# Copyright (c) 2010 OpenStack, LLC.
#
# 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://www.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.

"""
Monkey Patch httplib.HTTPResponse to buffer reads of headers. This can improve
performance when making large numbers of small HTTP requests.  This module
also provides helper functions to make HTTP connections using
BufferedHTTPResponse.

.. warning::

    If you use this, be sure that the libraries you are using do not access
    the socket directly (xmlrpclib, I'm looking at you :/), and instead
    make all calls through httplib.
"""

from urllib import quote
import logging
import time

from eventlet.green.httplib import HTTPConnection, HTTPResponse, _UNKNOWN, \
            CONTINUE, HTTPMessage


class BufferedHTTPResponse(HTTPResponse):
    """HTTPResponse class that buffers reading of headers"""

    def __init__(self, sock, debuglevel=0, strict=0,
                 method=None):          # pragma: no cover
        self.sock = sock
        self.fp = sock.makefile('rb')
        self.debuglevel = debuglevel
        self.strict = strict
        self._method = method

        self.msg = None

        # from the Status-Line of the response
        self.version = _UNKNOWN         # HTTP-Version
        self.status = _UNKNOWN          # Status-Code
        self.reason = _UNKNOWN          # Reason-Phrase

        self.chunked = _UNKNOWN         # is "chunked" being used?
        self.chunk_left = _UNKNOWN      # bytes left to read in current chunk
        self.length = _UNKNOWN          # number of bytes left in response
        self.will_close = _UNKNOWN      # conn will close at end of response

    def expect_response(self):
        self.fp = self.sock.makefile('rb', 0)
        version, status, reason = self._read_status()
        if status != CONTINUE:
            self._read_status = lambda: (version, status, reason)
            self.begin()
        else:
            self.status = status
            self.reason = reason.strip()
            self.version = 11
            self.msg = HTTPMessage(self.fp, 0)
            self.msg.fp = None


class BufferedHTTPConnection(HTTPConnection):
    """HTTPConnection class that uses BufferedHTTPResponse"""
    response_class = BufferedHTTPResponse

    def connect(self):
        self._connected_time = time.time()
        return HTTPConnection.connect(self)

    def putrequest(self, method, url, skip_host=0, skip_accept_encoding=0):
        self._method = method
        self._path = url
        self._txn_id = '-'
        return HTTPConnection.putrequest(self, method, url, skip_host,
                                         skip_accept_encoding)

    def putheader(self, header, value):
        if header.lower() == 'x-cf-trans-id':
            self._txn_id = value
        return HTTPConnection.putheader(self, header, value)

    def getexpect(self):
        response = BufferedHTTPResponse(self.sock, strict=self.strict,
                                       method=self._method)
        response.expect_response()
        return response

    def getresponse(self):
        response = HTTPConnection.getresponse(self)
        logging.debug("HTTP PERF: %.5f seconds to %s %s:%s %s (%s)" %
                (time.time() - self._connected_time, self._method, self.host,
                 self.port, self._path, self._txn_id))
        return response


def http_connect(ipaddr, port, device, partition, method, path,
                 headers=None, query_string=None):
    """
    Helper function to create a HTTPConnection object that is buffered
    for backend Swift services.

    :param ipaddr: IPv4 address to connect to
    :param port: port to connect to
    :param device: device of the node to query
    :param partition: partition on the device
    :param method: HTTP method to request ('GET', 'PUT', 'POST', etc.)
    :param path: request path
    :param headers: dictionary of headers
    :param query_string: request query string
    :returns: HTTPConnection object
    """
    conn = BufferedHTTPConnection('%s:%s' % (ipaddr, port))
    path = quote('/' + device + '/' + str(partition) + path)
    if query_string:
        path += '?' + query_string
    conn.path = path
    conn.putrequest(method, path)
    if headers:
        for header, value in headers.iteritems():
            conn.putheader(header, value)
    conn.endheaders()
    return conn

def http_connect_raw(ipaddr, port, method, path, headers=None,
                     query_string=None):
    """
    Helper function to create a HTTPConnection object that is buffered.

    :param ipaddr: IPv4 address to connect to
    :param port: port to connect to
    :param method: HTTP method to request ('GET', 'PUT', 'POST', etc.)
    :param path: request path
    :param headers: dictionary of headers
    :param query_string: request query string
    :returns: HTTPConnection object
    """
    conn = BufferedHTTPConnection('%s:%s' % (ipaddr, port))
    if query_string:
        path += '?' + query_string
    conn.path = path
    conn.putrequest(method, path)
    if headers:
        for header, value in headers.iteritems():
            conn.putheader(header, value)
    conn.endheaders()
    return conn
