"""
    Copyright (c) 2014 Ad Schellevis
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice,
     this list of conditions and the following disclaimer.

    2. 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.

    THIS SOFTWARE IS PROVIDED ``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
    AUTHOR 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.

    --------------------------------------------------------------------------------------
    package : configd
    function: unix domain socket process worker process
"""

__author__ = 'Ad Schellevis'

import os
import subprocess
import socket
import traceback
import syslog
import threading
import ConfigParser
import glob
import time
import uuid
import shlex
import tempfile
import ph_inline_actions
from modules import singleton


class Handler(object):
    """ Main handler class, opens unix domain socket and starts listening
        - New connections are handed over to a HandlerClient type object in a new thread
        - All possible actions are stored in 1 ActionHandler type object and parsed to every client for script execution

        processflow:
            Handler ( waits for client )
                -> new client is send to HandlerClient
                    -> execute ActionHandler command using Action objects
                    <- send back result string
    """
    def __init__(self, socket_filename, config_path, config_environment={}, simulation_mode=False):
        """ Constructor

        :param socket_filename: filename of unix domain socket to use
        :param config_path: location of configuration files
        :param simulation_mode: emulation mode, do not start actual (script) commands
        :return: object
        """
        self.socket_filename = socket_filename
        self.config_path = config_path
        self.simulation_mode = simulation_mode
        self.config_environment = config_environment
        self.single_threaded = False

    def run(self):
        """ Run process handler

        :return:
        """
        while True:
            try:
                # open action handler
                actHandler = ActionHandler(config_path=self.config_path,
                                           config_environment=self.config_environment)

                # remove previous socket ( if exists )
                try:
                    os.unlink(self.socket_filename)
                except OSError:
                    if os.path.exists(self.socket_filename):
                        raise

                sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
                sock.bind(self.socket_filename)
                os.chmod(self.socket_filename, 0o666)
                sock.listen(30)
                while True:
                    # wait for a connection to arrive
                    connection, client_address = sock.accept()
                    # spawn a client connection
                    cmd_thread = HandlerClient(connection=connection,
                                               client_address=client_address,
                                               action_handler=actHandler,
                                               simulation_mode=self.simulation_mode)
                    if self.single_threaded:
                        # run single threaded
                        cmd_thread.run()
                    else:
                        # run threaded
                        cmd_thread.start()

            except KeyboardInterrupt:
                # exit on <ctrl><c>
                if os.path.exists(self.socket_filename):
                    # cleanup, remove socket
                    os.remove(self.socket_filename)
                raise
            except SystemExit:
                # stop process handler on system exit
                if os.path.exists(self.socket_filename):
                    # cleanup on exit, remove socket
                    os.remove(self.socket_filename)
                return
            except:
                # something went wrong... send traceback to syslog, restart listener (wait for a short time)
                print (traceback.format_exc())
                syslog.syslog(syslog.LOG_ERR, 'Handler died on %s' % traceback.format_exc())
                time.sleep(1)


class HandlerClient(threading.Thread):
    """ Handle commands via specified socket connection
    """
    def __init__(self, connection, client_address, action_handler, simulation_mode=False):
        """
        :param connection: socket connection object
        :param client_address: client address ( from socket accept )
        :param action_handler: action handler object
        :param simulation_mode: Emulation mode, do not start actual (script) commands
        :return: None
        """
        threading.Thread.__init__(self)
        self.connection = connection
        self.client_address = client_address
        self.action_handler = action_handler
        self.simulation_mode = simulation_mode
        self.message_uuid = uuid.uuid4()

    def run(self):
        """ handle single action ( read data, execute command, send response )

        :return: None
        """
        result = ''
        exec_command = ''
        exec_action = ''
        exec_params = ''
        exec_in_background = False
        try:
            # receive command, maximum data length is 4k... longer messages will be truncated
            data = self.connection.recv(4096)
            # map command to action
            data_parts = shlex.split(data)
            if len(data_parts) == 0 or len(data_parts[0]) == 0:
                # no data found
                self.connection.sendall('no data\n')
            else:
                exec_command = data_parts[0]
                if exec_command[0] == "&":
                    # set run in background
                    exec_in_background = True
                    exec_command = exec_command[1:]
                if len(data_parts) > 1:
                    exec_action = data_parts[1]
                else:
                    exec_action = None
                if len(data_parts) > 2:
                    exec_params = data_parts[2:]
                else:
                    exec_params = None

                # when running in background, return this message uuid and detach socket
                if exec_in_background:
                    result = self.message_uuid
                    self.connection.sendall('%s\n%c%c%c' % (result, chr(0), chr(0), chr(0)))
                    self.connection.close()

                # execute requested action
                if self.simulation_mode:
                    self.action_handler.showAction(exec_command, exec_action, exec_params, self.message_uuid)
                    result = 'OK'
                else:
                    result = self.action_handler.execute(exec_command, exec_action, exec_params, self.message_uuid)

                if not exec_in_background:
                    # send response back to client( including trailing enter )
                    self.connection.sendall('%s\n' % result)
                else:
                    # log response
                    syslog.syslog(syslog.LOG_INFO, "message %s [%s.%s] returned %s " % (self.message_uuid,
                                                                                        exec_command,
                                                                                        exec_action,
                                                                                        unicode(result)[:100]))

            # send end of stream characters
            if not exec_in_background:
                self.connection.sendall("%c%c%c" % (chr(0), chr(0), chr(0)))
        except SystemExit:
            # ignore system exit related errors
            pass
        except:
            print (traceback.format_exc())
            syslog.syslog(syslog.LOG_ERR,
                          'unable to sendback response [%s] for [%s][%s][%s] {%s}, message was %s' % (result,
                                                                                                      exec_command,
                                                                                                      exec_action,
                                                                                                      exec_params,
                                                                                                      self.message_uuid,
                                                                                                      traceback.format_exc()))
        finally:
            if not exec_in_background:
                self.connection.close()

@singleton
class ActionHandler(object):
    """ Start/stop services and functions using configuration data defined in conf/actions_<topic>.conf
    """
    def __init__(self, config_path=None, config_environment=None):
        """ Initialize action handler to start system functions

        :param config_path: full path of configuration data
        :param config_environment: environment to use (if possible)
        :return:
        """
        if config_path is not None:
            self.config_path = config_path
        if config_environment is not None:
            self.config_environment = config_environment

        # try to load data on initial start
        if not hasattr(self, 'action_map'):
            self.load_config()

    def load_config(self):
        """ load action configuration from config files into local dictionary

        :return: None
        """

        self.action_map = {}
        for config_filename in glob.glob('%s/actions_*.conf' % self.config_path) \
                + glob.glob('%s/actions.d/actions_*.conf' % self.config_path):
            # this topic's name (service, filter, template, etc)
            # make sure there's an action map index for this topic
            topic_name = config_filename.split('actions_')[-1].split('.')[0]
            if topic_name not in self.action_map:
                self.action_map[topic_name] = {}

            # traverse config directory and open all filenames starting with actions_
            cnf = ConfigParser.RawConfigParser()
            cnf.read(config_filename)
            for section in cnf.sections():
                # map configuration data on object
                action_obj = Action(config_environment = self.config_environment)
                for act_prop in cnf.items(section):
                    setattr(action_obj, act_prop[0], act_prop[1])

                if section.find('.') > -1:
                    # at this moment we only support 2 levels of actions ( 3 if you count topic as well )
                    for alias in section.split('.')[0].split('|'):
                        if alias not in self.action_map[topic_name]:
                            self.action_map[topic_name][alias] = {}
                        self.action_map[topic_name][alias][section.split('.')[1]] = action_obj
                else:
                    for alias in section.split('|'):
                        self.action_map[topic_name][alias] = action_obj

    def listActions(self, attributes=[]):
        """ list all available actions
        :return: dict
        """
        result = {}
        for command in self.action_map:
            for action in self.action_map[command]:
                if type(self.action_map[command][action]) == dict:
                    # parse second level actions
                    # TODO: nesting actions may be better to solve recursive in here and in load_config part
                    for subAction in self.action_map[command][action]:
                        cmd='%s %s %s'%(command,action,subAction)
                        result[cmd] = {}
                        for actAttr in attributes:
                            if hasattr(self.action_map[command][action][subAction], actAttr):
                                result[cmd][actAttr] = getattr(self.action_map[command][action][subAction], actAttr)
                            else:
                                result[cmd][actAttr] = ''
                else:
                    cmd='%s %s'%(command,action)
                    result[cmd] = {}
                    for actAttr in attributes:
                        if hasattr(self.action_map[command][action], actAttr):
                            result[cmd][actAttr] = getattr(self.action_map[command][action], actAttr)
                        else:
                            result[cmd][actAttr] = ''

        return result

    def findAction(self, command, action, parameters):
        """ find action object

        :param command: command/topic for example interface
        :param action: action to run ( for example linkup )
        :param parameters: the parameters to supply
        :return: action object or None if not found
        """
        action_obj = None
        if command in self.action_map:
            if action in self.action_map[command]:
                if type(self.action_map[command][action]) == dict:
                    if parameters is not None and len(parameters) > 0 \
                            and parameters[0] in self.action_map[command][action]:
                        # 3 level action (  "interface linkup start" for example )
                        if isinstance(self.action_map[command][action][parameters[0]], Action):
                            action_obj = self.action_map[command][action][parameters[0]]
                            action_obj.setParameterStartPos(1)
                elif isinstance(self.action_map[command][action], Action):
                    action_obj = self.action_map[command][action]

        return action_obj

    def execute(self, command, action, parameters, message_uuid):
        """ execute configuration defined action

        :param command: command/topic for example interface
        :param action: action to run ( for example linkup )
        :param parameters: the parameters to supply
        :param message_uuid: message unique id
        :return: OK on success, else error code
        """
        action_params = []
        action_obj = self.findAction(command, action, parameters)

        if action_obj is not None:
            if parameters is not None and len(parameters) > action_obj.getParameterStartPos():
                action_params = parameters[action_obj.getParameterStartPos():]

            return '%s\n' % action_obj.execute(action_params, message_uuid)

        return 'Action not found\n'

    def showAction(self, command, action, parameters, message_uuid):
        """ debug/simulation mode: show action information
        :param command: command/topic for example interface
        :param action: action to run ( for example linkup )
        :param parameters: the parameters to supply
        :param message_uuid: message unique id
        :return: None
        """
        action_obj = self.findAction(command, action, parameters)
        print ('---------------------------------------------------------------------')
        print ('execute %s.%s with parameters : %s ' % (command, action, parameters))
        print ('action object %s (%s)' % (action_obj, action_obj.command))
        print ('---------------------------------------------------------------------')


class Action(object):
    """ Action class,  handles actual (system) calls.
    set command, parameters (template) type and log message
    """
    def __init__(self, config_environment):
        """ setup default properties
        :param config_environment: environment to use
        :return:
        """
        self.config_environment = config_environment
        self.command = None
        self.parameters = None
        self.type = None
        self.message = None
        self._parameter_start_pos = 0

    def setParameterStartPos(self, pos):
        """

        :param pos: start position of parameter list
        :return: position
        """
        self._parameter_start_pos = pos

    def getParameterStartPos(self):
        """ getter for _parameter_start_pos
        :return: start position of parameter list ( first argument can be part of action to start )
        """
        return self._parameter_start_pos

    def execute(self, parameters, message_uuid):
        """ execute an action

        :param parameters: list of parameters
        :param message_uuid: unique message id
        :return:
        """
        # send-out syslog message
        if self.message is not None:
            log_message = '[%s] ' % message_uuid
            if self.message.count('%s') > 0 and parameters is not None and len(parameters) > 0:
                log_message = log_message + self.message % tuple(parameters[0:self.message.count('%s')])
            else:
                log_message = log_message + self.message.replace("%s", "")
            syslog.syslog(syslog.LOG_NOTICE, log_message)

        # validate input
        if self.type is None:
            # no action type, nothing to do here
            return 'No action type'
        elif self.type.lower() in ('script', 'script_output'):
            # script type commands, basic script type only uses exit statuses, script_output sends back stdout data.
            if self.command is None:
                # no command supplied, exit
                syslog.syslog(syslog.LOG_ERR, '[%s] returned "No command"' % message_uuid)
                return 'No command'

            # build script command to execute, shared for both types
            script_command = self.command
            if self.parameters is not None and type(self.parameters) == str and len(parameters) > 0:
                script_command = '%s %s' % (script_command, self.parameters)
                if script_command.find('%s') > -1:
                    # use command execution parameters in action parameter template
                    # use quotes on parameters to prevent code injection
                    if script_command.count('%s') > len(parameters):
                        # script command accepts more parameters then given, fill with empty parameters
                        for i in range(script_command.count('%s')-len(parameters)):
                            parameters.append("")
                    elif len(parameters) > script_command.count('%s'):
                        # parameters then expected, fail execution
                        return 'Parameter mismatch'

                    # force escape of shell exploitable characters for all user parameters
                    for escape_char in ['`','$','!','(',')','|']:
                        for i in range(len(parameters[0:script_command.count('%s')])):
                            parameters[i] = parameters[i].replace(escape_char,'\\%s'%escape_char)

                    script_command = script_command % tuple(map(lambda x: '"'+x.replace('"', '\\"')+'"',
                                                                parameters[0:script_command.count('%s')]))
            if self.type.lower() == 'script':
                # execute script type command
                try:
                    exit_status = subprocess.call(script_command, env=self.config_environment, shell=True)
                    # send response
                    if exit_status == 0:
                        return 'OK'
                    else:
                        syslog.syslog(syslog.LOG_ERR, '[%s] returned exit status %d' % (message_uuid, exit_status))
                        return 'Error (%d)' % exit_status
                except:
                    syslog.syslog(syslog.LOG_ERR, '[%s] Script action failed at %s' % (message_uuid,
                                                                                       traceback.format_exc()))
                    return 'Execute error'
            elif self.type.lower() == 'script_output':
                try:
                    with tempfile.NamedTemporaryFile() as error_stream:
                        with tempfile.NamedTemporaryFile() as output_stream:
                            subprocess.check_call(script_command, env=self.config_environment, shell=True,
                                                                  stdout=output_stream, stderr=error_stream)
                            output_stream.seek(0)
                            error_stream.seek(0)
                            script_output = output_stream.read()
                            script_error_output = error_stream.read()
                            if len(script_error_output) > 0:
                                syslog.syslog(syslog.LOG_ERR, '[%s] Script action stderr returned "%s"' % (message_uuid,
                                              script_error_output.strip()[:255])
                                              )
                            return script_output
                except:
                    syslog.syslog(syslog.LOG_ERR, '[%s] Script action failed at %s' % (message_uuid,
                                                                                       traceback.format_exc()))
                    return 'Execute error'

            # fallback should never get here
            return "type error"
        elif self.type.lower() == 'inline':
            # Handle inline service actions
            try:
                # match parameters, serialize to parameter string defined by action template
                if len(parameters) > 0:
                    inline_act_parameters = self.parameters % tuple(parameters)
                else:
                    inline_act_parameters = ''

                return ph_inline_actions.execute(self, inline_act_parameters)

            except:
                syslog.syslog(syslog.LOG_ERR, '[%s] Inline action failed at %s' % (message_uuid,
                                                                                   traceback.format_exc()))
                return 'Execute error'

        return 'Unknown action type'
