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
    login_manager.login_view = 'auth.login'
    login_manager.login_message = '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. Parámetro explícito en la URL (?lang=es o ?lang=en)
        lang = request.args.get('lang')
        if lang and lang in app.config['LANGUAGES']:
            session['language'] = lang
            return lang
        
        # 2. Si el usuario está autenticado y tiene idioma configurado en su perfil, prevalece en toda la sesión
        from flask_login import current_user
        if current_user.is_authenticated and getattr(current_user, 'preferred_language', None):
            if current_user.preferred_language in app.config['LANGUAGES']:
                return current_user.preferred_language
        
        # 3. En la pantalla de Login (usuario no autenticado):
        # El idioma predeterminado del login debe ser español o respetar el idioma del navegador.
        # No debe verse afectado por cookies o sesiones residuales de otros usuarios.
        is_login = (request.endpoint == 'auth.login' or request.path.rstrip('/') == '/login')
        if is_login:
            # Solo si el usuario cambió el idioma explícitamente en el selector del login
            if session.get('login_lang_explicit') in app.config['LANGUAGES']:
                return session['login_lang_explicit']
            
            # Detectar según el navegador del usuario (soporta es-419, es-AR, es-ES, etc.)
            if request.accept_languages:
                for accepted_lang, _quality in request.accept_languages:
                    primary = accepted_lang.split('-')[0].lower()
                    if primary in app.config['LANGUAGES']:
                        return primary
            
            # Idioma predeterminado por defecto del login: Español
            return 'es'
        
        # 4. Para otras rutas: verificar si hay idioma en sesión (ej. selector manual)
        if 'language' in session and session['language'] in app.config['LANGUAGES']:
            return session['language']
        
        # 5. Detección automática del navegador por defecto (soporta subtags regionales)
        if request.accept_languages:
            for accepted_lang, _quality in request.accept_languages:
                primary = accepted_lang.split('-')[0].lower()
                if primary in app.config['LANGUAGES']:
                    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