require 'glue/validation'

module Glue 

# Extend the Validation methods defined in glue/validation.rb with 
# extra db related options.

module Validation

  # Encapsulates a list of validation errors.
  
  class Errors
    cattr_accessor :not_unique, 'The value is already used'
    cattr_accessor :invalid_relation, 'Invalid relations'
  end

  module ClassMethods 
    
    # Validates that the given field(s) contain unique values.
    # Ensures that if a record is found with a matching value,
    # that it is the same record, allowing updates.
    #
    # The Og libraries are required for this methdod to 
    # work. You can override this method if you want to
    # use another OR mapping library.
    #
    # === Example
    #
    # validate_unique :param, :msg => 'Value is already in use'
    #--
    # TODO: :unique should implicitly generate 
    # validate_unique.
    #++
    
    def validate_unique(*params)
      c = {
        :on => :save
      }
      c.update(params.pop) if params.last.is_a?(Hash)

      for name in params do
        c[:msg] ||= "#{self.name} with this #{name} already exists"

        code = %{
          others = obj.class.send(:find_by_#{name}, obj.send(:#{name}))
  
          unless others.empty?
            if (others.size != 1) or (others[0].oid != obj.oid)
              errors.add(:#{name}, '#{c[:msg]}')
            end
          end
        }

        validations! << [code, c[:on]]
      end
    end

    # Validate the related object or objects. Works
    # with all relations.
    
    def validate_related(*params)
      c = { 
        :msg => Glue::Validation::Errors.invalid_relation, 
        :on => :save 
      }
      c.update(params.pop) if params.last.is_a?(Hash)
      
      for name in params
        code = %{
          unless (obj.#{name}.is_a?(Array) ? obj.#{name} : [obj.#{name}]).inject(true) { |memo, obj| (obj.nil? or obj.valid?) and memo }
            errors.add(:#{name}, '#{c[:msg]}')
          end;
        }

        validations! << [code, c[:on]]
      end
    end
    alias_method :validate_associated, :validate_related

  end
  
end 

end

# * George Moschovitis <gm@navel.gr>
# * Bryan Soto