app.py

from flask import Flask,jsonify
from flask_smorest import Api
from db import db
import os
from flask_jwt_extended import JWTManager
from blocklist import BLOCKLIST

from resources.item import blp as ItemBlueprint
from resources.store import blp as StoreBlueprint
from resources.tag import blp as TagBlueprint
from resources.user import blp as UserBlueprint
from flask_migrate import Migrate


def create_app():
    app = Flask(__name__)

    app.config["PROPAGATE_EXCEPTIONS"] = True
    app.config["API_TITLE"] = "Stores And Items REST API"
    app.config["API_VERSION"] = "v1"
    app.config["OPENAPI_VERSION"] = "3.0.3"
    app.config["OPENAPI_URL_PREFIX"] = "/"
    app.config["OPENAPI_SWAGGER_UI_PATH"] = "/swagger-ui"
    app.config["OPENAPI_SWAGGER_UI_URL"] = "https://cdn.jsdelivr.net/npm/swagger-ui-dist/"

    app.config["SQLALCHEMY_DATABASE_URI"] =os.getenv("DATABASE_URL", "sqlite:///data.db")
    app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
    db.init_app(app)

    migrate=Migrate(app,db)

    api = Api(app)

    app.config["JWT_SECRET_KEY"]='alpha'
    jwt= JWTManager(app)


    # this fx is invoked When a fresh token is required but a non-fresh token is provided
    @jwt.needs_fresh_token_loader
    def token_not_fresh_callback(jwt_header, jwt_payload):
        return (
            jsonify(
                {
                    "description": "The token is not fresh.",
                    "error": "fresh_token_required",
                }
            ),
            401,
        )

    # whenever we receive a jwt this fx run and check if the token is in the block list
    @jwt.token_in_blocklist_loader
    def check_if_token_in_blocklist(jwt_header, jwt_payload):
        return jwt_payload["jti"] in BLOCKLIST

    # invoked when the token used is not valid
    @jwt.revoked_token_loader
    def revoked_token_callback(jwt_header, jwt_payload):
        return (
            jsonify(
                {"description": "The token has been revoked.", "error": "token_revoked"}
            ),
            401,
        )

    # this add information on JWT token
    @jwt.additional_claims_loader
    def add_claims_to_jwt(identity):
        if identity == 1:
            return {"is_admin": True}
        return {"is_admin": False}

    # when the above fx return true, this fx is invoked to indicate that the token is expired/logout
    @jwt.expired_token_loader
    def expired_token_callback(jwt_header, jwt_payload):
        return ( jsonify({"message": "The token has expired.", "error": "token_expired"}), 401,)

    @jwt.invalid_token_loader
    def invalid_token_callback(error):
        return (jsonify( {"message": "Signature verification failed.", "error": "invalid_token"}), 401,)

    @jwt.unauthorized_loader
    def missing_token_callback(error):
        return (
            jsonify(
                {
                    "description": "Request does not contain an access token.",
                    "error": "authorization_required",
                }
            ),
            401,
        )


    api.register_blueprint(ItemBlueprint)
    api.register_blueprint(StoreBlueprint)
    api.register_blueprint(TagBlueprint)
    api.register_blueprint(UserBlueprint)
    
    return app