/**
* Calculates the Levenshtein distance between two strings.
* Adapted from 'leven' (MIT License).
*/
export function leven(first: string, second: string): number {
if (first === second) {
return 0;
}
const swap = first;
if (first.length > second.length) {
first = second;
second = swap;
}
let firstLength = first.length;
let secondLength = second.length;
while (firstLength > 0 && (first.charCodeAt(firstLength - 1) === second.charCodeAt(secondLength - 1))) {
firstLength--;
secondLength--;
}
let start = 0;
while (start < firstLength && (first.charCodeAt(start) === second.charCodeAt(start))) {
start++;
}
firstLength -= start;
secondLength -= start;
if (firstLength === 0) {
return secondLength;
}
let bCharacterCode;
let result;
let temporary;
let temporary2;
let index = 0;
let index2 = 0;
const characterCodeCache = [];
const array = [];
while (index < firstLength) {
characterCodeCache[index] = first.charCodeAt(start + index);
array[index] = ++index;
}
while (index2 < secondLength) {
bCharacterCode = second.charCodeAt(start + index2);
temporary = index2++;
result = index2;
for (index = 0; index < firstLength; index++) {
temporary2 = bCharacterCode === characterCodeCache[index] ? temporary : temporary + 1;
temporary = array[index];
result = array[index] = temporary > result
? (temporary2 > result ? result + 1 : temporary2)
: (temporary2 > temporary ? temporary + 1 : temporary2);
}
}
return result as number;
}
/**
* Finds the closest match for a target string in a list of candidates.
*/
export function closestMatch(target: string, candidates: string[]): string | undefined {
if (!candidates || candidates.length === 0) return undefined;
let bestMatch: string | undefined;
let minDistance = Infinity;
for (const candidate of candidates) {
const distance = leven(target, candidate);
if (distance < minDistance) {
minDistance = distance;
bestMatch = candidate;
}
}
// Only suggest if reasonable similarity (e.g., within 3 edits or 40% length)
if (minDistance > 3 && minDistance > target.length * 0.4) {
return undefined;
}
return bestMatch;
}
