# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2013 IBM Corp.
# Copyright 2011 OpenStack Foundation
# 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 math
import re
import routes
import time

from oslo_log import log as logging
from oslo_serialization import jsonutils
import webob

from gceapi import exception
from gceapi import i18n
from gceapi.i18n import _
from gceapi import wsgi


LOG = logging.getLogger(__name__)

SUPPORTED_CONTENT_TYPES = (
    'application/json',
    'application/vnd.openstack.compute+json',
)

_MEDIA_TYPE_MAP = {
    'application/vnd.openstack.compute+json': 'json',
    'application/json': 'json',
}

_SANITIZE_KEYS = ['adminPass', 'admin_pass']

_SANITIZE_PATTERNS = [
    re.compile(r'(adminPass\s*[=]\s*[\"\']).*?([\"\'])', re.DOTALL),
    re.compile(r'(admin_pass\s*[=]\s*[\"\']).*?([\"\'])', re.DOTALL),
    re.compile(r'(<adminPass>).*?(</adminPass>)', re.DOTALL),
    re.compile(r'(<admin_pass>).*?(</admin_pass>)', re.DOTALL),
    re.compile(r'([\"\']adminPass[\"\']\s*:\s*[\"\']).*?([\"\'])', re.DOTALL),
    re.compile(r'([\"\']admin_pass[\"\']\s*:\s*[\"\']).*?([\"\'])', re.DOTALL)
]


class APIMapper(routes.Mapper):
    def routematch(self, url=None, environ=None):
        if url == "":
            result = self._match("", environ)
            return result[0], result[1]
        return routes.Mapper.routematch(self, url, environ)

    def connect(self, *args, **kargs):
        # NOTE(vish): Default the format part of a route to only accept json
        #             and xml so it doesn't eat all characters after a '.'
        #             in the url.
        kargs.setdefault('requirements', {})
        if not kargs['requirements'].get('format'):
            kargs['requirements']['format'] = 'json|xml'
        return routes.Mapper.connect(self, *args, **kargs)


class ProjectMapper(APIMapper):
    def resource(self, member_name, collection_name, **kwargs):
        if 'parent_resource' not in kwargs:
            kwargs['path_prefix'] = '{project_id}/'
        else:
            parent_resource = kwargs['parent_resource']
            p_collection = parent_resource['collection_name']
            p_member = parent_resource['member_name']
            kwargs['path_prefix'] = '{project_id}/%s/:%s_id' % (p_collection,
                                                                p_member)
        routes.Mapper.resource(self, member_name,
                                     collection_name,
                                     **kwargs)


class Request(webob.Request):
    """Add some OpenStack API-specific logic to the base webob.Request."""

    def __init__(self, *args, **kwargs):
        super(Request, self).__init__(*args, **kwargs)
        self._extension_data = {'db_items': {}}

    def cache_db_items(self, key, items, item_key='id'):
        """
        Allow API methods to store objects from a DB query to be
        used by API extensions within the same API request.

        An instance of this class only lives for the lifetime of a
        single API request, so there's no need to implement full
        cache management.
        """
        db_items = self._extension_data['db_items'].setdefault(key, {})
        for item in items:
            db_items[item[item_key]] = item

    def get_db_items(self, key):
        """
        Allow an API extension to get previously stored objects within
        the same API request.

        Note that the object data will be slightly stale.
        """
        return self._extension_data['db_items'][key]

    def get_db_item(self, key, item_key):
        """
        Allow an API extension to get a previously stored object
        within the same API request.

        Note that the object data will be slightly stale.
        """
        return self.get_db_items(key).get(item_key)

    def cache_db_instances(self, instances):
        self.cache_db_items('instances', instances, 'uuid')

    def cache_db_instance(self, instance):
        self.cache_db_items('instances', [instance], 'uuid')

    def get_db_instances(self):
        return self.get_db_items('instances')

    def get_db_instance(self, instance_uuid):
        return self.get_db_item('instances', instance_uuid)

    def cache_db_flavors(self, flavors):
        self.cache_db_items('flavors', flavors, 'flavorid')

    def cache_db_flavor(self, flavor):
        self.cache_db_items('flavors', [flavor], 'flavorid')

    def get_db_flavors(self):
        return self.get_db_items('flavors')

    def get_db_flavor(self, flavorid):
        return self.get_db_item('flavors', flavorid)

    def best_match_content_type(self):
        """Determine the requested response content-type."""
        if 'nova.best_content_type' not in self.environ:
            # Calculate the best MIME type
            content_type = None

            # Check URL path suffix
            parts = self.path.rsplit('.', 1)
            if len(parts) > 1:
                possible_type = 'application/' + parts[1]
                if possible_type in SUPPORTED_CONTENT_TYPES:
                    content_type = possible_type

            if not content_type:
                content_type = self.accept.best_match(SUPPORTED_CONTENT_TYPES)

            self.environ['nova.best_content_type'] = (content_type or
                                                      'application/json')

        return self.environ['nova.best_content_type']

    def get_content_type(self):
        """Determine content type of the request body.

        Does not do any body introspection, only checks header

        """
        if "Content-Type" not in self.headers:
            return None

        content_type = self.content_type

        # NOTE(markmc): text/plain is the default for eventlet and
        # other webservers which use mimetools.Message.gettype()
        # whereas twisted defaults to ''.
        if not content_type or content_type == 'text/plain':
            return None

        if content_type not in SUPPORTED_CONTENT_TYPES:
            raise exception.InvalidContentType(content_type=content_type)

        return content_type

    def best_match_language(self):
        """Determine the best available language for the request.

        :returns: the best language match or None if the 'Accept-Language'
                  header was not available in the request.
        """
        if not self.accept_language:
            return None
        return self.accept_language.best_match(
                i18n.get_available_languages())


class ActionDispatcher(object):
    """Maps method name to local methods through action name."""

    def dispatch(self, *args, **kwargs):
        """Find and call local method."""
        action = kwargs.pop('action', 'default')
        action_method = getattr(self, str(action), self.default)
        return action_method(*args, **kwargs)

    def default(self, data):
        raise NotImplementedError()


class TextDeserializer(ActionDispatcher):
    """Default request body deserialization."""

    def deserialize(self, datastring, action='default'):
        return self.dispatch(datastring, action=action)

    def default(self, datastring):
        return {}


class DictSerializer(ActionDispatcher):
    """Default request body serialization."""

    def serialize(self, data, action='default'):
        return self.dispatch(data, action=action)

    def default(self, data):
        return ""


class JSONDeserializer(TextDeserializer):

    def _from_json(self, datastring):
        try:
            return jsonutils.loads(datastring)
        except ValueError:
            msg = _("cannot understand JSON")
            raise exception.MalformedRequestBody(reason=msg)

    def default(self, datastring):
        return {'body': self._from_json(datastring)}


class JSONDictSerializer(DictSerializer):
    """Default JSON request body serialization."""

    def default(self, data):
        return jsonutils.dumps(data)


def serializers(**serializers):
    """Attaches serializers to a method.

    This decorator associates a dictionary of serializers with a
    method.  Note that the function attributes are directly
    manipulated; the method is not wrapped.
    """

    def decorator(func):
        if not hasattr(func, 'wsgi_serializers'):
            func.wsgi_serializers = {}
        func.wsgi_serializers.update(serializers)
        return func
    return decorator


def deserializers(**deserializers):
    """Attaches deserializers to a method.

    This decorator associates a dictionary of deserializers with a
    method.  Note that the function attributes are directly
    manipulated; the method is not wrapped.
    """

    def decorator(func):
        if not hasattr(func, 'wsgi_deserializers'):
            func.wsgi_deserializers = {}
        func.wsgi_deserializers.update(deserializers)
        return func
    return decorator


def response(code):
    """Attaches response code to a method.

    This decorator associates a response code with a method.  Note
    that the function attributes are directly manipulated; the method
    is not wrapped.
    """

    def decorator(func):
        func.wsgi_code = code
        return func
    return decorator


class ResponseObject(object):
    """Bundles a response object with appropriate serializers.

    Object that app methods may return in order to bind alternate
    serializers with a response object to be serialized.  Its use is
    optional.
    """

    def __init__(self, obj, code=None, headers=None, **serializers):
        """Binds serializers with an object.

        Takes keyword arguments akin to the @serializer() decorator
        for specifying serializers.  Serializers specified will be
        given preference over default serializers or method-specific
        serializers on return.
        """

        self.obj = obj
        self.serializers = serializers
        self._default_code = 200
        self._code = code
        self._headers = headers or {}
        self.serializer = None
        self.media_type = None

    def __getitem__(self, key):
        """Retrieves a header with the given name."""

        return self._headers[key.lower()]

    def __setitem__(self, key, value):
        """Sets a header with the given name to the given value."""

        self._headers[key.lower()] = value

    def __delitem__(self, key):
        """Deletes the header with the given name."""

        del self._headers[key.lower()]

    def _bind_method_serializers(self, meth_serializers):
        """Binds method serializers with the response object.

        Binds the method serializers with the response object.
        Serializers specified to the constructor will take precedence
        over serializers specified to this method.

        :param meth_serializers: A dictionary with keys mapping to
                                 response types and values containing
                                 serializer objects.
        """

        # We can't use update because that would be the wrong
        # precedence
        for mtype, serializer in meth_serializers.items():
            self.serializers.setdefault(mtype, serializer)

    def get_serializer(self, content_type, default_serializers=None):
        """Returns the serializer for the wrapped object.

        Returns the serializer for the wrapped object subject to the
        indicated content type.  If no serializer matching the content
        type is attached, an appropriate serializer drawn from the
        default serializers will be used.  If no appropriate
        serializer is available, raises InvalidContentType.
        """

        default_serializers = default_serializers or {}

        try:
            mtype = _MEDIA_TYPE_MAP.get(content_type, content_type)
            if mtype in self.serializers:
                return mtype, self.serializers[mtype]
            else:
                return mtype, default_serializers[mtype]
        except (KeyError, TypeError):
            raise exception.InvalidContentType(content_type=content_type)

    def preserialize(self, content_type, default_serializers=None):
        """Prepares the serializer that will be used to serialize.

        Determines the serializer that will be used and prepares an
        instance of it for later call.  This allows the serializer to
        be accessed by extensions for, e.g., template extension.
        """

        mtype, serializer = self.get_serializer(content_type,
                                                default_serializers)
        self.media_type = mtype
        self.serializer = serializer()

    def attach(self, **kwargs):
        """Attach slave templates to serializers."""

        if self.media_type in kwargs:
            self.serializer.attach(kwargs[self.media_type])

    def serialize(self, request, content_type, default_serializers=None):
        """Serializes the wrapped object.

        Utility method for serializing the wrapped object.  Returns a
        webob.Response object.
        """

        if self.serializer:
            serializer = self.serializer
        else:
            _mtype, _serializer = self.get_serializer(content_type,
                                                      default_serializers)
            serializer = _serializer()

        response = webob.Response()
        response.status_int = self.code
        for hdr, value in self._headers.items():
            response.headers[hdr] = str(value)
        response.headers['Content-Type'] = content_type
        if self.obj is not None:
            response.body = serializer.serialize(self.obj)

        return response

    @property
    def code(self):
        """Retrieve the response status."""

        return self._code or self._default_code

    @property
    def headers(self):
        """Retrieve the headers."""

        return self._headers.copy()


class ResourceExceptionHandler(object):
    """Context manager to handle Resource exceptions.

    Used when processing exceptions generated by API implementation
    methods (or their extensions).  Converts most exceptions to Fault
    exceptions, with the appropriate logging.
    """

    def __enter__(self):
        return None

    def __exit__(self, ex_type, ex_value, ex_traceback):
        if not ex_value:
            return True

        if isinstance(ex_value, exception.NotAuthorized):
            raise Fault(webob.exc.HTTPForbidden(
                    explanation=ex_value.format_message()))
        elif isinstance(ex_value, exception.Invalid):
            raise Fault(exception.ConvertedException(
                    code=ex_value.code,
                    explanation=ex_value.format_message()))

        # Under python 2.6, TypeError's exception value is actually a string,
        # so test # here via ex_type instead:
        # http://bugs.python.org/issue7853
        elif issubclass(ex_type, TypeError):
            exc_info = (ex_type, ex_value, ex_traceback)
            LOG.error(_('Exception handling resource: %s') % ex_value,
                    exc_info=exc_info)
            raise Fault(webob.exc.HTTPBadRequest())
        elif isinstance(ex_value, Fault):
            LOG.info(_("Fault thrown: %s"), unicode(ex_value))
            raise ex_value
        elif isinstance(ex_value, webob.exc.HTTPException):
            LOG.info(_("HTTP exception thrown: %s"), unicode(ex_value))
            raise Fault(ex_value)

        # We didn't handle the exception
        return False


def sanitize(msg):
    if not (key in msg for key in _SANITIZE_KEYS):
        return msg

    for pattern in _SANITIZE_PATTERNS:
        msg = re.sub(pattern, r'\1****\2', msg)
    return msg


class Resource(wsgi.Application):
    """WSGI app that handles (de)serialization and controller dispatch.

    WSGI app that reads routing information supplied by RoutesMiddleware
    and calls the requested action method upon its controller.  All
    controller action methods must accept a 'req' argument, which is the
    incoming wsgi.Request. If the operation is a PUT or POST, the controller
    method must also accept a 'body' argument (the deserialized request body).
    They may raise a webob.exc exception or return a dict, which will be
    serialized by requested content type.

    Exceptions derived from webob.exc.HTTPException will be automatically
    wrapped in Fault() to provide API friendly error responses.

    """

    def __init__(self, controller, **deserializers):
        """
        :param controller: object that implement methods created by routes lib
        """

        self.controller = controller

        default_deserializers = dict(json=JSONDeserializer)
        default_deserializers.update(deserializers)

        self.default_deserializers = default_deserializers
        self.default_serializers = dict(json=JSONDictSerializer)

    def get_action_args(self, request_environment):
        """Parse dictionary created by routes library."""

        # NOTE(Vek): Check for get_action_args() override in the
        # controller
        if hasattr(self.controller, 'get_action_args'):
            return self.controller.get_action_args(request_environment)

        try:
            args = request_environment['wsgiorg.routing_args'][1].copy()
        except (KeyError, IndexError, AttributeError):
            return {}

        try:
            del args['controller']
        except KeyError:
            pass

        try:
            del args['format']
        except KeyError:
            pass

        return args

    def get_body(self, request):
        try:
            content_type = request.get_content_type()
        except exception.InvalidContentType:
            LOG.debug(_("Unrecognized Content-Type provided in request"))
            return None, ''

        if not content_type:
            LOG.debug(_("No Content-Type provided in request"))
            return None, ''

        if len(request.body) <= 0:
            LOG.debug(_("Empty body provided in request"))
            return None, ''

        return content_type, request.body

    def deserialize(self, meth, content_type, body):
        meth_deserializers = getattr(meth, 'wsgi_deserializers', {})
        try:
            mtype = _MEDIA_TYPE_MAP.get(content_type, content_type)
            if mtype in meth_deserializers:
                deserializer = meth_deserializers[mtype]
            else:
                deserializer = self.default_deserializers[mtype]
        except (KeyError, TypeError):
            raise exception.InvalidContentType(content_type=content_type)

        if (hasattr(deserializer, 'want_controller')
                and deserializer.want_controller):
            return deserializer(self.controller).deserialize(body)
        else:
            return deserializer().deserialize(body)

    @webob.dec.wsgify(RequestClass=Request)
    def __call__(self, request):
        """WSGI method that controls (de)serialization and method dispatch."""

        # Identify the action, its arguments, and the requested
        # content type
        action_args = self.get_action_args(request.environ)
        action = action_args.pop('action', None)
        content_type, body = self.get_body(request)
        accept = request.best_match_content_type()

        # NOTE(Vek): Splitting the function up this way allows for
        #            auditing by external tools that wrap the existing
        #            function.  If we try to audit __call__(), we can
        #            run into troubles due to the @webob.dec.wsgify()
        #            decorator.
        return self._process_stack(request, action, action_args,
                               content_type, body, accept)

    def _process_stack(self, request, action, action_args,
                       content_type, body, accept):
        """Implement the processing stack."""

        # Get the implementing method
        try:
            meth = self.get_method(request, action, content_type, body)
        except (AttributeError, TypeError):
            return Fault(webob.exc.HTTPNotFound())
        except KeyError as ex:
            msg = _("There is no such action: %s") % ex.args[0]
            return Fault(webob.exc.HTTPBadRequest(explanation=msg))
        except exception.MalformedRequestBody:
            msg = _("Malformed request body")
            return Fault(webob.exc.HTTPBadRequest(explanation=msg))

        if body:
            msg = _("Action: '%(action)s', body: "
                    "%(body)s") % {'action': action,
                                   'body': unicode(body, 'utf-8')}
            LOG.debug(sanitize(msg))
        LOG.debug(_("Calling method %s") % str(meth))

        # Now, deserialize the request body...
        try:
            if content_type:
                contents = self.deserialize(meth, content_type, body)
            else:
                contents = {}
        except exception.InvalidContentType:
            msg = _("Unsupported Content-Type")
            return Fault(webob.exc.HTTPBadRequest(explanation=msg))
        except exception.MalformedRequestBody:
            msg = _("Malformed request body")
            return Fault(webob.exc.HTTPBadRequest(explanation=msg))

        # Update the action args
        action_args.update(contents)

        response = None
        try:
            with ResourceExceptionHandler():
                action_result = self.dispatch(meth, request, action_args)
        except Fault as ex:
            response = ex

        if not response:
            # No exceptions; convert action_result into a
            # ResponseObject
            resp_obj = None
            if type(action_result) is dict or action_result is None:
                resp_obj = ResponseObject(action_result)
            elif isinstance(action_result, ResponseObject):
                resp_obj = action_result
            else:
                response = action_result

            # Run post-processing extensions
            if resp_obj:
                # Do a preserialize to set up the response object
                serializers = getattr(meth, 'wsgi_serializers', {})
                resp_obj._bind_method_serializers(serializers)
                if hasattr(meth, 'wsgi_code'):
                    resp_obj._default_code = meth.wsgi_code
                resp_obj.preserialize(accept, self.default_serializers)
                response = resp_obj.serialize(request, accept,
                                              self.default_serializers)
        return response

    def get_method(self, request, action, content_type, body):
        """Look up the action-specific method and its extensions."""

        # Look up the method
        if self.controller:
            return getattr(self.controller, action)
        else:
            return getattr(self, action)

    def dispatch(self, method, request, action_args):
        """Dispatch a call to the action-specific method."""

        return method(req=request, **action_args)


class Fault(webob.exc.HTTPException):
    """Wrap webob.exc.HTTPException to provide API friendly response."""

    _fault_names = {
            400: "badRequest",
            401: "unauthorized",
            403: "forbidden",
            404: "itemNotFound",
            405: "badMethod",
            409: "conflictingRequest",
            413: "overLimit",
            415: "badMediaType",
            429: "overLimit",
            501: "notImplemented",
            503: "serviceUnavailable"}

    def __init__(self, exception):
        """Create a Fault for the given webob.exc.exception."""
        self.wrapped_exc = exception
        for key, value in self.wrapped_exc.headers.items():
            self.wrapped_exc.headers[key] = str(value)
        self.status_int = exception.status_int

    @webob.dec.wsgify(RequestClass=Request)
    def __call__(self, req):
        """Generate a WSGI response based on the exception passed to ctor."""

        user_locale = req.best_match_language()
        # Replace the body with fault details.
        code = self.wrapped_exc.status_int
        fault_name = self._fault_names.get(code, "computeFault")
        explanation = self.wrapped_exc.explanation
        LOG.debug(_("Returning %(code)s to user: %(explanation)s"),
                  {'code': code, 'explanation': explanation})

        explanation = i18n.translate(explanation, user_locale)
        fault_data = {
            fault_name: {
                'code': code,
                'message': explanation}}
        if code == 413 or code == 429:
            retry = self.wrapped_exc.headers.get('Retry-After', None)
            if retry:
                fault_data[fault_name]['retryAfter'] = retry

        # 'code' is an attribute on the fault tag itself
        metadata = {'attributes': {fault_name: 'code'}}

        content_type = req.best_match_content_type()
        serializer = {
            'application/json': JSONDictSerializer(),
        }[content_type]

        self.wrapped_exc.body = serializer.serialize(fault_data)
        self.wrapped_exc.content_type = content_type

        return self.wrapped_exc

    def __str__(self):
        return self.wrapped_exc.__str__()


class RateLimitFault(webob.exc.HTTPException):
    """
    Rate-limited request response.
    """

    def __init__(self, message, details, retry_time):
        """
        Initialize new `RateLimitFault` with relevant information.
        """
        hdrs = RateLimitFault._retry_after(retry_time)
        self.wrapped_exc = webob.exc.HTTPTooManyRequests(headers=hdrs)
        self.content = {
            "overLimit": {
                "code": self.wrapped_exc.status_int,
                "message": message,
                "details": details,
                "retryAfter": hdrs['Retry-After'],
            },
        }

    @staticmethod
    def _retry_after(retry_time):
        delay = int(math.ceil(retry_time - time.time()))
        retry_after = delay if delay > 0 else 0
        headers = {'Retry-After': '%d' % retry_after}
        return headers

    @webob.dec.wsgify(RequestClass=Request)
    def __call__(self, request):
        """
        Return the wrapped exception with a serialized body conforming to our
        error format.
        """
        user_locale = request.best_match_language()
        content_type = request.best_match_content_type()
        metadata = {"attributes": {"overLimit": ["code", "retryAfter"]}}

        self.content['overLimit']['message'] = \
                i18n.translate(
                        self.content['overLimit']['message'],
                        user_locale)
        self.content['overLimit']['details'] = \
                i18n.translate(
                        self.content['overLimit']['details'],
                        user_locale)

        serializer = {
            'application/json': JSONDictSerializer(),
        }[content_type]

        content = serializer.serialize(self.content)
        self.wrapped_exc.body = content
        self.wrapped_exc.content_type = content_type

        return self.wrapped_exc