#
#--
# Copyright (c) 2006-2007, John Mettraux, 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
#

require 'openwfe/rudefinitions'
require 'openwfe/utils'
require 'openwfe/util/otime'
require 'openwfe/util/scheduler'
require 'openwfe/expressions/timeout'
require 'openwfe/expressions/fe_condition'


#
# expressions like 'sleep' and 'cron'
#

module OpenWFE

    #
    # A parent class for CronExpression and SleepExpression, is never
    # used directly.
    # It contains a simple get_scheduler() method simplifying the scheduler
    # localization for <sleep/> and <cron/>.
    #
    class TimeExpression < FlowExpression
        include Schedulable

        attr_accessor \
            :applied_workitem,
            :scheduler_job_id

        #
        # Makes sure to cancel any scheduler job associated with this
        # expression
        #
        def cancel ()
            synchronize do

                ldebug { "cancel()..." }

                unschedule()

                return super()
            end
        end

        def unschedule ()

            ldebug { "unschedule() @scheduler_job_id is #{@scheduler_job_id}" }

            get_scheduler.unschedule(@scheduler_job_id) \
                if @scheduler_job_id
        end
    end

    #
    # The 'sleep' expression expects one attribute, either 'for', either
    # 'until'.
    #
    #     <sequence>
    #         <sleep for="10m12s" />
    #         <participant ref="alpha" />
    #     </sequence>
    #
    # will wait for 10 minutes and 12 seconds before sending a workitem
    # to participant 'alpha'.
    #
    class SleepExpression < TimeExpression

        attr_accessor \
            :awakening_time

        def apply (workitem)
            synchronize do

                sfor = lookup_attribute(:for, workitem)
                suntil = lookup_attribute(:until, workitem)

                tuntil = nil

                if suntil
                    tuntil = suntil
                elsif sfor
                    tfor = OpenWFE::parse_time_string(sfor)
                    ldebug { "apply() tfor is '#{tfor}'" }
                    tuntil = Time.new.to_f + tfor
                end

                if not tuntil
                    reply_to_parent(workitem)
                    return
                end

                @awakening_time = tuntil
                @applied_workitem = workitem.dup

                reschedule(get_scheduler)
            end
        end

        #def reply (workitem)
        #end

        #
        # This is the method called by the Scheduler instance attached to
        # the workflow engine when the 'sleep' of this expression is 
        # over
        #
        def trigger (params)
            ldebug do 
                "trigger() #{@fei.to_debug_s} waking up (#{Time.new.to_f}) "+
                "(scheduler #{get_scheduler.object_id})"
            end
            reply_to_parent(@applied_workitem)
        end

        #
        # [Re]schedules this expression, effectively registering it within
        # the scheduler.
        # This method is called when the expression is applied and each
        # time the owning engine restarts.
        #
        def reschedule (scheduler)

            ldebug do 
                "[re]schedule() " + 
                "will sleep until '#{@awakening_time}' " +
                "(#{OpenWFE::to_iso8601_date(@awakening_time)})"
            end

            @scheduler_job_id = 
                scheduler.schedule_at(@awakening_time, self, nil)

            ldebug do 
                "[re]schedule() @scheduler_job_id is '#{@scheduler_job_id}' "+
                " (scheduler #{scheduler.object_id})"
            end

            store_itself()
        end
    end

    #
    # Scheduling subprocesses for repeating execution
    #
    #     <cron tab="0 9-17 * * mon-fri" name="//reminder">
    #         <send-reminder/>
    #     </cron>
    #
    # In this short process definition snippet, the subprocess "send-reminder"
    # will get triggered once per hour (minute 0) from 0900 to 1700 and
    # this, from monday to friday.
    #
    # The 'name' of the cron indicates also at which level the cron should
    # be bound. A double slash means the cron is bound at engine level (and
    # will continue until it is unbound, as long as the engine is up, if the
    # engine is a persisted one, the cron will continue when the engine
    # restarts).
    #
    class CronExpression < TimeExpression

        attr_accessor \
            :raw_child, :tab, :name

        def apply (workitem)

            if @children.size < 1
                reply_to_parent(workitem)
                return
            end

            @applied_workitem = workitem.dup
            @applied_workitem.flow_expression_id = nil

            @tab = lookup_attribute(:tab, workitem)
            @name = lookup_attribute(:name, workitem)

            @raw_child, _fei = get_expression_pool.fetch(@children[0])
            @raw_child.parent_id = nil

            clean_children()

            @children = nil

            #
            # schedule self
            
            reschedule(get_scheduler)

            #
            # store self as a variable
            # (have to do it after the reschedule, so that the schedule
            # info is stored within the variable)

            set_variable(@name, self)

            #
            # resume flow
            
            reply_to_parent(workitem)
        end

        def reply (workitem)
            # discard silently... should never get called though
        end

        #def cancel ()
        #end
            #
            # implemented in parent TimeExpression class

        #
        # This is the method called each time, the scheduler triggers
        # this cron. The contained segment of process will get 
        # executed.
        #
        def trigger (params)
            #
            # launch raw child

            ldebug { "trigger() cron : #{@fei.to_debug_s}" }

            @raw_child.application_context = @application_context

            begin
                get_expression_pool.launch_template(
                    @fei.wfid, @raw_child, @applied_workitem.dup)
            rescue
                lerror do 
                    "trigger() cron caught exception\n"+
                    OpenWFE::exception_to_s($!)
                end
            end
        end

        #
        # This method is called at the first schedule of this expression
        # or each time the engine is restarted and this expression has
        # to be rescheduled.
        #
        def reschedule (scheduler)

            @scheduler_job_id = @name.dup

            @scheduler_job_id = "#{@fei.wfid}__#{@scheduler_job_id}" \
                if not OpenWFE::starts_with(@name, "//")

            get_scheduler.schedule(@tab, @scheduler_job_id, self, nil)

            ldebug { "reschedule() job id is '#{@scheduler_job_id}'" }

            #store_itself()
                #
                # done by the containing environment itself
        end
    end

    #
    # The 'when' expression will trigger a consequence when a condition
    # is met, like in
    #
    #     <when test="${variable:over} == true">
    #         <participant ref="toto" />
    #     </when>
    #
    # where the participant "toto" will receive a workitem when the (local)
    # variable "over" has the value true.
    #
    class WhenExpression < TimeExpression
        include ConditionMixin, TimeoutMixin

        attr_accessor \
            :frequency,
            :consequence_triggered

        DEFAULT_FREQUENCY = "20s"

        def apply (workitem)

            if @children.size < 1
                reply_to_parent(workitem)
                return
            end

            @applied_workitem = workitem.dup

            @frequency = 
                lookup_attribute(:frequency, workitem, DEFAULT_FREQUENCY)
            @frequency = 
                OpenWFE::parse_time_string(@frequency)

            determine_timeout()

            @consequence_triggered = false

            trigger(nil)
        end

        def reply (workitem)

            ldebug do 
                "reply() @consequence_triggered is '#{@consequence_triggered}'"
            end

            if @consequence_triggered
                reply_to_parent(workitem)
                return
            end

            result = OpenWFE::get_result(workitem)

            if result
                apply_consequence(workitem)
            else
                reschedule(get_scheduler)
            end
        end

        def cancel ()
            to_unschedule()
            super()
        end

        def trigger (params)

            ldebug { "trigger() params is #{params}" }

            if params == :do_timeout!
                #
                # do timeout...
                #
                reply_to_parent(@applied_workitem)
                return
            end

            @scheduler_job_id = nil

            evaluate_condition()
        end

        def reschedule (scheduler)

            @scheduler_job_id = 
                scheduler.schedule_in(@frequency, self, nil)

            ldebug { "reschedule() @scheduler_job_id is #{@scheduler_job_id}" }

            to_reschedule(scheduler)
        end

        def reply_to_parent (workitem)

            unschedule()
            unschedule_timeout()

            super(workitem)
        end

        protected

            def evaluate_condition

                if @children.size > 1
                    #
                    # trigger the evaluation of the first (condition) child

                    store_itself()

                    get_expression_pool.launch_template(
                        self, @children[0], @applied_workitem)
                else
                    #
                    # eval the attribute condition immediately

                    c = eval_condition(:test, @applied_workitem)

                    OpenWFE::set_result(@applied_workitem, c)

                    reply(@applied_workitem)
                end
            end

            def apply_consequence (workitem)

                @consequence_triggered = true

                store_itself()

                i = 1
                i = 0 if @children.size == 1

                get_expression_pool.apply(@children[i], workitem)
            end
    end

end