# -*- coding: utf-8 -*-
# Copyright 2014, 2015 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://w
ww.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


from twis
ted.internet import defer, reactor, protocol
from twisted.internet.error import DNSLookupError
from twisted.web.client import readBody, HTTPConnectionPool, Agent
from twisted.web.http_headers import Headers
from twisted.web._newclient import ResponseDone

from synapse.http.endpoint import matrix_federation_endpoint
from synapse.util.async import sleep
from synapse.util.logcontext import preserve_context_over_fn
import synapse.metrics

from syutil.jsonutil import encode_canonical_json

from synapse.api.errors import (
    SynapseError, Codes, HttpResponseException,
)

from syutil.crypto.jsonsign import sign_json

import simplejson as json
import logging
import sys
import urllib
import urlparse


logger = logging.getLogger(__name__)
outbound_logger = logging.getLogger("synapse.http.outbound")

metrics = synapse.metrics.get_metrics_for(__name__)

outgoing_requests_counter = metrics.register_counter(
    "requests",
    labels=["method"],
)
incoming_responses_counter = metrics.register_counter(
    "responses",
    labels=["method", "code"],
)


class MatrixFederationEndpointFactory(object):
    def __init__(self, hs):
        self.tls_context_factory = hs.tls_context_factory

    def endpointForURI(self, uri):
        destination = uri.netloc

        return matrix_federation_endpoint(
            reactor, destination, timeout=10,
            ssl_context_factory=self.tls_context_factory
        )


class MatrixFederationHttpClient(object):
    """HTTP client used to talk to other homeservers over the federation
    protocol. Send client certificates and signs requests.

    Attributes:
        agent (twisted.web.client.Agent): The twisted Agent used to send the
            requests.
    """

    def __init__(self, hs):
        self.hs = hs
        self.signing_key = hs.config.signing_key[0]
        self.server_name = hs.hostname
        pool = HTTPConnectionPool(reactor)
        pool.maxPersistentPerHost = 10
        self.agent = Agent.usingEndpointFactory(
            reactor, MatrixFederationEndpointFactory(hs), pool=pool
        )
        self.clock = hs.get_clock()
        self.version_string = hs.version_string
        self._next_id = 1

    def _create_url(self, destination, path_bytes, param_bytes, query_bytes):
        return urlparse.urlunparse(
            ("matrix", destination, path_bytes, param_bytes, query_bytes, "")
        )

    @defer.inlineCallbacks
    def _create_request(self, destination, method, path_bytes,
                        body_callback, headers_dict={}, param_bytes=b"",
                        query_bytes=b"", retry_on_dns_fail=True,
                        timeout=None):
        """ Creates and sends a request to the given url
        """
        headers_dict[b"User-Agent"] = [self.version_string]
        headers_dict[b"Host"] = [destination]

        url_bytes = self._create_url(
            destination, path_bytes, param_bytes, query_bytes
        )

        txn_id = "%s-O-%s" % (method, self._next_id)
        self._next_id = (self._next_id + 1) % (sys.maxint - 1)

        outbound_logger.info(
            "{%s} [%s] Sending request: %s %s",
            txn_id, destination, method, url_bytes
        )

        # XXX: Would be much nicer to retry only at the transaction-layer
        # (once we have reliable transactions in place)
        retries_left = 5

        http_url_bytes = urlparse.urlunparse(
            ("", "", path_bytes, param_bytes, query_bytes, "")
        )

        log_result = None
        try:
            while True:
                producer = None
                if body_callback:
                    producer = body_callback(method, http_url_bytes, headers_dict)

                try:
                    def send_request():
                        request_deferred = preserve_context_over_fn(
                            self.agent.request,
                            method,
                            url_bytes,
                            Headers(headers_dict),
                            producer
                        )

                        return self.clock.time_bound_deferred(
                            request_deferred,
                            time_out=timeout/1000. if timeout else 60,
                        )

                    response = yield preserve_context_over_fn(
                        send_request,
                    )

                    log_result = "%d %s" % (response.code, response.phrase,)
                    break
                except Exception as e:
                    if not retry_on_dns_fail and isinstance(e, DNSLookupError):
                        logger.warn(
                            "DNS Lookup failed to %s with %s",
                            destination,
                            e
                        )
                        log_result = "DNS Lookup failed to %s with %s" % (
                            destination, e
                        )
                        raise

                    logger.warn(
                        "{%s} Sending request failed to %s: %s %s: %s - %s",
                        txn_id,
                        destination,
                        method,
                        url_bytes,
                        type(e).__name__,
                        _flatten_response_never_received(e),
                    )

                    log_result = "%s - %s" % (
                        type(e).__name__, _flatten_response_never_received(e),
                    )

                    if retries_left and not timeout:
                        yield sleep(2 ** (5 - retries_left))
                        retries_left -= 1
                    else:
                        raise
        finally:
            outbound_logger.info(
                "{%s} [%s] Result: %s",
                txn_id,
                destination,
                log_result,
            )

        if 200 <= response.code < 300:
            pass
        else:
            # :'(
            # Update transactions table?
            body = yield preserve_context_over_fn(readBody, response)
            raise HttpResponseException(
                response.code, response.phrase, body
            )

        defer.returnValue(response)

    def sign_request(self, destination, method, url_bytes, headers_dict,
                     content=None):
        request = {
            "method": method,
            "uri": url_bytes,
            "origin": self.server_name,
            "destination": destination,
        }

        if content is not None:
            request["content"] = content

        request = sign_json(request, self.server_name, self.signing_key)

        auth_headers = []

        for key, sig in request["signatures"][self.server_name].items():
            auth_headers.append(bytes(
                "X-Matrix origin=%s,key=\"%s\",sig=\"%s\"" % (
                    self.server_name, key, sig,
                )
            ))

        headers_dict[b"Authorization"] = auth_headers

    @defer.inlineCallbacks
    def put_json(self, destination, path, data={}, json_data_callback=None):
        """ Sends the specifed json data using PUT

        Args:
            destination (str): The remote server to send the HTTP request
                to.
            path (str): The HTTP path.
            data (dict): A dict containing the data that will be used as
                the request body. This will be encoded as JSON.
            json_data_callback (callable): A callable returning the dict to
                use as the request body