from flask import Flask, jsonify
from flask_cors import CORS
from flask_jwt_extended import JWTManager
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
import os

# Create extensions but don't initialize them yet
db = SQLAlchemy()
migrate = Migrate()
jwt = JWTManager()
cors = CORS()


def create_app(config_name=None):
    """Application factory pattern"""
    app = Flask(__name__)
    
    # Load configuration
    if config_name is None:
        config_name = os.environ.get('FLASK_ENV', 'development')
    
    from app.config import config_by_name
    app.config.from_object(config_by_name[config_name])
    
    # Initialize extensions with app
    db.init_app(app)
    migrate.init_app(app, db)
    jwt.init_app(app)
    cors.init_app(app, resources={r"/api/*": {"origins": app.config.get('CORS_ORIGINS', '*')}})
    
    # Import models (required for migrations)
    from app.models import user, product, order
    
    # Register blueprints
    from app.routes import api_bp, health_bp
    app.register_blueprint(api_bp, url_prefix='/api')
    app.register_blueprint(health_bp)
    
    # Global error handlers
    @app.errorhandler(404)
    def not_found(error):
        return jsonify({'error': 'Not found'}), 404
    
    @app.errorhandler(500)
    def internal_error(error):
        return jsonify({'error': 'Internal server error'}), 500
    
    return app