//go:build linux

package ble

import (
	"fmt"
	"strings"
	"sync"
	"time"

	"github.com/muka/go-bluetooth/api"
	"github.com/muka/go-bluetooth/bluez"
	"github.com/muka/go-bluetooth/bluez/profile/adapter"
	"github.com/muka/go-bluetooth/bluez/profile/device"
	"github.com/muka/go-bluetooth/bluez/profile/gatt"
)

type Client struct {
	deviceName  string
	modeChan    chan string
	stopChan    chan struct{}
	mu          sync.Mutex
	connected   bool
	currentMode string
}

func New(deviceName string) *Client {
	c := &Client{
		deviceName: deviceName,
		modeChan:   make(chan string, 10),
		stopChan:   make(chan struct{}),
	}
	go c.run()
	return c
}

func (c *Client) SetMode(mode string) {
	if mode == "" {
		return
	}
	c.mu.Lock()
	if mode == c.currentMode {
		c.mu.Unlock()
		return
	}
	c.mu.Unlock()

	select {
	case c.modeChan <- mode:
	default:
	}
}

func (c *Client) Close() {
	close(c.stopChan)
}

func (c *Client) run() {
	retryDelay := time.Second
	maxRetryDelay := 30 * time.Second

	for {
		select {
		case <-c.stopChan:
			return
		default:
		}

		char, cleanup, err := c.connect()
		if err != nil {
			logWarn("BLE 连接失败: %v, %v后重试", err, retryDelay)
			select {
			case <-c.stopChan:
				return
			case <-time.After(retryDelay):
			}
			retryDelay *= 2
			if retryDelay > maxRetryDelay {
				retryDelay = maxRetryDelay
			}
			continue
		}

		retryDelay = time.Second
		c.mu.Lock()
		c.connected = true
		c.mu.Unlock()
		logInfo("BLE 已连接: %s", c.deviceName)

		disconnected := c.processLoop(char)

		c.mu.Lock()
		c.connected = false
		c.mu.Unlock()

		if cleanup != nil {
			cleanup()
		}

		if disconnected {
			logWarn("BLE 断开连接, 1秒后重连")
			select {
			case <-c.stopChan:
				return
			case <-time.After(time.Second):
			}
		}
	}
}

func (c *Client) processLoop(char *gatt.GattCharacteristic1) bool {
	for {
		select {
		case <-c.stopChan:
			return false
		case mode := <-c.modeChan:
			if err := c.writeMode(char, mode); err != nil {
				logError("BLE 写入失败: %v", err)
				return true
			}
			c.mu.Lock()
			c.currentMode = mode
			c.mu.Unlock()
			logDebug("BLE 模式已设置: %s", mode)
		}
	}
}

func (c *Client) connect() (*gatt.GattCharacteristic1, func(), error) {
	a, err := api.GetDefaultAdapter()
	if err != nil {
		return nil, nil, fmt.Errorf("获取蓝牙适配器失败: %w", err)
	}

	adapterProps, err := adapter.NewAdapter1FromAdapterID(string(a.Path()))
	if err != nil {
		return nil, nil, fmt.Errorf("初始化适配器失败: %w", err)
	}

	powered, err := adapterProps.GetPowered()
	if err != nil {
		return nil, nil, fmt.Errorf("获取适配器状态失败: %w", err)
	}
	if !powered {
		if err := adapterProps.SetPowered(true); err != nil {
			return nil, nil, fmt.Errorf("启动蓝牙适配器失败: %w", err)
		}
	}

	dev, cancel, err := c.scanAndConnect(a)
	if err != nil {
		return nil, nil, err
	}

	char, err := c.findCharacteristic(dev)
	if err != nil {
		cancel()
		dev.Disconnect()
		return nil, nil, err
	}

	cleanup := func() {
		dev.Disconnect()
		cancel()
	}

	return char, cleanup, nil
}

func (c *Client) scanAndConnect(a *adapter.Adapter1) (*device.Device1, func(), error) {
	discover, cancel, err := api.Discover(a, nil)
	if err != nil {
		return nil, nil, fmt.Errorf("开始扫描失败: %w", err)
	}

	timeout := time.After(10 * time.Second)

	for {
		select {
		case ev := <-discover:
			if ev == nil {
				continue
			}
			dev, err := device.NewDevice1(ev.Path)
			if err != nil {
				continue
			}
			name := dev.Properties.Name
			if name == c.deviceName {
				if err := dev.Connect(); err != nil {
					cancel()
					return nil, nil, fmt.Errorf("连接设备失败: %w", err)
				}
				return dev, cancel, nil
			}
		case <-timeout:
			cancel()
			return nil, nil, fmt.Errorf("扫描超时，未找到设备 %s", c.deviceName)
		case <-c.stopChan:
			cancel()
			return nil, nil, fmt.Errorf("扫描已取消")
		}
	}
}

func (c *Client) findCharacteristic(dev *device.Device1) (*gatt.GattCharacteristic1, error) {
	om, err := bluez.GetObjectManager()
	if err != nil {
		return nil, fmt.Errorf("获取 ObjectManager 失败: %w", err)
	}

	objects, err := om.GetManagedObjects()
	if err != nil {
		return nil, fmt.Errorf("获取管理对象失败: %w", err)
	}

	devPath := string(dev.Path())

	var servicePath string
	for path, ifaces := range objects {
		pathStr := string(path)
		if !strings.HasPrefix(pathStr, devPath+"/") {
			continue
		}
		if _, ok := ifaces[gatt.GattService1Interface]; ok {
			svc, err := gatt.NewGattService1(path)
			if err != nil {
				continue
			}
			uuid, err := svc.GetUUID()
			if err != nil {
				continue
			}
			if uuid == serviceUUID {
				servicePath = pathStr
				break
			}
		}
	}

	if servicePath == "" {
		return nil, fmt.Errorf("服务 %s 未找到", serviceUUID)
	}

	for path, ifaces := range objects {
		pathStr := string(path)
		if !strings.HasPrefix(pathStr, servicePath+"/") {
			continue
		}
		if _, ok := ifaces[gatt.GattCharacteristic1Interface]; ok {
			char, err := gatt.NewGattCharacteristic1(path)
			if err != nil {
				continue
			}
			uuid, err := char.GetUUID()
			if err != nil {
				continue
			}
			if uuid == charUUID {
				return char, nil
			}
		}
	}

	return nil, fmt.Errorf("特征 %s 未找到", charUUID)
}

func (c *Client) writeMode(char *gatt.GattCharacteristic1, mode string) error {
	options := map[string]interface{}{
		"type": "request",
	}
	return char.WriteValue([]byte(mode), options)
}

const (
	serviceUUID = "b8b7e001-7a6b-4f4f-9a8b-11c0ffee0001"
	charUUID    = "b8b7e002-7a6b-4f4f-9a8b-11c0ffee0001"
)