# -*- test-case-name: twisted.test.test_pb -*-

# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.


"""
Utility classes for spread.
"""

from twisted.internet import defer
from twisted.python.failure import Failure
from twisted.spread import pb
from twisted.protocols import basic
from twisted.internet import interfaces

from zope.interface import implements


class LocalMethod:
def __init__(self, local, name):
self.local = local
self.name = name

def __call__(self, *args, **kw):
return self.local.callRemote(self.name, *args, **kw)


class LocalAsRemote:
"""
A class useful for emulating the effects of remote behavior locally.
"""
reportAllTracebacks = 1

def callRemote(self, name, *args, **kw):
"""
Call a specially-designated local method.

self.callRemote('x') will first try to invoke a method named
sync_x and return its result (which should probably be a
Deferred). Second, it will look for a method called async_x,
which will be called and then have its result (or Failure)
automatically wrapped in a Deferred.
"""
if hasattr(self, 'sync_'+name):
return getattr(self, 'sync_'+name)(*args, **kw)
try:
method = getattr(self, "async_" + name)
return defer.succeed(method(*args, **kw))
except:
f = Failure()
if self.reportAllTracebacks:
f.printTraceback()
return defer.fail(f)

def remoteMethod(self, name):
return LocalMethod(self, name)


class LocalAsyncForwarder:
"""
A class useful for forwarding a locally-defined interface.
"""

def __init__(self, forwarded, interfaceClass, failWhenNotImplemented=0):
assert interfaceClass.providedBy(forwarded)
self.forwarded = forwarded
self.interfaceClass = interfaceClass
self.failWhenNotImplemented = failWhenNotImplemented

def _callMethod(self, method, *args, **kw):
return getattr(self.forwarded, method)(*args, **kw)

def callRemote(self, method, *args, **kw):
if self.interfaceClass.queryDescriptionFor(method):
result = defer.maybeDeferred(self._callMethod, method, *args, **kw)
return result
elif self.failWhenNotImplemented:
return defer.fail(
Failure(NotImplementedError,
"No Such Method in Interface: %s" % method))
else:
return defer.succeed(None)


class Pager:
"""
I am an object which pages out information.
"""
def __init__(self, collector, callback=None, *args, **kw):
"""
Create a pager with a Reference to a remote collector and
an optional callable to invoke upon completion.
"""
if callable(callback):
self.callback = callback
self.callbackArgs = args
self.callbackKeyword = kw
else:
self.callback = None
self._stillPaging = 1
self.collector = collector
collector.broker.registerPageProducer(self)

def stillPaging(self):
"""
(internal) Method called by Broker.
"""
if not self._stillPaging:
self.collector.callRemote("endedPaging")
if self.callback is not None:
self.callback(*self.callbackArgs, **self.callbackKeyword)
return self._stillPaging

def sendNextPage(self):
"""
(internal) Method called by Broker.
"""
self.collector.callRemote("gotPage", self.nextPage())

def nextPage(self):
"""
Override this to return an object to be sent to my collector.
"""
raise NotImplementedError()

def stopPaging(self):
"""
Call this when you're done paging.
"""
self._stillPaging = 0


class StringPager(Pager):
"""
A simple pager that splits a string into chunks.
"""
def __init__(self, collector, st, chunkSize=8192, callback=None, *args, **kw):
self.string = st
self.pointer = 0
self.chunkSize = chunkSize
Pager.__init__(self, collector, callback, *args, **kw)

def nextPage(self):
val = self.string[self.pointer:self.pointer+self.chunkSize]
self.pointer += self.chunkSize
if self.pointer >= len(self.string):
self.stopPaging()
return val


class FilePager(Pager):
"""
Reads a file in chunks and sends the chunks as they come.
"""
implements(interfaces.IConsumer)

def __init__(self, collector, fd, callback=None, *args, **kw):
self.chunks = []
Pager.__init__(self, collector, callback, *args, **kw)
self.startProducing(fd)

def startProducing(self, fd):
self.deferred = basic.FileSender().beginFileTransfer(fd, self)
self.deferred.addBoth(lambda x : self.stopPaging())

def registerProducer(self, producer, streaming):
self.producer = producer
if not streaming:
self.producer.resumeProducing()

def unregisterProducer(self):
self.producer = None

def write(self, chunk):
self.chunks.append(chunk)

def sendNextPage(self):
"""
Get the first chunk read and send it to collector.
"""
if not self.chunks:
return
val = self.chunks.pop(0)
self.producer.resumeProducing()
self.collector.callRemote("gotPage", val)


# Utility paging stuff.
class CallbackPageCollector(pb.Referenceable):
"""
I receive pages from the peer. You may instantiate a Pager with a
remote reference to me. I will call the callback with a list of pages
once they are all received.
"""
def __init__(self, callback):
self.pages = []
self.callback = callback

def remote_gotPage(self, page):
self.pages.append(page)

def remote_endedPaging(self):
self.callback(self.pages)


def getAllPages(referenceable, methodName, *args, **kw):
"""
A utility method that will call a remote method which expects a
PageCollector as the first argument.
"""
d = defer.Deferred()
referenceable.callRemote(methodName, CallbackPageCollector(d.callback), *args, **kw)
return d