#
#--
# Copyright (c) 2006-2007, John Mettraux, Nicolas Modrzyk OpenWFE.org
# 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 the "OpenWFE" 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.
#++
#
# $Id: definitions.rb 2725 2006-06-02 13:26:32Z jmettraux $
#

#
# "made in Japan"
#
# John Mettraux at openwfe.org
# Nicolas Modrzyk at openwfe.org
# 

require 'logger'

require 'openwfe/workitem'
require 'openwfe/rudefinitions'
require 'openwfe/service'
require 'openwfe/util/schedulers'
require 'openwfe/expool/expressionpool'
require 'openwfe/expool/expstorage'
require 'openwfe/expressions/expressionmap'
require 'openwfe/participants/participantmap'


module OpenWFE

    #
    # The simplest implementation of the OpenWFE workflow engine.
    # No persistence is used, everything is stored in memory.
    #
    class Engine < Service
        include OwfeServiceLocator

        def initialize ()

            super(S_ENGINE, {})

            @application_context[@service_name] = self

            build_scheduler()

            build_expression_map()
            build_expression_storage()
            build_expression_pool()

            build_participant_map()

            $OWFE_LOG = Logger.new("engine.log") unless $LOG
        end

        #
        # Launches a [business] process.
        # The 'launch_object' param may contain either a LaunchItem instance, 
        # either a String containing the URL of the process definition
        # to launch (with an empty LaunchItem created on the fly).
        #
        def launch (launch_object)

            launchitem = nil

            if launch_object.kind_of? OpenWFE::LaunchItem
                launchitem = launch_object
            elsif launch_object.kind_of? Class
                launchitem = LaunchItem.new(launch_object)
            elsif launch_object.kind_of? String
                launchitem = OpenWFE::LaunchItem.new
                if launch_object[0] == '<'
                    launchitem.workflowDefinitionUrl = "field:__definition"
                    launchitem['definition'] = launch_object
                else
                    launchitem.workflowDefinitionUrl = launch_object
                end
            end

            get_expression_pool.launch(launchitem)
        end

        #
        # This method is used to feed a workitem back to the engine (after
        # it got sent to a worklist or wherever by a participant).
        # Participant implementations themselves do call this method usually.
        #
        def reply (workitem)

            get_expression_pool.reply(workitem.last_expression_id, workitem)
        end

        #
        # Registers a participant in this [embedded] engine.
        # This method is a shortcut to the ParticipantMap method
        # with the same name.
        #
        def register_participant (regex, participant=nil, &block)

            get_participant_map.register_participant(regex, participant, &block)
        end

        #
        # Given a participant name, returns the participant in charge
        # of handling workitems for that name.
        # May be useful in some embedded contexts.
        #
        def get_participant (participant_name)

            get_participant_map.lookup_participant(participant_name)
        end

        #
        # Stopping the engine will stop all the services in the
        # application context.
        #
        def stop

            linfo { "stop() stopping engine '#{@service_name}'" }

            @application_context.each do |name, service|
                next if name == self.service_name
                #service.stop if service.respond_to? :stop
                if service.kind_of? ServiceMixin
                    service.stop
                    linfo do 
                        "stop() stopped service '#{service.service_name}' "+
                        "(#{service.class})"
                    end
                end
            end
        end

        protected

            #
            # the following methods may get overridden upon extension
            # see for example file_persisted_engine.rb
            #

            def build_expression_map ()
                init_service(S_EXPRESSION_MAP, ExpressionMap)
            end

            def build_expression_pool ()
                init_service(S_EXPRESSION_POOL, ExpressionPool)
            end

            def build_expression_storage ()
                init_service(S_EXPRESSION_STORAGE, InMemoryExpressionStorage)
            end

            def build_participant_map ()
                init_service(S_PARTICIPANT_MAP, ParticipantMap)
            end
            
            def build_scheduler ()
                init_service(S_SCHEDULER, SchedulerService)
            end

    end

end