// Global logging toggles
// const fileLogging = false;
const consoleLogging = true;


// Imports
// const fs = require('fs');
const http = require('http');
const express = require('express');


// Global server setup
const app = express();
const clientPath = __dirname+'/../html';
console.log('Serving static from ' + clientPath);
app.use(express.json());
app.use(express.static(clientPath));
const server = http.createServer(app);


// Check if string is already in array
function isStringUnique(arr, str) {
    let match = true;
    for (const s of arr)
        if (s === str) {
            match = false;
            break;
        }
    return match;
}

// Generate the partial ID after username
function generatePartialID() {
    return Math.floor(Math.random()*10000).toString().padStart(4, '0');
}


// User data
const users = [];
// Incoming user connection
app.post('/connect', (req, res) => {
    // Generate id, save user
    const { name } = req.body;
    let id = generatePartialID();
    const name_id = users.map(u => `${u.name}#${u.id}`);
    while (!isStringUnique(name_id, `${name}#${id}`))
        id = generatePartialID();
    users.push({
        socket: req.socket,
        date: new Date(),
        chats: {},
        name,
        id
    });
    // Log connection, send back id
    if (consoleLogging)
        console.log(`User with ID '${name}#${id}' connected.`);
    res.status(200).json({ id });
});

// User has disconnected
app.post('/disconnect', (req, res) => {
    const { name, id } = req.body;
    for (let i = 0; i < users.length; i++)
        if (users[i].name === name && users[i].id === id) {
            // If id is valid, delete all user data
            if (consoleLogging)
                console.log(`User with ID '${name}#${id}' disconnected.`);
            users.splice(i, 1);
            break;
        }
    // Confirm disconnect
    res.status(200).send();
});

// User wants to measure ping
app.get('/ping', (req, res) => {
    res.status(200).send();
});

// User wants to change name
app.post('/nickname', (req, res) => {
    const { oldName, name, id } = req.body;

    // Check if name is taken, if not, append id until unique
    const name_id = users.map(u => `${u.name}#${u.id}`);
    let currentID = id;
    while (!isStringUnique(name_id, `${name}#${currentID}`))
        currentID = generatePartialID();

    // Change username
    for (const u of users)
        if (u.name === oldName && u.id === id) {
            if (consoleLogging)
                console.log(`(Re-)named user with ID '${oldName}#${id}'.`);
            u.name = name;
            u.id = currentID;
            break;
        }

    // Confirm renaming
    res.status(200).json({ id: currentID });
});

// User is pulling messages
app.post('/getChat', (req, res) => {
    const { name, id } = req.body;

    // Go through users' chats, retrieve messages, save by username
    let chats = {};
    const fullName = `${name}#${id}`;
    for (const u of users)
        if (fullName in u.chats) {
            const len = u.chats[fullName].length;
            if (len > 0)
                chats[`${u.name}#${u.id}`] = u.chats[fullName].splice(0, len);
        }

    // No chat messages were found
    if (Object.keys(chats).length === 0) {
        res.status(204).send();
        return;
    }

    // Log if messages were delivered
    if (consoleLogging)
        console.log(`Delivered messages to user with ID '${fullName}'.`);

    // Send back data
    res.status(200).json(chats);
});

// User sent new message
app.post('/message', (req, res) => {
    const { name, id, recipient, message } = req.body;

    // Search for senders' name, save message
    for (const u of users)
        if (u.name === name && u.id === id) {
            if (!u.chats[recipient])
                u.chats[recipient] = [];
            u.chats[recipient].push(message);
            break;
        }

    // Log message for debugging
    if (consoleLogging)
        console.log(`User '${name}#${id}' sent message '${message}'.`);

    // Confirm process
    res.status(200).send();
});

// User requesting all names
app.get('/getNames', (req, res) => {
    if (consoleLogging)
        console.log('Some user requested all names.');

    res.status(200).json(users.map(u => {
        return {
            name: u.name,
            id: u.id
        };
    }));
});

// Internal server error
server.on('error', err => {
    console.error('Internal server error', err);
});

// Server has closed
server.on('close', () => {
    console.log('Shutting down server ...');
});

// Listen on port 3000 for webserver connection
server.listen(3000, () => {
    console.log('Server running on port 3000');
});