(module.define "ytilitu.converter.units"
  (nullary
    (define select2-options
      (object language (object searching (nullary "searching..."))
        placeholder "unit here"
        ajax
        (object url
          (l (params) (+ "/json/converter/units/suggest-names/" (if* params.term params.term "")))
          data (l (params) #f)
          processResults (l (data) (object results (data.map (l (a) (object text a id a)))))
          dataType "json" delay 250 minimumInputLength 1)))
    (define selects (chain select2 ($ "#unit-from,#unit-to") select2-options))
    (define inputs ($ "#value-from,#value-to"))
    (define (unit-convert& from to value c) (define xhr (new XMLHttpRequest))
      (xhr.open "get" (encodeURI (+ "/json/converter/units/convert/" from "/" to "/" value)))
      (set xhr.onload (nullary (if (= 200 xhr.status) (c (JSON.parse xhr.responseText)))))
      (xhr.send))
    (chain on (selects.add inputs)
      "change"
      (l (event)
        (let ((unit-from (chain val (selects.eq 0))) (unit-to (chain val (selects.eq 1))))
          (if (and unit-from unit-to)
            (let*
              ( (input-from (inputs.eq 0)) (input-to (inputs.eq 1)) (value-from (input-from.val))
                (value-to (input-to.val)) (value-from-valid (jQuery.isNumeric value-from))
                (value-to-valid (jQuery.isNumeric value-to)))
              (switch event.target.id
                ("value-from"
                  (unit-convert& unit-from unit-to
                    value-from (l (result) (input-to.val (get result 0))))
                  break)
                ("value-to"
                  (if value-to-valid
                    (unit-convert& unit-to unit-from
                      value-to (l (result) (input-from.val (get result 0)))))
                  break)
                ("unit-from"
                  (if value-from
                    (unit-convert& unit-from unit-to
                      value-from (l (result) (input-to.val (get result 0)))))
                  break)
                ("unit-to"
                  (if value-from
                    (unit-convert& unit-from unit-to
                      value-from (l (result) (input-to.val (get result 0)))))
                  break)))))))
    (selects.each
      (l (index a) (define selected (a.getAttribute "data-selected"))
        (and selected
          (chain trigger (chain append (jQuery a) (new Option selected selected #t #t)) "change"))))))