feat: add core i18n runtime and catalogs

lib/i18n/catalog.ts

@@ -0,0 +1,53 @@
+import { enCatalog } from "../../locales/en";
+import { trCatalog } from "../../locales/tr";
+import type { I18nNamespace, TranslationCatalog } from "./types";
+
+export const DEFAULT_LOCALE = "tr";
+export const BUILT_IN_LOCALES = ["tr", "en"] as const;
+
+export const BUILT_IN_CATALOGS: Record<string, TranslationCatalog> = {
+  tr: trCatalog,
+  en: enCatalog,
+};
+
+export function getBuiltInCatalog(locale: string): TranslationCatalog | null {
+  return BUILT_IN_CATALOGS[locale] ?? null;
+}
+
+export function pickNamespaces(
+  catalog: TranslationCatalog,
+  namespaces: readonly I18nNamespace[],
+): Partial<TranslationCatalog> {
+  return Object.fromEntries(
+    namespaces.map((namespace) => [namespace, catalog[namespace] ?? {}]),
+  ) as Partial<TranslationCatalog>;
+}
+
+export function flattenCatalog(
+  catalog: Partial<TranslationCatalog>,
+  namespaces: readonly I18nNamespace[],
+): Record<string, string> {
+  const entries: Record<string, string> = {};
+
+  for (const namespace of namespaces) {
+    const namespaceCatalog = catalog[namespace] ?? {};
+    for (const [key, value] of Object.entries(namespaceCatalog)) {
+      entries[`${namespace}.${key}`] = value;
+    }
+  }
+
+  return entries;
+}
+
+export function compareCatalogKeys(
+  left: TranslationCatalog,
+  right: TranslationCatalog,
+  namespaces: readonly I18nNamespace[],
+): { missingInLeft: string[]; missingInRight: string[] } {
+  const leftKeys = new Set(Object.keys(flattenCatalog(left, namespaces)));
+  const rightKeys = new Set(Object.keys(flattenCatalog(right, namespaces)));
+  return {
+    missingInLeft: [...rightKeys].filter((key) => !leftKeys.has(key)).sort(),
+    missingInRight: [...leftKeys].filter((key) => !rightKeys.has(key)).sort(),
+  };
+}