import type { Observable } from 'observable-fns';
import type { ObservablePromise } from '../observable-promise.ts';
import type { $errors, $events, $terminate, $worker } from '../symbols.ts';
import type { TransferDescriptor } from '../transferable.ts';
interface ObservableLikeSubscription {
    unsubscribe(): any;
}
interface ObservableLike<T> {
    subscribe(onNext: (value: T) => any, onError?: (error: any) => any, onComplete?: () => any): ObservableLikeSubscription;
    subscribe(listeners: {
        complete?(): any;
        error?(error: any): any;
        next?(value: T): any;
    }): ObservableLikeSubscription;
}
/** Unwraps `Promise<T>` or `ObservableLike<T>` to their inner type `T`. */
export type StripAsync<Type> = Type extends Promise<infer PromiseBaseType> ? PromiseBaseType : Type extends ObservableLike<infer ObservableBaseType> ? ObservableBaseType : Type;
type StripTransfer<Type> = Type extends TransferDescriptor<infer BaseType> ? BaseType : Type;
/** An object whose keys are method names and values are functions, representing a worker module's methods. */
export type ModuleMethods = Record<string, (...args: any) => any>;
type ProxyableArgs<Args extends any[]> = Args extends [arg0: infer Arg0, ...rest: infer RestArgs] ? [Arg0 extends Transferable ? Arg0 | TransferDescriptor<Arg0> : Arg0, ...RestArgs] : Args;
/** A function proxied from a worker thread, returning an `ObservablePromise` of the unwrapped result. */
export type ProxyableFunction<Args extends any[], ReturnType> = Args extends [] ? () => ObservablePromise<StripTransfer<StripAsync<ReturnType>>> : (...args: ProxyableArgs<Args>) => ObservablePromise<StripTransfer<StripAsync<ReturnType>>>;
/** Proxy object mapping a worker module's methods to their proxied counterparts. */
export type ModuleProxy<Methods extends ModuleMethods> = {
    [method in keyof Methods]: ProxyableFunction<Parameters<Methods[method]>, ReturnType<Methods[method]>>;
};
/** Internal symbol-keyed properties attached to every spawned thread. */
export interface PrivateThreadProps {
    [$errors]: Observable<Error>;
    [$events]: Observable<WorkerEvent>;
    [$terminate]: () => Promise<void>;
    [$worker]: Worker;
}
/** A thread wrapping a single exposed function. */
export type FunctionThread<Args extends any[] = any[], ReturnType = any> = ProxyableFunction<Args, ReturnType> & PrivateThreadProps;
/** A thread wrapping an exposed module of functions. */
export type ModuleThread<Methods extends ModuleMethods = any> = ModuleProxy<Methods> & PrivateThreadProps;
interface AnyFunctionThread extends PrivateThreadProps {
    (...args: any[]): ObservablePromise<any>;
}
interface AnyModuleThread extends PrivateThreadProps {
}
/** Worker thread. Either a `FunctionThread` or a `ModuleThread`. */
export type Thread = AnyFunctionThread | AnyModuleThread;
/** List of `Transferable` objects to be transferred with a message. */
export type TransferList = Transferable[];
/** Worker instance. Either a web worker or a node.js Worker provided by `worker_threads`. */
export interface Worker extends EventTarget {
    postMessage(value: any, transferList?: TransferList): void;
    /** In nodejs return type is Promise while in browser return type is void */
    terminate(callback?: (error?: Error, exitCode?: number) => void): void | Promise<number>;
}
/** Options for configuring a worker thread, extending the standard `WorkerOptions`. */
export interface ThreadsWorkerOptions extends WorkerOptions {
    /** Whether to apply CORS protection workaround. Defaults to true. */
    CORSWorkaround?: boolean;
    /** Prefix for the path passed to the Worker constructor. Web worker only. */
    _baseURL?: string;
    /** Resource limits passed on to Node worker_threads */
    resourceLimits?: {
        /** The size of a pre-allocated memory range used for generated code. */
        codeRangeSizeMb?: number;
        /** The maximum size of the main heap in MB. */
        maxOldGenerationSizeMb?: number;
        /** The maximum size of a heap space for recently created objects. */
        maxYoungGenerationSizeMb?: number;
    };
    /** Data passed on to node.js worker_threads. */
    workerData?: any;
}
/** Worker implementation. Either web worker or a node.js Worker class. */
export declare class WorkerImplementation extends EventTarget implements Worker {
    constructor(path: string, options?: ThreadsWorkerOptions);
    postMessage(value: any, transferList?: TransferList): void;
    terminate(): void | Promise<number>;
}
/** Class to spawn workers from a blob or source string. */
export declare class BlobWorker extends WorkerImplementation {
    constructor(blob: Blob, options?: ThreadsWorkerOptions);
    static fromText(source: string, options?: ThreadsWorkerOptions): WorkerImplementation;
}
/** Export shape for platform-specific worker implementations. */
export interface ImplementationExport {
    blob: typeof BlobWorker;
    default: typeof WorkerImplementation;
}
/** Event as emitted by worker thread. Subscribe to using `Thread.events(thread)`. */
export declare enum WorkerEventType {
    internalError = "internalError",
    message = "message",
    termination = "termination"
}
/** Event indicating an internal error occurred in the worker. */
export interface WorkerInternalErrorEvent {
    error: Error;
    type: WorkerEventType.internalError;
}
/** Event containing a message received from the worker. */
export interface WorkerMessageEvent<Data> {
    data: Data;
    type: WorkerEventType.message;
}
/** Event indicating the worker has been terminated. */
export interface WorkerTerminationEvent {
    type: WorkerEventType.termination;
}
/** Union of all possible worker event types. */
export type WorkerEvent = WorkerInternalErrorEvent | WorkerMessageEvent<any> | WorkerTerminationEvent;
export {};
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