# app/__init__.py

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

    db.init_app(app)
    migrate.init_app(app, db)
    login_manager.init_app(app)
    login_manager.login_view = 'auth.login'

    with app.app_context():
        # Enable connection ping only for PostgreSQL
        if app.config['SQLALCHEMY_DATABASE_URI'].startswith("postgresql"):
            from sqlalchemy import event, text
            from sqlalchemy.exc import DisconnectionError

            @event.listens_for(db.engine, "engine_connect")
            def ping_connection(connection, branch):
                if branch:
                    return
                try:
                    connection.execution_options(isolation_level="AUTOCOMMIT").scalar(text("SELECT 1"))
                except:
                    raise DisconnectionError()

    from app.main import main
    from app.auth import auth

    app.register_blueprint(main)
    app.register_blueprint(auth)

    @app.template_filter('datetimeformat')
    def datetimeformat(value, format="%Y-%m-%d"):
        return value.strftime(format) if value else ""

    return app