"""
Flask job application system - Application factory module.
"""
from pathlib import Path
from flask import Flask, redirect, url_for, flash
from flask_mail import Mail
from flask_wtf.csrf import CSRFProtect, CSRFError
from config import Config

# Initialize extensions (not bound to app yet)
mail = Mail()
csrf = CSRFProtect()


def create_app(config_class=Config):
    """
    Application factory function.
    Creates and configures the Flask application instance.

    Args:
        config_class: Configuration class to use (defaults to Config)

    Returns:
        Configured Flask application instance
    """
    # Create Flask app instance
    # Specify template and static folders relative to project root (parent of app/)
    app = Flask(__name__,
                template_folder='../templates',
                static_folder='../static')

    # Load configuration
    app.config.from_object(config_class)

    # Initialize extensions with app
    mail.init_app(app)
    csrf.init_app(app)

    # Ensure applications folder exists
    Path(app.config['APPLICATIONS_FOLDER']).mkdir(exist_ok=True)

    # Register error handlers
    @app.errorhandler(CSRFError)
    def handle_csrf_error(e):
        """Handle CSRF validation errors."""
        flash('Sicherheitsfehler: Die Sitzung ist abgelaufen. Bitte laden Sie die Seite neu und versuchen Sie es erneut.', 'error')
        return redirect(url_for('page1_email')), 400

    @app.errorhandler(429)
    def handle_rate_limit_error(e):
        """Handle rate limit errors."""
        return str(e), 429

    # Register routes
    from app.routes import register_routes
    register_routes(app, mail)

    return app