import { invoke, transformCallback } from './tauri'

export interface Event<T> {
  type: string
  payload: T
}

export type EventCallback<T> = (event: Event<T>) => void

/**
 * listen to an event from the backend
 *
 * @param event the event name
 * @param handler the event handler callback
 */
function listen<T>(
  event: string,
  handler: EventCallback<T>,
  once = false
): void {
  invoke({
    cmd: 'listen',
    event,
    handler: transformCallback(handler, once),
    once
  })
}

/**
 * emits an event to the backend
 *
 * @param event the event name
 * @param [payload] the event payload
 */
function emit(event: string, payload?: string): void {
  invoke({
    cmd: 'emit',
    event,
    payload
  })
}

export { listen, emit }