import gzip
from flask import Flask, request


def create_app(compress: bool = True) -> Flask:
    app = Flask(__name__)

    @app.after_request
    def compress_response(response):
        if not compress:
            return response
        accept_encoding = request.headers.get("Accept-Encoding", "")
        if "gzip" not in accept_encoding.lower():
            return response
        if response.status_code < 200 or response.status_code >= 300:
            return response
        if "Content-Encoding" in response.headers:
            return response
        content_type = response.headers.get("Content-Type", "")
        if not content_type.startswith(
            ("text/", "application/javascript", "application/json")
        ):
            return response

        response.direct_passthrough = False
        response.data = gzip.compress(response.data)
        response.headers["Content-Encoding"] = "gzip"
        response.headers["Vary"] = "Accept-Encoding"
        response.headers["Content-Length"] = len(response.data)
        return response

    return app