import os
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
from flask_bcrypt import Bcrypt
from flask_login import LoginManager
from flask_compress import Compress
from flask_minify import Minify

# Initialize Flask extensions
db = SQLAlchemy()
migrate = Migrate()
bcrypt = Bcrypt()
login_manager = LoginManager()
compress = Compress()
minify = Minify(html=True, js=True, cssless=True, fail_safe=True)

login_manager.login_view = 'auth.login'
login_manager.login_message_category = 'info'

def create_app():
    app = Flask(__name__)

    # Load configuration
    config_name = os.getenv('FLASK_CONFIG', 'DevelopmentConfig')  # Default to DevelopmentConfig
    app.config.from_object(f'app.config.{config_name}')

    # Fingerprinted URLs allow long-lived static caching across releases.
    import hashlib
    from pathlib import Path
    from flask import url_for
    asset_versions = {}
    for filename in ('css/tailwind.css', 'js/diy-turbo.min.js', 'images/favicon.svg'):
        asset_versions[filename] = hashlib.sha256((Path(app.static_folder) / filename).read_bytes()).hexdigest()[:12]

    @app.context_processor
    def asset_helpers():
        return {'asset_url': lambda filename: url_for('static', filename=filename, v=asset_versions.get(filename, ''))}

    @app.after_request
    def cache_policy(response):
        from flask import request
        from flask_login import current_user
        if request.endpoint == 'static' and request.args.get('v') == asset_versions.get(request.view_args.get('filename')):
            response.headers['Cache-Control'] = 'public, max-age=31536000, immutable'
        elif current_user.is_authenticated:
            response.headers['Cache-Control'] = 'private, no-store'
        return response

    # Initialize extensions
    db.init_app(app)
    migrate.init_app(app, db)
    bcrypt.init_app(app)
    login_manager.init_app(app)
    compress.init_app(app)
    minify.init_app(app)


    # Import models here to avoid circular imports
    from app.models import User  # Import the User model

    # Set up the user_loader function
    @login_manager.user_loader
    def load_user(user_id):
        return db.session.get(User, int(user_id))

    # Register blueprints
    from app.routes.auth import auth
    from app.routes.data import data
    from app.routes.main import main
    from app.routes.user import user
    from app.routes.reading import reading
    app.register_blueprint(main, url_prefix='/')
    app.register_blueprint(auth, url_prefix='/auth')
    app.register_blueprint(user, url_prefix='/user')
    app.register_blueprint(data, url_prefix="/data")
    app.register_blueprint(reading, url_prefix="/reading")

    return app