Language switch implemented

utils/language.ts

@@ -0,0 +1,47 @@
+import { languages, exceptions, mappings } from "./languages.json";
+
+const checkTypes = {
+    exception: exceptions,
+    mapping: mappings
+}
+
+type CheckType = keyof typeof checkTypes;
+
+export const langTypes = [
+    "source",
+    "target"
+] as const;
+
+type LangType = typeof langTypes[number];
+
+const isKeyOf = <T extends object>(obj: T) => (key: keyof any): key is keyof T => key in obj;
+
+export function replaceBoth(
+    checkType: CheckType,
+    langs: {
+        [key in LangType]: string
+    }
+): {
+    [key in LangType]: string
+} {
+    const [source, target] = langTypes.map(langType => {
+        const object = checkTypes[checkType][langType];
+        const langCode = langs[langType];
+        return isKeyOf(object)(langCode) ? object[langCode] : langCode;
+    });
+    return { source, target };
+}
+
+export function retrieveFiltered(source: string, target: string) {
+    const current = {
+        source: target,
+        target: source
+    };
+    const [sourceLangs, targetLangs] = langTypes.map(type => (
+        Object.entries(languages).filter(([code]) => (
+            !Object.keys(exceptions[type]).includes(code)
+            && current[type] !== code
+        ))
+    ));
+    return { sourceLangs, targetLangs };
+}