"use strict"

var combine = require("./stream").combine

module.exports = function(tuples, seed) {
	var streams = tuples.map(function(tuple) {
		var stream = tuple[0]
		if (stream._state.state === 0) stream(undefined)
		return stream
	})

	var newStream = combine(function() {
		var changed = arguments[arguments.length - 1]

		streams.forEach(function(stream, idx) {
			if (changed.indexOf(stream) > -1) {
				seed = tuples[idx][1](seed, stream._state.value)
			}
		})

		return seed
	}, streams)

	return newStream
}