from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_login import LoginManager
import os

db = SQLAlchemy()
login_manager = LoginManager()

def create_app():
    # Frontend path
    base_dir = os.path.abspath(os.path.dirname(__file__))
    template_dir = os.path.join(base_dir, '..', 'frontend', 'templates')
    static_dir = os.path.join(base_dir, '..', 'frontend', 'static')

    # DB path
    instance_path = os.path.join(base_dir, '..', 'instance')
    os.makedirs(instance_path, exist_ok=True)

    app = Flask(
        __name__,
        template_folder=template_dir,
        static_folder=static_dir,
        instance_path=os.path.abspath(instance_path)
    )

    app.config['SECRET_KEY'] = 'IddAhxI%$G%2X3joI04i'
    app.config['SQLALCHEMY_DATABASE_URI'] = f"sqlite:///{os.path.join(app.instance_path, 'users.db')}"
    app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

    # Init extensions
    db.init_app(app)
    login_manager.init_app(app)
    login_manager.login_view = "login"

    # Import models for user_loader
    from backend.models import User

    @login_manager.user_loader
    def load_user(user_id):
        return User.query.get(int(user_id))

    # Import routes and give app
    from backend import routes
    routes.init_app(app)

    # Create DB if needed
    with app.app_context():
        db.create_all()

    return app