From 773c2862360cf083b91bfd25629a30debedba1ac Mon Sep 17 00:00:00 2001
From: Kenearos <kenearos@googlemail.com>
Date: Tue, 12 May 2026 00:15:39 +0200
Subject: [PATCH] feat(image-import): add inline levenshtein distance helper

---
 image-import.js | 28 ++++++++++++++++++++++++++++
 test-suite.js   | 31 +++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/image-import.js b/image-import.js
index 95bf302..25dd8a8 100644
--- a/image-import.js
+++ b/image-import.js
@@ -175,6 +175,34 @@ class ImageImporter {
 
         return { month, year, entries: validEntries, notes };
     }
+
+    /**
+     * Levenshtein distance (O(m*n) DP, inline).
+     * Inputs are expected to already be normalized.
+     * @param {string} a
+     * @param {string} b
+     * @returns {number}
+     */
+    levenshtein(a, b) {
+        if (a === b) return 0;
+        if (!a.length) return b.length;
+        if (!b.length) return a.length;
+        const m = a.length, n = b.length;
+        const dp = Array.from({ length: m + 1 }, () => new Array(n + 1).fill(0));
+        for (let i = 0; i <= m; i++) dp[i][0] = i;
+        for (let j = 0; j <= n; j++) dp[0][j] = j;
+        for (let i = 1; i <= m; i++) {
+            for (let j = 1; j <= n; j++) {
+                const cost = a[i - 1] === b[j - 1] ? 0 : 1;
+                dp[i][j] = Math.min(
+                    dp[i - 1][j] + 1,
+                    dp[i][j - 1] + 1,
+                    dp[i - 1][j - 1] + cost
+                );
+            }
+        }
+        return dp[m][n];
+    }
 }
 
 // Verbatim system prompt — German with Umlaute (per spec §7.3).
diff --git a/test-suite.js b/test-suite.js
index 90230bf..492f63b 100644
--- a/test-suite.js
+++ b/test-suite.js
@@ -716,6 +716,37 @@ runner.test('Parse: leerer Name wird verworfen', (t) => {
     t.assertEqual(result.entries.length, 1, 'Nur gueltiger Name bleibt');
 });
 
+// ============================================================================
+// ImageImporter Tests - Levenshtein (Feature A)
+// ============================================================================
+
+runner.test('Levenshtein: identische Strings = 0', (t) => {
+    const importer = new ImageImporter(null);
+    t.assertEqual(importer.levenshtein('max mustermann', 'max mustermann'), 0, 'Identisch');
+});
+
+runner.test('Levenshtein: leerer String', (t) => {
+    const importer = new ImageImporter(null);
+    t.assertEqual(importer.levenshtein('', 'abc'), 3, '0 vs 3 Zeichen');
+    t.assertEqual(importer.levenshtein('abc', ''), 3, '3 vs 0 Zeichen');
+    t.assertEqual(importer.levenshtein('', ''), 0, 'Beide leer');
+});
+
+runner.test('Levenshtein: 1 Substitution', (t) => {
+    const importer = new ImageImporter(null);
+    t.assertEqual(importer.levenshtein('abc', 'abd'), 1, '1 Subst');
+});
+
+runner.test('Levenshtein: 1 Insertion', (t) => {
+    const importer = new ImageImporter(null);
+    t.assertEqual(importer.levenshtein('max mustermann', 'max mustermannn'), 1, '1 zusaetzliches n');
+});
+
+runner.test('Levenshtein: 2 Distanz', (t) => {
+    const importer = new ImageImporter(null);
+    t.assertEqual(importer.levenshtein('mueller', 'mueler'), 1, 'ein l weniger');
+});
+
 // ============================================================================
 // Display Functions
 // ============================================================================