/**
 * @name levenshteinDistance
 * @category Text
 * @description Calculate the Levenshtein distance between two strings
 *
 * @param {string} left First string
 * @param {string} right Second string
 * @returns {number} The Levenshtein distance between the two strings
 *
 * @since 0.0.1
 */
export function levenshteinDistance(left: string, right: string): number {
  if (left === right) return 0;

  if (left.length === 0) return right.length;
  if (right.length === 0) return left.length;

  // Create empty edit distance matrix for all possible modifications of
  // substrings of left to substrings of right
  const distanceMatrix = Array(right.length + 1).fill(null).map(() => Array(left.length + 1).fill(null));

  // Fill the first row of the matrix
  // If this is the first row, we're transforming from an empty string to left
  // In this case, the number of operations equals the length of left substring
  for (let i = 0; i <= left.length; i++)
    distanceMatrix[0]![i]! = i;

  // Fill the first column of the matrix
  // If this is the first column, we're transforming empty string to right
  // In this case, the number of operations equals the length of right substring
  for (let j = 0; j <= right.length; j++)
    distanceMatrix[j]![0]! = j;

  for (let j = 1; j <= right.length; j++) {
    for (let i = 1; i <= left.length; i++) {
      const indicator = left[i - 1] === right[j - 1] ? 0 : 1;
      distanceMatrix[j]![i]! = Math.min(
        distanceMatrix[j]![i - 1]! + 1, // deletion
        distanceMatrix[j - 1]![i]! + 1, // insertion
        distanceMatrix[j - 1]![i - 1]! + indicator, // substitution
      );
    }
  }

  return distanceMatrix[right.length]![left.length]!;
}