add docstrings

database.py

@@ -1,21 +1,35 @@
 import sqlite3
+"""
+Classes:
+Database - implement intercaction with the database.
+"""
+
 class Database():
+    """
+    Implement intercaction with the database.
+    
+    Methods:
+    add_user, find_user, add_feed, subscribe_user,
+    unsubscribe_user, delete_feed, find_feeds,
+    find_user_feeds, find_feed_items, update_feed_items.
+    """
     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, FOREIGN KEY(user_id) REFERENCES users(id), FOREIGN KEY(feed_id) REFERENCES feeds(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 UNIQUE INDEX IF NOT EXISTS subscriptions_index ON subscriptions (user_id, feed_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))')
-        self.cur.execute('CREATE UNIQUE INDEX IF NOT EXISTS feed_item_index ON feeds_last_items (feed_id, date)')
 
     def add_user(self, telegram_id: str) -> int:
+        """Add a user's telegram id to the database and return his 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 his database id."""
         self.cur.execute('SELECT id FROM users WHERE telegram_id = ?', [telegram_id])
         row = self.cur.fetchone()
         if row is None:
@@ -23,35 +37,43 @@ class Database():
         return row[0]
 
     def add_feed(self, url: str) -> int:
+        """Add a feed from 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 from the database."""
         self.cur.execute('DELETE FROM feeds WHERE id = ?', [feed_id])
         self.conn.commit()
 
     def find_feeds(self) -> list:
+        """Get a list of feeds from the database and returns it."""
         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 feed items and return it."""
         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 feed items from the database with a list items that receive."""
         for i in range(len(new_items)):
             new_items[i] = (feed_id,) + new_items[i]