# -*- test-case-name: idavoll.test.test_gateway -*-
#
# Copyright (c) 2003-2008 Ralph Meijer
# See LICENSE for details.

"""
Web resources and client for interacting with pubsub services.
"""

import cgi
from time import gmtime, strftime
import urllib
import urlparse

import simplejson

from twisted.application import service
from twisted.internet import defer, reactor
from twisted.python import log
from twisted.web import client
from twisted.web2 import http, http_headers, resource, responsecode
from twisted.web2 import channel, server
from twisted.web2.stream import readStream
from twisted.words.protocols.jabber.jid import JID
from twisted.words.protocols.jabber.error import StanzaError
from twisted.words.xish import domish

from wokkel.pubsub import Item
from wokkel.pubsub import PubSubClient

from idavoll import error

NS_ATOM = 'http://www.w3.org/2005/Atom'
MIME_ATOM_ENTRY = 'application/atom+xml;type=entry'
MIME_JSON = 'application/json'

class XMPPURIParseError(ValueError):
    """
    Raised when a given XMPP URI couldn't be properly parsed.
    """



def getServiceAndNode(uri):
    """
    Given an XMPP URI, extract the publish subscribe service JID and node ID.
    """

    try:
        scheme, rest = uri.split(':', 1)
    except ValueError:
        raise XMPPURIParseError("No URI scheme component")

    if scheme != 'xmpp':
        raise XMPPURIParseError("Unknown URI scheme")

    if rest.startswith("//"):
        raise XMPPURIParseError("Unexpected URI authority component")

    try:
        entity, query = rest.split('?', 1)
    except ValueError:
        raise XMPPURIParseError("No URI query component")

    if not entity:
        raise XMPPURIParseError("Empty URI path component")

    try:
        jid = JID(entity)
    except Exception, e:
        raise XMPPURIParseError("Invalid JID: %s" % e.message)

    params = cgi.parse_qs(query)

    try:
        nodeIdentifier = params['node'][0]
    except (KeyError, ValueError):
        raise XMPPURIParseError("No node in query component of URI")

    return jid, nodeIdentifier



class WebStreamParser(object):
    def __init__(self):
        self.elementStream = domish.elementStream()
        self.elementStream.DocumentStartEvent = self.docStart
        self.elementStream.ElementEvent = self.elem
        self.elementStream.DocumentEndEvent = self.docEnd
        self.done = False


    def docStart(self, elem):
        self.document = elem


    def elem(self, elem):
        self.document.addChild(elem)


    def docEnd(self):
        self.done = True


    def parse(self, stream):
        def endOfStream(result):
            if not self.done:
                raise Exception("No more stuff?")
            else:
                return self.document

        d = readStream(stream, self.elementStream.parse)
        d.addCallback(endOfStream)
        return d



class CreateResource(resource.Resource):
    """
    A resource to create a publish-subscribe node.
    """
    def __init__(self, backend, serviceJID, owner):
        self.backend = backend
        self.serviceJID = serviceJID
        self.owner = owner


    http_GET = None


    def http_POST(self, request):
        """
        Respond to a POST request to create a new node.
        """

        def toResponse(nodeIdentifier):
            uri = 'xmpp:%s?;node=%s' % (self.serviceJID.full(), nodeIdentifier)
            stream = simplejson.dumps({'uri': uri})
            return http.Response(responsecode.OK, stream=stream)

        d = self.backend.createNode(None, self.owner)
        d.addCallback(toResponse)
        return d



class DeleteResource(resource.Resource):
    """
    A resource to create a publish-subscribe node.
    """
    def __init__(self, backend, serviceJID, owner):
        self.backend = backend
        self.serviceJID = serviceJID
        self.owner = owner


    http_GET = None


    def http_POST(self, request):
        """
        Respond to a POST request to create a new node.
        """

        def respond(result):
            return http.Response(responsecode.NO_CONTENT)

        def getNode():
            if request.args.get('uri'):
                jid, nodeIdentifier = getServiceAndNode(request.args['uri'][0])
                return defer.succeed(nodeIdentifier)
            else:
                raise http.HTTPError(http.Response(responsecode.BAD_REQUEST,
                                                   "No URI given"))

        def trapNotFound(failure):
            failure.trap(error.NodeNotFound)
            return http.StatusResponse(responsecode.NOT_FOUND,
                                       "Node not found")

        def trapXMPPURIParseError(failure):
            failure.trap(XMPPURIParseError)
            return http.StatusResponse(responsecode.BAD_REQUEST,
                    "Malformed XMPP URI: %s" % failure.value.message)

        d = getNode()
        d.addCallback(self.backend.deleteNode, self.owner)
        d.addCallback(respond)
        d.addErrback(trapNotFound)
        d.addErrback(trapXMPPURIParseError)
        return d



class PublishResource(resource.Resource):
    """
    A resource to publish to a publish-subscribe node.
    """

    def __init__(self, backend, serviceJID, owner):
        self.backend = backend
        self.serviceJID = serviceJID
        self.owner = owner


    http_GET = None


    def checkMediaType(self, request):
        ctype = request.headers.getHeader('content-type')

        if not ctype:
            raise http.HTTPError(
                http.StatusResponse(
                    responsecode.BAD_REQUEST,
                    "No specified Media Type"))

        if (ctype.mediaType != 'application' or
            ctype.mediaSubtype != 'atom+xml' or
            ctype.params.get('type') != 'entry' or
            ctype.params.get('charset', 'utf-8') != 'utf-8'):
            raise http.HTTPError(
                http.StatusResponse(
                    responsecode.UNSUPPORTED_MEDIA_TYPE,
                    "Unsupported Media Type: %s" %
                        http_headers.generateContentType(ctype)))


    def parseXMLPayload(self, stream):
        p = WebStreamParser()
        return p.parse(stream)


    def http_POST(self, request):
        """
        Respond to a POST request to create a new item.
        """

        def toResponse(nodeIdentifier):
            uri = 'xmpp:%s?;node=%s' % (self.serviceJID.full(), nodeIdentifier)
            stream = simplejson.dumps({'uri': uri})
            return http.Response(responsecode.OK, stream=stream)

        def gotNode(nodeIdentifier, payload):
            item = Item(id='current', payload=payload)
            d = self.backend.publish(nodeIdentifier, [item], self.owner)
            d.addCallback(lambda _: nodeIdentifier)
            return d

        def getNode():
            if request.args.get('uri'):
                jid, nodeIdentifier = getServiceAndNode(request.args['uri'][0])
                return defer.succeed(nodeIdentifier)
            else:
                return self.backend.createNode(None, self.owner)

        def doPublish(payload):
            d = getNode()
            d.addCallback(gotNode, payload)
            return d

        def trapNotFound(failure):
            failure.trap(error.NodeNotFound)
            return http.StatusResponse(responsecode.NOT_FOUND,
                                       "Node not found")

        def trapXMPPURIParseError(failure):
            failure.trap(XMPPURIParseError)
            return http.StatusResponse(responsecode.BAD_REQUEST,
                    "Malformed XMPP URI: %s" % failure.value.message)

        self.checkMediaType(request)
        d = self.parseXMLPayload(request.stream)
        d.addCallback(doPublish)
        d.addCallback(toResponse)
        d.addErrback(trapNotFound)
        d.addErrback(trapXMPPURIParseError)
        return d



class ListResource(resource.Resource):
    def __init__(self, service):
        self.service = service


    def render(self, request):
        def responseFromNodes(nodeIdentifiers):
            return http.Response(responsecode.OK,
                                 stream=simplejson.dumps(nodeIdentifiers))

        d = self.service.getNodes()
        d.addCallback(responseFromNodes)
        return d



# Service for subscribing to remote XMPP Pubsub nodes and web resources

def extractAtomEntries(items):
    """
    Extract atom entries from a list of publish-subscribe items.

    @param items: List of L{domish.Element}s that represent publish-subscribe
                  items.
    @type items: C{list}
    """

    atomEntries = []

    for item in items:
        # ignore non-items (i.e. retractions)
        if item.name != 'item':
            continue

        atomEntry = None
        for element in item.elements():
            # extract the first element that is an atom entry
            if element.uri == NS_ATOM and element.name == 'entry':
                atomEntry = element
                break

        if atomEntry:
            atomEntries.append(atomEntry)

    return atomEntries



def constructFeed(service, nodeIdentifier, entries, title):
    nodeURI = 'xmpp:%s?;node=%s' % (service.full(), nodeIdentifier)
    now = strftime("%Y-%m-%dT%H:%M:%SZ", gmtime())

    # Collect the received entries in a feed
    feed = domish.Element((NS_ATOM, 'feed'))
    feed.addElement('title', content=title)
    feed.addElement('id', content=nodeURI)
    feed.addElement('updated', content=now)

    for entry in entries:
        feed.addChild(entry)

    return feed



class RemoteSubscriptionService(service.Service, PubSubClient):
    """
    Service for subscribing to remote XMPP Publish-Subscribe nodes.

    Subscriptions are created with a callback HTTP URI that is POSTed
    to with the received items in notifications.
    """

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


    def startService(self):
        self.callbacks = {}


    def trapNotFound(self, failure):
        failure.trap(StanzaError)
        if not failure.value.condition == 'item-not-found':
            raise failure
        raise error.NodeNotFound


    def subscribeCallback(self, jid, nodeIdentifier, callback):

        def newCallbackList(result):
            callbackList = set()
            self.callbacks[jid, nodeIdentifier] = callbackList
            return callbackList

        def callbackForLastItem(items, callback):
            atomEntries = extractAtomEntries(items)

            if not atomEntries:
                return

            self._postTo([callback], jid, nodeIdentifier, atomEntries[0],
                         'application/atom+xml;type=entry')

        try:
            callbackList = self.callbacks[jid, nodeIdentifier]
        except KeyError:
            d = self.subscribe(jid, nodeIdentifier, self.jid)
            d.addCallback(newCallbackList)
        else:
            d = self.items(jid, nodeIdentifier, 1)
            d.addCallback(callbackForLastItem, callback)
            d.addCallback(lambda _: callbackList)

        d.addCallback(lambda callbackList: callbackList.add(callback))
        d.addErrback(self.trapNotFound)
        return d


    def unsubscribeCallback(self, jid, nodeIdentifier, callback):
        try:
            callbackList = self.callbacks[jid, nodeIdentifier]
            callbackList.remove(callback)
        except KeyError:
            return defer.fail(error.NotSubscribed())

        if not callbackList:
            self.unsubscribe(jid, nodeIdentifier, self.jid)

        return defer.succeed(None)


    def itemsReceived(self, recipient, service, nodeIdentifier, items):
        """
        Fire up HTTP client to do callback
        """

        atomEntries = extractAtomEntries(items)

        # Don't notify if there are no atom entries
        if not atomEntries:
            return

        if len(atomEntries) == 1:
            contentType = 'application/atom+xml;type=entry'
            payload = atomEntries[0]
        else:
            contentType = 'application/atom+xml;type=feed'
            payload = constructFeed(service, nodeIdentifier, atomEntries,
                                    title='Received item collection')

        self.callCallbacks(service, nodeIdentifier, payload, contentType)


    def deleteReceived(self, recipient, service, nodeIdentifier):
        """
        Fire up HTTP client to do callback
        """

        self.callCallbacks(service, nodeIdentifier, eventType='DELETED')


    def _postTo(self, callbacks, service, nodeIdentifier,
                      payload=None, contentType=None, eventType=None):
        postdata = None
        nodeURI = 'xmpp:%s?;node=%s' % (service.full(), nodeIdentifier)
        headers = {'Referer': nodeURI.encode('utf-8'),
                   'PubSub-Service': service.full().encode('utf-8')}

        if payload:
            postdata = payload.toXml().encode('utf-8')
            if contentType:
                headers['Content-Type'] = "%s;charset=utf-8" % contentType

        if eventType:
            headers['Event'] = eventType

        def postNotification(callbackURI):
            d = client.getPage(str(callbackURI),
                                   method='POST',
                                   postdata=postdata,
                                   headers=headers)
            d.addErrback(log.err)

        for callbackURI in callbacks:
            reactor.callLater(0, postNotification, callbackURI)

    def callCallbacks(self, service, nodeIdentifier,
                            payload=None, contentType=None, eventType=None):
        try:
            callbacks = self.callbacks[service, nodeIdentifier]
        except KeyError:
            return

        self._postTo(callbacks, service, nodeIdentifier, payload, contentType,
                     eventType)




class RemoteSubscribeBaseResource(resource.Resource):
    """
    Base resource for remote pubsub node subscription and unsubscription.

    This resource accepts POST request with a JSON document that holds
    a dictionary with the keys C{uri} and C{callback} that respectively map
    to the XMPP URI of the publish-subscribe node and the callback URI.

    This class should be inherited with L{serviceMethod} overridden.

    @cvar serviceMethod: The name of the method to be called with
                         the JID of the pubsub service, the node identifier
                         and the callback URI as received in the HTTP POST
                         request to this resource.
    """
    serviceMethod = None
    errorMap = {
            error.NodeNotFound:
                (responsecode.FORBIDDEN, "Node not found"),
            error.NotSubscribed:
                (responsecode.FORBIDDEN, "No such subscription found"),
    }

    def __init__(self, service):
        self.service = service
        self.params = None


    http_GET = None


    def http_POST(self, request):
        def trapNotFound(failure):
            err = failure.trap(*self.errorMap.keys())
            code, msg = self.errorMap[err]
            return http.StatusResponse(code, msg)

        def respond(result):
            return http.Response(responsecode.NO_CONTENT)

        def gotRequest(result):
            uri = self.params['uri']
            callback = self.params['callback']

            jid, nodeIdentifier = getServiceAndNode(uri)
            method = getattr(self.service, self.serviceMethod)
            d = method(jid, nodeIdentifier, callback)
            return d

        def storeParams(data):
            self.params = simplejson.loads(data)

        def trapXMPPURIParseError(failure):
            failure.trap(XMPPURIParseError)
            return http.StatusResponse(responsecode.BAD_REQUEST,
                    "Malformed XMPP URI: %s" % failure.value.message)

        d = readStream(request.stream, storeParams)
        d.addCallback(gotRequest)
        d.addCallback(respond)
        d.addErrback(trapNotFound)
        d.addErrback(trapXMPPURIParseError)
        return d



class RemoteSubscribeResource(RemoteSubscribeBaseResource):
    """
    Resource to subscribe to a remote publish-subscribe node.

    The passed C{uri} is the XMPP URI of the node to subscribe to and the
    C{callback} is the callback URI. Upon receiving notifications from the
    node, a POST request will be perfomed on the callback URI.
    """
    serviceMethod = 'subscribeCallback'



class RemoteUnsubscribeResource(RemoteSubscribeBaseResource):
    """
    Resource to unsubscribe from a remote publish-subscribe node.

    The passed C{uri} is the XMPP URI of the node to unsubscribe from and the
    C{callback} is the callback URI that was registered for it.
    """
    serviceMethod = 'unsubscribeCallback'



class RemoteItemsResource(resource.Resource):
    """
    Resource for retrieving items from a remote pubsub node.
    """

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


    def render(self, request):
        try:
            maxItems = int(request.args.get('max_items', [0])[0]) or None
        except ValueError:
            return http.StatusResponse(responsecode.BAD_REQUEST,
                    "The argument max_items has an invalid value.")

        try:
            uri = request.args['uri'][0]
        except KeyError:
            return http.StatusResponse(responsecode.BAD_REQUEST,
                    "No URI for the remote node provided.")

        try:
            jid, nodeIdentifier = getServiceAndNode(uri)
        except XMPPURIParseError:
            return http.StatusResponse(responsecode.BAD_REQUEST,
                    "Malformed XMPP URI: %s" % uri)

        def respond(items):
            """Create a feed out the retrieved items."""
            contentType = http_headers.MimeType('application',
                                                'atom+xml',
                                                {'type': 'feed'})
            atomEntries = extractAtomEntries(items)
            feed = constructFeed(jid, nodeIdentifier, atomEntries,
                                    "Retrieved item collection")
            payload = feed.toXml().encode('utf-8')
            return http.Response(responsecode.OK, stream=payload,
                                 headers={'Content-Type': contentType})

        def trapNotFound(failure):
            failure.trap(StanzaError)
            if not failure.value.condition == 'item-not-found':
                raise failure
            return http.StatusResponse(responsecode.NOT_FOUND,
                                       "Node not found")

        d = self.service.items(jid, nodeIdentifier, maxItems)
        d.addCallback(respond)
        d.addErrback(trapNotFound)
        return d



# Client side code to interact with a service as provided above

def getPageWithFactory(url, contextFactory=None, *args, **kwargs):
    """Download a web page.

    Download a page. Return the factory that holds a deferred, which will
    callback with a page (as a string) or errback with a description of the
    error.

    See HTTPClientFactory to see what extra args can be passed.
    """

    scheme, host, port, path = client._parse(url)
    factory = client.HTTPClientFactory(url, *args, **kwargs)
    factory.protocol.handleStatus_204 = lambda self: self.handleStatus_200()

    if scheme == 'https':
        from twisted.internet import ssl
        if contextFactory is None:
            contextFactory = ssl.ClientContextFactory()
        reactor.connectSSL(host, port, factory, contextFactory)
    else:
        reactor.connectTCP(host, port, factory)
    return factory



class CallbackResource(resource.Resource):
    """
    Web resource for retrieving gateway notifications.
    """

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


    http_GET = None


    def http_POST(self, request):
        p = WebStreamParser()
        d = p.parse(request.stream)
        d.addCallback(self.callback, request.headers)
        d.addCallback(lambda _: http.Response(responsecode.NO_CONTENT))
        return d



class GatewayClient(service.Service):
    """
    Service that provides client access to the HTTP Gateway into Idavoll.
    """

    agent = "Idavoll HTTP Gateway Client"

    def __init__(self, baseURI, callbackHost=None, callbackPort=None):
        self.baseURI = baseURI
        self.callbackHost = callbackHost or 'localhost'
        self.callbackPort = callbackPort or 8087
        root = resource.Resource()
        root.child_callback = CallbackResource(lambda *args, **kwargs: self.callback(*args, **kwargs))
        self.site = server.Site(root)


    def startService(self):
        self.port = reactor.listenTCP(self.callbackPort,
                                      channel.HTTPFactory(self.site))


    def stopService(self):
        return self.port.stopListening()


    def _makeURI(self, verb, query=None):
        uriComponents = urlparse.urlparse(self.baseURI)
        uri = urlparse.urlunparse((uriComponents[0],
                                   uriComponents[1],
                                   uriComponents[2] + verb,
                                   '',
                                   query and urllib.urlencode(query) or '',
                                   ''))
        return uri


    def callback(self, data, headers):
        pass


    def create(self):
        f = getPageWithFactory(self._makeURI('create'),
                    method='POST',
                    agent=self.agent)
        return f.deferred.addCallback(simplejson.loads)


    def publish(self, entry, xmppURI=None):
        query = xmppURI and {'uri': xmppURI}

        f = getPageWithFactory(self._makeURI('publish', query),
                    method='POST',
                    postdata=entry.toXml().encode('utf-8'),
                    headers={'Content-Type': MIME_ATOM_ENTRY},
                    agent=self.agent)
        return f.deferred.addCallback(simplejson.loads)


    def listNodes(self):
        f = getPageWithFactory(self._makeURI('list'),
                    method='GET',
                    agent=self.agent)
        return f.deferred.addCallback(simplejson.loads)


    def subscribe(self, xmppURI):
        params = {'uri': xmppURI,
                  'callback': 'http://%s:%s/callback' % (self.callbackHost,
                                                         self.callbackPort)}
        f = getPageWithFactory(self._makeURI('subscribe'),
                    method='POST',
                    postdata=simplejson.dumps(params),
                    headers={'Content-Type': MIME_JSON},
                    agent=self.agent)
        return f.deferred


    def unsubscribe(self, xmppURI):
        params = {'uri': xmppURI,
                  'callback': 'http://%s:%s/callback' % (self.callbackHost,
                                                         self.callbackPort)}
        f = getPageWithFactory(self._makeURI('unsubscribe'),
                    method='POST',
                    postdata=simplejson.dumps(params),
                    headers={'Content-Type': MIME_JSON},
                    agent=self.agent)
        return f.deferred


    def items(self, xmppURI, maxItems=None):
        query = {'uri': xmppURI}
        if maxItems:
             query['max_items'] = int(maxItems)
        f = getPageWithFactory(self._makeURI('items', query),
                    method='GET',
                    agent=self.agent)
        return f.deferred