module Preact::Component::NativeComponentConstructor
  # for should_component_update we apply ruby semantics for comparing props
  # to do so, we convert the props to ruby hashes and then compare
  # this makes sure, that for example rubys Nil object gets handled properly
  def self.extended(base)
    component_name = base.to_s
    %x{
      base.preact_component = class extends Opal.global.Preact.Component {
        constructor(props) {
          super(props);
          if (base.$default_state_defined()) {
            this.state = base.$state().$to_n();
          } else {
            this.state = {};
          };
          this.__ruby_instance = base.$new(this);
          var defined_refs = #{base.defined_refs};
          for (var ref in defined_refs) {
            if (defined_refs[ref] != null) {
              let r = ref; // to ensure closure for function below gets correct ref name
              this[ref] = function(element) {
                const oper = Opal.Preact;
                element = oper.native_element_or_component_to_ruby(element);
                oper.register_active_component(this);
                try {
                  #{`this.__ruby_instance`.instance_exec(`element`, &`defined_refs[r]`)}
                } catch (e) { console.error(e.message === nil ? 'error at' : e.message, e.stack); }
                oper.unregister_active_component(this);
              }
              this[ref] = this[ref].bind(this);
            } else {
              this[ref] = Opal.global.Preact.createRef();
            }
          }
        }
        static get displayName() {
          return #{component_name};
        }
        render(props, state) {
          const oper = Opal.Preact;
          oper.render_buffer.push([]);
          oper.register_active_component(this);
          try {
            let block_result = #{`this.__ruby_instance`.instance_exec(&`base.render_block`)};
            if (block_result && block_result !== nil) { oper.render_block_result(block_result); }
          } catch (e) {
            if (oper.using_did_catch) { throw e; }
            else { console.error(e.message === nil ? 'error at' : e.message, e.stack); }
          }
          oper.unregister_active_component(this);
          let result = oper.render_buffer.pop();
          return (result.length === 1) ? result[0] : result;
        }
        shouldComponentUpdate(next_props, next_state) {
          const oper = Opal.Preact;
          if (base.should_component_update_block) {
            oper.register_active_component(this);
            let result;
            try {
              result = #{!!`this.__ruby_instance`.instance_exec(`oper.Props.$new({props: next_props})`, `oper.State.$new({state: next_state })`, &`base.should_component_update_block`)};
            } catch (e) { console.error(e.message === nil ? 'error at' : e.message, e.stack); }
            oper.unregister_active_component(this);
            return result;
          }
          if (!oper.props_are_equal(this.props, next_props)) { return true; }
          if (oper.state_is_not_equal(this.state, next_state)) { return true; }
          return false;
        }
        validateProp(props, propName, componentName) {
          try { base.$validate_prop(propName, props[propName]) }
          catch (e) { return new Error(componentName + " Error: prop validation failed: " + e.message); }
          return null;
        }
      }
    }
  end
end