host-listener.ts

import * as d from '../declarations';
import { BUILD } from '@app-data';
import { doc, plt, supportsListenerOptions, win } from '@platform';
import { HOST_FLAGS, LISTENER_FLAGS } from '@utils';

export const addHostEventListeners = (elm: d.HostElement, hostRef: d.HostRef, listeners: d.ComponentRuntimeHostListener[]) => {
  if (BUILD.hostListener && listeners) {
    // this is called immediately within the element's constructor
    // initialize our event listeners on the host element
    // we do this now so that we can listen to events that may
    // have fired even before the instance is ready

    listeners.map(([flags, name, method]) => {
      const target = BUILD.hostListenerTarget ? getHostListenerTarget(elm, flags) : elm;
      const handler = hostListenerProxy(hostRef, method);
      const opts = hostListenerOpts(flags);
      plt.ael(target, name, handler, opts);
      (hostRef.$rmListeners$ = hostRef.$rmListeners$ || []).push(() => plt.rel(target, name, handler, opts));
    });
  }
};

const hostListenerProxy = (hostRef: d.HostRef, methodName: string) => (ev: Event) => {
  if (BUILD.lazyLoad) {
    if (hostRef.$flags$ & HOST_FLAGS.isListenReady) {
      // instance is ready, let's call it's member method for this event
      hostRef.$lazyInstance$[methodName](ev);
    } else {
      (hostRef.$queuedListeners$ = hostRef.$queuedListeners$ || []).push([methodName, ev]);
    }
  } else {
    (hostRef.$hostElement$ as any)[methodName](ev);
  }
};

const getHostListenerTarget = (elm: Element, flags: number): EventTarget => {
  if (BUILD.hostListenerTargetDocument && flags & LISTENER_FLAGS.TargetDocument) return doc;
  if (BUILD.hostListenerTargetWindow && flags & LISTENER_FLAGS.TargetWindow) return win;
  if (BUILD.hostListenerTargetBody && flags & LISTENER_FLAGS.TargetBody) return doc.body;
  return elm;
};

// prettier-ignore
const hostListenerOpts = (flags: number) =>
  supportsListenerOptions
    ? ({
        passive: (flags & LISTENER_FLAGS.Passive) !== 0,
        capture: (flags & LISTENER_FLAGS.Capture) !== 0,
      })
    : (flags & LISTENER_FLAGS.Capture) !== 0;