require 'extlib/dictionary'

module DataMapper
  module Validate

    ##
    #
    # @author Guy van den Berg
    # @since  0.9
    class ValidationErrors

      include Enumerable

      @@default_error_messages = {
        :absent                   => '%s must be absent',
        :inclusion                => '%s must be one of %s',
        :invalid                  => '%s has an invalid format',
        :confirmation             => '%s does not match the confirmation',
        :accepted                 => '%s is not accepted',
        :nil                      => '%s must not be nil',
        :blank                    => '%s must not be blank',
        :length_between           => '%s must be between %s and %s characters long',
        :too_long                 => '%s must be at most %s characters long',
        :too_short                => '%s must be at least %s characters long',
        :wrong_length             => '%s must be %s characters long',
        :taken                    => '%s is already taken',
        :not_a_number             => '%s must be a number',
        :not_an_integer           => '%s must be an integer',
        :greater_than             => '%s must be greater than %s',
        :greater_than_or_equal_to => '%s must be greater than or equal to %s',
        :equal_to                 => '%s must be equal to %s',
        :not_equal_to             => '%s must not be equal to %s',
        :less_than                => '%s must be less than %s',
        :less_than_or_equal_to    => '%s must be less than or equal to %s',
        :value_between            => '%s must be between %s and %s',
        :primitive                => '%s must be of type %s'
      }

      # Holds a hash with all the default error messages that can be replaced by your own copy or localizations.
      cattr_writer :default_error_messages

      def self.default_error_message(key, field, *values)
        field = Extlib::Inflection.humanize(field)
        @@default_error_messages[key] % [field, *values].flatten
      end

      attr_reader :resource

      def initialize(resource)
        @resource = resource
        @errors   = Dictionary.new
      end

      # Clear existing validation errors.
      def clear!
        errors.clear
      end

      # Add a validation error. Use the field_name :general if the errors does
      # not apply to a specific field of the Resource.
      #
      # @param [Symbol] field_name the name of the field that caused the error
      # @param [String] message    the message to add
      def add(field_name, message)
        # see 6abe8fff in extlib, but don't enforce
        # it unless Edge version is installed
        if message.respond_to?(:try_call)

          # DM resource
          message = if resource.respond_to?(:model) && resource.model.respond_to?(:properties)
            message.try_call(resource, resource.model.properties[field_name])
          else
            # pure Ruby object
            message.try_call(resource)
          end
        end
        (errors[field_name] ||= []) << message
      end

      # Collect all errors into a single list.
      def full_messages
        errors.inject([]) do |list, pair|
          list += pair.last
        end
      end

      # Return validation errors for a particular field name or an empty array
      #
      # This method is a necessary requirement for active_model compatibility.
      #
      # @param [Symbol] field_name the name of the field you want an error for
      # @return [Array<Array<String>>]
      #   array of validation errors or empty array, if there are no errors on given field
      def [](field_name)
        errors[field_name] ||= []
      end

      # Return validation errors for a particular field_name.
      #
      # @param [Symbol] field_name the name of the field you want an error for
      # @return [Array<DataMapper::Validate::Error>]
      #   array of validation errors or empty array, if there are no errors on given field
      def on(field_name)
        errors_for_field = errors[field_name]
        errors_for_field.blank? ? nil : errors_for_field.uniq
      end

      def each
        errors.map.each do |k, v|
          next if v.blank?
          yield(v)
        end
      end

      def empty?
        @errors.empty?
      end

      def method_missing(meth, *args, &block)
        errors.send(meth, *args, &block)
      end

      private
      def errors
        @errors
      end

    end # class ValidationErrors
  end # module Validate
end # module DataMapper
