import os

from flask import Flask, render_template
from flask_sqlalchemy import SQLAlchemy
from flask_login import LoginManager
from werkzeug.exceptions import HTTPException
from flask_migrate import Migrate

from app.logger import log

# instantiate extensions
login_manager = LoginManager()
db = SQLAlchemy()
migration = Migrate()


def create_app(environment="development"):

    from config import config
    from app.views import (
        main_blueprint,
        auth_blueprint,
        user_blueprint,
        books_blueprint,
    )
    from app.models import (
        User,
        AnonymousUser,
    )

    # Instantiate app.
    app = Flask(__name__)

    # Set app config.
    env = os.environ.get("APP_ENV", environment)
    configuration = config(env)
    app.config.from_object(configuration)
    configuration.configure(app)
    log(log.INFO, "Configuration: [%s]", configuration.ENV)

    # Set up extensions.
    db.init_app(app)
    migration.init_app(app, db)
    login_manager.init_app(app)

    # Register blueprints.
    app.register_blueprint(auth_blueprint)
    app.register_blueprint(main_blueprint)
    app.register_blueprint(user_blueprint)
    app.register_blueprint(books_blueprint)

    # Set up flask login.
    @login_manager.user_loader
    def get_user(id):
        return User.query.get(int(id))

    login_manager.login_view = "auth.login"
    login_manager.login_message_category = "info"
    login_manager.anonymous_user = AnonymousUser

    # Error handlers.
    @app.errorhandler(HTTPException)
    def handle_http_error(exc):
        return render_template("error.html", error=exc), exc.code

    return app