import platform
from typing import Dict

from PyQt5.QtNetwork import QNetworkRequest

from UM.Application import Application


class HttpRequestScope:
    """Modifies a request in some way. This concept is sometimes called a request interceptor.

    Could be used to add authorization headers or set user agents, for example
    """

    def requestHook(self, request: QNetworkRequest) -> None:
        """Invoked after request-specific headers are set and before HttpRequestData is created"""

        pass

    @staticmethod
    def addHeaders(request: QNetworkRequest, header_dict: Dict) -> None:
        for key, value in header_dict.items():
            request.setRawHeader(key.encode("utf-8"), value.encode("utf-8"))


class DefaultUserAgentScope(HttpRequestScope):
    """Adds a User-Agent header"""

    def __init__(self, application: Application) -> None:
        self.header_dict = {
            "User-Agent": "%s/%s (%s %s)" % (application.getApplicationName(),
                                             application.getVersion(),
                                             platform.system(),
                                             platform.machine())
        }

    def requestHook(self, request: QNetworkRequest) -> None:
        super().requestHook(request)
        self.addHeaders(request, self.header_dict)


class JsonDecoratorScope(HttpRequestScope):
    """Extends a scope by adding Content-Type and Accept for application/json

    Should be used for Json requests which only accept a Json response
    """

    def __init__(self, base: HttpRequestScope) -> None:
        self.base = base
        self.header_dict = {
            "Content-Type": "application/json",
            "Accept": "application/json"
        }

    def requestHook(self, request: QNetworkRequest) -> None:
        # not calling super().request_hook() because base will do that.
        self.base.requestHook(request)
        self.addHeaders(request, self.header_dict)