from flask import Flask, request, session
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
from flask_login import LoginManager
from flask_cors import CORS
from flask_babel import Babel, gettext as _
from config.config import Config

# Initialize extensions
db = SQLAlchemy()
migrate = Migrate()
login_manager = LoginManager()
cors = CORS()
babel = Babel()

def create_app(config_class=Config):
    app = Flask(__name__)
    app.config.from_object(config_class)
    
    # Initialize extensions with app
    db.init_app(app)
    migrate.init_app(app, db)
    login_manager.init_app(app)
    cors.init_app(app)
    
    # Login manager configuration
    from flask_babel import lazy_gettext
    login_manager.login_view = 'auth.login'
    login_manager.login_message = lazy_gettext('Por favor inicia sesión para acceder a esta página.')
    login_manager.login_message_category = 'info'
    
# Import models to ensure they are registered
    from app.models import user
    # Register blueprints
    from app.routes import auth_bp, classrooms_bp, buildings_bp, main_bp, schedule_bp, genetic_bp, genetic_web_bp, admin_bp, my_subjects_bp
    from app.routes.api import api_auth_bp, api_classrooms_bp, api_reservations_bp, api_optimizer_bp
    from app.security import SecurityFilterChain
    
    app.register_blueprint(auth_bp, url_prefix="/")
    app.register_blueprint(classrooms_bp, url_prefix="/classrooms")
    app.register_blueprint(buildings_bp)
    app.register_blueprint(main_bp, url_prefix="/")
    app.register_blueprint(schedule_bp, url_prefix="/schedule")
    app.register_blueprint(genetic_bp)
    app.register_blueprint(genetic_web_bp)
    app.register_blueprint(admin_bp)
    app.register_blueprint(my_subjects_bp)

    # Register REST API (v1) Blueprints with Stateless JWT support
    app.register_blueprint(api_auth_bp)
    app.register_blueprint(api_classrooms_bp)
    app.register_blueprint(api_reservations_bp)
    app.register_blueprint(api_optimizer_bp)

    # Initialize Enterprise Security Pipeline (SecurityFilterChain)
    SecurityFilterChain(app)
    
    # Language selector function
    def get_locale():
        # 1. Si el usuario está autenticado y tiene idioma configurado explícitamente en su perfil, prevalece.
        from flask_login import current_user
        if current_user.is_authenticated:
            if getattr(current_user, 'preferred_language', None) and current_user.preferred_language in app.config['LANGUAGES']:
                return current_user.preferred_language
            # El idioma por defecto siempre será español a menos que se configure a mano
            return app.config['BABEL_DEFAULT_LOCALE']
        
        # 2. Parámetro explícito en la URL (?lang=es o ?lang=en) (para usuarios no autenticados o login)
        lang = request.args.get('lang')
        if lang and lang in app.config['LANGUAGES']:
            session['language'] = lang
            return lang
            
        # 3. Si ya hay un idioma guardado en la sesión
        if 'language' in session and session['language'] in app.config['LANGUAGES']:
            return session['language']
            
        # 4. Primera vez que se accede a la web (sin sesión): respetar el idioma del navegador
        if request.accept_languages:
            for accepted_lang, _quality in request.accept_languages:
                primary = accepted_lang.split('-')[0].lower()
                if primary in app.config['LANGUAGES']:
                    session['language'] = primary  # Se guarda para la sesión actual
                    return primary

        # Fallback del sistema: Español
        return app.config['BABEL_DEFAULT_LOCALE']


    # Babel context processor
    @app.context_processor
    def inject_conf_vars():
        return dict(
            languages=app.config['LANGUAGES'],
            current_lang=str(get_locale())
        )

    
    # Configure Babel
    babel.init_app(app, locale_selector=get_locale)
    
    # Register localized date and datetime formatters for Jinja2 templates
    from flask_babel import format_date, format_datetime
    app.jinja_env.globals['format_date'] = format_date
    app.jinja_env.globals['format_datetime'] = format_datetime
    app.jinja_env.filters['format_date'] = format_date
    app.jinja_env.filters['format_datetime'] = format_datetime
    
    return app