"use strict";

const Promise = require("bluebird");
const propagateAbort = require("@promistream/propagate-abort");
const propagatePeek = require("@promistream/propagate-peek");

const { validateArguments } = require("@validatem/core");
const required = require("@validatem/required");
const isFunction = require("@validatem/is-function");

module.exports = function mapStream(_mapCallback) {
	let [ mapCallback ] = validateArguments(arguments, {
		mapCallback: [ required, isFunction ]
	});

	return {
		_promistreamVersion: 0,
		description: `map stream`,
		abort: propagateAbort,
		peek: propagatePeek,
		read: function produceValue_mapStream(source) {
			return Promise.try(() => {
				return source.read();
			}).then((value) => {
				return mapCallback(value);
			});
		}
	};
};