#
#--
# Copyright (c) 2007-2008, 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/expressions/flowexpression'
require 'openwfe/expressions/iterator'
require 'openwfe/expressions/fe_command'


module OpenWFE

    #
    # The 'iterator' expression can be used like that for example :
    #
    #     <iterator
    #         on-value="alice, bob, charles"
    #         to-variable="user-name"
    #     >
    #         <set 
    #             field="${user-name} comment" 
    #             value="(please fill this field)"
    #         />
    #     </iterator>
    #
    # Within the iteration, the workitem field "\_\_ic__" contains the number
    # of elements in the iteration and the field "\_\_ip__" the index of the
    # current iteration.
    #
    # The 'iterator' expression understands the same cursor commands as the
    # CursorExpression. One can thus exit an iterator or skip steps in it.
    #
    #     iterator :on_value => "alice, bob, charles, doug", to_variable => "v" do
    #         sequence do
    #             participant :variable_ref => "v"
    #             skip 1, :if => "${f:reply} == 'skip next'"
    #         end
    #     end
    #
    # For more information about those commands, see CursorCommandExpression.
    #
    class IteratorExpression < FlowExpression
        include CommandMixin

        names :iterator

        uses_template

        #
        # an Iterator instance that holds the list of values being iterated
        # upon.
        #
        attr_accessor :iterator

        def apply (workitem)

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

            @iterator = Iterator.new(self, workitem)

            return reply_to_parent(workitem) \
                if @iterator.size < 1

            reply workitem
        end

        def reply (workitem)

            command, step = determine_command_and_step workitem

            vars = if not command

                @iterator.next workitem

            elsif command == C_BREAK or command == C_CANCEL

                nil

            elsif command == C_REWIND or command == C_CONTINUE

                @iterator.rewind workitem

            elsif command.match "^#{C_JUMP}"

                @iterator.jump workitem, step

            else # C_SKIP or C_BACK

                @iterator.skip workitem, step
            end

            return reply_to_parent(workitem) \
                unless vars

            @children = []

            get_expression_pool.tlaunch_child(
                self,
                raw_children.first,
                @iterator.index,
                workitem,
                true, # registering child
                vars)
            
            store_itself
        end
    end

end