module Neo4j::Shared
  module Enum
    extend ActiveSupport::Concern

    class ConflictingEnumMethodError < Neo4j::Error; end

    module ClassMethods
      attr_reader :neo4j_enum_data

      # Similar to ActiveRecord enum, maps an integer value on the database to
      # a set of enum keys.
      #
      # @example Base example
      #   class Media
      #     include Neo4j::ActiveNode
      #     enum type: [:image, :video, :unknown]
      #   end
      #   Media.types # => { :images => 0, :video => 1, :unknown => 2 }
      #
      #   media.video!
      #   media.image? # => false
      #   media.type # => :video
      #
      #   Media.videos # => All medias with type = 1 (:video)
      #   Media.where(type: :video) # => All medias with type = 1 (:video)
      #
      # @example Prefix-ing an enum
      #   Media.enum type: [:image, :video, :unknown], _prefix: :enum
      #
      #   media.enum_video!
      #   media.enum_video? # => true
      #
      # @example Suffix-ing an enum
      #   Media.enum type: [:image, :video, :unknown], _suffix: true
      #
      #   media.video_type!
      #   media.video_type? # => true
      #
      # @example Disable index: :exact for enum elements
      #   Media.enum type: [:image, :video, :unknown], _index: false
      #
      # @example Define a custom mapping for keys-numbers
      #   Media.enum type: { image: 1, video: 2, unknown: 3 }
      #
      # @see http://edgeapi.rubyonrails.org/classes/ActiveRecord/Enum.html
      def enum(parameters = {})
        options, parameters = *split_options_and_parameters(parameters)
        parameters.each do |property_name, enum_keys|
          enum_keys = normalize_key_list enum_keys
          @neo4j_enum_data ||= {}
          @neo4j_enum_data[property_name] = enum_keys
          define_property(property_name, enum_keys, options)
          define_enum_methods(property_name, enum_keys, options)
        end
      end

      protected

      def normalize_key_list(enum_keys)
        case enum_keys
        when Hash
          enum_keys
        when Array
          Hash[enum_keys.each_with_index.to_a]
        else
          fail ArgumentError, 'Invalid parameter for enum. Please provide an Array or an Hash.'
        end
      end

      VALID_OPTIONS_FOR_ENUMS = [:_index, :_prefix, :_suffix, :_default]
      DEFAULT_OPTIONS_FOR_ENUMS = {
        _index: true
      }

      def split_options_and_parameters(parameters)
        options = DEFAULT_OPTIONS_FOR_ENUMS.clone
        new_parameters = {}
        parameters.each do |k, v|
          if VALID_OPTIONS_FOR_ENUMS.include? k
            options[k] = v
          else
            new_parameters[k] = v
          end
        end
        [options, new_parameters]
      end

      def define_property(property_name, enum_keys, options)
        property_options = build_property_options(enum_keys, options)
        property property_name, property_options
        serialize property_name, Neo4j::Shared::TypeConverters::EnumConverter.new(enum_keys, property_options)
      end

      def build_property_options(_enum_keys, options = {})
        {
          default: options[:_default]
        }
      end

      def define_enum_methods(property_name, enum_keys, options)
        define_enum_methods_?(property_name, enum_keys, options)
        define_enum_methods_!(property_name, enum_keys, options)
        define_class_methods(property_name, enum_keys)
      end

      def define_class_methods(property_name, enum_keys)
        plural_property_name = property_name.to_s.pluralize.to_sym
        define_singleton_method(plural_property_name) do
          enum_keys
        end
      end

      def define_enum_methods_?(property_name, enum_keys, options)
        enum_keys.keys.each do |enum_value|
          method_name = build_method_name(enum_value, property_name, options)
          check_enum_method_conflicts! property_name, :"#{method_name}?"
          define_method("#{method_name}?") do
            __send__(property_name).to_s.to_sym == enum_value
          end
        end
      end

      def define_enum_methods_!(property_name, enum_keys, options)
        enum_keys.keys.each do |enum_value|
          method_name = build_method_name(enum_value, property_name, options)
          check_enum_method_conflicts! property_name, :"#{method_name}!"
          define_method("#{method_name}!") do
            __send__("#{property_name}=", enum_value)
          end
        end
      end

      def build_method_name(base_name, property_name, options)
        method_name = base_name
        method_name = "#{method_name}_#{property_name}" if options[:_suffix]
        method_name = "#{options[:_prefix]}_#{method_name}" if options[:_prefix]
        method_name
      end

      def check_enum_method_conflicts!(property_name, method_name)
        fail ConflictingEnumMethodError,
             "The enum `#{property_name}` is trying to define a `#{method_name}` method, "\
             'that is already defined. Try to use options `:prefix` or `:suffix` '\
             'to avoid conflicts.' if instance_methods(false).include?(method_name)
      end
    end
  end
end