//go:build windows

package clipboard

import (
	"b612.me/win32api"
	"errors"
	"fmt"
	"runtime"
	"sync"
	"sync/atomic"
	"syscall"
	"time"
	"unsafe"
)

var stopSign chan struct{}
var isListening uint32

/*
func listenMethod2() (<-chan Clipboard, error) {
	if atomic.LoadUint32(&isListening) == 1 {
		return nil, errors.New("Already listening")
	}
	atomic.StoreUint32(&isListening, 1)
	res := make(chan Clipboard, 3)
	stopSign = make(chan struct{})
	hWnd, err := win32api.CreateWindowEx(0,
		"Message",
		"B612 Clipboard Listener",
		0,
		0, 0, 500, 500,
		0, 0, 0, nil)
	if hWnd == 0 || err != nil {
		return nil, fmt.Errorf("Failed to create window: %v,hWnd:%v", err, hWnd)
	}
	set, err := win32api.AddClipboardFormatListener(hWnd)
	if !set || err != nil {
		return nil, fmt.Errorf("Failed to set clipboard listener: %v", err)
	}
	fetcher := make(chan struct{}, 8)
	go fetchListener(hWnd, fetcher)
	go func() {
		for {
			select {
			case <-stopSign:
				fmt.Println("stopped")
				atomic.StoreUint32(&isListening, 0)
				close(res)
				close(stopSign)
				win32api.RemoveClipboardFormatListener(win32api.HWND(hWnd))
				win32api.DestoryWindow(hWnd)
				return
			case <-fetcher:
				cb, err := Get()
				if err != nil {
					fmt.Println(err)
				}
				if atomic.LoadUint32(&isListening) == 1 {
					res <- cb
					continue
				}
			}
		}
	}()
	return res, nil
}
func fetchListener(hWnd win32api.HWND, res chan struct{}) {
	for {
		var msg win32api.MSG
		_, err := win32api.GetMessage(&msg, hWnd, 0, 0)
		if msg.Message == 0x0012 {
			return
		}
		if err == nil && win32api.DWORD(msg.Message) == win32api.WM_CLIPBOARDUPDATE {
			res <- struct{}{}
		}
	}
}

func PauseListen() error {
	if atomic.LoadUint32(&isListening) == 0 {
		return errors.New("Not listening")
	}
	atomic.StoreUint32(&isListening, 2)
	return nil
}

func RecoverListen() error {
	if atomic.LoadUint32(&isListening) == 0 {
		return errors.New("Not Listening")
	}
	atomic.StoreUint32(&isListening, 1)
	return nil
}


func StopListen() error {
	defer func() {
		if r := recover(); r != nil {
			fmt.Println("StopListen panic:", r)
		}
	}()
	if atomic.LoadUint32(&isListening) == 0 {
		return nil
	}
	stopSign <- struct{}{}
	return nil
}


func Listen(onlyMeta bool) (<-chan Clipboard, error) {
	if atomic.LoadUint32(&isListening) != 0 {
		return nil, errors.New("Already listening")
	}
	atomic.StoreUint32(&isListening, 1)
	res := make(chan Clipboard, 3)
	stopSign = make(chan struct{})
	go func() {
		var storeSeq win32api.DWORD
		for {
			select {
			case <-stopSign:
				atomic.StoreUint32(&isListening, 0)
				close(res)
				close(stopSign)
				return
			case <-time.After(time.Millisecond * 900):
				seq, err := win32api.GetClipboardSequenceNumber()
				if err != nil {
					continue
				}
				if seq != storeSeq {
					storeSeq = seq
					//fmt.Println("Clipboard updated", seq, storeSeq)
					if atomic.LoadUint32(&isListening) == 1 {
						if !onlyMeta {
							cb, err := Get()
							if err != nil {
								continue
							}
							if atomic.LoadUint32(&isListening) == 1 {
								res <- cb
								continue
							}
						} else {
							cb, err := GetMeta()
							if err != nil {
								continue
							}
							if atomic.LoadUint32(&isListening) == 1 {
								res <- cb
								continue
							}
						}
					}
				}
			}

		}
	}()
	return res, nil
}
*/

const WM_USER_STOP = win32api.WM_USER + 1

var clipboardChannel chan Clipboard
var onlyMetaGlobal bool

var hwndGlobal win32api.HWND

var lastSequence win32api.DWORD
var sequenceMux sync.Mutex

func clipboardWndProc(hWnd win32api.HWND, uMsg win32api.UINT, wParam win32api.WPARAM, lParam win32api.LPARAM) win32api.LRESULT {
	switch uMsg {
	case 0x031D: // WM_CLIPBOARDUPDATE
		// 标记需要检查剪贴板
		go checkClipboard(false)
		return 0
	case WM_USER_STOP:
		win32api.PostQuitMessage(0)
		return 0
	case 0x0002: // WM_DESTROY
		win32api.PostQuitMessage(0)
		return 0
	}
	return win32api.DefWindowProc(hWnd, uMsg, wParam, lParam)
}

// 检查剪贴板是否真的有变化
func checkClipboard(ignoreMessage bool) {
	if atomic.LoadUint32(&isListening) != 1 {
		return
	}

	sequenceMux.Lock()
	defer sequenceMux.Unlock()

	// 获取当前剪贴板序列号
	var currentSeq win32api.DWORD
	runInWorker(func() {
		currentSeq, _ = win32api.GetClipboardSequenceNumber()
	})

	// 如果序列号没有变化，跳过
	if !ignoreMessage && currentSeq == lastSequence {
		return
	}
	lastSequence = currentSeq

	// 尝试读取剪贴板，带重试机制
	var cb Clipboard
	var err error
	maxRetries := 3
	retryDelay := 10 * time.Millisecond

	for i := 0; i < maxRetries; i++ {
		runInWorker(func() {
			if !onlyMetaGlobal {
				cb, err = getClipboardWithRetry()
			} else {
				cb, err = getMetaWithRetry()
			}
		})

		if err == nil {
			break
		}

		// 如果剪贴板被占用，稍等再试
		if i < maxRetries-1 {
			time.Sleep(retryDelay)
			retryDelay *= 2 // 指数退避
		}
	}

	if err == nil && clipboardChannel != nil {
		select {
		case clipboardChannel <- cb:
		default:
			// channel满了，移除最旧的
			select {
			case <-clipboardChannel:
				clipboardChannel <- cb
			default:
			}
		}
	}
}

func handleClipboardUpdate() {
	if atomic.LoadUint32(&isListening) != 1 {
		return
	}

	var cb Clipboard
	var err error
	if !onlyMetaGlobal {
		cb, err = Get()
	} else {
		cb, err = GetMeta()
	}
	if err == nil && clipboardChannel != nil {
		select {
		case clipboardChannel <- cb:
		default:
			// channel满了，丢弃旧数据
		}
	}
}

func Listen(onlyMeta bool) (<-chan Clipboard, error) {
	if atomic.LoadUint32(&isListening) != 0 {
		return nil, errors.New("Already listening")
	}
	atomic.StoreUint32(&isListening, 1)

	res := make(chan Clipboard, 10) // 增大缓冲区
	clipboardChannel = res
	onlyMetaGlobal = onlyMeta
	stopSign = make(chan struct{})

	// 初始化序列号
	runInWorker(func() {
		lastSequence, _ = win32api.GetClipboardSequenceNumber()
	})

	go func() {
		runtime.LockOSThread()
		defer runtime.UnlockOSThread()

		defer func() {
			if hwndGlobal != 0 {
				win32api.RemoveClipboardFormatListener(hwndGlobal)
				win32api.DestroyWindow(hwndGlobal)
				hwndGlobal = 0
			}
			atomic.StoreUint32(&isListening, 0)
			close(res)
			clipboardChannel = nil
		}()

		hInstance, err := win32api.GetModuleHandle(nil)
		if err != nil {
			return
		}

		className := fmt.Sprintf("ClipListener_%d", time.Now().UnixNano())

		var wc win32api.WNDCLASSEX
		wc.CbSize = win32api.UINT(unsafe.Sizeof(wc))
		wc.Style = 0
		wc.LpfnWndProc = syscall.NewCallback(clipboardWndProc)
		wc.CbClsExtra = 0
		wc.CbWndExtra = 0
		wc.HInstance = hInstance
		wc.HIcon = 0
		wc.HCursor = 0
		wc.HbrBackground = 0
		wc.LpszMenuName = nil
		wc.LpszClassName = syscall.StringToUTF16Ptr(className)
		wc.HIconSm = 0

		_, err = win32api.RegisterClassEx(&wc)
		if err != nil {
			return
		}

		hwnd, err := win32api.CreateWindowEx(
			0, className, "", 0,
			0, 0, 0, 0,
			0, 0, hInstance, unsafe.Pointer(nil))
		if err != nil {
			return
		}
		hwndGlobal = hwnd

		ok, err := win32api.AddClipboardFormatListener(hwnd)
		if err != nil || !ok {
			win32api.DestroyWindow(hwnd)
			return
		}
		go func() {
			ticker := time.NewTicker(5000 * time.Millisecond)
			defer ticker.Stop()

			for {
				select {
				case <-stopSign:
					return
				case <-ticker.C:
					// 定期检查，防止遗漏
					go checkClipboard(false)
				}
			}
		}()
		// 监听停止信号
		go func() {
			<-stopSign
			if hwndGlobal != 0 {
				win32api.PostMessage(hwndGlobal, WM_USER_STOP, 0, 0)
			}
		}()

		// 消息循环
		for {
			var msg win32api.MSG
			ret, err := win32api.GetMessage(&msg, 0, 0, 0)

			if ret == 0 {
				// 收到WM_QUIT消息，正常退出
				break
			}

			if ret == 0xFFFFFFFF {
				// GetMessage出错
				if err != nil {
					fmt.Printf("GetMessage error: %v\n", err)
				}
				continue
			}

			win32api.TranslateMessage(&msg)
			win32api.DispatchMessage(&msg)
		}
	}()

	return res, nil
}

func StopListen() {
	if atomic.LoadUint32(&isListening) == 1 && stopSign != nil {
		close(stopSign)
	}
}

// 在工作线程中执行剪贴板操作
func runInWorker(fn func()) {
	done := make(chan struct{})
	clipboardWorker <- func() {
		fn()
		close(done)
	}
	<-done
}