import { OkxEvents, OkxEventPayloadMap } from '.';

export type OkxEventHandler<T extends OkxEvents> = (payload: OkxEventPayloadMap[T]) => void;

export type OkxEventListener<T extends OkxEvents> = T extends OkxEvents
  ? { event: T; handler: OkxEventHandler<T> }
  : never;

export type OkxEventListeners = OkxEventListener<OkxEvents>[];

export interface OkxEventEmitter {
  on(listener: OkxEventListener<OkxEvents>): void;
  off(listener: OkxEventListener<OkxEvents>): void;
  emit<T extends OkxEvents>(event: T, payload: OkxEventPayloadMap[T]): void;
}

export class SimpleOkxEventEmitter implements OkxEventEmitter {
  private subscriptions: {
    [key: string]: OkxEventHandler<any>[]; // Use generic parameter for listener type
  } = {};

  on(listener: OkxEventListener<OkxEvents>): void {
    const { event, handler } = listener;
    if (!this.subscriptions[event]) {
      this.subscriptions[event] = [];
    }
    this.subscriptions[event].push(handler);
  }

  off(listener: OkxEventListener<OkxEvents>): void {
    const { event, handler } = listener;
    if (this.subscriptions[event]) {
      this.subscriptions[event] = this.subscriptions[event].filter(
        listener => listener !== handler,
      );
    }
  }

  emit<T extends OkxEvents>(event: T, payload: OkxEventPayloadMap[T]): void {
    if (this.subscriptions[event]) {
      this.subscriptions[event].forEach(handler => {
        console.log('emit', event, payload);
        handler(payload);
      });
    }
  }
}