From 7e27203f7424ae7a992eca6f33482b269ef8af49 Mon Sep 17 00:00:00 2001
From: Alexander Polynomdivision <digitalmail555@googlemail.com>
Date: Tue, 9 Oct 2018 12:48:12 +0200
Subject: [PATCH] fix: Crash when comparing two long words

---
 frontend/package.json                         |  3 +-
 .../levenshtein/__tests__/levenshtein.test.ts | 21 -------------
 frontend/src/algorithms/levenshtein/index.ts  | 30 -------------------
 frontend/src/pages/review.tsx                 |  5 ++--
 4 files changed, 5 insertions(+), 54 deletions(-)
 delete mode 100644 frontend/src/algorithms/levenshtein/__tests__/levenshtein.test.ts
 delete mode 100644 frontend/src/algorithms/levenshtein/index.ts

diff --git a/frontend/package.json b/frontend/package.json
index 9390332..2fddb4f 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,6 +1,6 @@
 {
     "name": "seminarfach",
-    "version": "1.0.0",
+    "version": "1.0.1",
     "description": "",
     "main": "index.js",
     "scripts": {
@@ -12,6 +12,7 @@
     "dependencies": {
         "@material-ui/core": "^1.5.1",
         "@material-ui/icons": "^2.0.3",
+        "js-levenshtein": "^1.1.4",
         "react": "^16.4.2",
         "react-dom": "^16.4.2",
         "react-redux": "^5.0.7",
diff --git a/frontend/src/algorithms/levenshtein/__tests__/levenshtein.test.ts b/frontend/src/algorithms/levenshtein/__tests__/levenshtein.test.ts
deleted file mode 100644
index fd098ce..0000000
--- a/frontend/src/algorithms/levenshtein/__tests__/levenshtein.test.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-import { lev, levW } from "../";
-
-test("lev(abc, abc) == 0", () => {
-    expect(lev("abc", "abc", 3, 3)).toBe(0);
-    expect(levW("abc", "abc")).toBe(0);
-});
-
-test("lev(abc, abd) == 1", () => {
-    expect(lev("abc", "abd", 3, 3)).toBe(1);
-    expect(levW("abc", "abd")).toBe(1);
-});
-
-test("lev(abc, abcd) == 1", () => {
-    expect(lev("abc", "abcd", 3, 4)).toBe(1);
-    expect(levW("abc", "abcd")).toBe(1);
-});
-
-test("lev(abcd, bcd) == 1", () => {
-    expect(lev("abcd", "bcd", 4, 3)).toBe(1);
-    expect(levW("abcd", "bcd")).toBe(1);
-});
diff --git a/frontend/src/algorithms/levenshtein/index.ts b/frontend/src/algorithms/levenshtein/index.ts
deleted file mode 100644
index 1405d21..0000000
--- a/frontend/src/algorithms/levenshtein/index.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-function one(a: string, b: string, i: number, j: number): number {
-    if (a[i] === b[j]) {
-        return 0;
-    }
-
-    return 1;
-}
-
-// Computes the difference between the strings a and b.
-// @a, b: The strings to compare
-// @i, j: From where to compare (a_i and b_j)
-// @ret : The distance in insertions, deletions and changes
-export function lev(a: string, b: string, i: number, j: number): number {
-    if (Math.min(i, j) === 0) {
-        return Math.max(i, j);
-    } else {
-        return Math.min(
-            lev(a, b, i - 1, j) + 1,
-            lev(a, b, i, j - 1) + 1,
-            lev(a, b, i - 1, j - 1) + one(a, b, i, j)
-        );
-    }
-};
-
-// Computes the difference between the strings a and b.
-// @a, b: The strings to compare
-// @ret : The distance in insertions, deletions and changes
-export function levW(a: string, b: string): number {
-    return lev(a, b, a.length, b.length);
-}
diff --git a/frontend/src/pages/review.tsx b/frontend/src/pages/review.tsx
index 2c3afe4..6b2539f 100644
--- a/frontend/src/pages/review.tsx
+++ b/frontend/src/pages/review.tsx
@@ -27,7 +27,8 @@ import {
 } from "../models/vocab";
 import { ReviewType, IReviewMetadata } from "../models/review";
 
-import { levW } from "../algorithms/levenshtein";
+//@ts-ignore
+import lev from "js-levenshtein";
 import {
     LEVENSHTEIN_MAX_DISTANCE, MAX_ERROR_THRESHOLD,
     REVIEW_HELP_MOD
@@ -213,7 +214,7 @@ const ReviewPageWithRouter = withRouter(
             // Map all possible answers to lowercase ( => ignore casing)
             const answers = current.answers.map((el) => el.toLowerCase());
             // Calculate the distances to all possible answers
-            const dists = answers.map((el) => levW(input.toLowerCase(), el));
+            const dists = answers.map((el) => lev(input.toLowerCase(), el));
             // Find the lowest distance
             const minDist = Math.min(...dists);