# -*- coding: utf-8 -*-
#
# Copyright 2012 OpenStack LLC.
# All Rights Reserved.
#
#    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.

import copy
import json
import logging
import os
import socket
import ssl
import textwrap

from keystoneclient import adapter
import six
import six.moves.urllib.parse as urlparse

from ironicclient import exc


# NOTE(deva): Record the latest version that this client was tested with.
#             We still have a lot of work to do in the client to implement
#             microversion support in the client properly! See
#             http://specs.openstack.org/openstack/ironic-specs/specs/kilo/api-microversions.html # noqa
#             for full details.
DEFAULT_VER = '1.6'


LOG = logging.getLogger(__name__)
USER_AGENT = 'python-ironicclient'
CHUNKSIZE = 1024 * 64  # 64kB

API_VERSION = '/v1'
API_VERSION_SELECTED_STATES = ('user', 'negotiated', 'default')


def _trim_endpoint_api_version(url):
    """Trim API version and trailing slash from endpoint."""
    return url.rstrip('/').rstrip(API_VERSION)


def _extract_error_json(body):
    """Return  error_message from the HTTP response body."""
    error_json = {}
    try:
        body_json = json.loads(body)
        if 'error_message' in body_json:
            raw_msg = body_json['error_message']
            error_json = json.loads(raw_msg)
    except ValueError:
        pass

    return error_json


class VersionNegotiationMixin(object):
    def negotiate_version(self, conn, resp):
        """Negotiate the server version

        Assumption: Called after receiving a 406 error when doing a request.

        param conn: A connection object
        param resp: The response object from http request
        """
        if self.api_version_select_state not in API_VERSION_SELECTED_STATES:
            raise RuntimeError(
                'Error: self.api_version_select_state should be one of the '
                'values in: "%(valid)s" but had the value: "%(value)s"' %
                {'valid': ', '.join(API_VERSION_SELECTED_STATES),
                 'value': self.api_version_select_state})
        min_ver, max_ver = self._parse_version_headers(resp)
        # NOTE: servers before commit 32fb6e99 did not return version headers
        # on error, so we need to perform a GET to determine
        # the supported version range
        if not max_ver:
            LOG.debug('No version header in response, requesting from server')
            if self.os_ironic_api_version:
                base_version = ("/v%s" %
                                str(self.os_ironic_api_version).split('.')[0])
            else:
                base_version = API_VERSION
            resp = self._make_simple_request(conn, 'GET', base_version)
            min_ver, max_ver = self._parse_version_headers(resp)
        # If the user requested an explicit version or we have negotiated a
        # version and still failing then error now.  The server could
        # support the version requested but the requested operation may not
        # be supported by the requested version.
        if self.api_version_select_state == 'user':
            raise exc.UnsupportedVersion(textwrap.fill(
                "Requested API version %(req)s is not supported by the "
                "server or the requested operation is not supported by the "
                "requested version.  Supported version range is %(min)s to "
                "%(max)s"
                % {'req': self.os_ironic_api_version,
                   'min': min_ver, 'max': max_ver}))
        if self.api_version_select_state == 'negotiated':
            raise exc.UnsupportedVersion(textwrap.fill(
                "No API version was specified and the requested operation was "
                "not supported by the client's negotiated API version "
                "%(req)s.  Supported version range is: %(min)s to %(max)s"
                % {'req': self.os_ironic_api_version,
                   'min': min_ver, 'max': max_ver}))

        # TODO(deva): cache the negotiated version for this server
        negotiated_ver = min(self.os_ironic_api_version, max_ver)
        if negotiated_ver < min_ver:
            negotiated_ver = min_ver
        # server handles microversions, but doesn't support
        # the requested version, so try a negotiated version
        self.api_version_select_state = 'negotiated'
        self.os_ironic_api_version = negotiated_ver
        LOG.debug('Negotiated API version is %s', negotiated_ver)

        return negotiated_ver

    def _generic_parse_version_headers(self, accessor_func):
        min_ver = accessor_func('X-OpenStack-Ironic-API-Minimum-Version',
                                None)
        max_ver = accessor_func('X-OpenStack-Ironic-API-Maximum-Version',
                                None)
        return min_ver, max_ver

    def _parse_version_headers(self, accessor_func):
        # NOTE(jlvillal): Declared for unit testing purposes
        raise NotImplementedError()

    def _make_simple_request(self, conn, method, url):
        # NOTE(jlvillal): Declared for unit testing purposes
        raise NotImplementedError()


class HTTPClient(VersionNegotiationMixin):

    def __init__(self, endpoint, **kwargs):
        self.endpoint = endpoint
        self.endpoint_trimmed = _trim_endpoint_api_version(endpoint)
        self.auth_token = kwargs.get('token')
        self.auth_ref = kwargs.get('auth_ref')
        self.os_ironic_api_version = kwargs.get('os_ironic_api_version',
                                                DEFAULT_VER)
        self.api_version_select_state = kwargs.get(
            'api_version_select_state', 'default')
        self.connection_params = self.get_connection_params(endpoint, **kwargs)

    @staticmethod
    def get_connection_params(endpoint, **kwargs):
        parts = urlparse.urlparse(endpoint)

        path = _trim_endpoint_api_version(parts.path)

        _args = (parts.hostname, parts.port, path)
        _kwargs = {'timeout': (float(kwargs.get('timeout'))
                               if kwargs.get('timeout') else 600)}

        if parts.scheme == 'https':
            _class = VerifiedHTTPSConnection
            _kwargs['ca_file'] = kwargs.get('ca_file', None)
            _kwargs['cert_file'] = kwargs.get('cert_file', None)
            _kwargs['key_file'] = kwargs.get('key_file', None)
            _kwargs['insecure'] = kwargs.get('insecure', False)
        elif parts.scheme == 'http':
            _class = six.moves.http_client.HTTPConnection
        else:
            msg = 'Unsupported scheme: %s' % parts.scheme
            raise exc.EndpointException(msg)

        return (_class, _args, _kwargs)

    def get_connection(self):
        _class = self.connection_params[0]
        try:
            return _class(*self.connection_params[1][0:2],
                          **self.connection_params[2])
        except six.moves.http_client.InvalidURL:
            raise exc.EndpointException()

    def log_curl_request(self, method, url, kwargs):
        curl = ['curl -i -X %s' % method]

        for (key, value) in kwargs['headers'].items():
            header = '-H \'%s: %s\'' % (key, value)
            curl.append(header)

        conn_params_fmt = [
            ('key_file', '--key %s'),
            ('cert_file', '--cert %s'),
            ('ca_file', '--cacert %s'),
        ]
        for (key, fmt) in conn_params_fmt:
            value = self.connection_params[2].get(key)
            if value:
                curl.append(fmt % value)

        if self.connection_params[2].get('insecure'):
            curl.append('-k')

        if 'body' in kwargs:
            curl.append('-d \'%s\'' % kwargs['body'])

        curl.append(urlparse.urljoin(self.endpoint_trimmed, url))
        LOG.debug(' '.join(curl))

    @staticmethod
    def log_http_response(resp, body=None):
        status = (resp.version / 10.0, resp.status, resp.reason)
        dump = ['\nHTTP/%.1f %s %s' % status]
        dump.extend(['%s: %s' % (k, v) for k, v in resp.getheaders()])
        dump.append('')
        if body:
            dump.extend([body, ''])
        LOG.debug('\n'.join(dump))

    def _make_connection_url(self, url):
        (_class, _args, _kwargs) = self.connection_params
        base_url = _args[2]
        return '%s/%s' % (base_url, url.lstrip('/'))

    def _parse_version_headers(self, resp):
        return self._generic_parse_version_headers(resp.getheader)

    def _make_simple_request(self, conn, method, url):
        conn.request(method, self._make_connection_url(url))
        return conn.getresponse()

    def _http_request(self, url, method, **kwargs):
        """Send an http request with the specified characteristics.

        Wrapper around httplib.HTTP(S)Connection.request to handle tasks such
        as setting headers and error handling.
        """
        # Copy the kwargs so we can reuse the original in case of redirects
        kwargs['headers'] = copy.deepcopy(kwargs.get('headers', {}))
        kwargs['headers'].setdefault('User-Agent', USER_AGENT)
        if self.os_ironic_api_version:
            kwargs['headers'].setdefault('X-OpenStack-Ironic-API-Version',
                                         self.os_ironic_api_version)
        if self.auth_token:
            kwargs['headers'].setdefault('X-Auth-Token', self.auth_token)

        self.log_curl_request(method, url, kwargs)
        conn = self.get_connection()

        try:
            conn_url = self._make_connection_url(url)
            conn.request(method, conn_url, **kwargs)
            resp = conn.getresponse()

            # TODO(deva): implement graceful client downgrade when connecting
            # to servers that did not support microversions. Details here:
            # http://specs.openstack.org/openstack/ironic-specs/specs/kilo/api-microversions.html#use-case-3b-new-client-communicating-with-a-old-ironic-user-specified  # noqa

            if resp.status == 406:
                negotiated_ver = self.negotiate_version(conn, resp)
                kwargs['headers']['X-OpenStack-Ironic-API-Version'] = (
                    negotiated_ver)
                return self._http_request(url, method, **kwargs)

        except socket.gaierror as e:
            message = ("Error finding address for %(url)s: %(e)s"
                       % dict(url=url, e=e))
            raise exc.EndpointNotFound(message)
        except (socket.error, socket.timeout) as e:
            endpoint = self.endpoint
            message = ("Error communicating with %(endpoint)s %(e)s"
                       % dict(endpoint=endpoint, e=e))
            raise exc.ConnectionRefused(message)

        body_iter = ResponseBodyIterator(resp)

        # Read body into string if it isn't obviously image data
        body_str = None
        if resp.getheader('content-type', None) != 'application/octet-stream':
            body_str = ''.join([chunk for chunk in body_iter])
            self.log_http_response(resp, body_str)
            body_iter = six.StringIO(body_str)
        else:
            self.log_http_response(resp)

        if 400 <= resp.status < 600:
            LOG.warn("Request returned failure status.")
            error_json = _extract_error_json(body_str)
            raise exc.from_response(
                resp, error_json.get('faultstring'),
                error_json.get('debuginfo'), method, url)
        elif resp.status in (301, 302, 305):
            # Redirected. Reissue the request to the new location.
            return self._http_request(resp['location'], method, **kwargs)
        elif resp.status == 300:
            raise exc.from_response(resp, method=method, url=url)

        return resp, body_iter

    def json_request(self, method, url, **kwargs):
        kwargs.setdefault('headers', {})
        kwargs['headers'].setdefault('Content-Type', 'application/json')
        kwargs['headers'].setdefault('Accept', 'application/json')

        if 'body' in kwargs:
            kwargs['body'] = json.dumps(kwargs['body'])

        resp, body_iter = self._http_request(url, method, **kwargs)
        content_type = resp.getheader('content-type', None)

        if resp.status == 204 or resp.status == 205 or content_type is None:
            return resp, list()

        if 'application/json' in content_type:
            body = ''.join([chunk for chunk in body_iter])
            try:
                body = json.loads(body)
            except ValueError:
                LOG.error('Could not decode response body as JSON')
        else:
            body = None

        return resp, body

    def raw_request(self, method, url, **kwargs):
        kwargs.setdefault('headers', {})
        kwargs['headers'].setdefault('Content-Type',
                                     'application/octet-stream')
        return self._http_request(url, method, **kwargs)


class VerifiedHTTPSConnection(six.moves.http_client.HTTPSConnection):
    """httplib-compatibile connection using client-side SSL authentication

    :see http://code.activestate.com/recipes/
            577548-https-httplib-client-connection-with-certificate-v/
    """

    def __init__(self, host, port, key_file=None, cert_file=None,
                 ca_file=None, timeout=None, insecure=False):
        six.moves.http_client.HTTPSConnection.__init__(self, host, port,
                                                       key_file=key_file,
                                                       cert_file=cert_file)
        self.key_file = key_file
        self.cert_file = cert_file
        if ca_file is not None:
            self.ca_file = ca_file
        else:
            self.ca_file = self.get_system_ca_file()
        self.timeout = timeout
        self.insecure = insecure

    def connect(self):
        """Connect to a host on a given (SSL) port.

        If ca_file is pointing somewhere, use it to check Server Certificate.

        Redefined/copied and extended from httplib.py:1105 (Python 2.6.x).
        This is needed to pass cert_reqs=ssl.CERT_REQUIRED as parameter to
        ssl.wrap_socket(), which forces SSL to check server certificate against
        our client certificate.
        """
        sock = socket.create_connection((self.host, self.port), self.timeout)

        if self._tunnel_host:
            self.sock = sock
            self._tunnel()

        if self.insecure is True:
            kwargs = {'cert_reqs': ssl.CERT_NONE}
        else:
            kwargs = {'cert_reqs': ssl.CERT_REQUIRED, 'ca_certs': self.ca_file}

        if self.cert_file:
            kwargs['certfile'] = self.cert_file
            if self.key_file:
                kwargs['keyfile'] = self.key_file

        self.sock = ssl.wrap_socket(sock, **kwargs)

    @staticmethod
    def get_system_ca_file():
        """Return path to system default CA file."""
        # Standard CA file locations for Debian/Ubuntu, RedHat/Fedora,
        # Suse, FreeBSD/OpenBSD
        ca_path = ['/etc/ssl/certs/ca-certificates.crt',
                   '/etc/pki/tls/certs/ca-bundle.crt',
                   '/etc/ssl/ca-bundle.pem',
                   '/etc/ssl/cert.pem']
        for ca in ca_path:
            if os.path.exists(ca):
                return ca
        return None


class SessionClient(VersionNegotiationMixin, adapter.LegacyJsonAdapter):
    """HTTP client based on Keystone client session."""

    def _parse_version_headers(self, resp):
        return self._generic_parse_version_headers(resp.headers.get)

    def _make_simple_request(self, conn, method, url):
        # NOTE: conn is self.session for this class
        return conn.request(url, method, raise_exc=False)

    def _http_request(self, url, method, **kwargs):
        kwargs.setdefault('user_agent', USER_AGENT)
        kwargs.setdefault('auth', self.auth)
        if getattr(self, 'os_ironic_api_version', None):
            kwargs['headers'].setdefault('X-OpenStack-Ironic-API-Version',
                                         self.os_ironic_api_version)

        endpoint_filter = kwargs.setdefault('endpoint_filter', {})
        endpoint_filter.setdefault('interface', self.interface)
        endpoint_filter.setdefault('service_type', self.service_type)
        endpoint_filter.setdefault('region_name', self.region_name)

        resp = self.session.request(url, method,
                                    raise_exc=False, **kwargs)
        if resp.status_code == 406:
            negotiated_ver = self.negotiate_version(self.session, resp)
            kwargs['headers']['X-OpenStack-Ironic-API-Version'] = (
                negotiated_ver)
            return self._http_request(url, method, **kwargs)
        if 400 <= resp.status_code < 600:
            error_json = _extract_error_json(resp.content)
            raise exc.from_response(resp, error_json.get('faultstring'),
                                    error_json.get('debuginfo'), method, url)
        elif resp.status_code in (301, 302, 305):
            # Redirected. Reissue the request to the new location.
            location = resp.headers.get('location')
            resp = self._http_request(location, method, **kwargs)
        elif resp.status_code == 300:
            raise exc.from_response(resp, method=method, url=url)
        return resp

    def json_request(self, method, url, **kwargs):
        kwargs.setdefault('headers', {})
        kwargs['headers'].setdefault('Content-Type', 'application/json')
        kwargs['headers'].setdefault('Accept', 'application/json')

        if 'body' in kwargs:
            kwargs['data'] = json.dumps(kwargs.pop('body'))

        resp = self._http_request(url, method, **kwargs)
        body = resp.content
        content_type = resp.headers.get('content-type', None)
        status = resp.status_code
        if status == 204 or status == 205 or content_type is None:
            return resp, list()
        if 'application/json' in content_type:
            try:
                body = resp.json()
            except ValueError:
                LOG.error('Could not decode response body as JSON')
        else:
            body = None

        return resp, body

    def raw_request(self, method, url, **kwargs):
        kwargs.setdefault('headers', {})
        kwargs['headers'].setdefault('Content-Type',
                                     'application/octet-stream')
        return self._http_request(url, method, **kwargs)


class ResponseBodyIterator(object):
    """A class that acts as an iterator over an HTTP response."""

    def __init__(self, resp):
        self.resp = resp

    def __iter__(self):
        while True:
            yield self.next()

    def next(self):
        chunk = self.resp.read(CHUNKSIZE)
        if chunk:
            return chunk
        else:
            raise StopIteration()


def _construct_http_client(*args, **kwargs):
    session = kwargs.pop('session', None)
    auth = kwargs.pop('auth', None)

    if session:
        service_type = kwargs.pop('service_type', 'baremetal')
        interface = kwargs.pop('endpoint_type', None)
        region_name = kwargs.pop('region_name', None)
        os_ironic_api_version = kwargs.pop('os_ironic_api_version',
                                           DEFAULT_VER)
        session_client = SessionClient(session=session,
                                       auth=auth,
                                       interface=interface,
                                       service_type=service_type,
                                       region_name=region_name,
                                       service_name=None,
                                       user_agent='python-ironicclient')
        # Append an ironic specific variable to session
        session_client.os_ironic_api_version = os_ironic_api_version
        session_client.api_version_select_state = (
            kwargs.pop('api_version_select_state', 'default'))
        return session_client
    else:
        return HTTPClient(*args, **kwargs)
