implement update manager

.gitignore

@@ -3,6 +3,7 @@
 
 # Python
 /.venv
+/__pycache__
 
 # Database
 /*.db

database.py

@@ -1,6 +1,7 @@
 import sqlite3
 
 from exceptions import DisplayableException
+from rss import FeedItem
 
 
 class Database:
@@ -97,6 +98,11 @@ class Database:
             return 0
         return int(row[0])
 
+    def find_feed_subscribers(self, feed_id: int) -> list:
+        """Return feed subscribers"""
+        self.cur.execute('SELECT telegram_id FROM users WHERE id IN (SELECT user_id FROM subscriptions WHERE feed_id = ?)', [feed_id])
+        return self.cur.fetchall()
+
     def find_feeds(self) -> list:
         """Get a list of feeds."""
         self.cur.execute('SELECT * FROM feeds')
@@ -113,10 +119,10 @@ class Database:
         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:
+    def update_feed_items(self, feed_id: int, new_items: list[FeedItem]) -> 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]
+            new_items[i] = [feed_id] + list(new_items[i].__dict__.values())
 
         self.cur.execute('DELETE FROM feeds_last_items WHERE feed_id = ?', [feed_id])
         self.cur.executemany(

rss.py

@@ -1,19 +1,19 @@
 import feedparser
 
 
-class FeedItem():
+class FeedItem:
     def __init__(self, url: str, title: str, description: str, date: str) -> None:
         self.url = url
         self.title = title
         self.description = description
         self.date = date
 
-class Feed():
+class Feed:
     def __init__(self, url: str, items: list[FeedItem]) -> None:
         self.url = url
         self.items = items
 
-class RssReader():
+class RssReader:
     def get_feed(self, url: str) -> Feed:
         f = feedparser.parse(url)
         items = self.__get_items(f.entries)

update_manager.py

@@ -0,0 +1,44 @@
+from rss import RssReader, FeedItem
+from database import Database
+from telegram import Notifier
+
+
+class UpdateManager:
+    def __init__(self, database: Database, notifier: Notifier, rss_reader: RssReader) -> None:
+        self.database = database
+        self.notifier = notifier
+        self.rss_reader = rss_reader
+
+    def update(self):
+        feeds = self.database.find_feeds()
+
+        for feed_id, feed_url in feeds:
+            new_items = self.rss_reader.get_feed(feed_url).items
+            old_items = self.database.find_feed_items(feed_id)
+
+            diff = self.__calculate_difference(new_items, old_items)
+
+            if not diff:
+                continue
+
+            chat_ids = self.database.find_feed_subscribers(feed_id)
+            chat_ids = list(map(lambda x: x[0], chat_ids))
+            self.notifier.send_updates(chat_ids, diff)
+            self.database.update_feed_items(feed_id, new_items)
+
+    def __calculate_difference(self, new_items: list[FeedItem], old_items: list[tuple]) -> list[FeedItem]:
+        if not old_items:
+            return new_items
+        
+        diff = []
+        urls = list(map(lambda x: x[1], old_items))
+
+        for item in new_items:
+            if item.url not in urls:
+                diff.append(item)
+
+        return diff
+
+
+        
+