feat: add subscribtion scheduler with ai, pagination

database.py

@@ -15,6 +15,29 @@ class Database:
                     preferences TEXT
                 )
             """)
+            await db.execute("""
+            CREATE TABLE IF NOT EXISTS sent_vacancies (
+                user_id INTEGER,
+                vacancy_url TEXT,
+                PRIMARY KEY (user_id, vacancy_url)
+            )
+        """)
+            await db.commit()
+
+    async def is_vacancy_sent(self, user_id: int, url: str) -> bool:
+        async with aiosqlite.connect(self.db_path) as db:
+            async with db.execute(
+                "SELECT 1 FROM sent_vacancies WHERE user_id = ? AND vacancy_url = ?", 
+                (user_id, url)
+            ) as cursor:
+                return await cursor.fetchone() is not None
+
+    async def mark_vacancy_as_sent(self, user_id: int, url: str):
+        async with aiosqlite.connect(self.db_path) as db:
+            await db.execute(
+                "INSERT OR IGNORE INTO sent_vacancies (user_id, vacancy_url) VALUES (?, ?)",
+                (user_id, url)
+            )
             await db.commit()
 
     async def add_user(self, user_id: int):
@@ -44,3 +67,18 @@ class Database:
                 (user_id,)
             ) as cursor:
                 return await cursor.fetchone()
+
+    async def count_users(self) -> int:
+        #Возвращает количество зарегистрированных пользователей
+        async with aiosqlite.connect(self.db_path) as db:
+            async with db.execute("SELECT COUNT(*) FROM users") as cursor:
+                result = await cursor.fetchone()
+                return result[0] if result else 0
+    async def clear_sent_vacancies(self, user_id: int):
+            #Очищает историю отправленных вакансий для пользователя
+            async with aiosqlite.connect(self.db_path) as db:
+                await db.execute(
+                        "DELETE FROM sent_vacancies WHERE user_id = ?",
+                    (user_id,)
+                )
+                await db.commit()