from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
from flask_login import LoginManager
import pymysql
from config import Config

db = SQLAlchemy()
migrate = Migrate()
login_manager = LoginManager()

def create_app():
    app = Flask(__name__)
    app.config.from_object(Config)
    
    # Initialize extensions
    db.init_app(app)
    migrate.init_app(app, db)
    login_manager.init_app(app)
    login_manager.login_view = 'auth.login'
    login_manager.login_message = 'Please log in to access this page.'
    
    # MySQL connection (read-only) - initialized when needed
    def get_mysql_connection():
        if not hasattr(app, 'mysql_connection') or app.mysql_connection is None:
            try:
                app.mysql_connection = pymysql.connect(
                    host=app.config['MYSQL_CONFIG']['host'],
                    database=app.config['MYSQL_CONFIG']['database'],
                    user=app.config['MYSQL_CONFIG']['user'],
                    password=app.config['MYSQL_CONFIG']['password'],
                    port=app.config['MYSQL_CONFIG']['port'],
                    autocommit=False  # Ensure read-only behavior
                )
            except Exception as e:
                print(f"MySQL connection failed: {e}")
                app.mysql_connection = None
        return app.mysql_connection
    
    # Make connection function available to app context
    app.get_mysql_connection = get_mysql_connection
    
    # Register blueprints
    from blueprints.auth import auth_bp
    from blueprints.main import main_bp
    
    app.register_blueprint(auth_bp, url_prefix='/auth')
    app.register_blueprint(main_bp)
    
    # User loader for Flask-Login
    from models import Users
    
    @login_manager.user_loader
    def load_user(user_id):
        return Users.query.get(int(user_id))
    
    # Note: Database tables will be managed by Flask-Migrate
    # Use 'flask db init', 'flask db migrate', 'flask db upgrade' commands
    
    return app

if __name__ == '__main__':
    app = create_app()
    app.run(debug=True)