.gitignore

@@ -3,3 +3,6 @@
 
 # Python
 /.venv
+
+# Database
+/*.db

database.py

@@ -0,0 +1,76 @@
+import sqlite3
+"""
+Classes:
+Database - implement intercaction with the database.
+"""
+
+class Database():
+    """Implement intercaction with the database."""
+
+    def __init__(self, path: str) -> None:
+        """Create a database file if not exists."""
+        self.conn = sqlite3.connect(path)
+        self.cur = self.conn.cursor()
+        self.cur.execute('CREATE TABLE IF NOT EXISTS users (id INTEGER, telegram_id NUMERIC NOT NULL UNIQUE, PRIMARY KEY(id))')
+        self.cur.execute('CREATE TABLE IF NOT EXISTS feeds (id INTEGER, url TEXT NOT NULL UNIQUE, PRIMARY KEY(id))')
+        self.cur.execute('CREATE TABLE IF NOT EXISTS subscriptions (user_id INTEGER, feed_id INTEGER, UNIQUE (user_id, feed_id), FOREIGN KEY(user_id) REFERENCES users(id), FOREIGN KEY(feed_id) REFERENCES feeds(id))')
+        self.cur.execute('CREATE TABLE IF NOT EXISTS feeds_last_items (feed_id INTEGER, url TEXT NOT NULL UNIQUE, title TEXT, description TEXT, date NUMERIC, FOREIGN KEY(feed_id) REFERENCES feeds(id))')
+
+    def add_user(self, telegram_id: str) -> int:
+        """Add a user's telegram id to the database and return its database id."""
+        self.cur.execute('INSERT INTO users (telegram_id) VALUES (?)', [telegram_id])
+        self.conn.commit()
+        return self.cur.lastrowid
+
+    def find_user(self, telegram_id: str) -> int | None:
+        """Get a user's telegram id and return its database id."""
+        self.cur.execute('SELECT id FROM users WHERE telegram_id = ?', [telegram_id])
+        row = self.cur.fetchone()
+        if row is None:
+            return None
+        return row[0]
+
+    def add_feed(self, url: str) -> int:
+        """Add a feed to the database and return its id."""
+        self.cur.execute('INSERT INTO feeds (url) VALUES (?)', [url])
+        self.conn.commit()
+        return self.cur.lastrowid
+
+    def subscribe_user(self, user_id: int, feed_id: int) -> None:
+        """Subscribe a user to the feed."""
+        self.cur.execute('INSERT INTO subscriptions (user_id, feed_id) VALUES (?, ?)', [user_id, feed_id])
+        self.conn.commit()
+
+    def unsubscribe_user(self, user_id: int, feed_id: int) -> None:
+        """Unsubscribe a user from the feed."""
+        self.cur.execute('DELETE FROM subscriptions WHERE feed_id = ? AND user_id = ?', [feed_id, user_id])
+        self.conn.commit()
+
+    def delete_feed(self, feed_id: int) -> None:
+        """Delete a feed."""
+        self.cur.execute('DELETE FROM feeds WHERE id = ?', [feed_id])
+        self.conn.commit()
+
+    def find_feeds(self) -> list:
+        """Get a list of feeds."""
+        self.cur.execute('SELECT * FROM feeds')
+        return self.cur.fetchall()
+
+    def find_user_feeds(self, user_id: int) -> list:
+        """Return a list of feeds the user is subscribed to."""
+        self.cur.execute('SELECT * FROM feeds WHERE id IN (SELECT feed_id FROM subscriptions WHERE user_id = ?)', [user_id])
+        return self.cur.fetchall()
+
+    def find_feed_items(self, feed_id: int) -> list:
+        """Get last feed items."""
+        self.cur.execute('SELECT * FROM feeds_last_items WHERE feed_id = ?', [feed_id])
+        return self.cur.fetchall()
+
+    def update_feed_items(self, feed_id: int, new_items: list) -> None:
+        """Replace last feed items with a list items that receive."""
+        for i in range(len(new_items)):
+            new_items[i] = (feed_id,) + new_items[i]
+
+        self.cur.execute('DELETE FROM feeds_last_items WHERE feed_id = ?', [feed_id])
+        self.cur.executemany('INSERT INTO feeds_last_items (feed_id, url, title, description, date) VALUES (?, ?, ?, ?, ?)', new_items)
+        self.conn.commit()