Build Flask WAF log converter app

app/__init__.py

@@ -0,0 +1,28 @@
+from pathlib import Path
+
+from flask import Flask, flash, render_template
+from werkzeug.exceptions import RequestEntityTooLarge
+
+from app.config import Config
+from app.routes import main_blueprint
+
+
+def create_app(config_class: type[Config] = Config) -> Flask:
+    """Application factory used by Flask and Gunicorn."""
+    app = Flask(__name__, instance_relative_config=True)
+    app.config.from_object(config_class)
+
+    output_dir = Path(app.config["OUTPUT_DIRECTORY"])
+    if not output_dir.is_absolute():
+        output_dir = Path(app.instance_path) / output_dir
+    app.config["OUTPUT_DIRECTORY"] = output_dir
+    output_dir.mkdir(parents=True, exist_ok=True)
+
+    app.register_blueprint(main_blueprint)
+
+    @app.errorhandler(RequestEntityTooLarge)
+    def handle_file_too_large(_error):
+        flash("The uploaded file is too large.", "danger")
+        return render_template("index.html"), 413
+
+    return app