# frozen_string_literal: true

module Unparser
  # Original code before vendoring and reduction from: https://github.com/mbj/anima.
  class Anima < Module
    include Adamantium, Equalizer.new(:attributes)

    # Return names
    #
    # @return [AttributeSet]
    attr_reader :attributes

    # Initialize object
    #
    # @return [undefined]
    #
    # rubocop:disable Lint/MissingSuper
    def initialize(*names)
      @attributes = names.uniq.map(&Attribute.public_method(:new)).freeze
    end
    # rubocop:enable Lint/MissingSuper

    # Return new anima with attributes added
    #
    # @return [Anima]
    #
    # @example
    #   anima = Anima.new(:foo)
    #   anima.add(:bar) # equals Anima.new(:foo, :bar)
    #
    def add(*names)
      new(attribute_names + names)
    end

    # Return new anima with attributes removed
    #
    # @return [Anima]
    #
    # @example
    #   anima = Anima.new(:foo, :bar)
    #   anima.remove(:bar) # equals Anima.new(:foo)
    #
    def remove(*names)
      new(attribute_names - names)
    end

    # Return attributes hash for instance
    #
    # @param [Object] object
    #
    # @return [Hash]
    def attributes_hash(object)
      attributes.each_with_object({}) do |attribute, attributes_hash|
        attributes_hash[attribute.name] = attribute.get(object)
      end
    end

    # Return attribute names
    #
    # @return [Enumerable<Symbol>]
    def attribute_names
      attributes.map(&:name)
    end
    memoize :attribute_names

    # Initialize instance
    #
    # @param [Object] object
    #
    # @param [Hash] attribute_hash
    #
    # @return [self]
    def initialize_instance(object, attribute_hash)
      assert_known_attributes(object.class, attribute_hash)
      attributes.each do |attribute|
        attribute.load(object, attribute_hash)
      end
      self
    end

    # Static instance methods for anima infected classes
    module InstanceMethods
      # Initialize an anima infected object
      #
      # @param [#to_h] attributes
      #   a hash that matches anima defined attributes
      #
      # @return [undefined]
      #
      # rubocop:disable Lint/MissingSuper
      def initialize(attributes)
        self.class.anima.initialize_instance(self, attributes)
      end
      # rubocop:enable Lint/MissingSuper

      # Return a hash representation of an anima infected object
      #
      # @example
      #   anima.to_h # => { :foo => : bar }
      #
      # @return [Hash]
      #
      # @api public
      def to_h
        self.class.anima.attributes_hash(self)
      end

      # Return updated instance
      #
      # @example
      #   klass = Class.new do
      #     include Anima.new(:foo, :bar)
      #   end
      #
      #   foo = klass.new(:foo => 1, :bar => 2)
      #   updated = foo.with(:foo => 3)
      #   updated.foo # => 3
      #   updated.bar # => 2
      #
      # @param [Hash] attributes
      #
      # @return [Anima]
      #
      # @api public
      def with(attributes)
        self.class.new(to_h.update(attributes))
      end
    end # InstanceMethods

    private

    # Infect the instance with anima
    #
    # @param [Class, Module] scope
    #
    # @return [undefined]
    def included(descendant)
      descendant.instance_exec(self, attribute_names) do |anima, names|
        # Define anima method
        define_singleton_method(:anima) { anima }

        # Define instance methods
        include InstanceMethods

        # Define attribute readers
        attr_reader(*names)

        # Define equalizer
        include Equalizer.new(*names)
      end
    end

    # Fail unless keys in +attribute_hash+ matches #attribute_names
    #
    # @param [Class] klass
    #   the class being initialized
    #
    # @param [Hash] attribute_hash
    #   the attributes to initialize +object+ with
    #
    # @return [undefined]
    #
    # @raise [Error]
    def assert_known_attributes(klass, attribute_hash)
      keys = attribute_hash.keys

      unknown = keys - attribute_names
      missing = attribute_names - keys

      unless unknown.empty? && missing.empty?
        fail Error.new(klass, missing, unknown)
      end
    end

    # Return new instance
    #
    # @param [Enumerable<Symbol>] attributes
    #
    # @return [Anima]
    def new(attributes)
      self.class.new(*attributes)
    end
  end # Anima
end # Unparser