import { ComponentConfig, Component, ViewModeChangedEventArgs, ViewMode } from './Component';
import { DOM } from '../DOM';
import { ArrayUtils } from '../utils/ArrayUtils';
import { i18n } from '../localization/i18n';

/**
 * Configuration interface for a {@link Container}.
 *
 * @category Configs
 */
export interface ContainerConfig extends ComponentConfig {
  /**
   * Child components of the container.
   */
  components?: Component<ComponentConfig>[];
}

/**
 * A container component that can contain a collection of child components.
 * Components can be added at construction time through the {@link ContainerConfig#components} setting, or later
 * through the {@link Container#addComponent} method. The UIManager automatically takes care of all components, i.e. it
 * initializes and configures them automatically.
 *
 * In the DOM, the container consists of an outer <div> (that can be configured by the config) and an inner wrapper
 * <div> that contains the components. This double-<div>-structure is often required to achieve many advanced effects
 * in CSS and/or JS, e.g. animations and certain formatting with absolute positioning.
 *
 * DOM example:
 * <code>
 *     <div class='ui-container'>
 *         <div class='container-wrapper'>
 *             ... child components ...
 *         </div>
 *     </div>
 * </code>
 *
 * @category Components
 */
export class Container<Config extends ContainerConfig> extends Component<Config> {
  /**
   * A reference to the inner element that contains the components of the container.
   */
  protected innerContainerElement: DOM;
  private componentsToAppend: Component<ComponentConfig>[];
  private componentsToPrepend: Component<ComponentConfig>[];
  private componentsToRemove: Component<ComponentConfig>[];
  private componentsInPersistentViewMode: number;

  constructor(config: Config) {
    super(config);

    this.config = this.mergeConfig(
      config,
      {
        cssClass: 'ui-container',
        components: [],
      } as Config,
      this.config,
    );

    this.componentsToAppend = [];
    this.componentsToPrepend = [];
    this.componentsToRemove = [];
    this.componentsInPersistentViewMode = 0;
  }

  /**
   * Adds a child component to the container.
   * @param component the component to add
   */
  addComponent(component: Component<ComponentConfig>) {
    this.config.components.push(component);
    this.componentsToAppend.push(component);
  }

  /**
   * Adds a child component as the first component in the container.
   * @param component the component to add
   */
  prependComponent(component: Component<ComponentConfig>) {
    this.config.components.unshift(component);
    this.componentsToPrepend.push(component);
  }

  /**
   * Removes a child component from the container.
   * @param component the component to remove
   * @returns {boolean} true if the component has been removed, false if it is not contained in this container
   */
  removeComponent(component: Component<ComponentConfig>): boolean {
    if (ArrayUtils.remove(this.config.components, component) != null) {
      this.componentsToRemove.push(component);
      return true;
    } else {
      return false;
    }
  }

  /**
   * Gets an array of all child components in this container.
   * @returns {Component<ComponentConfig>[]}
   */
  getComponents(): Component<ComponentConfig>[] {
    return this.config.components;
  }

  /**
   * Removes all child components from the container.
   */
  removeComponents(): void {
    for (const component of this.getComponents().slice()) {
      this.removeComponent(component);
    }
  }

  /**
   * Updates the DOM of the container with the current components.
   *
   * This is called automatically after construction. However, when you dynamically
   * add or remove components at runtime, you must call `updateComponents()` to
   * re-render the container’s children.
   */
  updateComponents(): void {
    /* We cannot just clear the container to remove all elements and then re-add those that should stay, because
     * IE looses the innerHTML of unattached elements, leading to empty elements within the container (e.g. missing
     * subtitle text in SubtitleLabel).
     * Instead, we keep a list of elements to add and remove, leaving remaining elements alone. By keeping them in
     * the DOM, their content gets preserved in all browsers.
     */
    let component: Component<ComponentConfig>;

    while ((component = this.componentsToRemove.shift()) !== undefined) {
      component.getDomElement().remove();
    }

    while ((component = this.componentsToAppend.shift()) !== undefined) {
      this.innerContainerElement.append(component.getDomElement());
    }

    while ((component = this.componentsToPrepend.shift()) !== undefined) {
      this.innerContainerElement.prepend(component.getDomElement());
    }
  }

  protected toDomElement(): DOM {
    // Create the container element (the outer <div>)
    const containerElement = new DOM(
      this.config.tag,
      {
        id: this.config.id,
        class: this.getCssClasses(),
        role: this.config.role,
        'aria-label': i18n.performLocalization(this.config.ariaLabel),
      },
      this,
    );

    if (typeof this.config.tabIndex === 'number') {
      containerElement.attr('tabindex', this.config.tabIndex.toString());
    }

    // Create the inner container element (the inner <div>) that will contain the components
    const innerContainer = new DOM(this.config.tag, {
      class: this.prefixCss('container-wrapper'),
    });
    this.innerContainerElement = innerContainer;

    for (const initialComponent of this.config.components) {
      this.componentsToAppend.push(initialComponent);
    }
    this.updateComponents();

    containerElement.append(innerContainer);

    return containerElement;
  }

  protected suspendHideTimeout(): void {
    // to be implemented in subclass
  }

  protected resumeHideTimeout(): void {
    // to be implemented in subclass
  }

  protected trackComponentViewMode(mode: ViewMode) {
    if (mode === ViewMode.Persistent) {
      this.componentsInPersistentViewMode++;
    } else if (mode === ViewMode.Temporary) {
      this.componentsInPersistentViewMode = Math.max(this.componentsInPersistentViewMode - 1, 0);
    }

    if (this.componentsInPersistentViewMode > 0) {
      // There is at least one component that must not be hidden,
      // therefore the hide timeout must be suspended
      this.suspendHideTimeout();
    } else {
      this.resumeHideTimeout();
    }
  }
}