/*
* @license Apache-2.0
*
* Copyright (c) 2021 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

// TypeScript Version: 2.0

/**
* Callback invoked upon function completion.
*/
type DoneNullary = () => void;

/**
* Callback invoked upon function completion.
*
* @param error - error argument
*/
type DoneUnary = ( error: Error | null ) => void;

/**
* Callback invoked upon function completion.
*
* @param error - error argument
* @param result - function result
*/
type DoneBinary = ( error: Error | null, result: any ) => void;

/**
* Callback invoked upon function completion.
*
* @param error - error argument
* @param result - function result
*/
type DoneCallback = DoneNullary | DoneUnary | DoneBinary;

/**
* Binary function to compose.
*
* @param result - result
* @param next - invoked upon function completion
*/
type BinaryFunction = ( result: any, next: DoneCallback ) => void;

/**
* Function to compose.
*
* ## Notes
*
* -   Only the leftmost function is explicitly permitted to accept multiple arguments. All other functions are evaluated as binary functions.
*
* @param args - arguments
* @param next - invoked upon function completion
*/
type VariadicFunction = ( ...args: Array<any> ) => void;

/**
* Pipeline function.
*
* @param args - arguments
* @param done - callback to invoke after invoking all functions
*/
type PipelineFunction = ( ...args: Array<any> ) => void;

/**
* Function sequence.
*
* @param f0 - first function to evaluate
* @param f1 - second function to evaluate
* @param f - remaining functions to evaluate in sequential order
* @returns pipeline function
*
* @example
* function a( x, next ) {
*     setTimeout( onTimeout, 0 );
*     function onTimeout() {
*         next( null, 2*x );
*     }
* }
*
* function b( x, next ) {
*     setTimeout( onTimeout, 0 );
*     function onTimeout() {
*         next( null, x+3 );
*     }
* }
*
* function c( x, next ) {
*     setTimeout( onTimeout, 0 );
*     function onTimeout() {
*         next( null, x/5 );
*     }
* }
*
* var f = funseqAsync( a, b, c );
*
* function done( error, result ) {
*     if ( error ) {
*         throw error;
*     }
*     console.log( result );
*     // => 3
* }
*
* f( 6, done );
*/
declare function funseqAsync( f0: VariadicFunction, f1: BinaryFunction, ...f: Array<BinaryFunction> ): PipelineFunction; // tslint-disable-line max-line-length


// EXPORTS //

export = funseqAsync;
