refactor: apply consistent formatting and improve code readability across backend modules

backend/app/database.py

@@ -1,11 +1,24 @@
+import json
+import sqlite3
+import time
 from contextlib import contextmanager
 from pathlib import Path
-import sqlite3
 from typing import Iterator
 
-from backend.app.config import logger, DB_PATH, update_constants_from_db, OLLAMA_HOST, CRON_HOURS, MIN_CRON_HOURS, \
-    SYNC_COOLDOWN_MINUTES, LLM_MODEL, LLM_TIMEOUT_SECONDS, OLLAMA_API_TIMEOUT_SECONDS, ARTICLE_FETCH_TIMEOUT, \
-    MAX_ARTICLE_LENGTH
+from backend.app.config import (
+    ARTICLE_FETCH_TIMEOUT,
+    CRON_HOURS,
+    DB_PATH,
+    LLM_MODEL,
+    LLM_TIMEOUT_SECONDS,
+    MAX_ARTICLE_LENGTH,
+    MIN_CRON_HOURS,
+    OLLAMA_API_TIMEOUT_SECONDS,
+    OLLAMA_HOST,
+    SYNC_COOLDOWN_MINUTES,
+    logger,
+    update_constants_from_db,
+)
 
 
 class DatabaseManager:
@@ -41,7 +54,8 @@ class DatabaseManager:
                 schema_sql = f.read()
 
             with self.get_cursor() as cursor:
-                statements = [stmt.strip() for stmt in schema_sql.split(';') if stmt.strip()]
+                statements = [stmt.strip()
+                              for stmt in schema_sql.split(';') if stmt.strip()]
                 for statement in statements:
                     cursor.execute(statement)
 
@@ -85,14 +99,12 @@ class DatabaseManager:
         """
         Seed initial feeds from seed_feeds.json file.
         """
-        import json
-        from pathlib import Path
-
         try:
             seed_file = Path(__file__).parent / "seed_feeds.json"
 
             if not seed_file.exists():
-                logger.warning("⚠️ seed_feeds.json not found, skipping feed seeding")
+                logger.warning(
+                    "⚠️ seed_feeds.json not found, skipping feed seeding")
                 return
 
             with open(seed_file, 'r', encoding='utf-8') as f:
@@ -101,10 +113,7 @@ class DatabaseManager:
             for country, urls in feeds_data.items():
                 for url in urls:
                     cursor.execute(
-                        "INSERT OR IGNORE INTO feeds (country, url) VALUES (?, ?)",
-                        (country, url)
-                    )
-
+                        "INSERT OR IGNORE INTO feeds (country, url) VALUES (?, ?)", (country, url))
 
         except Exception as e:
             logger.error(f"❌ Failed to seed feeds: {e}")
@@ -182,8 +191,7 @@ class DatabaseManager:
                 conn.rollback()
             if "database is locked" in str(e).lower():
                 logger.warning(
-                    f"⚠️ Database temporarily locked, operation may need retry: {e}"
-                )
+                    f"⚠️ Database temporarily locked, operation may need retry: {e}")
             raise e
         except Exception as e:
             if conn:
@@ -194,7 +202,9 @@ class DatabaseManager:
                 conn.close()
 
     @contextmanager
-    def get_cursor_with_retry(self, readonly: bool = False, max_retries: int = 3) -> Iterator[sqlite3.Cursor]:
+    def get_cursor_with_retry(self,
+                              readonly: bool = False,
+                              max_retries: int = 3) -> Iterator[sqlite3.Cursor]:
         """
         Context manager with retry logic for database operations.
 
@@ -211,13 +221,13 @@ class DatabaseManager:
                     yield cursor
                 return
             except sqlite3.OperationalError as e:
-                if "database is locked" in str(e).lower() and attempt < max_retries:
+                if "database is locked" in str(
+                        e).lower() and attempt < max_retries:
                     wait_time = (attempt + 1) * 0.1
                     logger.warning(
                         f"⚠️ Database locked, retrying in {wait_time}s "
                         f"(attempt {attempt + 1}/{max_retries + 1})"
                     )
-                    import time
                     time.sleep(wait_time)
                     continue
                 raise e