index.js

const express = require("express");
const app = express();
const config = require("./config");


app.use(express.json()); 

/*
All the parameters to the endpoints below will simply be passed as a object in the body.
This is easily customizable.
*/
app.get("/comments", async (req, res)=>{
    try{
        let body = req.body;
        let url = config.url + "getCommentMetadata";
        let response = await _makeCall(url, body);
        res.status(200).send(response);
    }
    catch(error){
        handleError(res, error.message);
    }
});

app.get("/posts", async (req, res) => {
    try{
        let body = req.body;
        let url = config.url + "getPostMetadata";
        let response = await _makeCall(url, body);
        res.status(200).send(response);
    }   
    catch(error){
        handleError(res, error.message);
    }
});

app.post("/toggle-like-post", async (req, res) => {
    try{
        let body = req.body;
        let url = config.url + "toggleLikesOnPost";
        let response = await _makeCall(url, body);
        res.status(200).send(response);
    }
    catch(error){
        handleError(res, error.message);
    }
});

app.post("/toggle-like-comment", async (req, res) =>{
    try{
        let body = req.body;
        let url = config.url + "toggleLikesOnComment";
        let response = await _makeCall(url, body);
        res.status(200).send(response);
    }
    catch(error){
        handleError(res, error.message);
    }
});

app.post("/create-child", async (req, res) => {
    try{    
        let body = req.body;
        let url = config.url;
        if("post" in body){
            url += "createCommentOnPost";
        }
        else{
            url += "createReplyOnComment";
        }
        let response = await _makeCall(url, body);
        res.status(200).send(response);
    }   
    catch(error){
        handleError(res, error.message);
    }
});

app.post("/create-post", async (req, res)=>{
    try{
        let body = req.body;
        let url = config.url + "createPost";
        let response = await _makeCall(url, body);
        res.status(200).send(response);
    }
    catch(error){
        handleError(res, error.message);
    }

});

/*
This is where the magic happens. Each of the end points will pass in a query url
with an object of parameters. This function will construct the url and make the call.
*/
async function _makeCall(url, params){
    try{
        const keys = Object.keys(params);
        if (keys.length > 0) {
          url += "?"
          for (let index = 0; index < keys.length; index++) {
            const key = keys[index];
            if (Array.isArray(params[key])) { //It was an array of values
              let heading = `${key}=`;
              if (index > 0) {
                heading = `&${key}=`;
              }
              url += heading;
              url += (params[key]).join(`&${key}=`);
            } else { //It was just a single value
              if (index === 0) {
                url += key + "=" + params[key]
              } else {
                url += "&" + key + "=" + params[key]
              }
            }
          }
        }
        const token = config.token;
        const response = await fetch(url, {
                method: 'GET',
                headers: {
                    'Authorization': 'Bearer ' + token,
                    'Accept': 'application/json',
                    'Content-Type': 'application/json',
                }
        });
        const json = await response.json();
        if(json.error){
            throw Error("TigerGraphError:" + json.message);
        }
        return json;  
    }
    catch(error){
        throw Error(error.message);
    }
}

function handleError(res, errorMessage){
    if(errorMessage.indexOf("TigerGraphError") > 0){
        res.status(500).send({error:true, message:errorMessage})
    }
    else{
        res.status(400).send({error:true, message:errorMessage})
    }
}