import importlib
import os

from flask import Flask
from flask_migrate import Migrate
from flask_sqlalchemy import SQLAlchemy

_context = None


class ApplicationContext:
    """
    Interface for the flask application
    """

    def __init__(self, schema_module_name: str):
        self.schema_module = importlib.import_module(schema_module_name)
        self.db = SQLAlchemy()
        self.migrate = Migrate()
        self._app = Flask("flask")

        self._initialized = False
        self._enable_migrations = False

        self._app.config["SECRET_KEY"] = os.getenv("SECRET_KEY", "secret string")
        self._app.config["SQLALCHEMY_DATABASE_URI"] = os.getenv(
            "DATABASE_URL", "sqlite:////" + os.path.join(self._app.root_path, "data.db")
        )
        self._app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False

    @property
    def flask(self):
        if not self._initialized:
            raise RuntimeError("You must initialize first.")
        return self._app

    def initialize(self):
        self.db.init_app(self._app)
        if self._enable_migrations:
            self.migrate.init_app(self._app, self.db)
        self._initialized = True
        return self.flask


def initialize(schema_module_name: str = "ttfrog.schema"):
    global _context
    if not _context:
        _context = ApplicationContext(schema_module_name)
        _context.initialize()
    return _context