Maybe/app/javascript/controllers/rule/actions_controller.js

import { Controller } from "@hotwired/stimulus";

// Connects to data-controller="rule--actions"
export default class extends Controller {
  static values = { actionExecutors: Array };
  static targets = [
    "destroyField",
    "actionValue",
    "selectTemplate",
    "textTemplate"
  ];

  remove(e) {
    if (e.params.destroy) {
      this.destroyFieldTarget.value = true;
      this.element.classList.add("hidden");
    } else {
      this.element.remove();
    }
  }

  handleActionTypeChange(e) {
    const actionExecutor = this.actionExecutorsValue.find(
      (executor) => executor.key === e.target.value,
    );

    // Clear any existing input elements first
    this.#clearFormFields();

    if (actionExecutor.type === "select") {
      this.#buildSelectFor(actionExecutor);
    } else if (actionExecutor.type === "text") {
      this.#buildTextInputFor();
    } else {
      // Hide for any type that doesn't need a value (e.g. function)
      this.#hideActionValue();
    }
  }

  #hideActionValue() {
    this.actionValueTarget.classList.add("hidden");
  }

  #clearFormFields() {
    // Remove all children from actionValueTarget
    this.actionValueTarget.innerHTML = "";
  }

  #buildSelectFor(actionExecutor) {
    // Clone the select template
    const template = this.selectTemplateTarget.content.cloneNode(true);
    const selectEl = template.querySelector("select");

    // Add options to the select element
    if (selectEl) {
      selectEl.innerHTML = "";
      if (!actionExecutor.options || actionExecutor.options.length === 0) {
        selectEl.disabled = true;
        const optionEl = document.createElement("option");
        optionEl.textContent = "(none)";
        selectEl.appendChild(optionEl);
      } else {
        selectEl.disabled = false;
        for (const option of actionExecutor.options) {
          const optionEl = document.createElement("option");
          optionEl.value = option[1];
          optionEl.textContent = option[0];
          selectEl.appendChild(optionEl);
        }
      }
    }

    // Add the template content to the actionValue target and ensure it's visible
    this.actionValueTarget.appendChild(template);
    this.actionValueTarget.classList.remove("hidden");
  }

  #buildTextInputFor() {
    // Clone the text template
    const template = this.textTemplateTarget.content.cloneNode(true);

    // Ensure the input is always empty
    const inputEl = template.querySelector("input");
    if (inputEl) inputEl.value = "";

    // Add the template content to the actionValue target and ensure it's visible
    this.actionValueTarget.appendChild(template);
    this.actionValueTarget.classList.remove("hidden");
  }
}