function clampBrightness(value) {
  var n = Number(value)
  if (!isFinite(n)) return 1
  return Math.max(1, Math.min(100, Math.round(n)))
}

function normalizeScale(scale) {
  var n = parseFloat(String(scale || ""))
  if (!isFinite(n)) return ""
  return String(Math.round(n * 100) / 100)
}

function gcd(a, b) {
  while (b) {
    var remainder = a % b
    a = b
    b = remainder
  }
  return a
}

function cleanScale(scale, width, height) {
  var requested = Number(scale)
  var modeWidth = Number(width)
  var modeHeight = Number(height)
  if (!isFinite(requested) || !isFinite(modeWidth) || !isFinite(modeHeight)
      || requested <= 0 || modeWidth <= 0 || modeHeight <= 0) return ""

  var divisor = gcd(Math.round(modeWidth * 120), Math.round(modeHeight * 120))
  var scaleUnits = Math.round(requested * 120)
  if (scaleUnits > divisor) scaleUnits = divisor
  while (divisor % scaleUnits !== 0) scaleUnits++
  return normalizeScale(scaleUnits / 120)
}

function brightnessName(percent) {
  var p = Math.round(percent)
  if (p >= 95) return "Sun blast"
  if (p >= 80) return "Solar flare"
  if (p >= 65) return "Golden hour"
  if (p >= 45) return "Even day"
  if (p >= 30) return "Soft glow"
  if (p >= 20) return "Lamp light"
  if (p >= 10) return "Candlelit"
  return "Night owl"
}

function parseDisplays(raw) {
  var displays = []
  try {
    displays = raw ? JSON.parse(String(raw)) : []
  } catch (e) {
    displays = []
  }
  if (!Array.isArray(displays)) displays = []

  var count = 0
  for (var i = 0; i < displays.length; i++) {
    if (displays[i] && displays[i].enabled) count++
  }

  return {
    displays: displays,
    enabledDisplayCount: count
  }
}

if (typeof module !== "undefined") {
  module.exports = {
    clampBrightness: clampBrightness,
    normalizeScale: normalizeScale,
    cleanScale: cleanScale,
    brightnessName: brightnessName,
    parseDisplays: parseDisplays
  }
}