#! /usr/bin/python3 -s
#
# Copyright (c) 2013-2019 - Adjacent Link LLC, Bridgewater, New Jersey
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# * Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in
#   the documentation and/or other materials provided with the
#   distribution.
# * Neither the name of Adjacent Link LLC nor the names of its
#   contributors may be used to endorse or promote products derived
#   from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#

from __future__ import absolute_import, division, print_function

# Force sys.stdout to be unbuffered w/o using the python -u option, which
# does not always work as #!/usr/bin/env python -u
# Solution from:
# https://stackoverflow.com/questions/107705/disable-output-buffering

import gc
import importlib
import json
import os
import argparse
import traceback
import sys

import etce.loader
import etce.utils
from etce.config import ConfigDictionary
from etce.platform import Platform
from etce.sshclient import SSHClient

#gc.garbage.append(sys.stdout)
#sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)

def sendreturnandexit(isexception,
                      result):    
    tracebackmsg = ''
    if isexception:
        tracebackmsg = traceback.format_exc()
    print(SSHClient.RETURNVALUE_OPEN_DEMARCATOR)
    print(json.dumps({ 'isexception':isexception, 'result':result, 'traceback':tracebackmsg }))
    print(SSHClient.RETURNVALUE_CLOSE_DEMARCATOR)
    sys.stdout.flush()
    
    if(isexception):
        sys.exit(1)
    else:
        sys.exit(0)


usagestr = '''
description: Dynamically loads and runs the Python method:

             modulename.methodname(methodarg1, methodarg2, ...).
             
             where modulename specifies a Python module found in the
             "etce" package. 

             etce-field-exec is not intended to be called directly. It
             is invoked by other etce applications over an SSH connection on
             field nodes to perform work.
'''
parser = argparse.ArgumentParser(description=usagestr,
                                 formatter_class=argparse.RawDescriptionHelpFormatter)

parser.add_argument('--cwd',
                    action='store',
                    default='',
                    help='''Specifies the subdirectory under the WORK_DIRECTORY configuration
                    root directory where etce will switch to before executing 
                    the named method. Default is just WORK_DIRECTORY itself''')
parser.add_argument('modulename',
                    metavar='MODULENAME',
                    action='store',
                    help='''A module found in the python etce package
                    on the remote host.''')
parser.add_argument('methodname',
                    metavar='METHODNAME',
                    action='store',
                    help='''The method from module to invoke. The method
                    must either be defined at the top level of the target
                    module, or as a method of a class with name that matches
                    the module name (for example a class MyModule in mymodule.py.''')
parser.add_argument('methodargs',
                    metavar='METHODARGS',
                    nargs='*',
                    action='store',
                    help='''The arguments to the method being invoked.''')

args = parser.parse_args()

config = etce.config.ConfigDictionary()

verbose = config.get('etce', 'VERBOSE').upper() == 'ON'

ret = ''

# determinte the subdirectory under WORK_DIRECTORY to run from
etcedir = ConfigDictionary().get('etce', 'WORK_DIRECTORY')

while args.cwd.find('/') == 0:
    args.cwd = args.cwd[1:]

if '..' in args.cwd.split('/'):
    sendreturnandexit(True, '".." not permitted in working directory name')

if '.' in args.cwd.split('/'):
    if args.cwd == '.':
        args.cwd = ''
    else:
        sendreturnandexit(True, '"." not permitted in working directory name')

# switch to working dir
workingdir = etcedir

if len(args.cwd) > 0:
    workingdir = os.path.join(etcedir, args.cwd)

if not os.path.exists(workingdir):
    hostname = Platform().hostname()
    print('Creating working directory "%s" on host "%s"' % (workingdir, hostname))
    os.makedirs(workingdir)

if not os.path.isdir(workingdir):
    hostname = Platform().hostname()
    sendreturnandexit(True,
                      'Working directory path "%s" exists on host "%s" but ' \
                      'is not a directory. Quitting.' % (workingdir, hostname))

os.chdir(workingdir)

if verbose:
    print('etce: Running from %s' % workingdir)

try:
    method = etce.loader.load_etce_method(args.modulename, args.methodname)

    if method:
        if len(args.methodargs) == 2:
            if verbose:
                print("(%s,%s)" % (args.modulename, args.methodname))
            ret = method()
        else:
            if verbose:
                print("(%s,%s,%s)" % \
                    (args.modulename, args.methodname, ' '.join(args.methodargs)))

            typedargs = [ etce.utils.configstrtoval(arg) for arg in args.methodargs ]

            ret = method(*typedargs)

    else:
        sendreturnandexit(True, 'Module(%s) or method(%s) not found.' \
                          % (args.modulename, args.methodname))

    sendreturnandexit(False, ret)

except Exception as e:
    sendreturnandexit(True, str(e))
