import dgram from "node:dgram"

export function createWolPacket(mac) {
    const parts = mac.split(/[:-]/);
    if (parts.length !== 6) throw new Error("Invalid MAC address")
    const hex = parts.map(p => {
        const n = parseInt(p, 16);
        if (isNaN(n)) throw new Error("Invalid MAC address");
        return n;
    });

    const packet = Buffer.alloc(102);
    // Fill the first 6 bytes with 0xFF
    packet.fill(0xFF, 0, 6);

    // Repeat the MAC address 16 times
    for(let i = 0; i < 16; i++) {
        hex.forEach((byte, index) => {
            packet[6 + (i * 6) + index] = byte;
        });
    }

    return packet;
}

export async function sendWolPacket(mac, broadcast = "255.255.255.255", port = 9) {
    const packet = createWolPacket(mac);
    const socket = dgram.createSocket("udp4");

    await new Promise((resolve, reject) => {
        socket.once("error", reject);
        socket.bind(() => {
            socket.setBroadcast(true);
            socket.send(packet, port, broadcast, err => {
                socket.close();
                if (err) reject(err);
                else resolve();
            });
        });
    });
}