Code refactoring

- Code refactoring
- Fix a bug that the other player will not become the host of the room at once, when the player disconnect in link play.

> Maybe add many unknown bugs. XD
> The song database `arcsong.db` will not used in the future. You can use a tool in `tool` folder to import old data.

latest version/api/songs.py

@@ -1,14 +1,13 @@
-from server.sql import Connect
-from server.sql import Sql
-import time
+from core.sql import Connect
+from core.sql import Sql
 
 
 def get_song_info(song_id):
     # 查询指定歌曲信息，返回字典
     r = {}
 
-    with Connect('./database/arcsong.db') as c:
-        c.execute('''select * from songs where sid=:a''', {'a': song_id})
+    with Connect('') as c:
+        c.execute('''select * from chart where song_id=:a''', {'a': song_id})
         x = c.fetchone()
         if x:
             r = {'song_id': x[0],
@@ -34,8 +33,8 @@ def get_songs(query=None):
     # 查询全部歌曲信息，返回字典列表
     r = []
 
-    with Connect('./database/arcsong.db') as c:
-        x = Sql.select(c, 'songs', [], query)
+    with Connect('') as c:
+        x = Sql.select(c, 'chart', [], query)
 
         if x:
             for i in x: