text: /**
   * the sun is inside the triangle.
   * @param {Object} today - desired day.
   * @param {boolean} today.isSunInside - sun inside of today's triangle.
   * @param {number} today.sideRatio - side ratio of today's triangle.
   * @param {number} today.perimeter - perimeter of today's triangle.
   * @param {Object} yesterday - day before of the prediction.
   * @param {number} yesterday.sideRatio - side ratio of yesterday's triangle.
   * @param {number} yesterday.perimeter - perimeter of yesterday's triangle.
   * @param {Object} tomorrow - day after the prediction.
   * @param {number} tomorrow.sideRatio - side ratio of tomorrow's triangle.
   * @param {number} tomorrow.perimeter - perimeter of tomorrow's triangle.
   *
   * @return {string} - forecast for the given day.
   */
  export function predictForecast(today, yesterday, tomorrow) {
    if (today.isSunInside) {
      return (today.sideRatio < yesterday.sideRatio && today.sideRatio < tomorrow.sideRatio) ? 'drought' :
        (today.perimeter > yesterday.perimeter && today.perimeter > tomorrow.perimeter) ? 'maxRain' : 'rain';
    } else {
      return (today.sideRatio < yesterday.sideRatio && today.sideRatio < tomorrow.sideRatio) ? 'optimal' : 'normal';
    }
  }
  