#
# 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/flowexpression'
require 'ru/ruutils'


module OpenWFEru

    #
    # An environment is a store for variables.
    # It's an expression as it's storable in the expression pool.
    #
    class Environment < FlowExpression

        attr_accessor \
            :variables

        def initialize \
            (id, parent, environment_id, application_context, attributes)

            super(id, parent, environment_id, application_context, attributes)

            @variables = {}
        end

        def [] (key)
            if OpenWFEru::starts_with(key, "//")
                return get_expression_pool()\
                    .get_engine_environment()[key[2..-1]]
            end
            if OpenWFEru::starts_with(key, "/")
                return get_root_environment()[key[1..-1]]
            end

            value = @variables[key]

            return value \
                if @variables.has_key?(key) or is_engine_environment?
                #if value or is_engine_environment?

            return get_parent()[key] if @parentId

            return get_expression_pool().fetch_engine_environment()[key]
        end

        def []= (key, value)
            if OpenWFEru::starts_with(key, "//")
                key = key[2..-1]
                get_expression_pool().fetch_engine_environment()[key] = value
            elsif OpenWFEru::starts_with(key, "/")
                key = key[1..-1]
                get_root_environment()[key] = value
            else
                @variables[key] = value
                store_itself()

                ldebug { "[]= #{@fei.to_debug_s}  :  '#{key}' -> '#{value}'" }
            end
        end

        def delete (key)
            if OpenWFEru::starts_with(key, "//")
                key = key[2..-1]
                get_expression_pool().fetch_engine_environment().delete(key)
            elsif OpenWFEru::starts_with(key, "/")
                key = key[1..-1]
                get_root_environment().delete(key)
            else
                @variables.delete(key)
            end
        end

        #
        # This method is usually called before the environment gets wiped
        # out of the expression pool.
        # It takes care of removing subprocess templates pointed at by
        # variables in this environment.
        #
        def unbind ()
            @variables.each do |key, value|
                get_expression_pool().remove(value) \
                    if value.kind_of? OpenWFE::FlowExpressionId
            end
        end

        #
        # Returns true if this environment is the engine environment
        #
        def is_engine_environment?
            return @fei == get_expression_pool().engine_environment_id
        end

        protected

            def get_root_environment ()
                #ldebug { "get_root_environment()\n#{self}" }
                return self if not @parent_id
                return get_parent().get_root_environment()
            end
    end

end