package transport

import (
	"context"
	"errors"
	"fmt"
	"os"
	"sync"
	"time"

	"tinygo.org/x/bluetooth"
)

func bleLog(msg string) {
	line := fmt.Sprintf("[BLE] %s | %s\n", time.Now().Format("15:04:05.000"), msg)
	fmt.Print(line)
	f, err := os.OpenFile("kvmote_debug.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return
	}
	defer f.Close()
	f.WriteString(line)
}

var (
	NusServiceUUID = bluetooth.NewUUID([16]byte{0x6e, 0x40, 0x00, 0x01, 0xb5, 0xa3, 0xf3, 0x93, 0xe0, 0xa9, 0xe5, 0x0e, 0x24, 0xdc, 0xca, 0x9e})
	NusRxUUID      = bluetooth.NewUUID([16]byte{0x6e, 0x40, 0x00, 0x02, 0xb5, 0xa3, 0xf3, 0x93, 0xe0, 0xa9, 0xe5, 0x0e, 0x24, 0xdc, 0xca, 0x9e})
)

type RealBleTransport struct {
	adapter    *bluetooth.Adapter
	device     bluetooth.Device
	rxChar     bluetooth.DeviceCharacteristic
	connected  bool
	mu         sync.Mutex
	address    bluetooth.Address
	found      bool
}

func NewBleTransport() *RealBleTransport {
	return &RealBleTransport{
		adapter: bluetooth.DefaultAdapter,
	}
}

func (t *RealBleTransport) Detect(ctx context.Context) (bool, error) {
	t.mu.Lock()
	if t.found {
		t.mu.Unlock()
		return true, nil
	}
	t.mu.Unlock()

	fmt.Println("[BLE] Iniciando Scan...")
	if err := t.adapter.Enable(); err != nil {
		return false, err
	}

	foundChan := make(chan bluetooth.Address, 1)
	go func() {
		t.adapter.Scan(func(adapter *bluetooth.Adapter, result bluetooth.ScanResult) {
			hasUUID := result.HasServiceUUID(NusServiceUUID)
			bleLog(fmt.Sprintf("visto: nome=%q hasNUS=%v addr=%s", result.LocalName(), hasUUID, result.Address.String()))
			if result.LocalName() == "KVMote" || hasUUID {
				adapter.StopScan()
				select {
				case foundChan <- result.Address:
				default:
				}
			}
		})
	}()

	select {
	case addr := <-foundChan:
		t.mu.Lock()
		t.address = addr
		t.found = true
		t.mu.Unlock()
		fmt.Println("[BLE] Encontrado!")
		return true, nil
	case <-ctx.Done():
		t.adapter.StopScan()
		return false, ctx.Err()
	case <-time.After(5 * time.Second):
		t.adapter.StopScan()
		return false, errors.New("não encontrado")
	}
}

func (t *RealBleTransport) Connect(ctx context.Context) error {
	t.mu.Lock()
	addr := t.address
	t.mu.Unlock()

	var device bluetooth.Device
	var services []bluetooth.DeviceService
	var err error

	for cycle := 1; cycle <= 3; cycle++ {
		if cycle > 1 {
			bleLog(fmt.Sprintf("Reconectando (ciclo %d)...", cycle))
			time.Sleep(1 * time.Second)
		}

		bleLog(fmt.Sprintf("Conectando (ciclo %d)...", cycle))
		device, err = t.adapter.Connect(addr, bluetooth.ConnectionParams{})
		if err != nil {
			bleLog(fmt.Sprintf("  Connect erro: %v", err))
			continue
		}

		t.mu.Lock()
		t.device = device
		t.mu.Unlock()

		// Delay crucial para BT 4.0 estabilizar a conexão antes de pedir serviços
		bleLog("Aguardando estabilização (2s)...")
		time.Sleep(2 * time.Second)

		bleLog("DiscoverServices...")
		services, err = device.DiscoverServices(nil)
		if err != nil {
			bleLog(fmt.Sprintf("  DiscoverServices erro: %v", err))
			// Tenta mais uma vez após um pequeno delay antes de desistir do ciclo
			time.Sleep(1 * time.Second)
			bleLog("DiscoverServices (retry)...")
			services, err = device.DiscoverServices(nil)
			if err != nil {
				bleLog(fmt.Sprintf("  DiscoverServices retry erro: %v", err))
				go func() { defer func() { recover() }(); device.Disconnect() }()
				continue
			}
		}
		break
	}
	if err != nil {
		return fmt.Errorf("erro ao descobrir serviços: %w", err)
	}

	bleLog(fmt.Sprintf("Serviços encontrados: %d", len(services)))
	nusIdx := -1
	for i, s := range services {
		bleLog(fmt.Sprintf("  [%d] %s", i, s.UUID().String()))
		if s.UUID() == NusServiceUUID {
			nusIdx = i
		}
	}
	if nusIdx < 0 {
		return errors.New("serviço NUS não encontrado")
	}

	bleLog("Buscando característica RX...")
	chars, err := services[nusIdx].DiscoverCharacteristics([]bluetooth.UUID{NusRxUUID})
	if err != nil || len(chars) == 0 {
		return errors.New("característica não encontrada")
	}

	t.mu.Lock()
	t.rxChar = chars[0]
	t.connected = true
	t.mu.Unlock()
	
	fmt.Println("[BLE] PRONTO!")
	t.Send([]byte{'H'})
	return nil
}

func (t *RealBleTransport) Disconnect() error {
	t.mu.Lock()
	defer t.mu.Unlock()
	if !t.connected { return nil }

	// Proteção contra crash no Windows
	go func() {
		defer func() { recover() }()
		t.device.Disconnect()
	}()

	t.connected = false
	return nil
}

func (t *RealBleTransport) IsConnected() bool {
	t.mu.Lock()
	defer t.mu.Unlock()
	return t.connected
}

func (t *RealBleTransport) Send(data []byte) error {
	t.mu.Lock()
	defer t.mu.Unlock()
	if !t.connected { return nil }
	_, err := t.rxChar.WriteWithoutResponse(data)
	return err
}

func (t *RealBleTransport) SendLossy(data []byte) error {
	return t.Send(data)
}

func (t *RealBleTransport) DeviceLabel() string { return "KVMote (BLE)" }
func (t *RealBleTransport) ClipboardConfig() (int, int, bool) { return 65536, 5, true }