//! adapted for mithril from flyd https://github.com/paldepind/flyd
"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
}