discourse/app/assets/javascripts/admin/addon/components/simple-list.js

import { arrayContentDidChange } from "@ember/-internals/metal";
import Component from "@ember/component";
import { action } from "@ember/object";
import { empty } from "@ember/object/computed";
import { isEmpty } from "@ember/utils";
import { classNameBindings } from "@ember-decorators/component";
import discourseComputed from "discourse/lib/decorators";

@classNameBindings(":simple-list", ":value-list")
export default class SimpleList extends Component {
  @empty("newValue") inputEmpty;

  inputDelimiter = null;
  newValue = "";
  collection = null;
  values = null;
  choices = null;
  allowAny = false;

  didReceiveAttrs() {
    super.didReceiveAttrs(...arguments);
    this.set("collection", this._splitValues(this.values, this.inputDelimiter));
    this.set("isPredefinedList", !this.allowAny && !isEmpty(this.choices));
  }

  keyDown(event) {
    if (event.which === 13) {
      this.addValue(this.newValue);
      return;
    }
  }

  @action
  changeValue(index, event) {
    this.collection.replace(index, 1, [event.target.value]);
    arrayContentDidChange(this.collection, index);
    this._onChange();
  }

  @action
  addValue(newValue) {
    if (!newValue) {
      return;
    }

    this.set("newValue", null);
    this.collection.addObject(newValue);
    this._onChange();
  }

  @action
  removeValue(value) {
    this.collection.removeObject(value);
    this._onChange();
  }

  @action
  shift(operation, index) {
    let futureIndex = index + operation;

    if (futureIndex > this.collection.length - 1) {
      futureIndex = 0;
    } else if (futureIndex < 0) {
      futureIndex = this.collection.length - 1;
    }

    const shiftedValue = this.collection[index];
    this.collection.removeAt(index);
    this.collection.insertAt(futureIndex, shiftedValue);

    this._onChange();
  }

  _onChange() {
    this.onChange?.(this.collection);
  }

  @discourseComputed("choices", "values")
  validValues(choices, values) {
    return choices.filter((name) => !values.includes(name));
  }

  @discourseComputed("collection")
  showUpDownButtons(collection) {
    return collection.length - 1 ? true : false;
  }

  _splitValues(values, delimiter) {
    return values && values.length
      ? values.split(delimiter || "\n").filter(Boolean)
      : [];
  }
}