#
# Copyright (c) 2006, 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 'ru/rudefinitions'
require 'ru/contextual'
require 'ru/dollar'
require 'ru/logging'


module OpenWFEru

    #
    # FlowExpression
    #

    class FlowExpression
        include Contextual, Logging

        attr_accessor \
            :fei, \
            :parent_id, \
            :environment_id, \
            :attributes, \
            :children, \
            :apply_time 

        def initialize (fei, parent_id, env_id, app_context, attributes)

            @fei = fei
            @parent_id = parent_id
            @environment_id = env_id
            @application_context = app_context
            @attributes = attributes

            @apply_time = nil

            #ldebug do
            #    "initialize()\n"+
            #    "self   : #{@fei}\n"+
            #    "parent : #{@parent_id}"
            #end
        end

        #
        # the two most important methods for flow expressions

        def apply (workitem)
            get_parent().reply(workitem) if @parent_id
        end

        def reply (workitem)
            #
            # a default implementation
            #
            reply_to_parent(workitem)
        end

        def reply_to_parent (workitem)
            get_expression_pool.reply_to_parent(self, workitem)
        end

        #
        # some convenience methods

        def get_parent ()
            get_expression_pool().fetch(@parent_id)
        end

        def get_expression_pool ()
            @application_context[S_EXPRESSION_POOL]
        end

        def get_expression_map ()
            @application_context[S_EXPRESSION_MAP]
        end

        def store_itself ()
            get_expression_pool().update(self)
        end

        def get_environment ()
            return nil if not @environment_id
            return get_expression_pool().fetch(@environment_id)
        end

        #
        # Returns true if the expression's environment was generated
        # for itself (usually DefineExpression do have such envs)
        #
        def owns_its_environment? ()

            #ldebug { "owns_its_environment?()  #{@fei.to_debug_s}" }

            return false if not @environment_id

            ei = @fei.dup()
            vi = @environment_id.dup()

            ei.expressionName = "neutral"
            vi.expressionName = "neutral"

            #ldebug do
            #    "owns_its_environment?()\n"+
            #    "   exp  #{ei.to_debug_s}\n"+
            #    "   env  #{vi.to_debug_s}"
            #end

            return ei == vi
        end

        def set_variable (varname, value)
            get_environment()[varname] = value
        end

        def lookup_variable (varname)
            return get_environment()[varname]
        end

        def delete_variable (varname)
            get_environment().delete(varname)
        end

        def lookup_attribute (attname, workitem)
            text = @attributes[attname]
            return nil if not text
            return OpenWFEru::dosub(text, self, workitem)
        end

        def lookup_boolean_attribute (attname, workitem, default=false)
            value = lookup_attribute(attname, workitem)
            return default if not value
            return value.downcase == 'true'
        end

        def lookup_attributes (attributes, workitem)
            result = {}
            attributes.each do |k, v|
                result[k] = OpenWFEru::dosub(v, self, workitem)
            end
            return result
        end

        def list_attributes (workitem)
            result = {}
            @attributes.each do |k, v|
                result[k] = OpenWFEru::dosub(v, self, workitem)
                ldebug { "list_attributes()    added '#{k}' -> '#{result[k]}'" }
            end
            return result
        end

        #
        # creates a new environment just for this expression
        #
        def new_environment ()

            ldebug { "new_environment() for #{@fei.to_debug_s}" }

            @environment_id = @fei.dup
            @environment_id.expressionName = EN_ENVIRONMENT

            parent_fei = nil
            parent = nil
            parent = get_expression_pool().fetch(@parent_id) if @parent_id
            parent_fei = parent.environment_id if parent

            env = Environment\
                .new(@environment_id, parent_fei, nil, @application_context, nil)

            ldebug { "new_environment() is #{env.fei.to_debug_s}" }

            env.store_itself()
        end

        #
        # takes care of removing all the children
        #
        def clean_children
            @children.each do |children_fei|
                get_expression_pool.remove(children_fei)
            end
        end

        #
        # some eye candy
        #
        def to_s
            s = "* #{@fei.to_debug_s}"

            if @parent_id
                s << "\n   `--p--> #{@parent_id.to_debug_s}"
            end

            if @environment_id
                s << "\n   `--e--> #{@environment_id.to_debug_s}"
            end

            if @children
                @children.each do |c|
                    sc = if c.kind_of?(OpenWFE::FlowExpressionId)
                        c.to_debug_s
                    else
                        ">#{c.to_s}<"
                    end
                    s << "\n   `--c--> #{sc}"
                end
            end

            return s
        end
    end

end