use osu's previewtime

app.py

 #!/usr/bin/env python2
 
 import sqlite3
+import re
+import os
 from flask import Flask, g, jsonify
 
 app = Flask(__name__)
@@ -21,6 +23,42 @@ def query_db(query, args=(), one=False):
     return (rv[0] if rv else None) if one else rv
 
 
+def parse_osu(osu):
+    osu_lines = open(osu, 'r').read().replace('\x00', '').split('\n')
+    sections = {}
+    current_section = (None, [])
+
+    for line in osu_lines:
+        line = line.strip()
+        secm = re.match('^\[(\w+)\]$', line)
+        if secm:
+            if current_section:
+                sections[current_section[0]] = current_section[1]
+            current_section = (secm.group(1), [])
+        else:
+            if current_section:
+                current_section[1].append(line)
+            else:
+                current_section = ('Default', [line])
+    
+    if current_section:
+        sections[current_section[0]] = current_section[1]
+
+    return sections
+
+
+def get_osu_key(osu, section, key, default=None):
+    sec = osu[section]
+    for line in sec:
+        ok = line.split(':', 1)[0].strip()
+        ov = line.split(':', 1)[1].strip()
+
+        if ok.lower() == key.lower():
+            return ov
+
+    return default
+
+
 @app.teardown_appcontext
 def close_connection(exception):
     db = getattr(g, '_database', None)
@@ -30,19 +68,25 @@ def close_connection(exception):
 
 @app.route('/api/songs')
 def route_api_songs():
-	songs = query_db('select * from songs where enabled = 1')
-	songs_out = []
-	for song in songs:
-		print song
-		songs_out.append(
-			{'id': song[0], 'title': song[1], 'title_en': song[2], 'stars': {
-				'easy': song[3], 'normal': song[4],
-				'hard': song[5], 'oni': song[6]
-			}}
-		)
+    songs = query_db('select * from songs where enabled = 1')
+    songs_out = []
+    for song in songs:
+        osus = [osu for osu in os.listdir('songs/%s' % song[0]) if osu in ['easy.osu', 'normal.osu', 'hard.osu', 'oni.osu']]
+        if osus:
+            osud = parse_osu('songs/%s/%s' % (song[0], osus[0]))
+            preview = int(get_osu_key(osud, 'General', 'PreviewTime', 0))
+        else:
+            preview = 0
+
+        songs_out.append(
+            {'id': song[0], 'title': song[1], 'title_en': song[2], 'stars': {
+                'easy': song[3], 'normal': song[4],
+                'hard': song[5], 'oni': song[6]
+            }, 'preview': preview}
+        )
 
-	return jsonify(songs_out)
+    return jsonify(songs_out)
 
 
 if __name__ == '__main__':
-	app.run(port=34801)
+    app.run(port=34801)

src/js/songselect.js

@@ -7,7 +7,7 @@ function SongSelect(){
 	var _preview;
 	var _preview_to;
 
-	this.startPreview = function(id, first_open=true) {
+	this.startPreview = function(id, prvtime, first_open=true) {
 		var start = Date.now();
 		setTimeout(function(){
 			bgm.pause();
@@ -19,11 +19,11 @@ function SongSelect(){
 			var delay = end - start;
 			var no_delay = first_open ? 0 : 300;
 
-			_preview.currentTime = _preview.duration/2-10;
+			_preview.currentTime = prvtime/1000;
 			_preview.volume = 0.5;
 
 			_preview.addEventListener('ended', function(){
-				this.currentTime = this.duration/2-10;
+				this.currentTime = prvtime/1000;
 				this.play();
 			}, false);
 			
@@ -99,7 +99,7 @@ function SongSelect(){
 
 
 				if(!$('.opened').length) {
-					_this.startPreview($(this).data('song-id'));				
+					_this.startPreview($(this).data('song-id'), $(this).data('preview'));				
 					assets.sounds["don"].play();
 					assets.sounds["song-select"].pause();
 					assets.sounds["song-select"].currentTime = 0;
@@ -113,7 +113,7 @@ function SongSelect(){
 					});
 				} else {
 					_preview.pause();
-					_this.startPreview($(this).data('song-id'), false);				
+					_this.startPreview($(this).data('song-id'), $(this).data('preview'), false);				
 					assets.sounds["ka"].play();
 				}
 			};
@@ -146,8 +146,9 @@ function SongSelect(){
 			var songID = song.id;
 			var songTitle = song.title;
 			var songTitleSpace = songTitle.replace(/ /g, ' ');
+			var songPreview = song.preview;
 			
-			_code += "<div id='song-"+songID+"' class='song' data-title='"+songTitle+"' data-song-id='"+songID+"'><div class='song-title'>";
+			_code += "<div id='song-"+songID+"' class='song' data-title='"+songTitle+"' data-song-id='"+songID+"' data-preview='"+songPreview+"'><div class='song-title'>";
 			for (var c=0; c<songTitle.length; c++) {
 				var ch = songTitle.charAt(c) == ' ' ? '&nbsp;' : songTitle.charAt(c);
 				var cl = ch == '&nbsp;' ? 'song-title-char song-title-space' : 'song-title-char';