import { ISimpleDictionary } from '../baseframework/ISimpleDictionary';
import { SimpleDictionary } from '../baseframework/SimpleDictionary';

/**
 * Stores information associated with an event handler.
 *
 * @class EventToken
 */
class EventToken {
  /**
   * The listener function which is directly added to the document event.
   *
   * @memberof EventToken
   */
  public readonly listener: (args: any) => void;

  /**
   * Creates an instance of EventToken.
   *
   * @param {Document} sender The document from which the event originates.
   * @param {string} event The name of the event.
   * @param {unknown} owner The owner of the handler.
   * @param {(...args: any[]) => void} handler The function to handle the event.
   * @memberof EventToken
   */
  constructor(
    public readonly sender: Document,
    public readonly event: string,
    public readonly owner: unknown,
    public readonly handler: (...args: any[]) => void
  ) {
    this.listener = (arg) => handler.call(owner, sender, arg);
  }

  /**
   * Checks if this event token is functionally the same as other event token.
   *
   * @param {EventToken} other The other event token.
   * @return {*}  {boolean} `true` if both event tokens are equal, `false` otherwise.
   * @memberof EventToken
   */
  equals(other: EventToken): boolean {
    return (
      this.sender === other.sender &&
      this.event === other.event &&
      this.owner === other.owner &&
      this.handler === other.handler
    );
  }
}

/**
 * Provides helper functions and properties for HTML document manipulation.
 *
 * @export
 * @class BrowserDocument
 */
// @dynamic()
export class BrowserDocument {
  /**
   * Stores tokens for registered events.
   *
   * @private
   * @static
   * @type {EventToken[]}
   * @memberof BrowserDocument
   */
  private static eventTokens: EventToken[] = [];

  /**
   * Gets a dictionary with the parameters of the current query string.
   *
   * @readonly
   * @static
   * @type {ISimpleDictionary<string, string>}
   * @memberof BrowserDocument
   */
  public static get queryString(): ISimpleDictionary<string, string> {
    const urlParams = new URLSearchParams(BrowserDocument.getSearch());
    const dict = new SimpleDictionary<string, string>();
    urlParams.forEach((value: string, key: string) =>
      dict.addEntry(key, value)
    );
    return dict;
  }

  /**
   * Gets the search part (query string) of the current URL.
   *
   * @private
   * @static
   * @return {*}  {string} The query string.
   * @memberof BrowserDocument
   */
  public static getSearch(): string {
    return window.location.search;
  }

  /**
   * Adds an event handler to the given event.
   *
   * @static
   * @param {Document} sender The document from which the event originates.
   * @param {string} event The name of the event.
   * @param {unknown} owner The owner of the handler.
   * @param {(...args: any[]) => void} handler The function to handle the event.
   * @memberof BrowserDocument
   */
  public static attachEvent(
    sender: Document,
    event: string,
    owner: unknown,
    handler: (...args: any[]) => void
  ): void {
    const token = new EventToken(sender, event, owner, handler);
    BrowserDocument.eventTokens.push(token);
    sender.addEventListener(event, token.listener);
  }

  /**
   * Removes an event handler from the given event.
   *
   * @static
   * @param {Document} sender The document from which the event originates.
   * @param {string} event The name of the event.
   * @param {unknown} owner The owner of the handler.
   * @param {(...args: any[]) => void} handler The function which used to handle the event.
   * @memberof BrowserDocument
   */
  public static detachEvent(
    sender: Document,
    event: string,
    owner: unknown,
    handler: (...args: any[]) => void
  ): void {
    const searchToken = new EventToken(sender, event, owner, handler);
    const idx = BrowserDocument.eventTokens.findIndex((x) =>
      x.equals(searchToken)
    );
    if (idx !== -1) {
      const token = BrowserDocument.eventTokens[idx];
      sender.removeEventListener(event, token.listener);
      BrowserDocument.eventTokens.splice(idx, 1);
    }
  }
}