#
#--
# Copyright (c) 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/expressions/flowexpression'
require 'openwfe/expressions/fe_utils'


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.
    #
    class IteratorExpression < WithTemplateExpression

        attr_accessor \
            :iterator

        def apply (workitem)

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

            @iterator = Iterator.new(self, workitem)

            reply(workitem)
        end

        def reply (workitem)

            unless @iterator.has_next?
                reply_to_parent(workitem)
                return
            end

            @iterator.next(self, workitem)

            store_itself()

            get_expression_pool.launch_template(
                self, 0, @children[0], workitem, nil)
        end
    end

    #
    # Iterator instances keep track of the position of an iteration.
    # This class is meant to be used both by <iterator> and 
    # <concurrent-iterator>.
    #
    class Iterator

        attr_accessor \
            :iteration_list,
            :to_field,
            :to_variable,
            :value_separator,
            :counter

        def initialize (iterator_expression, workitem)

            @to_field = iterator_expression\
                .lookup_attribute(:to_field, workitem)
            @to_variable = iterator_expression\
                .lookup_attribute(:to_variable, workitem)

            @value_separator = iterator_expression\
                .lookup_attribute(:value_separator, workitem)

            @value_separator = /,\s*/ unless @value_separator

            @counter = 0

            raw_list = OpenWFE::lookup_vf_attribute(
                iterator_expression, workitem, :value, :on)

            @iteration_list = extract_iteration_list(raw_list)

            workitem.attributes['__ic__'] = @iteration_list.length
        end

        #
        # Has the iteration a next element ?
        #
        def has_next?
            @iteration_list.length > 0
        end

        #
        # Prepares the iterator expression and the workitem for the next 
        # iteration.
        #
        def next (iterator_expression, workitem)

            value = @iteration_list.pop

            if @to_field
                workitem.attributes[@to_field] = value
            else
                iterator_expression.set_variable(@to_variable, value)
            end

            workitem.attributes['__ip__'] = @counter

            @counter = @counter + 1
        end

        protected

            def extract_iteration_list (raw_list)

                l = if is_suitable_list(raw_list)
                    raw_list
                else
                    extract_list_from_string(raw_list.to_s)
                end

                return l.reverse
            end

            def is_suitable_list (instance)
                instance.respond_to? :pop and \
                instance.respond_to? :reverse and \
                instance.respond_to? :length
            end

            def extract_list_from_string (s)
                s.split(@value_separator)
            end
    end

end