Add language endpoint to developer APIs (#41)

* Added languages endpoint and its tests

pages/api/graphql.ts

@@ -1,21 +1,31 @@
-import { ApolloServer, gql, IResolvers } from "apollo-server-micro";
+import { ApolloServer, gql, IResolvers, ApolloError, UserInputError } from "apollo-server-micro";
 import { NextApiHandler } from "next";
 import NextCors from "nextjs-cors";
 import { googleScrape, textToSpeechScrape } from "@utils/translate";
+import { retrieveFromType, getName } from "@utils/language";
 
 export const typeDefs = gql`
+    enum LangType {
+        SOURCE,
+        TARGET
+    }
     type Query {
         translation(source: String="auto" target: String="en" query: String!): Translation!
         audio(lang: String! query: String!): Entry!
+        languages(type: LangType): [Language]!
     }
     type Translation {
         source: Entry!
         target: Entry!
     }
     type Entry {
-        lang: String!
-        text: String
-        audio: [Int]
+        lang: Language!
+        text: String!
+        audio: [Int]!
+    }
+    type Language {
+        code: String!
+        name: String!
     }
 `;
 
@@ -25,35 +35,65 @@ export const resolvers: IResolvers = {
             const { source, target, query } = args;
             return {
                 source: {
-                    lang: source,
+                    lang: {
+                        code: source
+                    },
                     text: query
                 },
                 target: {
-                    lang: target
+                    lang: {
+                        code: target
+                    }
                 }
             };
         },
         audio(_, args) {
+            const { lang, query } = args;
             return {
-                lang: args.lang,
-                text: args.query
+                lang: {
+                    code: lang
+                },
+                text: query
             };
+        },
+        languages(_, args) {
+            const { type } = args;
+            const langEntries = retrieveFromType(type?.toLocaleLowerCase());
+            return langEntries.map(([code, name]) => ({ code, name }));
         }
     },
     Translation: {
         async target(parent) {
             const { source, target } = parent;
-            const { translationRes } = await googleScrape(source.lang, target.lang, source.text);
+            const textScrape = await googleScrape(source.lang.code, target.lang.code, source.text);
+
+            if ("errorMsg" in textScrape)
+                throw new ApolloError(textScrape.errorMsg);
             return {
                 lang: target.lang,
-                text: translationRes
+                text: textScrape.translationRes
             };
         }
     },
     Entry: {
         async audio(parent) {
             const { lang, text } = parent;
-            return await textToSpeechScrape(lang, text);
+            const audio = await textToSpeechScrape(lang.code, text);
+            if (!audio)
+                throw new ApolloError("An error occurred while retrieving the audio");
+            return audio;
+        }
+    },
+    Language: {
+        name(parent) {
+            const { code, name } = parent;
+            if (name)
+                return name;
+
+            const newName = getName(code);
+            if (!newName)
+                throw new UserInputError("Invalid language code");
+            return newName;
         }
     }
 };

pages/api/v1/[[...slug]].ts

@@ -3,9 +3,11 @@ import NextCors from "nextjs-cors";
 import { googleScrape, textToSpeechScrape } from "@utils/translate";
 
 type Data = {
-    translation?: string,
-    audio?: number[],
-    error?: string
+    translation: string,
+} | {
+    audio: number[]
+} | {
+    error: string
 };
 
 const methods = ["GET"];
@@ -39,11 +41,11 @@ const handler: NextApiHandler<Data> = async (req, res) => {
             : res.status(500).json({ error: "An error occurred while retrieving the audio" });
     }
 
-    const { translationRes, errorMsg } = await googleScrape(source, target, query);
+    const textScrape = await googleScrape(source, target, query);
 
-    if (errorMsg)
-        return res.status(500).json({ error: errorMsg });
-    res.status(200).json({ translation: translationRes });
+    if ("errorMsg" in textScrape)
+        return res.status(500).json({ error: textScrape.errorMsg });
+    res.status(200).json({ translation: textScrape.translationRes });
 }
 
 export default handler;

pages/api/v1/languages/[[...slug]].ts

@@ -0,0 +1,47 @@
+import { NextApiHandler } from "next";
+import NextCors from "nextjs-cors";
+import { retrieveFromType } from "@utils/language";
+
+type Data = {
+    languages: {
+        code: string,
+        name: string
+    }[]
+} | {
+    error: string
+};
+
+const methods = ["GET"];
+
+const handler: NextApiHandler<Data> = async (req, res) => {
+    await NextCors(req, res, {
+        methods,
+        origin: "*",
+        preflightContinue: true
+    });
+
+    const {
+        query: { slug },
+        method
+    } = req;
+
+    if (slug && Array.isArray(slug) && slug.length > 1)
+        return res.status(404).json({ error: "Not Found" });
+
+    if (!method || !methods.includes(method)) {
+        res.setHeader("Allow", methods);
+        return res.status(405).json({ error: "Method Not Allowed" });
+    }
+
+    const type = slug?.[0];
+
+    if (type !== undefined && type !== "source" && type !== "target")
+        return res.status(400).json({ error: "Type should be 'source', 'target' or empty" });
+
+    const langEntries = retrieveFromType(type);
+    const languages = langEntries.map(([code, name]) => ({ code, name }));
+
+    res.status(200).json({ languages });
+}
+
+export default handler;