Extensions cleanup (#257)

* [Cleanup] Add enums and types

* Extract "default languages" from ISOLanguages

The "default languages" will also be translated depending on which language the user selected

src/screens/util/Extensions.ts

@@ -0,0 +1,44 @@
+import { IExtension, TranslationKey } from 'typings';
+import { DefaultLanguage, langCodeToName } from 'util/language';
+import { t } from 'i18next';
+
+export enum ExtensionState {
+    INSTALLED = 'INSTALLED',
+    UPDATE_PENDING = 'UPDATE_PENDING',
+}
+
+export type GroupedExtensionsResult<KEY extends string = string> = [KEY, IExtension[]][];
+
+export type GroupedByExtensionState = {
+    [state in ExtensionState]: IExtension[];
+};
+
+export type GroupedByLanguage = {
+    [language in DefaultLanguage]: IExtension[];
+} & {
+    [language: string]: IExtension[];
+};
+
+export type GroupedExtensions = GroupedByExtensionState & GroupedByLanguage;
+
+export const extensionLanguageToTranslationKey: { [state in ExtensionState | DefaultLanguage]: TranslationKey } = {
+    [ExtensionState.INSTALLED]: 'extension.state.label.installed',
+    [ExtensionState.UPDATE_PENDING]: 'extension.state.label.update_pending',
+    [DefaultLanguage.ALL]: 'extension.language.all',
+    [DefaultLanguage.OTHER]: 'extension.language.other',
+    [DefaultLanguage.LOCAL_SOURCE]: 'source.local_source.title',
+};
+
+export const isExtensionStateOrLanguage = (languageCode: string): boolean =>
+    [
+        ExtensionState.INSTALLED,
+        ExtensionState.UPDATE_PENDING,
+        DefaultLanguage.ALL,
+        DefaultLanguage.OTHER,
+        DefaultLanguage.LOCAL_SOURCE,
+    ].includes(languageCode as ExtensionState | DefaultLanguage);
+
+export const translateExtensionLanguage = (languageCode: string): string =>
+    isExtensionStateOrLanguage(languageCode)
+        ? (t(extensionLanguageToTranslationKey[languageCode as ExtensionState | DefaultLanguage]) as string)
+        : langCodeToName(languageCode);