const forge = require('node-forge');
const dgram = require('dgram');
const net = require('net');
const crypto = require('crypto');

const UDP_KEY = Buffer.from('6c1ec8e2bb9bb59ab50b0daf649b410a', 'hex');

const server = dgram.createSocket({type: 'udp4'});
server.on('error', err => {
    if (err && err.code === 'EADDRINUSE') {
        console.log('[TuyaAccessory] Discovery error: Port 6666 is in use. Will retry in 15 seconds.');
    } else {
        console.log(`[TuyaAccessory] Discovery error:\n${err.stack}`);
        server.close();
    }
});
server.on('close', () => {
    console.log('[TuyaAccessory] Discovery stopped on 6666.');
});

server.on('message', (msg, info) => {
    translate(6666, msg, info);
});

server.bind(6666, () => {
    console.log('[TuyaAccessory] Discovery started on 6666.');
});

const sserver = dgram.createSocket('udp4');
sserver.on('error', err => {
    if (err && err.code === 'EADDRINUSE') {
        console.log('[TuyaAccessory] Discovery error: Port 6667 is in use. Will retry in 15 seconds.');
    } else {
        console.log(`[TuyaAccessory] Discovery error:\n${err.stack}`);
        sserver.close();
    }
});
sserver.on('close', () => {
    console.log('[TuyaAccessory] Discovery stopped on 6667.');
});

sserver.on('message', (msg, info) => {
    translate(6667, msg, info);
});

sserver.bind(6667, () => {
    console.log('[TuyaAccessory] Discovery started on 6667.');
});

function translate(port, msg, info) {
    if (!(msg instanceof Buffer)) return;
    const len = msg.length;

    if (len < 16 ||
        msg.readUInt32BE(0) !== 0x000055aa ||
        msg.readUInt32BE(len - 4) !== 0x0000aa55
    ) {
        console.log(`[TuyaDiscovery] Incompatible UDP from ${info.address}:${port} 0x${msg.readUInt32BE(0).toString(16).padStart(8, '0')}...0x${msg.readUInt32BE(len - 4).toString(16).padStart(8, '0')}`);
        return;
    }

    const size = msg.readUInt32BE(12);
    if (len - 8 < size) {
        console.log(`[TuyaDiscovery] ERROR: UDP from ${info.address}:${port} size ${len - size}`);
        return;
    }

    const cleanMsg = msg.slice(len - size + 4, len - 8);

    let decryptedMsg,
        result;
    try {
        const decipher = crypto.createDecipheriv('aes-128-ecb', UDP_KEY, '');
        decryptedMsg = decipher.update(cleanMsg, 'utf8', 'utf8');
        decryptedMsg += decipher.final('utf8');
    } catch(ex) {
        decryptedMsg = cleanMsg.toString('utf8');
    }

    try {
        result = JSON.parse(decryptedMsg);
        console.log(`${info.address}:${port}`, JSON.stringify(result));
    } catch (ex) {
        console.log(`${info.address}:${port} Failed`, msg.toString('hex'));
    }

    console.log('  ');

    return result;
}