Move i18n setup to TypeScript

ts/util/setupI18n.ts

@@ -0,0 +1,87 @@
+// Copyright 2018-2020 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { LocaleMessagesType } from '../types/I18N';
+import { LocalizerType } from '../types/Util';
+
+export function setupI18n(
+  locale: string,
+  messages: LocaleMessagesType
+): LocalizerType {
+  if (!locale) {
+    throw new Error('i18n: locale parameter is required');
+  }
+  if (!messages) {
+    throw new Error('i18n: messages parameter is required');
+  }
+
+  const getMessage: LocalizerType = (key, substitutions) => {
+    // eslint-disable-next-line no-console
+    const log =
+      typeof window !== 'undefined' ? window.SignalWindow.log : console;
+
+    const entry = messages[key];
+    if (!entry) {
+      log.error(
+        `i18n: Attempted to get translation for nonexistent key '${key}'`
+      );
+      return '';
+    }
+    if (Array.isArray(substitutions) && substitutions.length > 1) {
+      throw new Error(
+        'Array syntax is not supported with more than one placeholder'
+      );
+    }
+    if (
+      typeof substitutions === 'string' ||
+      typeof substitutions === 'number'
+    ) {
+      throw new Error('You must provide either a map or an array');
+    }
+
+    const { message } = entry;
+    if (!substitutions) {
+      return message;
+    }
+    if (Array.isArray(substitutions)) {
+      return substitutions.reduce(
+        (result, substitution) => result.replace(/\$.+?\$/, substitution),
+        message
+      );
+    }
+
+    const FIND_REPLACEMENTS = /\$([^$]+)\$/g;
+
+    let match = FIND_REPLACEMENTS.exec(message);
+    let builder = '';
+    let lastTextIndex = 0;
+
+    while (match) {
+      if (lastTextIndex < match.index) {
+        builder += message.slice(lastTextIndex, match.index);
+      }
+
+      const placeholderName = match[1];
+      const value = substitutions[placeholderName];
+      if (!value) {
+        log.error(
+          `i18n: Value not provided for placeholder ${placeholderName} in key '${key}'`
+        );
+      }
+      builder += value || '';
+
+      lastTextIndex = FIND_REPLACEMENTS.lastIndex;
+      match = FIND_REPLACEMENTS.exec(message);
+    }
+
+    if (lastTextIndex < message.length) {
+      builder += message.slice(lastTextIndex);
+    }
+
+    return builder;
+  };
+
+  getMessage.getLocale = () => locale;
+
+  return getMessage;
+}