export function diffString(diff) {
  return diff < 0 ? `${diff}` : `+${diff}`
}

export default function calculateDiff({program, cooldownMin = null, minutes, seconds, calories}) {
  const {warmupMin, warmupCpm, cpm, cooldownCpm} = program;
  const actualWarmup = cooldownMin !== null && cooldownMin > 0
    ? Math.min(warmupMin, cooldownMin)
    : warmupMin;

  // Minutes in each section
  const minWarmup = calculateMins(0, actualWarmup, minutes, seconds);
  const minMain = calculateMins(actualWarmup, cooldownMin, minutes, seconds);
  const minCooldown = calculateMins(cooldownMin, null, minutes, seconds);

  // Expected calories in each section
  const calWarmup = minWarmup * warmupCpm;
  const calMain = minMain * cpm;
  const calCooldown = minCooldown * cooldownCpm;

  return Math.round(calories - (calWarmup + calMain + calCooldown));
}

function calculateMins(minMinutes, maxMinutes, minutes, seconds) {
  const fraction = seconds / 60;

  if (minMinutes === null || minMinutes < 0) {
    return 0.0;
  }

  if (minutes >= minMinutes) {
    if (maxMinutes !== null && minutes >= maxMinutes) {
      return maxMinutes - minMinutes;
    }

    return (minutes - minMinutes) + fraction;
  } else {
    return 0.0;
  }
}