package orchestrator

import (
	"encoding/hex"
	"fmt"
	"net"
	"strconv"
	"strings"
)

// SendWoL sends a Wake-on-LAN magic packet to broadcastIP:port for the
// given MAC (aa:bb:cc:dd:ee:ff). The packet is 6 bytes of 0xFF followed
// by the MAC repeated 16 times.
func SendWoL(mac, broadcastIP string, port int) error {
	macBytes, err := parseMAC(mac)
	if err != nil {
		return err
	}
	packet := make([]byte, 6+16*6)
	for i := 0; i < 6; i++ {
		packet[i] = 0xff
	}
	for i := 0; i < 16; i++ {
		copy(packet[6+i*6:], macBytes)
	}

	conn, err := net.Dial("udp", net.JoinHostPort(broadcastIP, strconv.Itoa(port)))
	if err != nil {
		return fmt.Errorf("dial wol: %w", err)
	}
	defer conn.Close()

	if _, err := conn.Write(packet); err != nil {
		return fmt.Errorf("write wol: %w", err)
	}
	return nil
}

func parseMAC(s string) ([]byte, error) {
	s = strings.ToLower(strings.TrimSpace(s))
	parts := strings.Split(s, ":")
	if len(parts) != 6 {
		return nil, fmt.Errorf("invalid MAC %q", s)
	}
	out := make([]byte, 6)
	for i, p := range parts {
		if len(p) != 2 {
			return nil, fmt.Errorf("invalid MAC octet %q", p)
		}
		b, err := hex.DecodeString(p)
		if err != nil {
			return nil, fmt.Errorf("invalid MAC %q: %w", s, err)
		}
		out[i] = b[0]
	}
	return out, nil
}