#    Copyright (C) 2009 Jeremy S. Sanders
#    Email: Jeremy Sanders <jeremy@jeremysanders.net>
#
#    This program is free software; you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation; either version 2 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License along
#    with this program; if not, write to the Free Software Foundation, Inc.,
#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
##############################################################################

from __future__ import division
import select
import subprocess
import os
import socket
import platform
import signal

from ..compat import cstr
from .. import qtall as qt
from .. import utils
from . import simpleread

def _(text, disambiguation=None, context="Capture"):
    return qt.QCoreApplication.translate(context, text, disambiguation)

class CaptureFinishException(Exception):
    """An exception to say when a stream has been finished."""

class CaptureStream(simpleread.Stream):
    """A special stream for capturing data."""

    def __init__(self):
        """Initialise the stream."""

        simpleread.Stream.__init__(self)
        self.buffer = ''
        self.continuousreads = 0
        self.bytesread = 0
        self.linesread = 0
        self.maxlines = None
        self.timedout = False

    def _setTimeout(self, timeout):
        """Setter for setting timeout property."""
        if timeout:
            self.timer = qt.QTimer.singleShot(timeout*1000,
                                               self._timedOut)
    timeout = property(None, _setTimeout, None,
                       "Time interval to stop in (seconds) or None")

    def _timedOut(self):
        self.timedout = True

    def getMoreData(self):
        """Override this to return more data from the source without
        blocking."""
        return ''

    def readLine(self):
        """Return a new line of data.

        Either returns new line or
        Raises StopIteration if there is no data, or more than 100 lines
        have been read."""

        while True:
            # we've reached the limit of lines or a timeout has occurred
            if self.linesread == self.maxlines:
                raise CaptureFinishException("Maximum number of lines read")
            if self.timedout:
                raise CaptureFinishException("Maximum time period occurred")

            # stop reading continous data greater than this many lines
            if self.continuousreads == 100:
                self.continuousreads = 0
                raise StopIteration

            index = self.buffer.find('\n')
            if index >= 0:
                # is there a line in the buffer?
                retn = self.buffer[:index]
                self.buffer = self.buffer[index+1:]
                self.linesread += 1
                self.continuousreads += 1
                return retn
            else:
                # if not, then read some more data
                data = self.getMoreData()

                if not data:
                    self.continuousreads = 0
                    raise StopIteration
                self.bytesread += len(data)
                self.buffer += data

    def close(self):
        """Close any allocated object."""
        pass

class FileCaptureStream(CaptureStream):
    """Capture from a file or named pipe."""

    def __init__(self, filename):
        CaptureStream.__init__(self)

        # open file
        self.fileobj = open(filename, 'rU')

        # make new thread to read file
        self.readerthread = utils.NonBlockingReaderThread(
            self.fileobj, exiteof=False)
        self.readerthread.start()

        self.name = filename

    def getMoreData(self):
        """Read data from the file."""
        try:
            data, done = self.readerthread.getNewData()
            if len(data) == 0 and done:
                raise CaptureFinishException("End of file")
            return data
        except OSError as e:
            raise CaptureFinishException("OSError: %s" % cstr(e))

    def close(self):
        """Close file."""
        self.fileobj.close()

class CommandCaptureStream(CaptureStream):
    """Capture from an external program."""

    def __init__(self, commandline):
        """Capture from commandline - this is passed to the shell."""
        CaptureStream.__init__(self)

        self.name = commandline
        self.popen = subprocess.Popen(commandline, shell=True,
                                      bufsize=0, stdout=subprocess.PIPE,
                                      universal_newlines=True)

        # make new thread to read stdout
        self.readerthread = utils.NonBlockingReaderThread(self.popen.stdout)
        self.readerthread.start()

    def getMoreData(self):
        """Read data from the command."""

        retn, done = self.readerthread.getNewData()

        if not retn:
            poll = self.popen.poll()
            if poll is not None:
                # process has ended
                raise CaptureFinishException("Process ended (status code %i)" %
                                             poll)
        return retn

    def close(self):
        """Close file."""

        if self.popen.poll() is None:
            # need to kill process if it is still running
            if platform.system() == 'Windows':
                # awful code (for windows)
                # use this to not have a ctypes dependency
                os.system('TASKKILL /PID %i /F' % self.popen.pid)
            else:
                # unix
                os.kill(self.popen.pid, signal.SIGTERM)

        try:
            self.popen.stdout.close()
        except EnvironmentError:
            # problems closing stdout for some reason
            pass

class SocketCaptureStream(CaptureStream):
    """Capture from an internet host."""

    def __init__(self, host, port):
        """Connect to host and port specified."""
        CaptureStream.__init__(self)

        self.name = '%s:%i' % (host, port)
        try:
            self.socket = socket.socket( socket.AF_INET,
                                         socket.SOCK_STREAM )
            self.socket.connect( (host, port) )
        except socket.error as e:
            self._handleSocketError(e)

    def _handleSocketError(self, e):
        """Special function to reraise exceptions
        because socket exceptions have changed in python 2.6 and
        behave differently on some platforms.
        """

        # clean up
        self.socket.close()

        # re-raise
        raise e

    def getMoreData(self):
        """Read data from the socket."""

        # see whether there is data to be read
        i, o, e = select.select([self.socket], [], [], 0)
        if i:
            try:
                retn = self.socket.recv(1024)
            except socket.error as e:
                self._handleSocketError(e)
            if len(retn) == 0:
                raise CaptureFinishException("Remote socket closed")
            return retn.decode('utf-8', errors='ignore')
        else:
            return ''

    def close(self):
        """Close the socket."""
        self.socket.close()

class OperationDataCaptureSet(object):
    """An operation for setting the results from a SimpleRead into the
    document's data from a data capture.

    This is a bit primative, but it is not obvious how to isolate the capturing
    functionality elsewhere."""

    descr = _('data capture')

    def __init__(self, simplereadobject):
        """Takes a simpleread object containing the data to be set."""
        self.simplereadobject = simplereadobject

    def do(self, doc):
        """Set the data in the document."""

        # set the data to the document and keep a list of what's changed
        readdata = {}
        self.simplereadobject.setOutput(readdata)

        # keep a copy of datasets which have changed from backup
        self.nameschanged = list(readdata)
        self.olddata = {}
        for name in self.nameschanged:
            if name in doc.data:
                self.olddata[name] = doc.data[name]
            doc.setData(name, readdata[name])

    def undo(self, doc):
        """Undo the results of the capture."""

        for name in self.nameschanged:
            if name in self.olddata:
                # replace datasets with what was there previously
                doc.setData(name, self.olddata[name])
            else:
                # or delete datasets that weren't there before
                doc.deleteData(name)
