index.js

const express = require('express')
const app = express()
const port = 3000
const fs = require('fs')
app.use(express.static("public"));

// default storage state
var obj = `{
    "robot_type" : "dancebot",
    "num_connected" : 0,
    "robots" : [],
    "offRobots" : []
}`;

// Write the storage default into 'Output.txt' .
fs.writeFile('public/output.json', obj, (err) => {
   // In case of a error throw err.
   if (err) throw err;
})

// open up the endpoint /robotJoin to a GET request
app.get('/robotJoin', (req, res) => {
    console.log("\n\nreq query: ", req.query);
    var exists = false;
    let output = getDataFromFile();

    console.log("output: ", output);

    var robocharge = "100%";
    var robomove = "stop";
    var roboecol = "blue";
    var roboexp = "happy";
    if(req.query['charge']!=null){
        robocharge = req.query['charge'];
    }
    if(req.query['move']!=null){
        robomove = req.query['move'];
    }
    // if(req.query['eyecol']!=null){
    //     roboecol = req.query['eyecol'];
    // }
    if(req.query['expression']!=null){
        roboexp = req.query['expression'];
    }

    if(req.query['id'] != null){
        var botlist = output.robots;
        for(i = 0; i < output.num_connected; i++){
            console.log(botlist[i]);
            let robot = botlist[i];
            console.log(robot['id']);
            if(robot['id'] === req.query['id']){
                console.log('successful find!');
                exists = true;
            }
        }
        for(i = 0; i < output.offRobots.length; i++){
            if(output.offRobots[i].id == req.query["id"]){ // Remove robot from off list if it's on it.
                output.offRobots.splice(i, 1);
                break;
            }
        }
    }

    // if robot is not specified, set him up with default settings and add id
    if(req.query['id'] == null){
        output.num_connected ++;
        var auto = 'auto_add_';
        var ROBOT_ID = auto.concat(output.num_connected.toString());
        var duck = `{"id":"${ROBOT_ID}","charge":"${robocharge}","move":"${robomove}","expression":"${roboexp}"}`;
        // var duck = `{"id":"${ROBOT_ID}","charge":"${robocharge}","move":"${robomove}","eyecol":"${roboecol}","expression":"${roboexp}"}`;
        output.robots.push(JSON.parse(duck));
        saveDataToFile(output);
    }
    else if(!exists){
        output.num_connected ++;
        var ROBOT_ID = req.query['id'];
        var duck = `{"id":"${ROBOT_ID}","charge":"${robocharge}","move":"${robomove}","expression":"${roboexp}"}`;
        // var duck = `{"id":"${ROBOT_ID}","charge":"${robocharge}","move":"${robomove}","eyecol":"${roboecol}","expression":"${roboexp}"}`;
        output.robots.push(JSON.parse(duck));
        saveDataToFile(output);
    }
    console.log(output);

    res.status(200).send('Number of Bots Added: ' + output.num_connected);
});

app.get("/robotUpdate", (req, res) => {
    // Find particular robot (either on or off) if id specified. Otherwise, return entire JSON output.
    let fileData = getDataFromFile();
    let output = {"id": req.query["id"], charge: '100%', move: 'stop', expression: 'happy', "status": "off"}; // Default starting point for all robots.
    if(req.query['id'] != null){
        let exists = false;
        for(let i = 0; i < fileData.num_connected; i++){
            if(fileData.robots[i]['id'] === req.query['id']){
                // Found robot and it's on.
                output = fileData.robots[i];
                output["status"] = "on";
                exists = true;
                break;
            }
        }
        if(!exists){
            // Look to see if it was turned off. Robots that were turned on then off are saved so they can pick up right where they left off. Robots that were never turned on are not since they'll start from the default.
            for(let j = 0; j < fileData.offRobots.length; j++){
                if(fileData.offRobots[j]['id'] === req.query['id']){
                    // Found robot and it's off.
                    output = fileData.offRobots[j];
                    output["status"] = "off";
                    break;
                }
            }
        }
    }
    console.log("robotUpdate returning ", output);
    res.send(output);
})

app.get('/robotLeave', (req, res) => {
    console.log("\n\nreq query: ", req.query);
    let output = getDataFromFile();

    console.log("output: ", output);

    if(req.query['id'] != null){
        var botlist = output.robots;
        for(i = 0; i < output.num_connected; i++){
            console.log(botlist[i]);
            let robot = botlist[i];
            console.log(robot['id']);
            if(robot['id'] === req.query['id']){
                console.log('successful find!');
                output.robots.splice(i, 1);
                output.num_connected--;

                output.offRobots.push(robot)
                saveDataToFile(output);
            }
        }
    }

    res.status(200).send('Successfully removed bot: ' + req.query['id'])
    console.log(output);
});

app.get('/userMove', (req, res) => {
    console.log("\n\nreq query: ", req.query);
    var exists = false;
    let output = getDataFromFile();

    console.log("output: ", output);

    if(req.query['id'] != null && req.query['move'] != null){
        var botlist = output.robots;
        for(i = 0; i < output.num_connected; i++){
            console.log(botlist[i]);
            let robot = botlist[i];
            console.log(robot['id']);
            if(robot['id'] === (req.query['id'])){
                console.log('successful find!');
                robot['move'] = req.query['move'];
                saveDataToFile(output);
            }
        }
    }

    res.status(200).send('Successfully changed movement of bot: ' + req.query['id'])
    console.log(output);
});

app.get('/userExpress', (req, res) => {
    console.log("\n\nreq query: ", req.query);
    var exists = false;
    let output = getDataFromFile();

    console.log("output: ", output);

    if(req.query['id'] != null && req.query['expression'] != null){
        var botlist = output.robots;
        for(i = 0; i < output.num_connected; i++){
            console.log(botlist[i]);
            let robot = botlist[i];
            console.log(robot['id']);
            if(robot['id'] === (req.query['id'])){
                console.log('successful find!');
                robot['expression'] = req.query['expression'];
                saveDataToFile(output);
            }
        }
    }

    res.status(200).send('Successfully changed expression of bot: ' + req.query['id'])
    console.log(output);
});


// listen at port 3000
app.listen(port, () => console.log(`Example app listening at http://localhost:${port}`));

// getDataFromFile returns a JSON object from a file.
function getDataFromFile() {
    // read the output.json file and parse the data
    let rawdata = fs.readFileSync('public/output.json');
    let output = JSON.parse(rawdata);
    console.log("Output.json has ", output);
    return output;
}

// saveDataToFile saves a JSON object to a file.
function saveDataToFile(data) {
    fs.writeFile('public/output.json', JSON.stringify(data), (err) => {
        if (err) throw err;
    })
}