import fs from "fs";
import { execSync } from "child_process";

const WG_CONF = "/etc/wireguard/wg0.conf";
const PEER_DB = "/etc/wireguard/peers.json";
const CLIENT_DIR = "/etc/wireguard/clients";

const SERVER_PUBLIC_KEY = "<SERVER_PUBLIC_KEY>";
const SERVER_IP = "<SERVER_PUBLIC_IP>";

function loadDb() {
    try {
        return JSON.parse(fs.readFileSync(PEER_DB, "utf8"));
    } catch {
        const initial = { lastIp: 1, active: {}, free: [] };
        fs.writeFileSync(PEER_DB, JSON.stringify(initial, null, 2));
        return initial;
    }
}

function saveDb(db) {
    fs.writeFileSync(PEER_DB, JSON.stringify(db, null, 2));
}

function allocateIp(db) {
    if (db.free.length > 0) {
        return db.free.shift(); // reuse old IP
    }

    db.lastIp++;
    if (db.lastIp >= 255) db.lastIp = 2;

    return `10.0.0.${db.lastIp}`;
}

function generateKeyPair() {
    const privateKey = execSync("wg genkey").toString().trim();
    const publicKey = execSync(`echo ${privateKey} | wg pubkey`).toString().trim();
    return { privateKey, publicKey };
}

// function addPeerToServer(publicKey, ip) {
//     const ipLast = ip.split(".")[3];

//     const peerEntry = `
// [Peer]
// PublicKey = ${publicKey}
// AllowedIPs = 10.0.0.${ipLast}/32
// `;

//     fs.appendFileSync(WG_CONF, peerEntry);

//     // apply config instantly
//     // execSync(`wg syncconf wg0 <(wg-quick strip wg0)`, { shell: "/bin/bash" });
//     execSync(`wg-quick strip wg0 > /tmp/wg0.tmp`);
//     execSync(`wg syncconf wg0 /tmp/wg0.tmp`);

// }

function addPeerToServer(publicKey, ip) {
    //     const peerEntry = `
    // [Peer]
    // PublicKey = ${publicKey}
    // AllowedIPs = ${ip}/32
    // `;

    //     fs.appendFileSync(WG_CONF, peerEntry);

    //     execSync("wg-quick strip wg0 > /tmp/wg0.tmp");
    //     execSync("wg syncconf wg0 /tmp/wg0.tmp");
    //     execSync("rm -f /tmp/wg0.tmp");
    execSync(
        `wg set wg0 peer ${publicKey} allowed-ips ${ip}/32`,
        { stdio: "inherit" }
    );
}


function generateClientConf(privateKey, ip) {
    return `
[Interface]
PrivateKey = ${privateKey}
Address = ${ip}/32
DNS = 1.1.1.1

[Peer]
PublicKey = ${SERVER_PUBLIC_KEY}
Endpoint = ${SERVER_IP}:51820
AllowedIPs = 10.0.0.0/24
PersistentKeepalive = 25
`;
}

export function createWireGuardConnection() {
    let db = loadDb();

    // 1. allocate IP
    const ip = allocateIp(db);

    // 2. generate keys
    const { privateKey, publicKey } = generateKeyPair();

    // 3. update server config
    addPeerToServer(publicKey, ip);

    // 4. update DB
    db.active[ip] = publicKey;
    saveDb(db);

    // 5. prepare client.conf
    const clientConf = generateClientConf(privateKey, ip);

    // (optional) save it
    if (!fs.existsSync(CLIENT_DIR)) fs.mkdirSync(CLIENT_DIR);
    fs.writeFileSync(`${CLIENT_DIR}/client-${ip}.conf`, clientConf);

    // 6. return to Electron app
    return { ip, publicKey, clientConf };
}


// -------- Disconnect VPN PART START -----------
const removePeerFromConf = (publicKey) => {
    const conf = fs.readFileSync(WG_CONF, "utf8");

    const peerRegex = new RegExp(
        `\\n\\[Peer\\][\\s\\S]*?PublicKey = ${publicKey}[\\s\\S]*?(?=\\n\\[Peer\\]|$)`,
        "g"
    );

    const updated = conf.replace(peerRegex, "\n");

    fs.writeFileSync(WG_CONF, updated);
}

function syncWireGuard() {
    execSync("wg-quick strip wg0 > /tmp/wg0.tmp");
    execSync("wg syncconf wg0 /tmp/wg0.tmp");
    execSync("rm -f /tmp/wg0.tmp");
}

export function disconnectWireGuardConnection(ip) {
    const db = loadDb();

    const publicKey = db.active[ip];
    if (!db.active[ip]) {
        return { success: false, message: "VPN already disconnected" };
    }

    // 1️⃣ Remove peer from live kernel
    execSync(`wg set wg0 peer ${publicKey} remove`);

    // 2️⃣ Remove from config file
    removePeerFromConf(publicKey);

    // 3️⃣ Sync config
    syncWireGuard();

    // 4️⃣ Update DB (free IP)
    delete db.active[ip];
    db.free.push(ip);
    saveDb(db);

    return {
        success: true,
        message: "VPN disconnected",
        ip
    };
}