from base64 import b64encode
import json
import socket

from flask import g
from flask.testing import FlaskClient
import gssapi
import pytest
from requests import Request
from requests_gssapi import HTTPSPNEGOAuth

from ceo_common.krb5.utils import get_fwd_tgt
from .utils import krb5ccname_ctx

__all__ = ['client']


@pytest.fixture(scope='session')
def client(app):
    app_client = app.test_client()
    yield CeodTestClient(app_client)


class CeodTestClient:
    def __init__(self, app_client: FlaskClient):
        self.client = app_client
        self.syscom_principal = 'ctdalek'
        # this is only used for the HTTPSNEGOAuth
        self.base_url = f'http://{socket.getfqdn()}'
        # for SPNEGO
        self.target_name = gssapi.Name('ceod/' + socket.getfqdn())

    def get_auth(self, principal):
        """Acquire a HTTPSPNEGOAuth instance for the principal."""
        name = gssapi.Name(principal)
        # the 'store' arg doesn't seem to work for DIR ccaches
        creds = gssapi.Credentials(name=name, usage='initiate')
        auth = HTTPSPNEGOAuth(
            opportunistic_auth=True,
            target_name=self.target_name,
            creds=creds,
        )
        return auth

    def get_headers(self, principal: str, need_cred: bool):
        with krb5ccname_ctx(principal):
            # Get the Authorization header (SPNEGO).
            # The method doesn't matter here because we just need to extract
            # the header using req.prepare().
            req = Request('GET', self.base_url, auth=self.get_auth(principal))
            headers = list(req.prepare().headers.items())
            if need_cred:
                # Get the X-KRB5-CRED header (forwarded TGT).
                cred = b64encode(get_fwd_tgt('ceod/' + socket.getfqdn())).decode()
                headers.append(('X-KRB5-CRED', cred))
        return headers

    def request(self, method: str, path: str, principal: str, need_cred: bool, **kwargs):
        # Make sure that we're not already in a request context, otherwise
        # g will get overridden
        with pytest.raises(RuntimeError):
            '' in g
        if principal is None:
            principal = self.syscom_principal
        headers = self.get_headers(principal, need_cred)
        resp = self.client.open(path, method=method, headers=headers, **kwargs)
        status = int(resp.status.split(' ', 1)[0])
        if resp.headers['content-type'] == 'application/json':
            data = json.loads(resp.data)
        else:
            data = [json.loads(line) for line in resp.data.splitlines()]
        return status, data

    def get(self, path, principal=None, need_cred=True, **kwargs):
        return self.request('GET', path, principal, need_cred, **kwargs)

    def post(self, path, principal=None, need_cred=True, **kwargs):
        return self.request('POST', path, principal, need_cred, **kwargs)

    def patch(self, path, principal=None, need_cred=True, **kwargs):
        return self.request('PATCH', path, principal, need_cred, **kwargs)

    def delete(self, path, principal=None, need_cred=True, **kwargs):
        return self.request('DELETE', path, principal, need_cred, **kwargs)