tmpl-flask/flaskapp/app.py

"""Flask web application main script"""

import os
import secrets
from typing import Optional
from typing import Type, List

from pathlib import Path
from dotenv import load_dotenv

from flask import Flask

from . import exts
from .routes import Routes
from . import pages
from . import admin
from . import errors
from . import db

routes: List[Type[Routes]] = [
    pages.RoutePages,
    admin.RouteAdmin,
    errors.RouteErrors,
]


def create_app() -> Flask:
    """Flask app factory function"""

    # Create an app object
    app = Flask(
        __name__,
        static_folder='../static',
        template_folder='../templates',
        instance_relative_config=True,
    )
    # Load sample configuation
    if app.debug:
        load_dotenv(
            Path(__file__).parent.parent / '.env'
        )
    # Get the token from environment
    # or generate it using secrets
    app.config['SECRET_KEY'] = os.getenv(
        'SECRET_KEY',
        secrets.token_hex(32),
    )

    # Configurate MySQL database
    db_name = os.getenv('MYSQL_DATABASE', '${REPO_NAME_SNAKE}')
    app.config.update({
        'MYSQL_DATABASE_HOST': os.getenv('MYSQL_HOST', 'localhost'),
        'MYSQL_DATABASE_PORT': parseint(os.getenv('MYSQL_PORT'), 3306),
        'MYSQL_DATABASE_USER': os.getenv('MYSQL_USER', 'root'),
        'MYSQL_DATABASE_PASSWORD': os.getenv('MYSQL_PASSWORD', ''),
    })

    # Load extensions
    for ext in exts.exts:
        ext.init_app(app)

    db.create_db(db_name)
    with app.app_context():
        db.init_db()

    # Create instance/ directory
    try:
        os.makedirs(app.instance_path)
    except OSError:
        pass

    # Add all routes
    for r in routes:
        r(app).add_routes()

    return app


def parseint(
        value: Optional[str],
        default: int) -> Optional[int]:
    """Parses integer from the string,
    returns default value on error

    Args:
        value (Optional[str]): String or None
        default (int): Default value

    Returns:
        Integer or None
    """

    try:
        return int(value or default)
    except ValueError:
        return default