#
#--
# Copyright (c) 2006-2008, 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.
#++
#

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

require 'openwfe/utils'
require 'openwfe/expressions/time'


module OpenWFE

    #
    # Scheduling subprocesses for repeating execution
    #
    #     <cron tab="0 9-17 * * mon-fri">
    #         <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.
    #
    # It's possible to specify 'every' instead of 'tab' :
    #
    #     cron :every => "10m3s" do
    #         send_reminder
    #     end
    #
    # The subprocess 'send_reminder' will thus be triggered every ten minutes 
    # and three seconds.
    #
    # The cron expression never replies [to its parent expression]. 
    # The classical usage for it is with a concurrence set to expect only 
    # one reply :
    #
    #     concurrence :count => 1 do
    #         participant :toto
    #         cron :every => "10m" do
    #             send_reminder_email :target => "toto@headlost.org.uk"
    #         end
    #     end
    #
    # The sub process 'send_reminder_email' will thus be triggered every 10 
    # minutes while concurrence is waiting for the answer (reply) of the
    # participant :toto.
    #
    # If the process instance containing a cron is paused, the cron won't get
    # triggered until the process is resumed.
    #
    class CronExpression < TimeExpression

        names :cron

        uses_template

        #++
        # keeping a copy of the child expression (this copy is used
        # for spawning a new expression each time cron triggers)
        #
        #attr_accessor :raw_child
        #--

        #
        # The cron 'tab', something like "0 9-17 * * mon-fri"
        #
        attr_accessor :tab

        #
        # If 'tab' is not, then 'every' should, the expression will trigger
        # at the frequency specified here (like for example "10m3s).
        #
        attr_accessor :every

        #
        # Keeping track of how many times the cron fired.
        #
        attr_accessor :counter

        #--
        #attr_accessor :name
        #attr_accessor :engine_cron
        #++


        def apply (workitem)

            return reply_to_parent(workitem) \
                if raw_children.size < 1

            @counter = 0
            #@engine_cron = false

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

            @tab = lookup_attribute :tab, workitem
            @every = lookup_attribute :every, workitem

            #@name = lookup_attribute :name, workitem
            #@name = fei.to_s unless @name

            #if @name[0, 2] == '//'
            #    @name = @name[1..-1]
            #    @engine_cron = true
            #end

            #forget = lookup_boolean_attribute :forget, workitem

            #@raw_child, _fei = get_expression_pool.fetch @children[0]
            #@raw_child.parent_id = nil
            #clean_children
            #@children = nil

            determine_scheduler_tags

            #
            # 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 (within self))

            #set_variable @name, self
            #set_variable @name, @fei

            #
            # resume flow (if not a engine level cron)
            
            #reply_to_parent(workitem) unless @engine_cron
            #reply_to_parent(workitem) if forget
        end

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

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

            return if paused?

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

            #@raw_child.application_context = @application_context
                # done in expool.launch_template()

            begin

                #template = @raw_child
                #template, _fei = get_expression_pool.fetch @children[0]
                template = raw_children.first

                #get_expression_pool.launch_template(
                #    @fei.wfid, nil, @counter, template, @applied_workitem.dup)
                child_fei = get_expression_pool.tlaunch_child(
                    self, template, @counter, @applied_workitem.dup, false)
                        #
                        # register_child is set to false, cron doesn't keep
                        # track of its spawned children

                #
                # update count and store self

                @counter += 1

                #if is_engine_cron?
                #    set_variable @name, self
                #else
                #    store_itself
                #end
                store_itself

            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)

            #return unless @applied_workitem

            #@scheduler_job_id = if @engine_cron
            #    "/" + @name
            #else
            #    "#{@fei.wfid}__#{@scheduler_job_id}"
            #end
            @scheduler_job_id = "#{@fei.wfid}__#{@scheduler_job_id}"

            method, arg0 = if @tab
                [ :schedule, @tab ]
            else
                [ :schedule_every, @every ]
            end

            get_scheduler.send(
                method,
                arg0,
                { 
                    :schedulable => self, 
                    :job_id => @scheduler_job_id,
                    :tags => @scheduler_tags })

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

end