#
#--
# 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.
#++
#

#
# "made in Japan"
#
# John Mettraux at openwfe.org
#

require 'openwfe/filterdef'


module OpenWFE

  #
  # This expression binds a filter definition into a variable.
  #
  #   class TestFilter48a0 < ProcessDefinition
  #     sequence do
  #
  #       set :field => "readable", :value => "bible"
  #       set :field => "writable", :value => "sand"
  #       set :field => "randw", :value => "notebook"
  #       set :field => "hidden", :value => "playboy"
  #
  #       alice
  #
  #       filter :name => "filter0" do
  #         sequence do
  #           bob
  #           charly
  #         end
  #       end
  #
  #       doug
  #     end
  #
  #     filter_definition :name => "filter0" do
  #       field :regex => "readable", :permissions => "r"
  #       field :regex => "writable", :permissions => "w"
  #       field :regex => "randw", :permissions => "rw"
  #       field :regex => "hidden", :permissions => ""
  #     end
  #   end
  #
  # In that example, the filter definition is done for filter 'filter0'.
  #
  # A filter definition accepts 4 attributes :
  #
  # * 'name' - simply naming the filter, the filter is then bound as a variable. This is the only mandatory attribute.
  #
  # * 'closed' - by default, set to 'false'. A closed filter will not allow modifications to unspecified fields.
  #
  # * 'add' - by default, set to 'true'. When true, this filter accepts adding new fields to the filtered workitem.
  #
  # * 'remove' - by default, set to 'true'. When true, this filter accepts removing fields to the filtered workitem.
  #
  #
  # Inside of the process definition, fields are identified via regular
  # expressions ('regex'), a 'permissions' string is then expected with four
  # possible values "rw", "w", "r" and "".
  #
  class FilterDefinitionExpression < FlowExpression

    is_definition

    names :filter_definition


    #
    # Will build the filter and bind it as a variable.
    #
    def apply (workitem)

      filter = build_filter workitem
      filter_name = lookup_attribute :name, workitem

      set_variable filter_name, filter \
        if filter_name and filter

      reply_to_parent workitem
    end

    protected

      #
      # Builds the filter (as described in the process definition)
      # and returns it.
      #
      def build_filter (workitem)

        filter = FilterDefinition.new

        # filter attributes

        type = lookup_downcase_attribute :type, workitem
        closed = lookup_downcase_attribute :closed, workitem

        filter.closed = (type == "closed" or closed == "true")

        add = lookup_downcase_attribute :add, workitem
        remove = lookup_downcase_attribute :remove, workitem

        filter.add_allowed = (add == "true")
        filter.remove_allowed = (remove == "true")

        # field by field

        @children.each do |fei|

          rawexp = get_expression_pool.fetch_expression fei
          get_expression_pool.remove fei

          add_field filter, rawexp, workitem
        end

        filter
      end

      #
      # builds and add a field (a line) of the filter.
      #
      def add_field (filter, rawexp, workitem)

        rawexp.load_attributes

        regex = rawexp.lookup_attribute :regex, workitem
        regex = rawexp.lookup_attribute :name, workitem unless regex

        permissions =
          rawexp.lookup_downcase_attribute :permissions, workitem

        filter.add_field regex, permissions
      end
  end

end