Event System

// Read: payload type is inferred from the event name
player.on('time', ({ time }) => updateSeekBar(time));

// One-shot
player.once('ready', () => console.log('player ready'));

// Unsubscribe
const handler = ({ time }: { time: number }) => updateSeekBar(time);
player.on('time', handler);
player.off('time', handler);

interface Player {
  on<K extends keyof EventMap>(event: K, handler: (payload: EventMap[K]) => void): void;
  off<K extends keyof EventMap>(event: K, handler: (payload: EventMap[K]) => void): void;
  once<K extends keyof EventMap>(event: K, handler: (payload: EventMap[K]) => void): void;
}

player.on('beforePlay', (event) => {
  if (!userIsLoggedIn()) {
    event.preventDefault(); // cancel the play
  }
});

player.on('beforeLoad', async (event) => {
  // Redirect to a different item
  event.data.item = await fetchLocalized(event.data.item.id);

  // Gate on an async operation, player waits for this promise
  event.delay(
    new Promise((resolve) => {
      confirmDialog('Play this?', resolve);
    }),
  );
});

player.on('playPrevented', ({ reason }) => {
  // reason: 'listener-prevented' | 'delay-rejected' | 'delay-timeout'
});

// External consumer, string form (the only form available on player.on):
player.on('plugin:equalizer:band:changed', ({ band }) => {
  // band payload shape matches EqualizerEvents['band:changed']
  console.log(`${band.frequency} Hz → ${band.gain} dB`);
});

// Inside a plugin body only (this.on is protected, not player.on):
import { EqualizerPlugin } from '@nomercy-entertainment/nomercy-player-core';

this.on(EqualizerPlugin, 'band:changed', ({ band }) => {
  // Typed from EqualizerPlugin's E generic, band is EqBand
});

class MyPlugin extends Plugin<...> {
  use(): void {
    this.on('time', ({ time }) => this.update(time));    // auto-disposed
    this.on(EqualizerPlugin, 'band:changed', ({ band }) => { // auto-disposed
      this.syncEq(band);
    });
  }
}

// Standard emit, auto-namespaced to plugin:<id>:<name>
this.emit('dataFetched', { count: 5 });

// Cancellable dispatch with mutation
const result = await this.dispatchBefore('beforeFetch', { url: targetUrl });
if (result.prevented) return;
await this.doFetch(result.data.url);
this.emit('fetched', { url: result.data.url });