refactor: adds new entry point and ORM

app.py

@@ -1,11 +0,0 @@
-from flask_sqlalchemy import SQLAlchemy
-from flask import Flask, render_template
-
-db = SQLAlchemy()
-app = Flask(__name__)
-app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///adogapet.db"
-db.init_app(app)
-
-@app.route("/")
-def hello_world():
-    return render_template("index.html")

app/__init__.py

@@ -0,0 +1,16 @@
+from flask import Flask
+
+from config import Config
+from app.extensions import db
+
+def create_app(config_class=Config):
+    app = Flask(__name__)
+    app.config.from_object(config_class)
+    db.init_app(app)
+    # Initialize Flask extensions here
+
+    # Register blueprints here
+    from app.main import bp as main_bp
+    app.register_blueprint(main_bp)
+
+    return app

app/extensions.py

@@ -0,0 +1,2 @@
+from flask_sqlalchemy import SQLAlchemy
+db = SQLAlchemy()

config.py

@@ -0,0 +1,10 @@
+import os
+
+basedir = os.path.abspath(os.path.dirname(__file__))
+
+
+class Config:
+    SECRET_KEY = os.environ.get('SECRET_KEY')
+    SQLALCHEMY_DATABASE_URI = os.environ.get('DATABASE_URI')\
+        or 'sqlite:///' + os.path.join(basedir, 'instance\\adogapet.db')
+    SQLALCHEMY_TRACK_MODIFICATIONS = False