package clipboard

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

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() (<-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 {
						cb, err := Get()
						if err != nil {
							continue
						}
						if atomic.LoadUint32(&isListening) == 1 {
							res <- cb
							continue
						}
					}
				}
			}

		}
	}()
	return res, nil
}