const deg2rad = 0.01745329251994328;

/*!
 * @brief Get the projected point ahead by a distance bases on current location and heading
 * @param x x UTM
 * @param y y UTM
 * @param distance in meters
 * @param heading  in degrees
 * @return projected coordinate in an array as [x,y]
 */
function projectedPointAheadByDistance(x, y, distance, heading) {
  let projectedX = 0, projectedY = 0;
  const radHeading = heading * deg2rad;
  projectedX = x + distance * Math.sin(radHeading);
  projectedY = y + distance * Math.cos(radHeading);

  return [projectedX, projectedY];
};

/**
 * @brief Get the projected point ahead by number of seconds bases on current location, speed and heading
 * @param x x UTM
 * @param y y UTM
 * @param speed in meters per second
 * @param heading  in degrees
 * @param aheadSecs in seconds
 * @return projected coordinate in an array as [x,y]
 */
function projectedPointAheadByTime(x, y, speed, heading, aheadSecs) {
  return projectedPointAheadByDistance(x, y, speed * aheadSecs, heading);
};

/**
 * An optimized version of Bubble Sort 
 * @param {*} arr the array to sort
  */
function bubbleSort(arr) {
  if (!arr || !arr.length) return;
  let n = arr.length, n2, v;
  do {
    n2 = 0;
    for (let k = 1; k < n; k++) {
      if (arr[k - 1].y > arr[k].y) {
        v = arr[k - 1];
        arr[k - 1] = arr[k];
        arr[k] = v;
        n2 = k;
      }
    }
    n = n2;
  }
  while (n2 != 0);
}

function segmentLengthP(a, b) {
  return segmentLength(a.x, a.y, b.x, b.y);
}

function segmentLength(x1, y1, x2, y2) {
  return Math.hypot(x1 - x2, y1 - y2);
}

module.exports = {
  projectedPointAheadByDistance, projectedPointAheadByTime, bubbleSort, segmentLengthP, segmentLength
}