import { Event } from "./event";
import { EventDescriptor, EventDescriptorSymbol } from "./descriptor";

export interface SyncEventCallback<TargetEvent = unknown> {
  (event: TargetEvent): void;
}

export interface EventCallback<TargetEvent extends Event = Event> {
  <E extends TargetEvent>(event: E): Promise<unknown | void> | unknown | void;
}

export function matchEventCallback(
  type: string | symbol,
  callback?: EventCallback | Function,
  options?: unknown
): (descriptor: EventDescriptor) => boolean {
  const optionsDescriptor = isOptionsDescriptor(options) ? options : undefined;
  return (descriptor) => {
    if (optionsDescriptor) {
      return optionsDescriptor === descriptor;
    }
    return (
      (!callback || callback === descriptor.callback) &&
      type === descriptor.type
    );
  };

  function isOptionsDescriptor(options: unknown): options is EventDescriptor {
    function isLike(options: unknown): options is Partial<EventDescriptor> {
      return !!options;
    }
    return isLike(options) && options[EventDescriptorSymbol] === true;
  }
}