feat: create dittoTranslations LRUCache, create DittoTranslator interface, create MastodonTranslation type, create DittoTranslation type, create Provider type and some other minor ones

src/translators/translator.ts

@@ -0,0 +1,65 @@
+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(
+    /** HTML-encoded content of the status. */
+    content: string,
+    /** Spoiler warning of the status. */
+    spoilerText: string,
+    /** Media descriptions of the status. */
+    mediaAttachments: { id: string; description: string }[],
+    /** Poll of the status. */
+    poll: { id: string; options: { title: string }[] } | null,
+    /** 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<DittoTranslation>;
+}
+
+/** 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),
+});