Default languages with env & langcodes typed (#94)

utils/language.ts

@@ -1,6 +1,8 @@
 import languagesJson from "./languages.json";
 const { languages, exceptions, mappings } = languagesJson;
 
+export type LangCode = keyof typeof languages;
+
 const checkTypes = {
     exception: exceptions,
     mapping: mappings
@@ -20,10 +22,10 @@ const isKeyOf = <T extends object>(obj: T) => (key: keyof any): key is keyof T =
 export function replaceBoth(
     checkType: CheckType,
     langs: {
-        [key in LangType]: string
+        [key in LangType]: LangCode
     }
 ): {
-    [key in LangType]: string
+    [key in LangType]: LangCode
 } {
     const [source, target] = langTypes.map(langType => {
         const object = checkTypes[checkType][langType];
@@ -33,8 +35,8 @@ export function replaceBoth(
     return { source, target };
 }
 
-export function retrieveFromType(type?: LangType): [string, string][] {
-    const langEntries = Object.entries(languages);
+export function retrieveFromType(type?: LangType) {
+    const langEntries = Object.entries(languages) as [LangCode, string][];
 
     if (!type)
         return langEntries;
@@ -43,6 +45,10 @@ export function retrieveFromType(type?: LangType): [string, string][] {
     ));
 }
 
-export function getName(code: string): string | null {
-    return isKeyOf(languages)(code) ? languages[code] : null;
+export function isValid(code: string | null | undefined): code is LangCode {
+    return !!code && isKeyOf(languages)(code);
+}
+
+export function getName(code: string): string | null {
+    return isValid(code) ? languages[code] : null;
 }

utils/reducer.ts

@@ -1,16 +1,26 @@
-import { replaceBoth } from "./language";
+import { replaceBoth, isValid, LangCode } from "./language";
 
-export const initialState = {
-    source: "auto",
-    target: "en",
+const defaultSourceLang = process.env["NEXT_PUBLIC_DEFAULT_SOURCE_LANG"];
+const defaultTargetLang = process.env["NEXT_PUBLIC_DEFAULT_TARGET_LANG"];
+
+type State = {
+    source: LangCode,
+    target: LangCode,
+    query: string,
+    delayedQuery: string,
+    translation: string,
+    isLoading: boolean
+}
+
+export const initialState: State = {
+    source: isValid(defaultSourceLang) ? defaultSourceLang : "auto",
+    target: isValid(defaultTargetLang) ? defaultTargetLang : "en",
     query: "",
     delayedQuery: "",
     translation: "",
     isLoading: true
 }
 
-type State = typeof initialState;
-
 export enum Actions {
     SET_FIELD,
     SET_ALL,
@@ -32,7 +42,7 @@ type Action = {
     type: Actions.SWITCH_LANGS
 }
 
-export default function reducer(state: State, action: Action) {
+export default function reducer(state: State, action: Action): State {
     const { source, target } = replaceBoth("exception", {
         source: state.target,
         target: state.source

utils/translate.ts

@@ -1,10 +1,10 @@
 import UserAgent from "user-agents";
 import cheerio from "cheerio";
-import { replaceBoth } from "./language";
+import { replaceBoth, LangCode } from "./language";
 
 export async function googleScrape(
-    source: string,
-    target: string,
+    source: LangCode,
+    target: LangCode,
     query: string
 ): Promise<{
     translationRes: string
@@ -57,8 +57,8 @@ export function extractSlug(slug: string[]): {
     }
 }
 
-export async function textToSpeechScrape(lang: string, text: string) {
-    const { target: parsedLang } = replaceBoth("mapping", { source: "", target: lang });
+export async function textToSpeechScrape(lang: LangCode, text: string) {
+    const { target: parsedLang } = replaceBoth("mapping", { source: "auto", target: lang });
 
     const lastSpace = text.lastIndexOf(" ", 200);
     const slicedText = text.slice(0, text.length > 200 && lastSpace !== -1 ? lastSpace : 200);