import { Args } from "./Args";
import { BatchProcess } from "./BatchProcess";
import { Task } from "./Task";
import { WhyNotHealthy } from "./WhyNotHealthy";
export type ChildEndReason = WhyNotHealthy | "tooMany";
export interface TypedEventEmitter<T> {
    once<E extends keyof T>(eventName: E, listener: (...args: Args<T[E]>) => void): this;
    on<E extends keyof T>(eventName: E, listener: (...args: Args<T[E]>) => void): this;
    off<E extends keyof T>(eventName: E, listener: (...args: Args<T[E]>) => void): this;
    emit<E extends keyof T>(eventName: E, ...args: Args<T[E]>): boolean;
    listeners<E extends keyof T>(event: E): Function[];
    removeAllListeners(eventName?: keyof T): this;
}
/**
 * This interface describes the BatchCluster's event names as fields. The type
 * of the field describes the event data payload.
 *
 * See {@link BatchClusterEmitter} for more details.
 */
export interface BatchClusterEvents {
    /**
     * Emitted when a child process has started
     */
    childStart: (childProcess: BatchProcess) => void;
    /**
     * Emitted when a child process has ended
     *
     * @example
     * ```typescript
     * bc.on("childEnd", (proc, reason) => {
     *   // Check if this was an unexpected exit (crash, error, timeout)
     *   if (proc.unexpectedExit && proc.exitCode !== 0) {
     *     logger.error(`Process crashed: ${reason}`, {
     *       exitCode: proc.exitCode,
     *       exitSignal: proc.exitSignal
     *     });
     *   }
     * });
     * ```
     */
    childEnd: (childProcess: BatchProcess, reason: ChildEndReason) => void;
    /**
     * Emitted when a child process fails to spin up and run the {@link BatchProcessOptions.versionCommand} successfully within {@link BatchClusterOptions.spawnTimeoutMillis}.
     *
     * @param childProcess will be undefined if the error is from {@link ChildProcessFactory.processFactory}
     */
    startError: (error: Error, childProcess?: BatchProcess) => void;
    /**
     * Emitted when an internal consistency check fails
     */
    internalError: (error: Error) => void;
    /**
     * Emitted when tasks receive data, which may be partial chunks from the task
     * stream.
     */
    taskData: (data: Buffer | string, task: Task<unknown> | undefined, proc: BatchProcess) => void;
    /**
     * Emitted when a task has been resolved
     */
    taskResolved: (task: Task<unknown>, proc: BatchProcess) => void;
    /**
     * Emitted when a task times out. Note that a `taskError` event always succeeds these events.
     */
    taskTimeout: (timeoutMs: number, task: Task<unknown>, proc: BatchProcess) => void;
    /**
     * Emitted when a task has an error
     */
    taskError: (error: Error, task: Task<unknown>, proc: BatchProcess) => void;
    /**
     * Emitted when child processes write to stdout or stderr without a current
     * task
     */
    noTaskData: (stdoutData: string | Buffer | null, stderrData: string | Buffer | null, proc: BatchProcess) => void;
    /**
     * Emitted when a process fails health checks
     */
    healthCheckError: (error: Error, proc: BatchProcess) => void;
    /**
     * Emitted when a child process has an error during shutdown
     */
    endError: (error: Error, proc?: BatchProcess) => void;
    /**
     * Emitted when this instance is in the process of ending.
     */
    beforeEnd: () => void;
    /**
     * Emitted when this instance has ended. No child processes should remain at
     * this point.
     */
    end: () => void;
}
/**
 * The BatchClusterEmitter signature is built up automatically by the
 * {@link BatchClusterEvents} interface, which ensures `.on`, `.off`, and
 * `.emit` signatures are all consistent, and include the correct data payloads
 * for all of BatchCluster's events.
 *
 * This approach has some benefits:
 *
 * - it ensures that on(), off(), and emit() signatures are all consistent,
 * - supports editor autocomplete, and
 * - offers strong typing,
 *
 * but has one drawback:
 *
 * - jsdocs don't list all signatures directly: you have to visit the event
 *   source interface.
 *
 * See {@link BatchClusterEvents} for a the list of events and their payload
 * signatures
 */
export type BatchClusterEmitter = TypedEventEmitter<BatchClusterEvents>;
