+import EventEmitter from 'events'
+import type {
+ ErrorHandler,
+ ExitHandler,
+ MessageHandler,
+ OnlineHandler
+} from './pool-worker'
+import type { WorkerChoiceStrategy } from './selection-strategies/selection-strategies-types'
+
+/**
+ * Pool events emitter.
+ */
+export class PoolEmitter extends EventEmitter {}
+
+/**
+ * Options for a poolifier pool.
+ */
+export interface PoolOptions<Worker> {
+ /**
+ * A function that will listen for message event on each worker.
+ */
+ messageHandler?: MessageHandler<Worker>
+ /**
+ * A function that will listen for error event on each worker.
+ */
+ errorHandler?: ErrorHandler<Worker>
+ /**
+ * A function that will listen for online event on each worker.
+ */
+ onlineHandler?: OnlineHandler<Worker>
+ /**
+ * A function that will listen for exit event on each worker.
+ */
+ exitHandler?: ExitHandler<Worker>
+ /**
+ * The worker choice strategy to use in this pool.
+ */
+ workerChoiceStrategy?: WorkerChoiceStrategy
+ /**
+ * Pool events emission.
+ *
+ * @default true
+ */
+ enableEvents?: boolean
+}
+
/**
* Contract definition for a poolifier pool.
*
- * @template Data Type of data sent to the worker.
- * @template Response Type of response of execution.
+ * @template Data Type of data sent to the worker. This can only be serializable data.
+ * @template Response Type of response of execution. This can only be serializable data.
*/
export interface IPool<Data = unknown, Response = unknown> {
/**
- * Shut down every current worker in this pool.
+ * Emitter on which events can be listened to.
+ *
+ * Events that can currently be listened to:
+ *
+ * - `'busy'`
*/
- destroy(): Promise<void>
+ readonly emitter?: PoolEmitter
/**
- * Perform the task specified in the constructor with the data parameter.
+ * Performs the task specified in the constructor with the data parameter.
*
- * @param data The input for the specified task.
+ * @param data The input for the specified task. This can only be serializable data.
* @returns Promise that will be resolved when the task is successfully completed.
*/
- execute(data: Data): Promise<Response>
+ execute: (data: Data) => Promise<Response>
+ /**
+ * Shutdowns every current worker in this pool.
+ */
+ destroy: () => Promise<void>
+ /**
+ * Sets the worker choice strategy in this pool.
+ *
+ * @param workerChoiceStrategy The worker choice strategy.
+ */
+ setWorkerChoiceStrategy: (workerChoiceStrategy: WorkerChoiceStrategy) => void
}