import os
import importlib.util
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
from flask_login import LoginManager

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


def create_app():
    app = Flask(__name__)
    app.config.from_object('app.config.Config')

    # Initialize core extensions
    db.init_app(app)
    migrate.init_app(app, db)
    login_manager.init_app(app)
    login_manager.login_view = 'auth.login'  # Redirect for @login_required

    # Register error handlers
    from .errors import bp as errors_bp
    app.register_blueprint(errors_bp)

    # Plugin auto-loader
    plugin_path = os.path.abspath(os.path.join(os.path.dirname(__file__), '..', 'plugins'))
    for plugin in os.listdir(plugin_path):
        full_path = os.path.join(plugin_path, plugin, 'routes.py')
        if os.path.isfile(full_path):
            spec = importlib.util.spec_from_file_location(f"plugins.{plugin}.routes", full_path)
            mod = importlib.util.module_from_spec(spec)
            spec.loader.exec_module(mod)
            if hasattr(mod, 'bp'):
                app.register_blueprint(mod.bp)

    return app


@login_manager.user_loader
def load_user(user_id):
    from plugins.auth.models import User
    return User.query.get(int(user_id))