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/purchase.py

@@ -0,0 +1,160 @@
+from time import time
+
+from .error import NoData, TicketNotEnough
+from .item import ItemFactory
+
+
+class Purchase:
+    '''
+        购买类\ 
+        properties: `user` - `User`类或子类的实例
+    '''
+
+    def __init__(self, c=None, user=None):
+        self.c = c
+        self.user = user
+        self.purchase_name: str = None
+        self.price: int = None
+        self.orig_price: int = None
+        self.discount_from: int = None
+        self.discount_to: int = None
+        self.discount_reason: str = None
+
+        self.items: list = []
+
+    @property
+    def price_displayed(self) -> int:
+        '''
+            返回显示的价格
+        '''
+        if self.discount_from > 0 and self.discount_to > 0:
+            if self.discount_from <= int(time() * 1000) <= self.discount_to:
+                if self.discount_reason == 'anni5tix':
+                    x = ItemFactory(self.c).get_item('anni5tix')
+                    x.item_id = 'anni5tix'
+                    x.select(self.user)
+                    if x.amount >= 1:
+                        return 0
+                return self.price
+        return self.orig_price
+
+    @property
+    def to_dict(self) -> dict:
+        price = self.price_displayed
+        r = {
+            'name': self.purchase_name,
+            'price': price,
+            'orig_price': self.orig_price,
+            'items': [x.to_dict(has_is_available=True) for x in self.items]
+        }
+        if self.discount_from > 0 and self.discount_to > 0:
+            r['discount_from'] = self.discount_from
+            r['discount_to'] = self.discount_to
+            if self.discount_reason == 'anni5tix' and price == 0:
+                r['discount_reason'] = self.discount_reason
+        return r
+
+    def select(self, purchase_name: str = None) -> 'Purchase':
+        '''
+            用purchase_name查询信息
+        '''
+        if purchase_name:
+            self.purchase_name = purchase_name
+
+        self.c.execute(
+            '''select * from purchase where purchase_name=:name''', {'name': purchase_name})
+        x = self.c.fetchone()
+        if not x:
+            raise NoData('The purchase `%s` does not exist.' %
+                         purchase_name, 501)
+
+        self.price = x[1]
+        self.orig_price = x[2]
+        self.discount_from = x[3] if x[3] else -1
+        self.discount_to = x[4] if x[4] else -1
+        self.discount_reason = x[5] if x[5] else ''
+        self.select_items()
+        return self
+
+    def select_items(self) -> None:
+        '''从数据库拉取purchase_item数据'''
+        self.c.execute(
+            '''select item_id, type, amount from purchase_item where purchase_name=:a''', {'a': self.purchase_name})
+        x = self.c.fetchall()
+        if not x:
+            raise NoData('The items of the purchase `%s` does not exist.' %
+                         self.purchase_name, 501)
+
+        self.items = []
+        t = None
+
+        for i in x:
+            if i[0] == self.purchase_name:
+                # 物品排序，否则客户端报错
+                t = ItemFactory.from_dict({
+                    'item_id': i[0],
+                    'type': i[1],
+                    'amount': i[2] if i[2] else 1
+                }, self.c)
+            else:
+                self.items.append(ItemFactory.from_dict({
+                    'item_id': i[0],
+                    'type': i[1],
+                    'amount': i[2] if i[2] else 1
+                }, self.c))
+        if t is not None:
+            self.items = [t] + self.items
+
+    def buy(self) -> None:
+        '''进行购买'''
+        if self.price is None or self.orig_price is None:
+            self.select()
+        if not self.items:
+            self.select_items()
+        self.user.select_user_about_ticket()
+        price_used = self.price_displayed
+
+        if self.user.ticket < price_used:
+            raise TicketNotEnough(
+                'The user does not have enough memories.', -6)
+
+        if not(self.orig_price == 0 or self.price == 0 and self.discount_from <= int(time() * 1000) <= self.discount_to):
+            if price_used == 0:
+                x = ItemFactory(self.c).get_item('anni5tix')
+                x.item_id = 'anni5tix'
+                x.amount = -1
+                x.user_claim_item(self.user)
+            else:
+                self.user.ticket -= price_used
+                self.user.update_user_about_ticket()
+
+        for i in self.items:
+            i.user_claim_item(self.user)
+
+
+class PurchaseList:
+    '''
+        购买列表类\ 
+        property: `user` - `User`类或子类的实例
+    '''
+
+    def __init__(self, c=None, user=None):
+        self.c = c
+        self.user = user
+        self.purchases: list = []
+
+    @property
+    def to_dict(self) -> list:
+        return [x.to_dict for x in self.purchases]
+
+    def select_from_type(self, item_type: str) -> 'PurchaseList':
+        self.c.execute('''select purchase_name from purchase_item where type = :a''', {
+                       'a': item_type})
+        x = self.c.fetchall()
+        if not x:
+            return self
+
+        self.purchases: list = []
+        for i in x:
+            self.purchases.append(Purchase(self.c, self.user).select(i[0]))
+        return self