from aiohttp.web import middleware

import config
from server.core.exceptions import Unauthorized


@middleware
async def auth_middleware(request, handler):
    """Authenticate a user.
    Authentication is performed by extracting AUTH_KEY from header

    Returns:
        None

    Raises:
        Unauthorized: If authorization token is invalid or missing.

    """
    if request.rel_url == request.app.router["health"].url_for():
        return await handler(request)

    if config.DEBUG:
        if request.path.startswith("/api/doc") or request.path.startswith("/static"):
            return await handler(request)

    api_key = request.headers.get("Authorization")
    if not api_key:
        raise Unauthorized("Authorization key is not provided.")

    if api_key != config.DNA_API_APPKEY:
        raise Unauthorized("Invalid authorization key.")

    return await handler(request)