#--
# Copyright (c) 2005-2012, John Mettraux, jmettraux@gmail.com
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
# Made in Japan.
#++


module Ruote::Exp

  #
  # This expression fell out of favour a long ago. At first it was used with
  # the 'if' expression :
  #
  #   _if do
  #     equals :field_value => 'customer', :other_value => 'British Petroleum'
  #     participant :ref => 'Allister'
  #   end
  #
  # but lately, the :test attribute of the 'if' expression is used :
  #
  #   _if :test => '${f:customer} == British Petroleum' do
  #     participant :ref => 'Allister'
  #   end
  #
  # In some cases, the 'if' expression vanishes and the :if attribute shared
  # by all expressions is used :
  #
  #   participant :ref => 'Al', :if => '${f:customer} == British Petroleum'
  #
  #
  # == attributes
  #
  # The 'equals' expression accepts those attributes :
  #
  # * :value
  # * :field_value
  # * :variable_value
  # * :val
  # * :field_val
  # * :variable_val
  #
  # and
  #
  # * :other_value
  # * :other_field_value
  # * :other_variable_value
  # * :other_val
  # * :other_field_val
  # * :other_variable_val
  #
  # With a bit of luck, they make sense on their own.
  #
  class EqualsExpression < FlowExpression

    names :equals

    def apply

      vals = grab_values

      h.applied_workitem['fields']['__result__'] = if vals.size < 2
        false
      else
        (vals.first == vals.last)
      end

      reply_to_parent(h.applied_workitem)
    end

    protected

    OTHER_REGEX = /^other\_(.+)$/

    def grab_values

      keys = attributes.keys.select { |k| ! COMMON_ATT_KEYS.include?(k) }

      keys.collect { |k| grab_value(k) }
    end

    def grab_value(k)

      attval = attribute(k)

      if m = OTHER_REGEX.match(k)
        k = m[1]
      end

      case k
        when /^f/ then h.applied_workitem['fields'][attval]
        when /^var/ then lookup_variable(attval)
        when /^val/ then attval
      end
    end
  end
end