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/core/linkplay.py

@@ -0,0 +1,147 @@
+from base64 import b64encode
+
+from core.error import ArcError, Timeout
+
+from .constant import Constant
+from .user import UserInfo
+
+
+def get_song_unlock(client_song_map: dict) -> bytes:
+    '''处理可用歌曲bit，返回bytes'''
+
+    user_song_unlock = [0] * 512
+    for i in range(0, 1024, 2):
+        x = 0
+        y = 0
+        if str(i) in client_song_map:
+            if client_song_map[str(i)][0]:
+                x += 1
+            if client_song_map[str(i)][1]:
+                x += 2
+            if client_song_map[str(i)][2]:
+                x += 4
+            if client_song_map[str(i)][3]:
+                x += 8
+        if str(i+1) in client_song_map:
+            if client_song_map[str(i+1)][0]:
+                y += 1
+            if client_song_map[str(i+1)][1]:
+                y += 2
+            if client_song_map[str(i+1)][2]:
+                y += 4
+            if client_song_map[str(i+1)][3]:
+                y += 8
+
+        user_song_unlock[i // 2] = y*16 + x
+
+    return bytes(user_song_unlock)
+
+
+class Player(UserInfo):
+    def __init__(self, c=None, user_id=None) -> None:
+        super().__init__(c, user_id)
+        self.player_id: int = 0
+        self.token: int = 0
+        self.key: bytes = None
+
+        self.__song_unlock: bytes = None
+        self.client_song_map: dict = None
+
+    def to_dict(self) -> dict:
+        return {
+            'userId': self.user_id,
+            'playerId': str(self.player_id),
+            'token': str(self.token),
+            'key': (b64encode(self.key)).decode()
+        }
+
+    @property
+    def song_unlock(self) -> bytes:
+        if self.__song_unlock is None:
+            self.get_song_unlock()
+        return self.__song_unlock
+
+    def get_song_unlock(self, client_song_map: dict = None) -> bytes:
+        if client_song_map is not None:
+            self.client_song_map = client_song_map
+        self.__song_unlock = get_song_unlock(self.client_song_map)
+
+
+class Room:
+    def __init__(self) -> None:
+        self.room_id: int = 0
+        self.room_code: str = 'AAAA00'
+
+        self.song_unlock: bytes = None
+
+    def to_dict(self) -> dict:
+        return {
+            'roomId': str(self.room_id),
+            'roomCode': self.room_code,
+            'orderedAllowedSongs': (b64encode(self.song_unlock)).decode()
+        }
+
+
+class LocalMultiPlayer:
+    def __init__(self, conn=None) -> None:
+        self.conn = conn
+        self.user: 'Player' = None
+        self.room: 'Room' = None
+
+        self.data_recv: tuple = None
+
+    def to_dict(self) -> dict:
+        return dict(self.room.to_dict(), **self.user.to_dict())
+
+    def data_swap(self, data: tuple) -> tuple:
+        self.conn.send(data)
+        if self.conn.poll(Constant.LINK_PLAY_TIMEOUT):
+            self.data_recv = self.conn.recv()
+            if self.data_recv[0] != 0:
+                raise ArcError('Link Play error.', self.data_recv[0])
+        else:
+            raise Timeout(
+                'Timeout when waiting for data from local udp server.')
+
+    def create_room(self, user: 'Player' = None) -> None:
+        '''创建房间'''
+        if user is not None:
+            self.user = user
+        user.select_user_about_name()
+        self.data_swap((1, self.user.name, self.user.song_unlock))
+        self.room = Room()
+        self.room.room_code = self.data_recv[1]
+        self.room.room_id = self.data_recv[2]
+        self.room.song_unlock = self.user.song_unlock
+        self.user.token = self.data_recv[3]
+        self.user.key = self.data_recv[4]
+        self.user.player_id = self.data_recv[5]
+
+    def join_room(self, room: 'Room' = None, user: 'Player' = None) -> None:
+        '''加入房间'''
+        if user is not None:
+            self.user = user
+        if room is not None:
+            self.room = room
+
+        self.user.select_user_about_name()
+        self.data_swap(
+            (2, self.user.name, self.user.song_unlock, room.room_code))
+        self.room.room_code = self.data_recv[1]
+        self.room.room_id = self.data_recv[2]
+        self.room.song_unlock = self.data_recv[6]
+        self.user.token = self.data_recv[3]
+        self.user.key = self.data_recv[4]
+        self.user.player_id = self.data_recv[5]
+
+    def update_room(self, user: 'Player' = None) -> None:
+        '''更新房间'''
+        if user is not None:
+            self.user = user
+        self.data_swap((3, self.user.token))
+        self.room = Room()
+        self.room.room_code = self.data_recv[1]
+        self.room.room_id = self.data_recv[2]
+        self.room.song_unlock = self.data_recv[5]
+        self.user.key = self.data_recv[3]
+        self.user.player_id = self.data_recv[4]