that can be played either randomly
-	or in a user-defined order.  It would probably be best to use a linked
-	list or vector to represent playlists, rather than creating a SQLite
-	table.  I will be able to easily rearrange tracks in the playlist this
-	way.  This will also make it easier to deal with playlist renames and
-	reordering by the user.
+	Playlists are a list of songs that the user has configured to play.  I
+	will create a pool of playlists that will be filled by user actions.
+
+	Playlists will be put on a "deck" that is used to give an order to the
+	next songs played.  When deck :: next() is called, find the first
+	playlist with PL_ENABLED set and call that playlists next() function.
+
+	When a playlist is empty, remove it from the deck.
+
+- Flags:
+	enum playlist_flags {
+		PL_ENABLED (1 << 0),
+		PL_RANDOM  (1 << 1),
+		PL_DRAIN   (1 << 2),
+	};
+
+- Playlist:
+	class Playlist : public Database {
+	private:
+		database<track_id> tracks; /* Keyed on track id */
+		unsigned int cur;
+		unsigned int flags;
+	public:
+		Playlist();
+		void add(vector<track_id> &);
+		void del(vector<track_id> &);
+		void set_flag(playlist_flags);
+		const unsigned int get_flags();
+		unsigned int size()
+
+		File &operator<<(File &);
+		File &operator>>(File &);
+
+		void sort();
+		void next();
+	}
+
+	File << flags << cur << tracks[0] << tracks[1] << ... << tracks[N];
+
+- Deck:
+	list<Playlist> deck;
+	File << deck[0] << endl;
+	File << deck[1] << endl;
+	File << deck[N] << endl;
 
 - API
-	/* Playlist management */
-	new_playlist();
-	del_playlist(playlist);
-	add_to_playlist(playlist, songid);
-	rm_from_playlist(playlist, songid);
-	playlist_size(playlist)
-	set_flag(playlist, flag)
+	deck :: init();
+		Read in the playlist file
+	deck :: new();
+		Adds a new playlist to the deck
+	deck :: rm(N)
+		Removes playlist N from the deck
+	Playlist *deck :: get(N)
+		Return playlist N from the deck
 
-- Flags
-	PL_ENABLED (1 << 0)
-	PL_RANDOM  (1 << 1)
-	PL_DRAIN   (1 << 2)
+- TODO										<<<<<
+	What if each playlist has its own playlist_id for tracks?  This would
+	allow for simpler removals, since I won't need to search for a track id.
+	I can easily create a function for mapping a list of playlist_ids to
+	track_ids...
+
+
+
+Filter: (lib/filter.cpp)
+	Filtering is used to generate a subset of songs for easier searching.
+
+- Index:
+	map<string, string> lowercase_cache;
+	map<string, set<string>> substring_cache;
+	Index filter_index("");
+
+- Parsing:
+	1) Convert the provided string into a list of words, using whitespace
+	   and the following characters as delimiters: \/,;()_~+"
+
+	For each word:
+	    2) Check the lowercase_cache to see if we have seen the word before,
+	       a) If we have, return the stored string
+	       b) Convert the string to lowercase and strip out remaining
+	          special characters.  Add the result to the lowercase_cache;
+	    3) Check the substring_cache to see if we have seen the word before,
+	       a) If we have, use the substring set returned
+	       b) Break the word into substrings from the front only.  For
+	          example:  "dalek" would contain the substrings
+	          {d, da, dal, dale, dalek}.  Add to the substring cache.
+
+- API:
+	filter :: add(string, track_id);
+		Parses the string and adds the track_id to the index.
+	void filter :: search(string, set<track_id> &);
+		Parse the string and fill in the set with matching tracks.
 
 
 
@@ -468,6 +541,12 @@ Future work:
 
 	Hint:  If feature B depends on A, implement A in 6.x and B in 6.x+1
 
+	- Break design doc into pieces: (6.1)
+		Createa script to join everything together cleanly.
+
+	- New default groups: (6.1)
+		Unplayed tracks
+
 	- Categories: (6.1)
 		Use these to make "groups of groups" for better organization.
 		Different categories can include Album, Artist and Genere
@@ -500,3 +579,15 @@ Future work:
 	- Track tag editor: (6.2)
 		Make a pop-up window for editing the tags of a track.  Be sure
 		to update the library information and the on-disk file.
+
+	- Clean up Scons files / build system: (6.0)				<<<<<
+		I just had to try looking up something for Josh.  I have no idea
+		how my build system works anymore.  This is bad.
+
+	- Album art: (6.1)
+
+	- Playlist custom sorting: (6.1)
+		Click column headers to choos sort order
+		Keep a list of fields that the user has selected and place new
+		fields in the front of this list.  Use a recursive stable sort
+		to do the sorting.