Merge branch 'translate-status' into 'main'

Feat: Support Machine Translations

Closes #201

See merge request soapbox-pub/ditto!537

deno.json

@@ -41,7 +41,7 @@
     "@isaacs/ttlcache": "npm:@isaacs/ttlcache@^1.4.1",
     "@lambdalisue/async": "jsr:@lambdalisue/async@^2.1.1",
     "@noble/secp256k1": "npm:@noble/secp256k1@^2.0.0",
-    "@nostrify/db": "jsr:@nostrify/db@^0.35.0",
+    "@nostrify/db": "jsr:@nostrify/db@^0.36.1",
     "@nostrify/nostrify": "jsr:@nostrify/nostrify@^0.36.0",
     "@nostrify/policies": "jsr:@nostrify/policies@^0.35.0",
     "@scure/base": "npm:@scure/base@^1.1.6",

deno.lock

@@ -22,7 +22,7 @@
     "jsr:@gleasonator/policy@0.8.0": "0.8.0",
     "jsr:@hono/hono@^4.4.6": "4.6.2",
     "jsr:@lambdalisue/async@^2.1.1": "2.1.1",
-    "jsr:@nostrify/db@0.35": "0.35.0",
+    "jsr:@nostrify/db@~0.36.1": "0.36.1",
     "jsr:@nostrify/nostrify@0.31": "0.31.0",
     "jsr:@nostrify/nostrify@0.32": "0.32.0",
     "jsr:@nostrify/nostrify@0.35": "0.35.0",
@@ -270,10 +270,10 @@
     "@lambdalisue/async@2.1.1": {
       "integrity": "1fc9bc6f4ed50215cd2f7217842b18cea80f81c25744f88f8c5eb4be5a1c9ab4"
     },
-    "@nostrify/db@0.35.0": {
+    "@nostrify/db@0.36.1": {
-      "integrity": "637191c41812544e361b7997dc44ea098f8bd7efebb28f37a8a7142a0ecada8d",
+      "integrity": "b65b89ca6fe98d9dbcc0402b5c9c07b8430c2c91f84ba4128ff2eeed70c3d49f",
       "dependencies": [
-        "jsr:@nostrify/nostrify@0.35",
+        "jsr:@nostrify/nostrify@0.36",
         "jsr:@nostrify/types@0.35",
         "npm:kysely@~0.27.3",
         "npm:nostr-tools@^2.7.0"
@@ -2048,7 +2048,7 @@
       "jsr:@gfx/canvas-wasm@~0.4.2",
       "jsr:@hono/hono@^4.4.6",
       "jsr:@lambdalisue/async@^2.1.1",
-      "jsr:@nostrify/db@0.35",
+      "jsr:@nostrify/db@~0.36.1",
       "jsr:@nostrify/nostrify@0.36",
       "jsr:@nostrify/policies@0.35",
       "jsr:@soapbox/kysely-pglite@1",

src/app.ts

@@ -1,4 +1,4 @@
-import { Context, Env as HonoEnv, Handler, Hono, Input as HonoInput, MiddlewareHandler } from '@hono/hono';
+import { type Context, Env as HonoEnv, Handler, Hono, Input as HonoInput, MiddlewareHandler } from '@hono/hono';
 import { cors } from '@hono/hono/cors';
 import { serveStatic } from '@hono/hono/deno';
 import { logger } from '@hono/hono/logger';
@@ -112,6 +112,7 @@ import {
   trendingStatusesController,
   trendingTagsController,
 } from '@/controllers/api/trends.ts';
+import { translateController } from '@/controllers/api/translate.ts';
 import { errorHandler } from '@/controllers/error.ts';
 import { frontendController } from '@/controllers/frontend.ts';
 import { metricsController } from '@/controllers/metrics.ts';
@@ -128,6 +129,8 @@ import { requireSigner } from '@/middleware/requireSigner.ts';
 import { signerMiddleware } from '@/middleware/signerMiddleware.ts';
 import { storeMiddleware } from '@/middleware/storeMiddleware.ts';
 import { uploaderMiddleware } from '@/middleware/uploaderMiddleware.ts';
+import { DittoTranslator } from '@/translators/translator.ts';
+import { translatorMiddleware } from '@/middleware/translatorMiddleware.ts';
 
 interface AppEnv extends HonoEnv {
   Variables: {
@@ -143,6 +146,8 @@ interface AppEnv extends HonoEnv {
     pagination: { since?: number; until?: number; limit: number };
     /** Normalized list pagination params. */
     listPagination: { offset: number; limit: number };
+    /** Translation service. */
+    translator?: DittoTranslator;
   };
 }
 
@@ -222,6 +227,13 @@ app.post('/api/v1/statuses/:id{[0-9a-f]{64}}/bookmark', requireSigner, bookmarkC
 app.post('/api/v1/statuses/:id{[0-9a-f]{64}}/unbookmark', requireSigner, unbookmarkController);
 app.post('/api/v1/statuses/:id{[0-9a-f]{64}}/pin', requireSigner, pinController);
 app.post('/api/v1/statuses/:id{[0-9a-f]{64}}/unpin', requireSigner, unpinController);
+app.post(
+  '/api/v1/statuses/:id{[0-9a-f]{64}}/translate',
+  requireSigner,
+  rateLimitMiddleware(30, Time.minutes(1)),
+  translatorMiddleware,
+  translateController,
+);
 app.post('/api/v1/statuses/:id{[0-9a-f]{64}}/reblog', requireSigner, reblogStatusController);
 app.post('/api/v1/statuses/:id{[0-9a-f]{64}}/unreblog', requireSigner, unreblogStatusController);
 app.post('/api/v1/statuses', requireSigner, createStatusController);

src/config.ts

@@ -271,6 +271,26 @@ class Conf {
   static get preferredLanguages(): LanguageCode[] | undefined {
     return Deno.env.get('DITTO_LANGUAGES')?.split(',')?.filter(ISO6391.validate) as LanguageCode[];
   }
+  /** Translation provider used to translate posts. */
+  static get translationProvider(): string | undefined {
+    return Deno.env.get('TRANSLATION_PROVIDER');
+  }
+  /** DeepL URL endpoint. */
+  static get deepLendpoint(): string | undefined {
+    return Deno.env.get('DEEPL_ENDPOINT');
+  }
+  /** DeepL API KEY. */
+  static get deepLapiKey(): string | undefined {
+    return Deno.env.get('DEEPL_API_KEY');
+  }
+  /** LibreTranslate URL endpoint. */
+  static get libreTranslateEndpoint(): string | undefined {
+    return Deno.env.get('LIBRETRANSLATE_ENDPOINT');
+  }
+  /** LibreTranslate API KEY. */
+  static get libreTranslateApiKey(): string | undefined {
+    return Deno.env.get('LIBRETRANSLATE_API_KEY');
+  }
   /** Cache settings. */
   static caches = {
     /** NIP-05 cache settings. */

src/controllers/api/instance.ts

@@ -129,7 +129,7 @@ const instanceV2Controller: AppController = async (c) => {
         max_expiration: 2629746,
       },
       translation: {
-        enabled: false,
+        enabled: true,
       },
     },
     nostr: {

src/controllers/api/translate.ts

@@ -0,0 +1,140 @@
+import { LanguageCode } from 'iso-639-1';
+import { z } from 'zod';
+
+import { AppController } from '@/app.ts';
+import { localeSchema } from '@/schema.ts';
+import { dittoTranslations, dittoTranslationsKey, MastodonTranslation } from '@/translators/translator.ts';
+import { parseBody } from '@/utils/api.ts';
+import { getEvent } from '@/queries.ts';
+import { renderStatus } from '@/views/mastodon/statuses.ts';
+
+const translateSchema = z.object({
+  lang: localeSchema,
+});
+
+const translateController: AppController = async (c) => {
+  const result = translateSchema.safeParse(await parseBody(c.req.raw));
+  const { signal } = c.req.raw;
+
+  if (!result.success) {
+    return c.json({ error: 'Bad request.', schema: result.error }, 422);
+  }
+
+  const translator = c.get('translator');
+  if (!translator) {
+    return c.json({ error: 'No translator configured.' }, 500);
+  }
+
+  const lang = result.data.lang.language.slice(0, 2) as LanguageCode;
+
+  const id = c.req.param('id');
+
+  const event = await getEvent(id, { signal });
+  if (!event) {
+    return c.json({ error: 'Record not found' }, 400);
+  }
+
+  const viewerPubkey = await c.get('signer')?.getPublicKey();
+
+  if (lang.toLowerCase() === event?.language?.toLowerCase()) {
+    return c.json({ error: 'Source and target languages are the same. No translation needed.' }, 400);
+  }
+
+  const status = await renderStatus(event, { viewerPubkey });
+  if (!status?.content) {
+    return c.json({ error: 'Bad request.', schema: result.error }, 400);
+  }
+
+  const translatedId = `${lang}-${id}` as dittoTranslationsKey;
+  const translationCache = dittoTranslations.get(translatedId);
+
+  if (translationCache) {
+    return c.json(translationCache.data, 200);
+  }
+
+  const mediaAttachments = status?.media_attachments.map((value) => {
+    return {
+      id: value.id,
+      description: value.description ?? '',
+    };
+  }) ?? [];
+
+  try {
+    const texts: string[] = [];
+
+    const mastodonTranslation: MastodonTranslation = {
+      content: '',
+      spoiler_text: '',
+      media_attachments: [],
+      poll: null,
+      detected_source_language: event.language ?? 'en',
+      provider: translator.getProvider(),
+    };
+
+    if ((status?.poll as MastodonTranslation['poll'])?.options) {
+      mastodonTranslation.poll = { id: (status?.poll as MastodonTranslation['poll'])?.id!, options: [] };
+    }
+
+    type TranslationIndex = {
+      [key: number]: 'content' | 'spoilerText' | 'poll' | { type: 'media'; id: string };
+    };
+    const translationIndex: TranslationIndex = {};
+    let index = 0;
+
+    // Content
+    translationIndex[index] = 'content';
+    texts.push(status.content);
+    index++;
+
+    // Spoiler text
+    if (status.spoiler_text) {
+      translationIndex[index] = 'spoilerText';
+      texts.push(status.spoiler_text);
+      index++;
+    }
+
+    // Media description
+    for (const [mediaIndex, value] of mediaAttachments.entries()) {
+      translationIndex[index + mediaIndex] = { type: 'media', id: value.id };
+      texts.push(mediaAttachments[mediaIndex].description);
+      index += mediaIndex;
+    }
+
+    // Poll title
+    if (status?.poll) {
+      for (const [pollIndex] of (status?.poll as MastodonTranslation['poll'])!.options.entries()) {
+        translationIndex[index + pollIndex] = 'poll';
+        texts.push((status.poll as MastodonTranslation['poll'])!.options[pollIndex].title);
+        index += pollIndex;
+      }
+    }
+
+    const data = await translator.translate(texts, event.language, lang, { signal });
+    const translatedTexts = data.results;
+
+    for (let i = 0; i < texts.length; i++) {
+      if (translationIndex[i] === 'content') {
+        mastodonTranslation.content = translatedTexts[i];
+      } else if (translationIndex[i] === 'spoilerText') {
+        mastodonTranslation.spoiler_text = translatedTexts[i];
+      } else if (translationIndex[i] === 'poll') {
+        mastodonTranslation.poll?.options.push({ title: translatedTexts[i] });
+      } else {
+        const media = translationIndex[i] as { type: 'media'; id: string };
+        mastodonTranslation.media_attachments.push({
+          id: media.id,
+          description: translatedTexts[i],
+        });
+      }
+    }
+
+    mastodonTranslation.detected_source_language = data.source_lang;
+
+    dittoTranslations.set(translatedId, { data: mastodonTranslation });
+    return c.json(mastodonTranslation, 200);
+  } catch {
+    return c.json({ error: 'Service Unavailable' }, 503);
+  }
+};
+
+export { translateController };

src/controllers/nostr/relay.ts

@@ -18,6 +18,7 @@ import * as pipeline from '@/pipeline.ts';
 import { RelayError } from '@/RelayError.ts';
 import { Storages } from '@/storages.ts';
 import { Time } from '@/utils/time.ts';
+import { purifyEvent } from '@/utils/purify.ts';
 
 /** Limit of initial events returned for a subscription. */
 const FILTER_LIMIT = 100;
@@ -105,7 +106,7 @@ function connectStream(socket: WebSocket, ip: string | undefined) {
 
     try {
       for (const event of await store.query(filters, { limit: FILTER_LIMIT, timeout: Conf.db.timeouts.relay })) {
-        send(['EVENT', subId, event]);
+        send(['EVENT', subId, purifyEvent(event)]);
       }
     } catch (e: any) {
       if (e instanceof RelayError) {
@@ -137,7 +138,7 @@ function connectStream(socket: WebSocket, ip: string | undefined) {
     relayEventsCounter.inc({ kind: event.kind.toString() });
     try {
       // This will store it (if eligible) and run other side-effects.
-      await pipeline.handleEvent(event, AbortSignal.timeout(1000));
+      await pipeline.handleEvent(purifyEvent(event), AbortSignal.timeout(1000));
       send(['OK', event.id, true, '']);
     } catch (e) {
       if (e instanceof RelayError) {

src/db/DittoTables.ts

@@ -1,5 +1,3 @@
-import { Nullable } from 'kysely';
-
 import { NPostgresSchema } from '@nostrify/db';
 
 export interface DittoTables extends NPostgresSchema {
@@ -12,7 +10,7 @@ export interface DittoTables extends NPostgresSchema {
 }
 
 type NostrEventsRow = NPostgresSchema['nostr_events'] & {
-  language: Nullable<string>;
+  language: string | null;
 };
 
 interface AuthorStatsRow {

src/interfaces/DittoEvent.ts

@@ -1,4 +1,5 @@
 import { NostrEvent } from '@nostrify/nostrify';
+import { LanguageCode } from 'iso-639-1';
 
 /** Ditto internal stats for the event's author. */
 export interface AuthorStats {
@@ -43,4 +44,6 @@ export interface DittoEvent extends NostrEvent {
   zap_sender?: DittoEvent | string;
   zap_amount?: number;
   zap_message?: string;
+  /** Language of the event (kind 1s are more accurate). */
+  language?: LanguageCode;
 }

src/middleware/translatorMiddleware.ts

@@ -0,0 +1,39 @@
+import { AppMiddleware } from '@/app.ts';
+import { Conf } from '@/config.ts';
+import { fetchWorker } from '@/workers/fetch.ts';
+import { DeepLTranslator } from '@/translators/DeepLTranslator.ts';
+import { LibreTranslateTranslator } from '@/translators/LibreTranslateTranslator.ts';
+
+/** Set the translator used for translating posts. */
+export const translatorMiddleware: AppMiddleware = async (c, next) => {
+  const deepLendpoint = Conf.deepLendpoint;
+  const deepLapiKey = Conf.deepLapiKey;
+  const libreTranslateEndpoint = Conf.libreTranslateEndpoint;
+  const libreTranslateApiKey = Conf.libreTranslateApiKey;
+  const translationProvider = Conf.translationProvider;
+
+  switch (translationProvider) {
+    case 'deepl':
+      if (deepLapiKey) {
+        c.set(
+          'translator',
+          new DeepLTranslator({ endpoint: deepLendpoint, apiKey: deepLapiKey, fetch: fetchWorker }),
+        );
+      }
+      break;
+    case 'libretranslate':
+      if (libreTranslateApiKey) {
+        c.set(
+          'translator',
+          new LibreTranslateTranslator({
+            endpoint: libreTranslateEndpoint,
+            apiKey: libreTranslateApiKey,
+            fetch: fetchWorker,
+          }),
+        );
+      }
+      break;
+  }
+
+  await next();
+};

src/schema.ts

@@ -1,4 +1,4 @@
-import ISO6391 from 'iso-639-1';
+import ISO6391, { LanguageCode } from 'iso-639-1';
 import { z } from 'zod';
 
 /** Validates individual items in an array, dropping any that aren't valid. */
@@ -41,7 +41,8 @@ const fileSchema = z.custom<File>((value) => value instanceof File);
 
 const percentageSchema = z.coerce.number().int().gte(1).lte(100);
 
-const languageSchema = z.string().transform((val, ctx) => {
+const languageSchema = z.string().transform<LanguageCode>((val, ctx) => {
+  val = val.toLowerCase();
   if (!ISO6391.validate(val)) {
     ctx.addIssue({
       code: z.ZodIssueCode.custom,
@@ -49,7 +50,19 @@ const languageSchema = z.string().transform((val, ctx) => {
     });
     return z.NEVER;
   }
-  return val;
+  return val as LanguageCode;
+});
+
+const localeSchema = z.string().transform<Intl.Locale>((val, ctx) => {
+  try {
+    return new Intl.Locale(val);
+  } catch {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: 'Invalid locale',
+    });
+    return z.NEVER;
+  }
 });
 
 export {
@@ -59,6 +72,7 @@ export {
   filteredArray,
   hashtagSchema,
   languageSchema,
+  localeSchema,
   percentageSchema,
   safeUrlSchema,
 };

src/storages/EventsDB.test.ts

@@ -7,7 +7,7 @@ import { Conf } from '@/config.ts';
 import { createTestDB } from '@/test.ts';
 
 Deno.test('count filters', async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   const event1 = await eventFixture('event-1');
@@ -18,7 +18,7 @@ Deno.test('count filters', async () => {
 });
 
 Deno.test('insert and filter events', async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   const event1 = await eventFixture('event-1');
@@ -35,7 +35,7 @@ Deno.test('insert and filter events', async () => {
 });
 
 Deno.test('query events with domain search filter', async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store, kysely } = db;
 
   const event1 = await eventFixture('event-1');
@@ -55,7 +55,7 @@ Deno.test('query events with domain search filter', async () => {
 });
 
 Deno.test('query events with language search filter', async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store, kysely } = db;
 
   const en = genEvent({ kind: 1, content: 'hello world!' });
@@ -72,7 +72,7 @@ Deno.test('query events with language search filter', async () => {
 });
 
 Deno.test('delete events', async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   const sk = generateSecretKey();
@@ -96,7 +96,7 @@ Deno.test('delete events', async () => {
 });
 
 Deno.test("user cannot delete another user's event", async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   const event = genEvent({ kind: 1, content: 'hello world', created_at: 1 });
@@ -113,7 +113,7 @@ Deno.test("user cannot delete another user's event", async () => {
 });
 
 Deno.test('admin can delete any event', async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   const sk = generateSecretKey();
@@ -137,7 +137,7 @@ Deno.test('admin can delete any event', async () => {
 });
 
 Deno.test('throws a RelayError when inserting an event deleted by the admin', async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   const event = genEvent();
@@ -154,7 +154,7 @@ Deno.test('throws a RelayError when inserting an event deleted by the admin', as
 });
 
 Deno.test('throws a RelayError when inserting an event deleted by a user', async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   const sk = generateSecretKey();
@@ -173,7 +173,7 @@ Deno.test('throws a RelayError when inserting an event deleted by a user', async
 });
 
 Deno.test('inserting replaceable events', async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   const sk = generateSecretKey();
@@ -190,7 +190,7 @@ Deno.test('inserting replaceable events', async () => {
 });
 
 Deno.test("throws a RelayError when querying an event with a large 'since'", async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   await assertRejects(
@@ -201,7 +201,7 @@ Deno.test("throws a RelayError when querying an event with a large 'since'", asy
 });
 
 Deno.test("throws a RelayError when querying an event with a large 'until'", async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   await assertRejects(
@@ -212,7 +212,7 @@ Deno.test("throws a RelayError when querying an event with a large 'until'", asy
 });
 
 Deno.test("throws a RelayError when querying an event with a large 'kind'", async () => {
-  await using db = await createTestDB();
+  await using db = await createTestDB({ pure: true });
   const { store } = db;
 
   await assertRejects(

src/storages/EventsDB.ts

@@ -1,5 +1,6 @@
 // deno-lint-ignore-file require-await
 
+import { LanguageCode } from 'iso-639-1';
 import { NPostgres, NPostgresSchema } from '@nostrify/db';
 import { NIP50, NKinds, NostrEvent, NostrFilter, NSchema as n } from '@nostrify/nostrify';
 import { Stickynotes } from '@soapbox/stickynotes';
@@ -12,6 +13,7 @@ import { RelayError } from '@/RelayError.ts';
 import { isNostrId, isURL } from '@/utils.ts';
 import { abortError } from '@/utils/abort.ts';
 import { purifyEvent } from '@/utils/purify.ts';
+import { DittoEvent } from '@/interfaces/DittoEvent.ts';
 
 /** Function to decide whether or not to index a tag. */
 type TagCondition = ({ event, count, value }: {
@@ -28,6 +30,8 @@ interface EventsDBOpts {
   pubkey: string;
   /** Timeout in milliseconds for database queries. */
   timeout: number;
+  /** Whether the event returned should be a Nostr event or a Ditto event. Defaults to false. */
+  pure?: boolean;
 }
 
 /** SQL database storage adapter for Nostr events. */
@@ -151,7 +155,7 @@ class EventsDB extends NPostgres {
       let query = super.getFilterQuery(trx, {
         ...filter,
         search: tokens.filter((t) => typeof t === 'string').join(' '),
-      }) as SelectQueryBuilder<DittoTables, 'nostr_events', Pick<DittoTables['nostr_events'], keyof NostrEvent>>;
+      }) as SelectQueryBuilder<DittoTables, 'nostr_events', DittoTables['nostr_events']>;
 
       const languages = new Set<string>();
 
@@ -175,7 +179,7 @@ class EventsDB extends NPostgres {
   override async query(
     filters: NostrFilter[],
     opts: { signal?: AbortSignal; timeout?: number; limit?: number } = {},
-  ): Promise<NostrEvent[]> {
+  ): Promise<DittoEvent[]> {
     filters = await this.expandFilters(filters);
 
     for (const filter of filters) {
@@ -199,6 +203,29 @@ class EventsDB extends NPostgres {
     return super.query(filters, { ...opts, timeout: opts.timeout ?? this.opts.timeout });
   }
 
+  /** Parse an event row from the database. */
+  protected override parseEventRow(row: DittoTables['nostr_events']): DittoEvent {
+    const event: DittoEvent = {
+      id: row.id,
+      kind: row.kind,
+      pubkey: row.pubkey,
+      content: row.content,
+      created_at: Number(row.created_at),
+      tags: row.tags,
+      sig: row.sig,
+    };
+
+    if (this.opts.pure) {
+      return event;
+    }
+
+    if (row.language) {
+      event.language = row.language as LanguageCode;
+    }
+
+    return event;
+  }
+
   /** Delete events based on filters from the database. */
   override async remove(filters: NostrFilter[], opts: { signal?: AbortSignal; timeout?: number } = {}): Promise<void> {
     this.console.debug('DELETE', JSON.stringify(filters));

src/test.ts

@@ -1,3 +1,5 @@
+import ISO6391, { LanguageCode } from 'iso-639-1';
+import lande from 'lande';
 import { NostrEvent } from '@nostrify/nostrify';
 import { finalizeEvent, generateSecretKey } from 'nostr-tools';
 
@@ -33,7 +35,7 @@ export function genEvent(t: Partial<NostrEvent> = {}, sk: Uint8Array = generateS
 }
 
 /** Create a database for testing. It uses `TEST_DATABASE_URL`, or creates an in-memory database by default. */
-export async function createTestDB() {
+export async function createTestDB(opts?: { pure?: boolean }) {
   const { testDatabaseUrl } = Conf;
   const { kysely } = DittoDB.create(testDatabaseUrl, { poolSize: 1 });
 
@@ -43,6 +45,7 @@ export async function createTestDB() {
     kysely,
     timeout: Conf.db.timeouts.default,
     pubkey: Conf.pubkey,
+    pure: opts?.pure ?? false,
   });
 
   return {
@@ -65,3 +68,15 @@ export async function createTestDB() {
 export function sleep(ms: number): Promise<void> {
   return new Promise((resolve) => setTimeout(resolve, ms));
 }
+
+export function getLanguage(text: string): LanguageCode | undefined {
+  const [topResult] = lande(text);
+  if (topResult) {
+    const [iso6393] = topResult;
+    const locale = new Intl.Locale(iso6393);
+    if (ISO6391.validate(locale.language)) {
+      return locale.language as LanguageCode;
+    }
+  }
+  return;
+}

src/translators/DeepLTranslator.test.ts

@@ -0,0 +1,52 @@
+import { assertEquals } from '@std/assert';
+
+import { Conf } from '@/config.ts';
+import { DeepLTranslator } from '@/translators/DeepLTranslator.ts';
+import { getLanguage } from '@/test.ts';
+
+const endpoint = Conf.deepLendpoint;
+const apiKey = Conf.deepLapiKey;
+const translationProvider = Conf.translationProvider;
+const deepL = 'deepl';
+
+Deno.test('DeepL translation with source language omitted', {
+  ignore: !(translationProvider === deepL && apiKey),
+}, async () => {
+  const translator = new DeepLTranslator({ fetch: fetch, endpoint, apiKey: apiKey as string });
+
+  const data = await translator.translate(
+    [
+      'Bom dia amigos',
+      'Meu nome é Patrick',
+      'Eu irei morar na America, eu prometo. Mas antes, eu devo mencionar que o lande está interpretando este texto como italiano, que estranho.',
+    ],
+    undefined,
+    'en',
+  );
+
+  assertEquals(data.source_lang, 'pt');
+  assertEquals(getLanguage(data.results[0]), 'en');
+  assertEquals(getLanguage(data.results[1]), 'en');
+  assertEquals(getLanguage(data.results[2]), 'en');
+});
+
+Deno.test('DeepL translation with source language set', {
+  ignore: !(translationProvider === deepL && apiKey),
+}, async () => {
+  const translator = new DeepLTranslator({ fetch: fetch, endpoint, apiKey: apiKey as string });
+
+  const data = await translator.translate(
+    [
+      'Bom dia amigos',
+      'Meu nome é Patrick',
+      'Eu irei morar na America, eu prometo. Mas antes, eu devo mencionar que o lande está interpretando este texto como italiano, que estranho.',
+    ],
+    'pt',
+    'en',
+  );
+
+  assertEquals(data.source_lang, 'pt');
+  assertEquals(getLanguage(data.results[0]), 'en');
+  assertEquals(getLanguage(data.results[1]), 'en');
+  assertEquals(getLanguage(data.results[2]), 'en');
+});

src/translators/DeepLTranslator.ts

@@ -0,0 +1,93 @@
+import { z } from 'zod';
+
+import { DittoTranslator, Provider, SourceLanguage, TargetLanguage } from '@/translators/translator.ts';
+import { languageSchema } from '@/schema.ts';
+
+interface DeepLTranslatorOpts {
+  /** DeepL endpoint to use. Default: 'https://api.deepl.com' */
+  endpoint?: string;
+  /** DeepL API key. */
+  apiKey: string;
+  /** Custom fetch implementation. */
+  fetch?: typeof fetch;
+}
+
+export class DeepLTranslator implements DittoTranslator {
+  private readonly endpoint: string;
+  private readonly apiKey: string;
+  private readonly fetch: typeof fetch;
+  private static provider: Provider = 'DeepL.com';
+
+  constructor(opts: DeepLTranslatorOpts) {
+    this.endpoint = opts.endpoint ?? 'https://api.deepl.com';
+    this.fetch = opts.fetch ?? globalThis.fetch;
+    this.apiKey = opts.apiKey;
+  }
+
+  async translate(
+    texts: string[],
+    source: SourceLanguage | undefined,
+    dest: TargetLanguage,
+    opts?: { signal?: AbortSignal },
+  ) {
+    const data = (await this.translateMany(texts, source, dest, opts)).translations;
+
+    return {
+      results: data.map((value) => value.text),
+      source_lang: data[0].detected_source_language,
+    };
+  }
+
+  /** DeepL translate request. */
+  private async translateMany(
+    texts: string[],
+    source: SourceLanguage | undefined,
+    targetLanguage: TargetLanguage,
+    opts?: { signal?: AbortSignal },
+  ) {
+    const body: any = {
+      text: texts,
+      target_lang: targetLanguage.toUpperCase(),
+      tag_handling: 'html',
+      split_sentences: '1',
+    };
+    if (source) {
+      body.source_lang = source.toUpperCase();
+    }
+
+    const headers = new Headers();
+    headers.append('Authorization', 'DeepL-Auth-Key' + ' ' + this.apiKey);
+    headers.append('Content-Type', 'application/json');
+
+    const request = new Request(this.endpoint + '/v2/translate', {
+      method: 'POST',
+      body: JSON.stringify(body),
+      headers,
+      signal: opts?.signal,
+    });
+
+    const response = await this.fetch(request);
+    const json = await response.json();
+    const data = DeepLTranslator.schema().parse(json);
+
+    return data;
+  }
+
+  /** DeepL response schema.
+   * https://developers.deepl.com/docs/api-reference/translate/openapi-spec-for-text-translation */
+  private static schema() {
+    return z.object({
+      translations: z.array(
+        z.object({
+          detected_source_language: languageSchema,
+          text: z.string(),
+        }),
+      ),
+    });
+  }
+
+  /** DeepL provider. */
+  getProvider(): Provider {
+    return DeepLTranslator.provider;
+  }
+}

src/translators/LibreTranslateTranslator.test.ts

@@ -0,0 +1,52 @@
+import { assertEquals } from '@std/assert';
+
+import { Conf } from '@/config.ts';
+import { LibreTranslateTranslator } from '@/translators/LibreTranslateTranslator.ts';
+import { getLanguage } from '@/test.ts';
+
+const endpoint = Conf.libreTranslateEndpoint;
+const apiKey = Conf.libreTranslateApiKey;
+const translationProvider = Conf.translationProvider;
+const libreTranslate = 'libretranslate';
+
+Deno.test('LibreTranslate translation with source language omitted', {
+  ignore: !(translationProvider === libreTranslate && apiKey),
+}, async () => {
+  const translator = new LibreTranslateTranslator({ fetch: fetch, endpoint, apiKey: apiKey as string });
+
+  const data = await translator.translate(
+    [
+      'Bom dia amigos',
+      'Meu nome é Patrick, um nome belo ou feio? A questão é mais profunda do que parece.',
+      'A respiração é mais importante do que comer e tomar agua.',
+    ],
+    undefined,
+    'ca',
+  );
+
+  assertEquals(data.source_lang, 'pt');
+  assertEquals(getLanguage(data.results[0]), 'ca');
+  assertEquals(getLanguage(data.results[1]), 'ca');
+  assertEquals(getLanguage(data.results[2]), 'ca');
+});
+
+Deno.test('LibreTranslate translation with source language set', {
+  ignore: !(translationProvider === libreTranslate && apiKey),
+}, async () => {
+  const translator = new LibreTranslateTranslator({ fetch: fetch, endpoint, apiKey: apiKey as string });
+
+  const data = await translator.translate(
+    [
+      'Bom dia amigos',
+      'Meu nome é Patrick, um nome belo ou feio? A questão é mais profunda do que parece.',
+      'A respiração é mais importante do que comer e tomar agua.',
+    ],
+    'pt',
+    'ca',
+  );
+
+  assertEquals(data.source_lang, 'pt');
+  assertEquals(getLanguage(data.results[0]), 'ca');
+  assertEquals(getLanguage(data.results[1]), 'ca');
+  assertEquals(getLanguage(data.results[2]), 'ca');
+});

src/translators/LibreTranslateTranslator.ts

@@ -0,0 +1,92 @@
+import { LanguageCode } from 'iso-639-1';
+import { z } from 'zod';
+
+import { DittoTranslator, Provider, SourceLanguage, TargetLanguage } from '@/translators/translator.ts';
+import { languageSchema } from '@/schema.ts';
+
+interface LibreTranslateTranslatorOpts {
+  /** Libretranslate endpoint to use. Default: 'https://libretranslate.com' */
+  endpoint?: string;
+  /** Libretranslate API key. */
+  apiKey: string;
+  /** Custom fetch implementation. */
+  fetch?: typeof fetch;
+}
+
+export class LibreTranslateTranslator implements DittoTranslator {
+  private readonly endpoint: string;
+  private readonly apiKey: string;
+  private readonly fetch: typeof fetch;
+  private static provider: Provider = 'libretranslate.com';
+
+  constructor(opts: LibreTranslateTranslatorOpts) {
+    this.endpoint = opts.endpoint ?? 'https://libretranslate.com';
+    this.fetch = opts.fetch ?? globalThis.fetch;
+    this.apiKey = opts.apiKey;
+  }
+
+  async translate(
+    texts: string[],
+    source: SourceLanguage | undefined,
+    dest: TargetLanguage,
+    opts?: { signal?: AbortSignal },
+  ) {
+    const translations = await Promise.all(
+      texts.map((text) => this.translateOne(text, source, dest, 'html', { signal: opts?.signal })),
+    );
+
+    return {
+      results: translations.map((value) => value.translatedText),
+      source_lang: translations[0]?.detectedLanguage?.language ?? source as LanguageCode, // cast is ok
+    };
+  }
+
+  private async translateOne(
+    q: string,
+    sourceLanguage: string | undefined,
+    targetLanguage: string,
+    format: 'html' | 'text',
+    opts?: { signal?: AbortSignal },
+  ) {
+    const body = {
+      q,
+      source: sourceLanguage?.toLowerCase() ?? 'auto',
+      target: targetLanguage.toLowerCase(),
+      format,
+      api_key: this.apiKey,
+    };
+
+    const headers = new Headers();
+    headers.append('Content-Type', 'application/json');
+
+    const request = new Request(this.endpoint + '/translate', {
+      method: 'POST',
+      body: JSON.stringify(body),
+      headers,
+      signal: opts?.signal,
+    });
+
+    const response = await this.fetch(request);
+    const json = await response.json();
+    const data = LibreTranslateTranslator.schema().parse(json);
+
+    return data;
+  }
+
+  /** Libretranslate response schema.
+   *  https://libretranslate.com/docs/#/translate/post_translate */
+  private static schema() {
+    return z.object({
+      translatedText: z.string(),
+      /** This field is only available if the 'source' is set to 'auto' */
+      detectedLanguage: z.object({
+        language: languageSchema,
+      }).optional(),
+    });
+  }
+
+  /** LibreTranslate provider. */
+  getProvider(): Provider {
+    return LibreTranslateTranslator.provider;
+  }
+}

src/translators/translator.ts

@@ -0,0 +1,59 @@
+import { LanguageCode } from 'iso-639-1';
+import { LRUCache } from 'lru-cache';
+
+import { Time } from '@/utils/time.ts';
+
+/** Supported providers. */
+export type Provider = 'DeepL.com' | 'libretranslate.com';
+
+/** Original language of the post */
+export type SourceLanguage = LanguageCode;
+
+/** Content will be translated to this language */
+export type TargetLanguage = LanguageCode;
+
+/** Entity returned by DittoTranslator and LRUCache */
+type DittoTranslation = {
+  data: MastodonTranslation;
+};
+
+export type MastodonTranslation = {
+  /** HTML-encoded translated content of the status. */
+  content: string;
+  /** The translated spoiler warning of the status. */
+  spoiler_text: string;
+  /** The translated media descriptions of the status. */
+  media_attachments: { id: string; description: string }[];
+  /** The translated poll of the status. */
+  poll: { id: string; options: { title: string }[] } | null;
+  //** The language of the source text, as auto-detected by the machine translation provider. */
+  detected_source_language: SourceLanguage;
+  /** The service that provided the machine translation. */
+  provider: Provider;
+};
+
+/** DittoTranslator class, used for status translation. */
+export interface DittoTranslator {
+  /** Translate the 'content' into 'targetLanguage'. */
+  translate(
+    texts: string[],
+    /** The language of the source text/status. */
+    sourceLanguage: SourceLanguage | undefined,
+    /** The status content will be translated into this language. */
+    targetLanguage: TargetLanguage,
+    /** Custom options. */
+    opts?: { signal?: AbortSignal },
+  ): Promise<{ results: string[]; source_lang: SourceLanguage }>;
+  getProvider(): Provider;
+}
+
+/** Includes the TARGET language and the status id.
+ *  Example: en-390f5b01b49a8ee6e13fe917420c023d889b3da8e983a14c9e84587e43d12c15
+ *  The example above means:
+ *  I want the status 390f5b01b49a8ee6e13fe917420c023d889b3da8e983a14c9e84587e43d12c15 translated to english (if it exists in the LRUCache). */
+export type dittoTranslationsKey = `${TargetLanguage}-${string}`;
+
+export const dittoTranslations = new LRUCache<dittoTranslationsKey, DittoTranslation>({
+  max: 1000,
+  ttl: Time.hours(6),
+});

src/views/mastodon/statuses.ts

@@ -113,7 +113,7 @@ async function renderStatus(event: DittoEvent, opts: RenderStatusOpts): Promise<
     sensitive: !!cw,
     spoiler_text: (cw ? cw[1] : subject?.[1]) || '',
     visibility: 'public',
-    language: event.tags.find((tag) => tag[0] === 'l' && tag[2] === 'ISO-639-1')?.[1] || null,
+    language: event.language ?? null,
     replies_count: event.event_stats?.replies_count ?? 0,
     reblogs_count: event.event_stats?.reposts_count ?? 0,
     favourites_count: event.event_stats?.reactions['+'] ?? 0,