from sets import Set
import warnings

from twisted.internet import interfaces, defer, main
from twisted.persisted import styles
from twisted.python import log, failure

from ops import ReadFileOp, WriteFileOp
from util import StateEventMachineType

class ConnectedSocket(log.Logger, styles.Ephemeral, object):
    __metaclass__ = StateEventMachineType
    __implements__ = interfaces.ITransport, interfaces.IProducer, interfaces.IConsumer
    events = ["write", "loseConnection", "writeDone", "writeErr", "readDone", "readErr", "shutdown"]
    bufferSize = 2**2**2**2
    producer = None
    writing = False
    reading = False
    write_shutdown = False
    read_shutdown = False

    def __init__(self, socket, protocol, sockfactory):
        self.state = "connected"
        from twisted.internet import reactor
        self.socket = socket
        self.protocol = protocol
        self.sf = sockfactory
        self.writebuf = []
        self.readbuf = reactor.AllocateReadBuffer(self.bufferSize)
        self.reactor = reactor
        self.bufferEvents = {"buffer full": Set(), "buffer empty": Set()}
        self.offset = 0
        self.writeBufferedSize = 0
        self.read_op = ReadFileOp(self)
        self.write_op = WriteFileOp(self) # XXX: these two should be specified like before, with a class field

    def addBufferCallback(self, handler, event):
        self.bufferEvents[event].add(handler)

    def removeBufferCallback(self, handler, event):
        self.bufferEvents[event].remove(handler)

    def callBufferHandlers(self, event, *a, **kw):
        for i in self.bufferEvents[event].copy():
            i(*a, **kw)

    def handle_connected_write(self, data):
        if self.writebuf and len(self.writebuf[-1]) < self.bufferSize: # mmmhhh silly heuristics
            self.writebuf[-1] += data
        else:
            self.writebuf.append(data)
        self.writeBufferedSize += len(data)
        if self.writeBufferedSize >= self.bufferSize:
            self.callBufferHandlers(event = "buffer full")
        if not self.writing:
            self.startWriting()

    handle_disconnecting_write = handle_connected_write

    def handle_disconnected_write(self, data):
        pass # blarf

    def writeSequence(self, iovec):
        self.write("".join(iovec))

    def _cbDisconnecting(self):
        if self.producer:
            return
        self.removeBufferCallback(self._cbDisconnecting, "buffer empty")
        self.connectionLost(failure.Failure(main.CONNECTION_DONE))

    def handle_connected_loseConnection(self):
        self.stopReading()
        if self.writing:
            self.addBufferCallback(self._cbDisconnecting, "buffer empty")
            self.state = "disconnecting"
        else:
            self.connectionLost(failure.Failure(main.CONNECTION_DONE))

    def handle_disconnecting_loseConnection(self):
        pass

    handle_disconnected_loseConnection = handle_disconnecting_loseConnection

    def _cbWriteShutdown(self):
        self.removeBufferCallback(self._cbWriteShutdown, "buffer empty")
        self.socket.shutdown(1)

    def handle_connected_shutdown(self, write = False, read = False):
        if read and not self.read_shutdown:
            self.read_shutdown = True
            self.socket.shutdown(0)
        if write and not self.write_shutdown:
            self.write_shutdown = True # don't need to keep "we are shutting write side down", right?
            if self.writing:
                self.addBufferCallback(self._cbWriteShutdown, "buffer empty")
            else:
                self.socket.shutdown(1)

    def connectionLost(self, reason):
#        log.msg("connectionLost called with reason", reason, "for socket", id(self))
#        import traceback
#        for i in traceback.format_stack():
#            log.msg(i[:-1])
        self.state = "disconnected"
        protocol = self.protocol
        del self.protocol
        # XXX: perhaps the following needs to be around to avoid resetting the connection ungracefully
#        try:
#            self.socket.shutdown(2)
#        except socket.error:
#            pass
        # this should call closesocket() and kill it dead!
        self.socket.close()
        del self.socket
        self.sf.connectionLost(reason)
        try:
            protocol.connectionLost(reason)
        except TypeError, e:
            # while this may break, it will only break on deprecated code
            # as opposed to other approaches that might've broken on
            # code that uses the new API (e.g. inspect).
            if e.args and e.args[0] == "connectionLost() takes exactly 1 argument (2 given)":
                warnings.warn("Protocol %s's connectionLost should accept a reason argument" % protocol,
                              category=DeprecationWarning, stacklevel=2)
                protocol.connectionLost()
            else:
                raise

    def startReading(self):
        self.reading = True
        try:
            self.read_op.initiateOp(self.socket.fileno(), self.readbuf)
        except WindowsError, we:
#            log.msg("initiating read failed with args %s" % (we,))
            self.connectionLost(failure.Failure(main.CONNECTION_DONE))

    def stopReading(self):
        self.reading = False

    def handle_connected_readDone(self, bytes):
        self.protocol.dataReceived(self.readbuf[:bytes])
        if self.reading:
            self.startReading()

    def handle_disconnecting_readDone(self, bytes):
        pass # a leftover read op from before we began disconnecting

    def handle_connected_readErr(self, ret, bytes):
#        log.msg("read failed with err %s" % (ret,))
        self.connectionLost(failure.Failure(main.CONNECTION_DONE))

    handle_disconnecting_readErr = handle_connected_readErr
    
    def handle_disconnected_readErr(self, ret, bytes):
        pass # no kicking the dead horse

    def handle_disconnected_readDone(self, bytes):
        pass # no kicking the dead horse

    def startWriting(self):
        self.writing = True
        b = buffer(self.writebuf[0], self.offset)
#        ll = map(len, self.writebuf)
#        log.msg("buffer lengths are", ll, "total", sum(ll))
        try:
            self.write_op.initiateOp(self.socket.fileno(), b)
        except WindowsError, we:
#            log.msg("initiating write failed with args %s" % (we,))
            self.connectionLost(failure.Failure(main.CONNECTION_DONE))

    def stopWriting(self):
        self.writing = False

    def handle_connected_writeDone(self, bytes):
        self.offset += bytes
        self.writeBufferedSize -= bytes
        if self.offset == len(self.writebuf[0]):
            del self.writebuf[0]
            self.offset = 0
        if self.writebuf == []:
            self.writing = False
            self.callBufferHandlers(event = "buffer empty")
        else:
            self.startWriting()

    handle_disconnecting_writeDone = handle_connected_writeDone

    def handle_connected_writeErr(self, ret, bytes):
        self.connectionLost(failure.Failure(main.CONNECTION_DONE))

    handle_disconnecting_writeErr = handle_connected_writeErr
    
    def handle_disconnected_writeErr(self, ret, bytes):
        pass # no kicking the dead horse

    def handle_disconnected_writeDone(self, bytes):
        pass # no kicking the dead horse

    # consumer interface implementation

    def registerProducer(self, producer, streaming):
        if self.producer is not None:
            raise RuntimeError("Cannot register producer %s, because producer %s was never unregistered." % (producer, self.producer))
        if self.state == "disconnected":
            producer.stopProducing()
        else:
            self.producer = producer
            self.streamingProducer = streaming
            self.addBufferCallback(self.milkProducer, "buffer empty")
            self.addBufferCallback(self.stfuProducer, "buffer full")
            if not streaming:
                producer.resumeProducing()

    def milkProducer(self):
        if not self.streamingProducer or self.producerPaused:
            self.producer.resumeProducing()
            self.producerPaused = 0

    def stfuProducer(self):
        self.producerPaused = 1
        self.producer.pauseProducing()
        
    def unregisterProducer(self):
        self.removeBufferCallback(self.stfuProducer, "buffer full")
        self.removeBufferCallback(self.milkProducer, "buffer empty")
        self.producer = None

    def stopConsuming(self):
        self.unregisterProducer()
        self.loseConnection()

    # producer interface implementation

    def resumeProducing(self):
        self.startReading()

    def pauseProducing(self):
        self.stopReading()

    def stopProducing(self):
        self.loseConnection()

    def __repr__(self):
        return self.repstr

    def logPrefix(self):
        return self.logstr

    # groan, stupid LineReceiver and LineOnlyReceiver want to see this in a transport
    disconnecting = property(lambda self: self.state == "disconnecting")