Merge pull request '添加 Levenshtein 算法（QMCv2）' (#33) from feat/levenshtein-key-finder into main

Reviewed-on: #33

docs/adb_dump.md

@@ -0,0 +1,9 @@
+# 利用 ADB 访问安卓私有数据
+
+```sh
+APP_ID="com.tencent.qqmusic" # QQ 音乐
+APP_ID="cn.kuwo.player" # 酷我
+
+adb shell su -c "tar c '/data/data/${APP_ID}/' | base64" \
+    | base64 -d | pv | tar -x --strip-components 2
+```

src/features/settings/panels/PanelQMCv2Key.tsx

@@ -2,43 +2,42 @@ import {
   Box,
   Button,
   ButtonGroup,
+  Checkbox,
   Flex,
   HStack,
   Heading,
   Icon,
   IconButton,
-  Input,
-  InputGroup,
-  InputLeftElement,
-  InputRightElement,
   List,
-  ListItem,
   Menu,
   MenuButton,
   MenuDivider,
   MenuItem,
   MenuList,
   Text,
-  VStack,
+  Tooltip,
 } from '@chakra-ui/react';
 import { useDispatch, useSelector } from 'react-redux';
-import { qmc2AddKey, qmc2ClearKeys, qmc2DeleteKey, qmc2UpdateKey } from '../settingsSlice';
+import { qmc2AddKey, qmc2AllowFuzzyNameSearch, qmc2ClearKeys } from '../settingsSlice';
 import { selectStagingQMCv2Settings } from '../settingsSelector';
 import React, { useState } from 'react';
-import { MdAdd, MdDelete, MdDeleteForever, MdExpandMore, MdFileUpload, MdVpnKey } from 'react-icons/md';
+import { MdAdd, MdDeleteForever, MdExpandMore, MdFileUpload } from 'react-icons/md';
 import { ImportFileModal } from './QMCv2/ImportFileModal';
+import { KeyInput } from './QMCv2/KeyInput';
+import { InfoOutlineIcon } from '@chakra-ui/icons';
 
 export function PanelQMCv2Key() {
   const dispatch = useDispatch();
-  const qmc2Keys = useSelector(selectStagingQMCv2Settings).keys;
+  const { keys: qmc2Keys, allowFuzzyNameSearch } = useSelector(selectStagingQMCv2Settings);
   const [showImportModal, setShowImportModal] = useState(false);
 
   const addKey = () => dispatch(qmc2AddKey());
-  const updateKey = (prop: 'name' | 'key', id: string, e: React.ChangeEvent<HTMLInputElement>) =>
-    dispatch(qmc2UpdateKey({ id, field: prop, value: e.target.value }));
-  const deleteKey = (id: string) => dispatch(qmc2DeleteKey({ id }));
   const clearAll = () => dispatch(qmc2ClearKeys());
 
+  const handleAllowFuzzyNameSearchCheckbox = (e: React.ChangeEvent<HTMLInputElement>) => {
+    dispatch(qmc2AllowFuzzyNameSearch({ enable: e.target.checked }));
+  };
+
   return (
     <Flex minH={0} flexDir="column" flex={1}>
       <Heading as="h2" size="lg">
@@ -50,7 +49,7 @@ export function PanelQMCv2Key() {
         客户端的情况下，其「离线加密文件」对应的「密钥」储存在独立的数据库文件内。
       </Text>
 
-      <Box pb={2} pt={2}>
+      <HStack pb={2} pt={2}>
         <ButtonGroup isAttached colorScheme="purple" variant="outline">
           <Button onClick={addKey} leftIcon={<Icon as={MdAdd} />}>
             添加一条密钥
@@ -68,48 +67,40 @@ export function PanelQMCv2Key() {
             </MenuList>
           </Menu>
         </ButtonGroup>
+
+        <HStack>
+          <Checkbox isChecked={allowFuzzyNameSearch} onChange={handleAllowFuzzyNameSearchCheckbox}>
+            <Text>匹配相似文件名</Text>
+          </Checkbox>
+          <Tooltip
+            hasArrow
+            closeOnClick={false}
+            label={
+              <Box>
+                <Text>若文件名匹配失败，则使用相似文件名的密钥。</Text>
+                <Text>
+                  使用「
+                  <ruby>
+                    莱文斯坦距离
+                    <rp> (</rp>
+                    <rt>Levenshtein distance</rt>
+                    <rp>)</rp>
+                  </ruby>
+                  」算法计算相似程度。
+                </Text>
+                <Text>若密钥数量过多，匹配时可能会造成浏览器卡顿或无响应一段时间。</Text>
               </Box>
+            }
+          >
+            <InfoOutlineIcon />
+          </Tooltip>
+        </HStack>
+      </HStack>
 
       <Box flex={1} minH={0} overflow="auto" pr="4">
         <List spacing={3}>
           {qmc2Keys.map(({ id, key, name }, i) => (
-            <ListItem key={id} mt={0} pt={2} pb={2} _even={{ bg: 'gray.50' }}>
-              <HStack>
-                <Text w="2em" textAlign="center">
-                  {i + 1}
-                </Text>
-
-                <VStack flex={1}>
-                  <Input
-                    variant="flushed"
-                    placeholder="文件名"
-                    value={name}
-                    onChange={(e) => updateKey('name', id, e)}
-                  />
-
-                  <InputGroup size="xs">
-                    <InputLeftElement pr="2">
-                      <Icon as={MdVpnKey} />
-                    </InputLeftElement>
-                    <Input variant="flushed" placeholder="密钥" value={key} onChange={(e) => updateKey('key', id, e)} />
-                    <InputRightElement>
-                      <Text pl="2" color={key.length ? 'green.500' : 'red.500'}>
-                        <code>{key.length || '?'}</code>
-                      </Text>
-                    </InputRightElement>
-                  </InputGroup>
-                </VStack>
-
-                <IconButton
-                  aria-label="删除该密钥"
-                  icon={<Icon as={MdDelete} boxSize={6} />}
-                  variant="ghost"
-                  colorScheme="red"
-                  type="button"
-                  onClick={() => deleteKey(id)}
-                />
-              </HStack>
-            </ListItem>
+            <KeyInput key={id} id={id} ekey={key} name={name} i={i} />
           ))}
         </List>
         {qmc2Keys.length === 0 && <Text>还没有添加密钥。</Text>}

src/features/settings/panels/QMCv2/InstructionsIOS.tsx

@@ -1,101 +1,51 @@
-import { Box, Code, Heading, ListItem, OrderedList, Text, UnorderedList } from '@chakra-ui/react';
-import { FilePathBlock } from '~/components/FilePathBlock';
-
-const EXAMPLE_MEDIA_ID = '0011wjLv1bIkvv';
-const EXAMPLE_NAME_IOS = '333407709-0011wjLv1bIkvv-1.mgalaxy';
-const EXAMPLE_NAME_DB = 'Q0M00011wjLv1bIkvv.mflac';
+import {
+  Accordion,
+  AccordionButton,
+  AccordionIcon,
+  AccordionItem,
+  AccordionPanel,
+  Box,
+  Heading,
+  Text,
+} from '@chakra-ui/react';
+import { InstructionsIOSCondition } from './InstructionsIOSCondition';
 
 export function InstructionsIOS() {
   return (
     <>
-      <Text>不推荐从该平台客户端提取文件，因为使用者需要对 iOS 设备进行完整备份。</Text>
-      <Heading as="h3" size="md" mt="3">
-        未越狱用户指南
-      </Heading>
-      <Text>未越狱用户需要对设备进行完整备份，并能提取备份内的文件。</Text>
-      <OrderedList>
-        <ListItem>
-          <Text>使用你喜欢的备份软件对 iOS 设备进行完整备份；</Text>
-        </ListItem>
-        <ListItem>
-          <Text>打开备份文件，并导航到下述目录：</Text>
-          <FilePathBlock>/AppDomain-com.tencent.QQMusic/Documents/mmkv/</FilePathBlock>
-        </ListItem>
-        <ListItem>
-          <Text>
-            提取或导出密钥数据库文件 <Code>filenameEkeyMap</Code>；
-          </Text>
-        </ListItem>
-        <ListItem>
-          <Text>
-            提交导出的 <Code>filenameEkeyMap</Code> 文件；
-          </Text>
-        </ListItem>
-        <ListItem>
-          <Text>按下「保存」来应用更改。</Text>
-        </ListItem>
-      </OrderedList>
-      <Heading as="h3" size="md" mt="3">
-        获取离线文件
-      </Heading>
       <Box>
-        <Text>通过客户端下载的音乐文件存储在备份的下述目录：</Text>
-        <Code>/AppDomain-com.tencent.QQMusic/Library/Application Support/com.tencent.QQMusic/iData/iMusic</Code>
-        <Text>
-          该目录又存在数个子目录，其子目录下保存的「<Code>*.mgalaxy</Code>」文件则是最终的加密文件。
-        </Text>
-        <Text>
-          格式：<Code>[随机数字]-[id]-[随机数字].mgalaxy</Code>
-        </Text>
-        <Text>
-          &#x3000;例：<Code>{EXAMPLE_NAME_IOS}</Code>
-        </Text>
+        <Text>iOS 设备获取应用私有文件比较麻烦，你需要越狱或使用一台 PC 或 Mac 来对 iOS 设备进行完整备份。</Text>
+        <Text>因此，建议换用 PC 或 Mac 重新下载音乐文件然后再尝试解密。</Text>
       </Box>
-      <Heading as="h3" size="md" mt="3">
-        解密离线文件
+      <Accordion allowToggle mt="2">
+        <AccordionItem>
+          <Heading as="h3" size="md">
+            <AccordionButton>
+              <Box as="span" flex="1" textAlign="left">
+                我的 iOS 设备已经越狱
+              </Box>
+              <AccordionIcon />
+            </AccordionButton>
           </Heading>
-      <OrderedList>
-        <ListItem>
-          <Text>
-            在上方的样例文件的情况下，得知其 id 为 <Code>{EXAMPLE_MEDIA_ID}</Code>；
-          </Text>
-        </ListItem>
-        <ListItem>
-          <Text>
-            查找密钥表，得到文件名「<Code>{EXAMPLE_NAME_DB}</Code>」；
-          </Text>
-        </ListItem>
-        <ListItem>
-          <Text>
-            将导出的「<Code>{EXAMPLE_NAME_IOS}</Code>」更名为数据库存储的文件名「
-            <Code>{EXAMPLE_NAME_DB}</Code>」；
-          </Text>
-        </ListItem>
-        <ListItem>
-          <Text>
-            回到主界面，提交离线文件「<Code>{EXAMPLE_NAME_DB}</Code>」。
-          </Text>
-        </ListItem>
-      </OrderedList>
-      <Heading as="h3" size="md" mt="3">
-        越狱用户参考
+          <AccordionPanel pb={4}>
+            <InstructionsIOSCondition jailbreak={true} />
+          </AccordionPanel>
+        </AccordionItem>
+
+        <AccordionItem>
+          <Heading as="h3" size="md">
+            <AccordionButton>
+              <Box as="span" flex="1" textAlign="left">
+                我的 iOS 设备没有越狱
+              </Box>
+              <AccordionIcon />
+            </AccordionButton>
           </Heading>
-      <Text>该节信息根据网络上公开的信息整理，仅供参考。</Text>
-      <UnorderedList>
-        <ListItem>
-          <Text>密钥数据库文件路径：</Text>
-          <FilePathBlock>
-            /var/mobile/Containers/Data/Application/&lt;随机&gt;/Documents/mmkv/filenameEkeyMap
-          </FilePathBlock>
-        </ListItem>
-        <ListItem>
-          <Text>离线音乐文件下载目录：</Text>
-          <FilePathBlock>
-            /var/mobile/Containers/Data/Application/&lt;随机&gt;/Library/Application
-            Support/com.tencent.QQMusic/iData/iMusic
-          </FilePathBlock>
-        </ListItem>
-      </UnorderedList>
+          <AccordionPanel pb={4}>
+            <InstructionsIOSCondition jailbreak={false} />
+          </AccordionPanel>
+        </AccordionItem>
+      </Accordion>
     </>
   );
 }

src/features/settings/panels/QMCv2/InstructionsIOSCondition.tsx

@@ -0,0 +1,101 @@
+import { Box, Code, Heading, Image, ListItem, OrderedList, Text } from '@chakra-ui/react';
+import iosAllowBackup from './iosAllowBackup.webp';
+import { FilePathBlock } from '~/components/FilePathBlock';
+
+const EXAMPLE_MEDIA_ID = '0011wjLv1bIkvv';
+const EXAMPLE_NAME_IOS = '333407709-0011wjLv1bIkvv-1.mgalaxy';
+const EXAMPLE_NAME_DB = 'Q0M00011wjLv1bIkvv.mflac';
+
+export function InstructionsIOSCondition({ jailbreak }: { jailbreak: boolean }) {
+  const useJailbreak = jailbreak;
+  const useBackup = !jailbreak;
+
+  const pathPrefix = jailbreak ? '/var/mobile/Containers/Data/Application/<随机>/' : '/AppDomain-';
+
+  return (
+    <>
+      <Heading as="h3" size="md">
+        获取密钥数据库文件
+      </Heading>
+      <OrderedList>
+        {useBackup && (
+          <ListItem>
+            <Text>首先需要在 iOS 客户端的设定允许备份：</Text>
+            <Image src={iosAllowBackup}></Image>
+          </ListItem>
+        )}
+        {useBackup && (
+          <ListItem>
+            <Text>使用你喜欢的备份软件对 iOS 设备进行完整备份；</Text>
+          </ListItem>
+        )}
+        <ListItem>
+          {useBackup && <Text>打开备份文件，并导航到下述目录：</Text>}
+          {useJailbreak && <Text>访问下述目录：</Text>}
+          <FilePathBlock>{pathPrefix}com.tencent.QQMusic/Documents/mmkv/</FilePathBlock>
+        </ListItem>
+        <ListItem>
+          <Text>
+            提取或导出密钥数据库文件 <Code>filenameEkeyMap</Code>；
+          </Text>
+        </ListItem>
+        <ListItem>
+          <Text>
+            提交导出的 <Code>filenameEkeyMap</Code> 文件；
+          </Text>
+        </ListItem>
+        <ListItem>
+          <Text>按下「保存」来应用更改。</Text>
+        </ListItem>
+      </OrderedList>
+
+      <Heading as="h3" size="md" mt="3">
+        获取离线文件
+      </Heading>
+      <Box>
+        <Text>访问下述目录：</Text>
+        <FilePathBlock>
+          {pathPrefix}com.tencent.QQMusic/Library/Application Support/com.tencent.QQMusic/iData/iMusic
+        </FilePathBlock>
+        <Text>
+          该目录又存在数个子目录，其子目录下保存的「<Code>[字符].m[字符]</Code>」文件则是最终的加密文件。
+        </Text>
+        <Text>
+          格式：<Code>[song_id]-[mid]-[随机数字].m[后缀]</Code>
+        </Text>
+        <Text>
+          &#x3000;例：<Code>{EXAMPLE_NAME_IOS}</Code>
+        </Text>
+      </Box>
+
+      <Heading as="h3" size="md" mt="3">
+        解密离线文件
+      </Heading>
+      <Text>勾选设定界面的「使用近似文件名匹配」可跳过该节内容。</Text>
+      <Text>⚠ 注意：若密钥过多，匹配过程可能会造成浏览器卡顿或无响应。</Text>
+      <OrderedList>
+        <ListItem>
+          <Text>
+            提取文件的 <Code>[mid]</Code> 部分，如 <Code>{EXAMPLE_MEDIA_ID}</Code>；
+          </Text>
+        </ListItem>
+        <ListItem>
+          <Text>
+            查找密钥表，得到文件名「<Code>{EXAMPLE_NAME_DB}</Code>」；
+          </Text>
+        </ListItem>
+        <ListItem>
+          <Text>
+            将文件更名为对应的文件名，如<Code display="inline">{EXAMPLE_NAME_IOS}</Code> ➔
+            <Code display="inline">{EXAMPLE_NAME_DB}</Code>；
+          </Text>
+        </ListItem>
+        <ListItem>
+          <Text>
+            回到主界面，提交文件「<Code>{EXAMPLE_NAME_DB}</Code>」。
+          </Text>
+        </ListItem>
+      </OrderedList>
+    </>
+  );
+}

src/features/settings/panels/QMCv2/KeyInput.tsx

@@ -0,0 +1,59 @@
+import {
+  HStack,
+  Icon,
+  IconButton,
+  Input,
+  InputGroup,
+  InputLeftElement,
+  InputRightElement,
+  ListItem,
+  Text,
+  VStack,
+} from '@chakra-ui/react';
+import { MdDelete, MdVpnKey } from 'react-icons/md';
+import { qmc2DeleteKey, qmc2UpdateKey } from '../../settingsSlice';
+import { useAppDispatch } from '~/hooks';
+import { memo } from 'react';
+
+export const KeyInput = memo(({ id, name, ekey, i }: { id: string; name: string; ekey: string; i: number }) => {
+  const dispatch = useAppDispatch();
+
+  const updateKey = (prop: 'name' | 'key', e: React.ChangeEvent<HTMLInputElement>) =>
+    dispatch(qmc2UpdateKey({ id, field: prop, value: e.target.value }));
+  const deleteKey = () => dispatch(qmc2DeleteKey({ id }));
+
+  return (
+    <ListItem mt={0} pt={2} pb={2} _even={{ bg: 'gray.50' }}>
+      <HStack>
+        <Text w="2em" textAlign="center">
+          {i + 1}
+        </Text>
+
+        <VStack flex={1}>
+          <Input variant="flushed" placeholder="文件名" value={name} onChange={(e) => updateKey('name', e)} />
+
+          <InputGroup size="xs">
+            <InputLeftElement pr="2">
+              <Icon as={MdVpnKey} />
+            </InputLeftElement>
+            <Input variant="flushed" placeholder="密钥" value={ekey} onChange={(e) => updateKey('key', e)} />
+            <InputRightElement>
+              <Text pl="2" color={ekey.length ? 'green.500' : 'red.500'}>
+                <code>{ekey.length || '?'}</code>
+              </Text>
+            </InputRightElement>
+          </InputGroup>
+        </VStack>
+
+        <IconButton
+          aria-label="删除该密钥"
+          icon={<Icon as={MdDelete} boxSize={6} />}
+          variant="ghost"
+          colorScheme="red"
+          type="button"
+          onClick={deleteKey}
+        />
+      </HStack>
+    </ListItem>
+  );
+});

src/features/settings/persistSettings.ts

@@ -10,11 +10,18 @@ const DEFAULT_STORAGE_KEY = 'um-react-settings';
 
 function mergeSettings(settings: ProductionSettings): ProductionSettings {
   return produce(settingsSlice.getInitialState().production, (draft) => {
-    for (const [k, v] of enumObject(settings.qmc2?.keys)) {
+    if (settings?.qmc2) {
+      const { allowFuzzyNameSearch, keys } = settings.qmc2;
+      for (const [k, v] of enumObject(keys)) {
         if (typeof v === 'string') {
           draft.qmc2.keys[k] = v;
         }
       }
+
+      if (typeof allowFuzzyNameSearch === 'boolean') {
+        draft.qmc2.allowFuzzyNameSearch = allowFuzzyNameSearch;
+      }
+    }
   });
 }
 

src/features/settings/settingsSelector.ts

@@ -1,5 +1,6 @@
 import type { DecryptCommandOptions } from '~/decrypt-worker/types';
 import type { RootState } from '~/store';
+import { closestByLevenshtein } from '~/util/levenshtein';
 import { hasOwn } from '~/util/objects';
 
 export const selectStagingQMCv2Settings = (state: RootState) => state.settings.staging.qmc2;
@@ -7,9 +8,21 @@ export const selectFinalQMCv2Settings = (state: RootState) => state.settings.pro
 
 export const selectDecryptOptionByFile = (state: RootState, name: string): DecryptCommandOptions => {
   const normalizedName = name.normalize();
-  const qmc2Keys = selectFinalQMCv2Settings(state).keys;
+
+  let qmc2Key: string | undefined;
+  const { keys: qmc2Keys, allowFuzzyNameSearch } = selectFinalQMCv2Settings(state);
+  if (hasOwn(qmc2Keys, normalizedName)) {
+    qmc2Key = qmc2Keys[normalizedName];
+  } else if (allowFuzzyNameSearch) {
+    const qmc2KeyStoreNames = Object.keys(qmc2Keys);
+    if (qmc2KeyStoreNames.length > 0) {
+      const closestName = closestByLevenshtein(normalizedName, qmc2KeyStoreNames);
+      console.debug('qmc2: key db could not find %o, using closest %o instead.', normalizedName, closestName);
+      qmc2Key = qmc2Keys[closestName];
+    }
+  }
 
   return {
-    qmc2Key: hasOwn(qmc2Keys, normalizedName) ? qmc2Keys[normalizedName] : undefined,
+    qmc2Key,
   };
 };

src/features/settings/settingsSlice.ts

@@ -6,12 +6,14 @@ import { objectify } from 'radash';
 export interface StagingSettings {
   qmc2: {
     keys: { id: string; name: string; key: string }[];
+    allowFuzzyNameSearch: boolean;
   };
 }
 
 export interface ProductionSettings {
   qmc2: {
     keys: Record<string, string>; // {  [fileName]: ekey  }
+    allowFuzzyNameSearch: boolean;
   };
 }
 
@@ -22,11 +24,13 @@ export interface SettingsState {
 const initialState: SettingsState = {
   staging: {
     qmc2: {
+      allowFuzzyNameSearch: false,
       keys: [],
     },
   },
   production: {
     qmc2: {
+      allowFuzzyNameSearch: false,
       keys: {},
     },
   },
@@ -39,12 +43,14 @@ const stagingToProduction = (staging: StagingSettings): ProductionSettings => ({
       (item) => item.name.normalize(),
       (item) => item.key.trim()
     ),
+    allowFuzzyNameSearch: staging.qmc2.allowFuzzyNameSearch,
   },
 });
 
 const productionToStaging = (production: ProductionSettings): StagingSettings => ({
   qmc2: {
     keys: Object.entries(production.qmc2.keys).map(([name, key]) => ({ id: nanoid(), name, key })),
+    allowFuzzyNameSearch: production.qmc2.allowFuzzyNameSearch,
   },
 });
 
@@ -81,6 +87,9 @@ export const settingsSlice = createSlice({
     qmc2ClearKeys(state) {
       state.staging.qmc2.keys = [];
     },
+    qmc2AllowFuzzyNameSearch(state, { payload: { enable } }: PayloadAction<{ enable: boolean }>) {
+      state.staging.qmc2.allowFuzzyNameSearch = enable;
+    },
     discardStagingChanges: (state) => {
       state.staging = productionToStaging(state.production);
     },
@@ -107,6 +116,7 @@ export const {
   qmc2DeleteKey,
   qmc2ClearKeys,
   qmc2ImportKeys,
+  qmc2AllowFuzzyNameSearch,
 
   commitStagingChange,
   discardStagingChanges,

src/util/__tests__/levenshtein.test.ts

@@ -0,0 +1,17 @@
+import { closestByLevenshtein, levenshtein } from '../levenshtein';
+
+test('levenshtein quick test', () => {
+  expect(levenshtein('cat', '')).toStrictEqual(3);
+  expect(levenshtein('', 'cat')).toStrictEqual(3);
+  expect(levenshtein('cat', 'cat')).toStrictEqual(0);
+  expect(levenshtein('cat', 'cut')).toStrictEqual(1);
+  expect(levenshtein('kitten', 'sitting')).toStrictEqual(3);
+  expect(levenshtein('tier', 'tor')).toStrictEqual(2);
+  expect(levenshtein('mississippi', 'swiss miss')).toStrictEqual(8);
+});
+
+test('closestByLevenshtein quick test', () => {
+  expect(closestByLevenshtein('cat', ['cut', 'dog', 'bat'])).toStrictEqual('cut');
+  expect(closestByLevenshtein('dag', ['dog', 'pumpkin'])).toStrictEqual('dog');
+  expect(closestByLevenshtein('hello', ['jello', 'yellow', 'bello'])).toStrictEqual('jello');
+});

src/util/levenshtein.ts

@@ -0,0 +1,77 @@
+const textEncoder = new TextEncoder();
+
+// translation of pseudocode from Wikipedia:
+// https://en.wikipedia.org/wiki/Levenshtein_distance#Iterative_with_two_matrix_rows
+export function levenshtein(str1: string, str2: string) {
+  if (str1 === str2) {
+    return 0;
+  }
+
+  if (str1.length === 0) {
+    return str2.length;
+  } else if (str2.length === 0) {
+    return str1.length;
+  }
+
+  // Convert them to Uint8Array to avoid expensive string APIs.
+  const s = textEncoder.encode(str1.toLowerCase());
+  const t = textEncoder.encode(str2.toLowerCase());
+  const m = s.byteLength;
+  const n = t.byteLength;
+
+  // create two work vectors of integer distances
+  let v0 = new Uint32Array(n + 1);
+  let v1 = new Uint32Array(n + 1);
+
+  // initialize v0 (the previous row of distances)
+  // this row is A[0][i]: edit distance from an empty s to t;
+  // that distance is the number of characters to append to  s to make t.
+  for (let i = 0; i <= n; i++) {
+    v0[i] = i;
+  }
+
+  for (let i = 0; i < m; i++) {
+    // calculate v1 (current row distances) from the previous row v0
+
+    // first element of v1 is A[i + 1][0]
+    //   edit distance is delete (i + 1) chars from s to match empty t
+    v1[0] = i + 1;
+
+    // use formula to fill in the rest of the row
+    for (let j = 0; j < n; j++) {
+      // calculating costs for A[i + 1][j + 1]
+      const deletionCost = v0[j + 1] + 1;
+      const insertionCost = v1[j] + 1;
+      const substitutionCost = v0[j] + (s[i] === t[j] ? 0 : 1);
+      v1[j + 1] = Math.min(deletionCost, insertionCost, substitutionCost);
+    }
+
+    // copy v1 (current row) to v0 (previous row) for next iteration
+    // since data in v1 is always invalidated, a swap without copy could be more efficient
+    [v0, v1] = [v1, v0];
+  }
+
+  // after the last swap, the results of v1 are now in v0
+  return v0[n];
+}
+
+export function closestByLevenshtein(str: string, candidates: string[]) {
+  // Faster than pre-calculate all and pass scores to Math.min.
+  const n = candidates.length;
+  if (n === 0) {
+    throw new Error('empty candidates');
+  }
+
+  let lowestIdx = 0;
+  let lowestScore = levenshtein(str, candidates[0]);
+
+  for (let i = 1; i < n; i++) {
+    const score = levenshtein(str, candidates[i]);
+    if (score < lowestScore) {
+      lowestScore = score;
+      lowestIdx = i;
+    }
+  }
+
+  return candidates[lowestIdx];
+}