import { EVENT_REFRESH, EVENT_RESIZE } from '../../constants/events';
import { AnyFunction, BaseComponent, ComponentConstructor } from '../../types';
import {
  addClass,
  append,
  apply,
  before,
  between,
  CSSProperties,
  empty,
  forEach as forEachItem,
  includes,
  isFunction,
  isHTMLElement,
  isString,
  matches,
  parseHtml,
  queryAll,
  removeNode,
  toArray,
} from '@splidejs/utils';
import { Slide, SlideComponent } from './Slide';


/**
 * The interface for the Slides component.
 *
 * @since 3.0.0
 */
export interface SlidesComponent extends BaseComponent {
  update(): void;
  register( slide: HTMLElement, index: number, slideIndex: number ): void;
  get( excludeClones?: boolean ): SlideComponent[];
  getIn( page: number ): SlideComponent[];
  getAt( index: number ): SlideComponent | undefined;
  add( slide: string | Element | Array<string | Element>, index?: number ): void;
  remove( selector: SlideMatcher ): void;
  forEach( iteratee: SlidesIteratee, excludeClones?: boolean ): void;
  filter( matcher: SlideMatcher ): SlideComponent[];
  style( prop: string, value: string | number, useContainer?: boolean ): void
  getLength( excludeClones?: boolean ): number;
  isEnough(): boolean;
}

/**
 * The iteratee function for Slides.
 *
 * @since 3.0.0
 */
export type SlidesIteratee = ( Slide: SlideComponent, index: number, Slides: SlideComponent[] ) => void

/**
 * The predicate function for Slides.
 *
 * @since 3.0.0
 */
export type SlidesPredicate = ( Slide: SlideComponent, index: number, Slides: SlideComponent[] ) => any

/**
 * The type for filtering SlideComponent objects.
 *
 * @since 3.0.0
 */
export type SlideMatcher = number | number[] | string | SlidesPredicate;

/**
 * The component for managing all slides include clones.
 *
 * @since 3.0.0
 *
 * @param Splide     - A Splide instance.
 * @param Components - A collection of components.
 * @param options    - Options.
 * @param event      - An EventInterface instance.
 *
 * @return An Slides component object.
 */
export const Slides: ComponentConstructor<SlidesComponent> = ( Splide, Components, options, event ) => {
  const { on, emit, bind } = event;
  const { slides, list } = Components.Elements;

  /**
   * Stores all SlideComponent objects.
   */
  const Slides: SlideComponent[] = [];

  /**
   * Called when the component is mounted.
   */
  function mount(): void {
    init();
    on( EVENT_REFRESH, destroy );
    on( EVENT_REFRESH, init );
  }

  /**
   * Initializes the component.
   */
  function init(): void {
    slides.forEach( ( slide, index ) => { register( slide, index, -1 ) } );
  }

  /**
   * Destroys the component.
   */
  function destroy(): void {
    forEach( Slide => { Slide.destroy() } );
    empty( Slides );
  }

  /**
   * Manually updates the status of all slides.
   */
  function update(): void {
    forEach( Slide => { Slide.update() } );
  }

  /**
   * Registers a slide element and creates a Slide object.
   * Needs to sort every time when a new slide is registered especially for clones.
   *
   * @param slide      - A slide element to register.
   * @param index      - A slide index.
   * @param slideIndex - A slide index for clones. This must be `-1` for regular slides.
   */
  function register( slide: HTMLElement, index: number, slideIndex: number ): void {
    const object = Slide( Splide, index, slideIndex, slide );
    object.mount();
    Slides.push( object );
    Slides.sort( ( Slide1, Slide2 ) => Slide1.index - Slide2.index );
  }

  /**
   * Returns all Slide objects.
   *
   * @param excludeClones - Optional. Determines whether to exclude clones or not.
   *
   * @return An array with Slide objects.
   */
  function get( excludeClones?: boolean ): SlideComponent[] {
    return excludeClones ? filter( Slide => ! Slide.isClone ) : Slides;
  }

  /**
   * Returns slides in the specified page.
   *
   * @param page - A page index.
   *
   * @return An array with slides that belong to the page.
   */
  function getIn( page: number ): SlideComponent[] {
    const { Controller } = Components;
    const index = Controller.toIndex( page );
    const max   = Controller.hasFocus() ? 1 : options.perPage;
    return filter( Slide => between( Slide.index, index, index + max - 1 ) );
  }

  /**
   * Returns a Slide object at the specified index.
   *
   * @param index - A slide index.
   *
   * @return A Slide object if available, or otherwise `undefined`.
   */
  function getAt( index: number ): SlideComponent | undefined {
    return filter( index )[ 0 ];
  }

  /**
   * Inserts a slide or slides at a specified index.
   *
   * @param items - A slide element, an HTML string or an array with them.
   * @param index - Optional. An index to insert the slide at. If omitted, appends it to the list.
   */
  function add( items: string | Element | Array<string | Element>, index?: number ): void {
    forEachItem( items, slide => {
      if ( isString( slide ) ) {
        slide = parseHtml( slide );
      }

      if ( isHTMLElement( slide ) ) {
        const ref = slides[ index ];
        ref ? before( ref, slide ) : append( list, slide );
        addClass( slide, options.classes.slide );
        observeImages( slide, apply( emit, EVENT_RESIZE ) );
      }
    } );

    emit( EVENT_REFRESH );
  }

  /**
   * Removes slides that match the matcher
   * that can be an index, an array with indices, a selector, or an iteratee function.
   *
   * @param matcher - An index, an array with indices, a selector string, or an iteratee function.
   */
  function remove( matcher: SlideMatcher ): void {
    removeNode( filter( matcher ).map( Slide => Slide.slide ) );
    emit( EVENT_REFRESH );
  }

  /**
   * Iterates over Slide objects by the iteratee function.
   *
   * @param iteratee      - An iteratee function that takes a Slide object, an index and an array with Slides.
   * @param excludeClones - Optional. Determines whether to exclude clones or not.
   */
  function forEach( iteratee: SlidesIteratee, excludeClones?: boolean ): void {
    get( excludeClones ).forEach( iteratee );
  }

  /**
   * Filters Slides by the matcher
   * that can be an index, an array with indices, a selector, or a predicate function.
   *
   * @param matcher - An index, an array with indices, a selector string, or a predicate function.
   *
   * @return An array with SlideComponent objects.
   */
  function filter( matcher: SlideMatcher ): SlideComponent[] {
    return Slides.filter( isFunction( matcher )
      ? matcher
      : Slide => isString( matcher )
        ? matches( Slide.slide, matcher )
        : includes( toArray( matcher ), Slide.index )
    );
  }

  /**
   * Adds a CSS rule to all slides or containers.
   *
   * @param prop         - A property name.
   * @param value        - A CSS value to add.
   * @param useContainer - Optional. Determines whether to apply the rule to the container or not.
   */
  function style( prop: CSSProperties, value: string | number, useContainer?: boolean ): void {
    forEach( Slide => { Slide.style( prop, value, useContainer ) } );
  }

  /**
   * Invokes the callback after all images in the element are loaded.
   *
   * @param elm      - An element that may contain images.
   * @param callback - A callback function.
   */
  function observeImages( elm: Element, callback: AnyFunction ): void {
    const images = queryAll( elm, 'img' );
    let { length } = images;

    if ( length ) {
      images.forEach( img => {
        bind( img, 'load error', () => {
          if ( ! --length ) {
            callback();
          }
        } );
      } );
    } else {
      callback();
    }
  }

  /**
   * Returns the length of slides.
   *
   * @param excludeClones - Optional. Determines whether to exclude clones or not.
   *
   * @return The length of slides.
   */
  function getLength( excludeClones?: boolean ): number {
    return excludeClones ? slides.length : Slides.length;
  }

  /**
   * Checks if the number of slides is over than the `perPage` option, including clones.
   *
   * @return `true` if there are enough slides, or otherwise `false`.
   */
  function isEnough(): boolean {
    return Slides.length > options.perPage;
  }

  return {
    mount,
    destroy,
    update,
    register,
    get,
    getIn,
    getAt,
    add,
    remove,
    forEach,
    filter,
    style,
    getLength,
    isEnough,
  };
};