(refactor): Enhance database connection and initialization with error

handling and logging

Implemented robust logging using the logging module
Improved database connection with try...except...finally blocks for better error handling and resource management
Enhanced database initialization with proper error handling and logging

database.py

@@ -1,44 +1,90 @@
 import os
+import logging
 import psycopg2
 from psycopg2 import IntegrityError
 from dotenv import load_dotenv
 from werkzeug.security import generate_password_hash
+
 load_dotenv()
 
+# Logging setup
+logging.basicConfig(
+    level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s"
+)
+logger = logging.getLogger(__name__)
+
+
 def get_connection():
     """Return a new connection to the PostgreSQL database."""
-    return psycopg2.connect(
+    try:
+        conn = psycopg2.connect(
             host=os.getenv("PG_HOST"),
             port=os.getenv("PG_PORT"),
             dbname=os.getenv("PG_DATABASE"),
             user=os.getenv("PG_USER"),
             password=os.getenv("PG_PASSWORD"),
-        connect_timeout=10
+            connect_timeout=10,
         )
+        return conn
+    except Exception as e:
+        logger.error(f"Database connection error: {e}")
+        raise
+
 
 def init_db():
     """Initialize the database tables."""
+    conn = None
+    try:
         conn = get_connection()
         cursor = conn.cursor()
+
         # Create subscribers table (if not exists)
-    cursor.execute("""
+        cursor.execute(
+            """
             CREATE TABLE IF NOT EXISTS subscribers (
                 id SERIAL PRIMARY KEY,
                 email TEXT UNIQUE NOT NULL
             )
-    """)
+        """
+        )
+
         # Create admin_users table (if not exists)
-    cursor.execute("""
+        cursor.execute(
+            """
             CREATE TABLE IF NOT EXISTS admin_users (
                 id SERIAL PRIMARY KEY,
                 username TEXT UNIQUE NOT NULL,
                 password TEXT NOT NULL
             )
-    """)
+        """
+        )
+
+        # Newsletter storage
+        cursor.execute(
+            """
+        CREATE TABLE IF NOT EXISTS newsletters (
+            id SERIAL PRIMARY KEY,
+            subject TEXT NOT NULL,
+            body TEXT NOT NULL,
+            sent_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
+        )
+        """
+        )
+
         conn.commit()
+        logger.info("Database initialized successfully.")
+    except Exception as e:
+        logger.error(f"Database initialization error: {e}")
+        if conn:
+            conn.rollback()  # Rollback if there's an error
+
+        raise
+    finally:
+        if conn:
             cursor.close()
             conn.close()
 
+
 def get_all_emails():
     """Return a list of all subscriber emails."""
     try:
@@ -46,78 +92,112 @@ def get_all_emails():
         cursor = conn.cursor()
         cursor.execute("SELECT email FROM subscribers")
         results = cursor.fetchall()
+        emails = [row[0] for row in results]
+        logger.debug(f"Retrieved emails: {emails}")
+        return emails
+    except Exception as e:
+        logger.error(f"Error retrieving emails: {e}")
+        return []
+    finally:
+        if conn:
             cursor.close()
             conn.close()
-        return [row[0] for row in results]
+
-    except Exception as e:
-        print(f"Error retrieving emails: {e}")
-        return []
 
 def add_email(email):
     """Insert an email into the subscribers table."""
+    conn = None
     try:
         conn = get_connection()
         cursor = conn.cursor()
         cursor.execute("INSERT INTO subscribers (email) VALUES (%s)", (email,))
         conn.commit()
-        cursor.close()
+        logger.info(f"Email {email} added successfully.")
-        conn.close()
         return True
     except IntegrityError:
+        logger.warning(f"Attempted to add duplicate email: {email}")
         return False
     except Exception as e:
-        print(f"Error adding email: {e}")
+        logger.error(f"Error adding email {email}: {e}")
         return False
+    finally:
+        if conn:
+            cursor.close()
+            conn.close()
+
 
 def remove_email(email):
     """Remove an email from the subscribers table."""
+    conn = None
     try:
         conn = get_connection()
         cursor = conn.cursor()
         cursor.execute("DELETE FROM subscribers WHERE email = %s", (email,))
-        conn.commit()
         rowcount = cursor.rowcount
-        cursor.close()
+        conn.commit()
-        conn.close()
+        logger.info(f"Email {email} removed successfully.")
         return rowcount > 0
     except Exception as e:
-        print(f"Error removing email: {e}")
+        logger.error(f"Error removing email {email}: {e}")
         return False
+    finally:
+        if conn:
+            cursor.close()
+            conn.close()
+
 
 def get_admin(username):
     """Retrieve admin credentials for a given username.
     Returns a tuple (username, password_hash) if found, otherwise None.
     """
+    conn = None
     try:
         conn = get_connection()
         cursor = conn.cursor()
-        cursor.execute("SELECT username, password FROM admin_users WHERE username = %s", (username,))
+        cursor.execute(
+            "SELECT username, password FROM admin_users WHERE username = %s",
+            (username,),
+        )
         result = cursor.fetchone()
-        cursor.close()
-        conn.close()
         return result  # (username, password_hash)
     except Exception as e:
-        print(f"Error retrieving admin: {e}")
+        logger.error(f"Error retrieving admin: {e}")
         return None
+    finally:
+        if conn:
+            cursor.close()
+            conn.close()
+
 
 def create_default_admin():
     """Create a default admin user if one doesn't already exist."""
     default_username = os.getenv("ADMIN_USERNAME", "admin")
     default_password = os.getenv("ADMIN_PASSWORD", "changeme")
-    hashed = generate_password_hash(default_password, method="pbkdf2:sha256")
+    hashed_password = generate_password_hash(default_password, method="pbkdf2:sha256")
+    conn = None
     try:
         conn = get_connection()
         cursor = conn.cursor()
+
         # Check if the admin already exists
-        cursor.execute("SELECT id FROM admin_users WHERE username = %s", (default_username,))
+        cursor.execute(
+            "SELECT id FROM admin_users WHERE username = %s", (default_username,)
+        )
         if cursor.fetchone() is None:
-            cursor.execute("INSERT INTO admin_users (username, password) VALUES (%s, %s)",
+            cursor.execute(
-                           (default_username, hashed))
+                "INSERT INTO admin_users (username, password) VALUES (%s, %s)",
+                (default_username, hashed_password),
+            )
             conn.commit()
-            print("Default admin created successfully")
+            logger.info("Default admin created successfully")
         else:
-            print("Default admin already exists")
+            logger.info("Default admin already exists")
+    except Exception as e:
+        logger.error(f"Error creating default admin: {e}")
+        if conn:
+            conn.rollback()
+    finally:
+        if conn:
             cursor.close()
             conn.close()
-    except Exception as e:
+
-        print(f"Error creating default admin: {e}")