#!/usr/bin/env python
# PythonDriver.py
#
#   Copyright (C) 2013 Diamond Light Source, Graeme Winter
#
#   This code is distributed under the BSD license, a copy of which is
#   included in the root directory of this package.
#
# A driver class to launch Python subprocesses with the shared environment
# but in a new address space.

import subprocess
import os
import sys
import copy

from DefaultDriver import DefaultDriver
from DriverHelper import kill_process

class PythonDriver(DefaultDriver):

  def __init__(self):
    DefaultDriver.__init__(self)

    self._popen = None

    return

  def start(self):

    # here self._executable refers to the Python program which should be
    # executed

    if self._executable is None:
      raise RuntimeError, 'no executable is set.'

    if os.name == 'nt':
      # pass in CL as a list of tokens
      command_line = [sys.executable]
      command_line.append(self._executable)
      for c in self._command_line:
        command_line.append(c)
    else:
      # now pass in the command line as a string and allow the
      # shell to parse it - note well though that the tokens
      # on the command line are quoted..

      command_line = '%s %s' % (sys.executable, self._executable)
      for c in self._command_line:
        command_line += ' \'%s\'' % c

    environment = copy.deepcopy(os.environ)

    for name in self._working_environment:
      added = self._working_environment[name][0]
      for value in self._working_environment[name][1:]:
        added += '%s%s' % (os.pathsep, value)

      if name in environment and \
             not name in self._working_environment_exclusive:
        environment[name] = '%s%s%s' % (added, os.pathsep,
                                        environment[name])
      else:
        environment[name] = added

    self._popen = subprocess.Popen(command_line,
                                   bufsize = 1,
                                   stdin = subprocess.PIPE,
                                   stdout = subprocess.PIPE,
                                   stderr = subprocess.STDOUT,
                                   cwd = self._working_directory,
                                   universal_newlines = True,
                                   env = environment,
                                   shell = True)

    return

  def check(self):
    '''Overload the default check method.'''

    return True

  def _check_executable(self, executable):
    if os.path.exists(executable):
      return executable
    return ''


  def _input(self, record):

    if not self.check():
      raise RuntimeError, 'child process has termimated'

    self._popen.stdin.write(record)

    return

  def _output(self):
    # need to put some kind of timeout facility on this...

    return self._popen.stdout.readline()

  def _status(self):
    # get the return status of the process

    return self._popen.poll()

  def close(self):

    if not self.check():
      raise RuntimeError, 'child process has termimated'

    self._popen.stdin.close()

    return

  def kill(self):
    kill_process(self._popen)

    return

if __name__ == '__main__':
  assert('XIA2CORE_ROOT') in os.environ

  pd = PythonDriver()
  pd.set_executable(os.path.join(os.environ['XIA2CORE_ROOT'],
                                 'Test', 'ExampleProgram.py'))
  pd.start()
  pd.close_wait()

  for record in pd.get_all_output():
    print record[:-1]