from urlparse import urlparse

from collections import namedtuple

from requests import Request, Session

from twilio.http import HttpClient, get_cert_file
from twilio.http.response import Response
from twilio.jwt.validation import ClientValidationJwt


ValidationPayload = namedtuple('ValidationPayload', ['method', 'path', 'query_string', 'all_headers',
                                                     'signed_headers', 'body'])


class ValidationClient(HttpClient):
    __SIGNED_HEADERS = ['authorization', 'host']

    def __init__(self, account_sid, api_key_sid, credential_sid, private_key):
        """
        Build a ValidationClient which signs requests with private_key and allows Twilio to
        validate request has not been tampered with.

        :param str account_sid: A Twilio Account Sid starting with 'AC'
        :param str api_key_sid: A Twilio API Key Sid starting with 'SK'
        :param str credential_sid: A Credential Sid starting with 'CR',
                                   corresponds to public key Twilio will use to verify the JWT.
        :param str private_key: The private key used to sign the Client Validation JWT.
        """
        self.account_sid = account_sid
        self.credential_sid = credential_sid
        self.api_key_sid = api_key_sid
        self.private_key = private_key

    def request(self, method, url, params=None, data=None, headers=None, auth=None, timeout=None,
                allow_redirects=False):
        """
        Make a signed HTTP Request

        :param str method: The HTTP method to use
        :param str url: The URL to request
        :param dict params: Query parameters to append to the URL
        :param dict data: Parameters to go in the body of the HTTP request
        :param dict headers: HTTP Headers to send with the request
        :param tuple auth: Basic Auth arguments
        :param float timeout: Socket/Read timeout for the request
        :param boolean allow_redirects: Whether or not to allow redirects
        See the requests documentation for explanation of all these parameters

        :return: An http response
        :rtype: A :class:`Response <twilio.rest.http.response.Response>` object
        """
        session = Session()
        session.verify = get_cert_file()

        request = Request(method.upper(), url, params=params, data=data, headers=headers, auth=auth)
        prepared_request = session.prepare_request(request)

        if 'Host' not in prepared_request.headers and 'host' not in prepared_request.headers:
            prepared_request.headers['Host'] = self._get_host(prepared_request)

        validation_payload = self._build_validation_payload(prepared_request)
        jwt = ClientValidationJwt(self.account_sid, self.api_key_sid, self.credential_sid,
                                  self.private_key, validation_payload)
        prepared_request.headers['Twilio-Client-Validation'] = jwt.to_jwt()

        response = session.send(
            prepared_request,
            allow_redirects=allow_redirects,
            timeout=timeout,
        )

        return Response(int(response.status_code), response.content.decode('utf-8'))

    def _build_validation_payload(self, request):
        """
        Extract relevant information from request to build a ClientValidationJWT
        :param PreparedRequest request: request we will extract information from.
        :return: ValidationPayload
        """
        parsed = urlparse(request.url)
        path = parsed.path
        query_string = parsed.query or ''

        return ValidationPayload(
            method=request.method,
            path=path,
            query_string=query_string,
            all_headers=request.headers,
            signed_headers=ValidationClient.__SIGNED_HEADERS,
            body=request.body or ''
        )

    def _get_host(self, request):
        """Pull the Host out of the request"""
        parsed = urlparse(request.url)
        return parsed.netloc
