Hooks implementation for Clearwater

hooks.rb

module Hooks
  def self.component *attrs, &render
    Class.new(Component) do
      attr_reader *attrs

      define_method :initialize do |**props|
        super()
        attrs.each { |attr| `self[#{attr}] = #{props[attr]}` }
      end

      define_method :run do
        @state_index = 0
        @effect_index = 0
        instance_exec &render
      end
    end
  end

  require 'clearwater/black_box_node'
  class Component
    include Clearwater::Component
    include Clearwater::BlackBoxNode

    attr_reader :states, :effect_markers, :cleanup_hooks, :vdom

    def initialize
      @states = []
      @effect_markers = []
      @cleanup_hooks = []
      @render_callbacks = []

      @effect_index = 0
      @state_index = 0
    end

    def node
      @node = run
    end

    def mount element
      @vdom = Clearwater::VirtualDOM::Document.pre_rendered(element, node)
      @can_render = true
    end

    def update previous
      @states = previous.states
      @effect_markers = previous.effect_markers
      @cleanup_hooks = previous.cleanup_hooks
      @vdom = previous.vdom
      @can_render = true
      previous.cancel_renders

      @vdom.render run
      nil
    end

    def unmount
      cancel_renders
      @cleanup_hooks.each do |block|
        block.call if block
      end
    end

    def cancel_renders
      @can_render = false
    end

    def use_state initial
      current_index = @state_index
      @states[current_index] ||= initial
      setter = proc do |new_value|
        @states[current_index] = new_value
        call
      end

      @state_index += 1

      [@states[current_index], setter]
    end

    def use_effect *markers, &effect
      current_index = @effect_index
      if @effect_markers[current_index] != markers
        @effect_markers[current_index] = markers
        if @cleanup_hooks[current_index]
          @cleanup_hooks[current_index].call
        end
        effect.call
      end

      @effect_index += 1
    end

    def cleanup &block
      @cleanup_hooks[@effect_index] = block
    end

    def call &block
      @render_callbacks << block if block
      return if @will_render || !@can_render
      @will_render = true
      Bowser.window.animation_frame do
        @will_render = false

        @vdom.render run
        @render_callbacks.each(&:call)
        @render_callbacks = []
      end
    end
  end
end