#!/usr/bin/env python
# SimpleDriver.py
#
#   Copyright (C) 2006 CCLRC, Graeme Winter
#
#   This code is distributed under the BSD license, a copy of which is 
#   included in the root directory of this package.
#
# 24th May 2006
# 
# An initial implementation of the simplest Driver type - the one which 
# just wraps the subprocess.Popen class. Note well: this will require 
# Python 2.4. 
# 
# Applicability: Windows/OS X/UNIX
#

import subprocess
import os
import copy

from DefaultDriver import DefaultDriver
from DriverHelper import kill_process

class SimpleDriver(DefaultDriver):

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

        self._popen = None

        return

    def start(self):
        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 = []
            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 = self._executable
            for c in self._command_line:
                command_line += ' \'%s\'' % c

        # portability issue here with the shell interaction?

        # if os.name == 'posix':
        #     shell = False
        # else:
        #     shell = True

        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)
        
        # somehow here test for failure - oh, you can't because
        # the shell spawned is probably still ok

        return

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

        # FIXME this may give false results if the child program
        # is too fast!

        if self._popen.poll() is None:
            return True

        # FIXME this should do a proper test!
        
        return True

    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__':
    # run a test for segmentation fault

    d = SimpleDriver()

    d.set_executable('EPSegv')
    d.start()
    d.close()
    while True:
        line = d.output()
        if not line:
            break

    d.check_for_errors()