Add language endpoint to developer APIs (#41)

* Added languages endpoint and its tests

utils/language.ts

@@ -33,11 +33,16 @@ export function replaceBoth(
     return { source, target };
 }
 
-export function retrieveFiltered() {
-    const [sourceLangs, targetLangs] = langTypes.map(type => (
-        Object.entries(languages).filter(([code]) => (
-            !Object.keys(exceptions[type]).includes(code)
-        ))
+export function retrieveFromType(type?: LangType): [string, string][] {
+    const langEntries = Object.entries(languages);
+
+    if (!type)
+        return langEntries;
+    return langEntries.filter(([code]) => (
+        !Object.keys(exceptions[type]).includes(code)
     ));
-    return { sourceLangs, targetLangs };
+}
+
+export function getName(code: string): string | null {
+    return isKeyOf(languages)(code) ? languages[code] : null;
 }

utils/translate.ts

@@ -7,8 +7,9 @@ export async function googleScrape(
     target: string,
     query: string
 ): Promise<{
-    translationRes?: string,
-    errorMsg?: string
+    translationRes: string
+} | {
+    errorMsg: string
 }> {
     const parsed = replaceBoth("mapping", { source, target });
     const res = await fetch(
@@ -56,10 +57,7 @@ export function extractSlug(slug: string[]): {
     }
 }
 
-export async function textToSpeechScrape(lang: string, text?: string) {
-    if (!text)
-        return null;
-
+export async function textToSpeechScrape(lang: string, text: string) {
     const { target: parsedLang } = replaceBoth("mapping", { source: "", target: lang });
 
     const lastSpace = text.lastIndexOf(" ", 200);