#
#--
# 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/condition'
require 'openwfe/expressions/wtemplate'
require 'openwfe/expressions/flowexpression'


#
# 'cursor' and 'loop' expressions
#

module OpenWFE

    A_COMMAND_FIELD = "command-field"
    F_COMMAND = "__cursor_command__"
    A_DISALLOW = "disallow"

    C_BACK = "back"
    C_SKIP = "skip"
    C_BREAK = "break"
    C_CANCEL = "cancel"
    C_REWIND = "rewind"
    C_CONTINUE = "continue"

    A_STEP = "step"

    #
    # The 'cursor' is much like a sequence, but you can go
    # back and forth within it.
    #
    class CursorExpression < WithTemplateExpression

        attr_accessor \
            :loop_id,
            :current_child_id,
            :current_child_fei

        #
        # apply / reply

        def apply (workitem)

            @loop_id = 0

            @current_child_id = -1

            clean_children_list()

            reply(workitem)
        end

        def reply (workitem)

            if @children.length < 1
                #
                # well, currently, no infinite empty loop allowed
                #
                reply_to_parent(workitem)
                return
            end

            command_field = lookup_command_field(workitem)
            command = lookup_command(command_field, workitem)
            disallow_list = lookup_disallow(workitem)

            command = nil \
                if disallow_list and disallow_list.include? command

            if command == C_BREAK or command == C_CANCEL
                reply_to_parent(workitem)
                return
            end

            if command == C_REWIND or command == C_CONTINUE
                @current_child_id = 0
            else
                step = lookup_step(command)
                @current_child_id = @current_child_id + step

                @current_child_id = 0 if @current_child_id < 0

                if @current_child_id >= @children.length
                    if not is_loop
                        reply_to_parent(workitem)
                        return
                    end
                    @loop_id += 1
                    @current_child_id = 0
                end
            end

            workitem.attributes.delete(command_field)

            @current_child_fei = nil

            store_itself()

            @current_child_fei = @children[@current_child_id]

            #
            # launch the next child as a template

            get_expression_pool.launch_template(
                self, @loop_id, @current_child_fei, workitem, nil)
        end

        #
        # takes care of cancelling the current child if necessary
        #
        def cancel ()
            get_expression_pool.cancel(@current_child_fei) \
                if @current_child_fei
            super()
        end

        #
        # returns false, the child class LoopExpression does return true.
        #
        def is_loop
            return false
        end

        protected

            def lookup_step (command)

                return 1 if not command

                step = 1

                ss = command.split()

                if ss.length > 1
                    step = Integer(ss[1])
                end

                step = -step if OpenWFE::starts_with(command, C_BACK)

                return step
            end

            def clean_children_list

                c = @children
                @children = []
                c.each do |child|
                    @children << child \
                        if child.kind_of? OpenWFE::FlowExpressionId
                end
            end

            def lookup_command_field (workitem)

                return lookup_attribute(A_COMMAND_FIELD, workitem, F_COMMAND)
            end

            def lookup_command (command_field, workitem)

                command = workitem.attributes[command_field]
                command = command.strip() if command

                return command
            end

            def lookup_disallow (workitem)

                return lookup_comma_list_attribute(A_DISALLOW, workitem)
            end
    end

    #
    # The 'loop' expression is like 'cursor' but it doesn't exit until
    # it's broken.
    #
    class LoopExpression < CursorExpression

        def is_loop
            return true
        end
    end

    #
    # 'skip', 'continue', and the like
    #
    class CursorCommandExpression < FlowExpression
        include ConditionMixin

        def apply (workitem)

            conditional = eval_condition(:if, workitem)
                #
                # for example : <break if="${approved} == true"/>

            if conditional == nil or conditional

                command = @fei.expression_name

                step = lookup_attribute(A_STEP, workitem, "1")
                step = Integer(step)

                command = "#{command} #{step}" if step != 1

                workitem.attributes[F_COMMAND] = command
            end

            reply_to_parent(workitem)
        end
    end

end