# -*- coding: utf-8 -*-
# http.py
# Copyright (C) 2015 LEAP
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
Twisted HTTP/HTTPS client.
"""

try:
    import twisted
except ImportError:
    print "*******"
    print "Twisted is needed to use leap.common.http module"
    print ""
    print "Install the extra requirement of the package:"
    print "$ pip install leap.common[Twisted]"
    import sys
    sys.exit(1)


from leap.common.certs import get_compatible_ssl_context_factory

from zope.interface import implements

from twisted.internet import reactor
from twisted.internet.defer import succeed

from twisted.web.client import Agent
from twisted.web.client import HTTPConnectionPool
from twisted.web.client import readBody
from twisted.web.http_headers import Headers
from twisted.web.iweb import IBodyProducer


def createPool(maxPersistentPerHost=10, persistent=True):
    pool = HTTPConnectionPool(reactor, persistent)
    pool.maxPersistentPerHost = maxPersistentPerHost
    return pool

_pool = createPool()


class HTTPClient(object):
    """
    HTTP client done the twisted way, with a main focus on pinning the SSL
    certificate.
    """

    def __init__(self, cert_file=None, pool=_pool):
        """
        Init the HTTP client

        :param cert_file: The path to the certificate file, if None given the
                          system's CAs will be used.
        :type cert_file: str
        """

        policy = get_compatible_ssl_context_factory(cert_file)

        self._agent = Agent(
            reactor,
            policy,
            pool=pool)

    def request(self, url, method='GET', body=None, headers={}):
        """
        Perform an HTTP request.

        :param url: The URL for the request.
        :type url: str
        :param method: The HTTP method of the request.
        :type method: str
        :param body: The body of the request, if any.
        :type body: str
        :param headers: The headers of the request.
        :type headers: dict

        :return: A deferred that fires with the body of the request.
        :rtype: twisted.internet.defer.Deferred
        """
        if body:
            body = HTTPClient.StringBodyProducer(body)
        d = self._agent.request(
            method, url, headers=Headers(headers), bodyProducer=body)
        d.addCallback(readBody)
        return d

    class StringBodyProducer(object):
        """
        A producer that writes the body of a request to a consumer.
        """

        implements(IBodyProducer)

        def __init__(self, body):
            """
            Initialize the string produer.

            :param body: The body of the request.
            :type body: str
            """
            self.body = body
            self.length = len(body)

        def startProducing(self, consumer):
            """
            Write the body to the consumer.

            :param consumer: Any IConsumer provider.
            :type consumer: twisted.internet.interfaces.IConsumer

            :return: A successful deferred.
            :rtype: twisted.internet.defer.Deferred
            """
            consumer.write(self.body)
            return succeed(None)

        def pauseProducing(self):
            pass

        def stopProducing(self):
            pass