package rdp

import (
	"io"
	"sync"
	"time"
	"unicode/utf16"
)

const (
	fastPathInputEventScancode = 0
	fastPathInputEventMouse    = 1
	fastPathInputEventUnicode  = 4

	fastPathInputKBRelease   = 0x01
	fastPathInputKBExtended  = 0x02
	fastPathInputKBExtended1 = 0x04

	ptrFlagsMove  = 0x0800
	ptrFlagsDown  = 0x8000
	ptrFlagsBtn1  = 0x1000
	ptrFlagsBtn2  = 0x2000
	ptrFlagsBtn3  = 0x4000
	ptrFlagsWheel = 0x0200
)

// InputSender 通过 Fast-Path Input 向远端发送键鼠事件 // Logan.Li
type InputSender struct {
	w  io.Writer
	mu *sync.Mutex
}

func NewInputSender(w io.Writer) *InputSender {
	return &InputSender{w: w}
}

func NewInputSenderWithLock(w io.Writer, mu *sync.Mutex) *InputSender {
	return &InputSender{w: w, mu: mu}
}

func (s *InputSender) Send(events []byte) error {
	if s.mu != nil {
		s.mu.Lock()
		defer s.mu.Unlock()
	}
	return WriteFastPathInput(s.w, events)
}

func (s *InputSender) Key(scancode int, down bool) error {
	flags := byte(0)
	if !down {
		flags |= fastPathInputKBRelease
	}
	code := uint16(scancode)
	if scancode&0xFF00 == 0xE000 {
		flags |= fastPathInputKBExtended
		code = uint16(scancode & 0xFF)
	}
	buf := []byte{byte(fastPathInputEventScancode<<5) | flags}
	buf = append(buf, byte(code))
	return s.Send(buf)
}

func (s *InputSender) MouseMove(x, y int) error {
	return s.mouseEvent(ptrFlagsMove, x, y)
}

func (s *InputSender) MouseButton(x, y, button int, down bool) error {
	flags := ptrFlagsDown
	// 浏览器 MouseEvent.button 使用 0/1/2 表示左/中/右键，RDP BTN2 才是右键。 // Logan.Li
	switch button {
	case 2:
		flags |= ptrFlagsBtn2
	case 1:
		flags |= ptrFlagsBtn3
	default:
		flags |= ptrFlagsBtn1
	}
	if !down {
		flags &^= ptrFlagsDown
	}
	return s.mouseEvent(flags, x, y)
}

func (s *InputSender) MouseWheel(x, y, deltaY int) error {
	scroll := -deltaY * 120 / 100
	if scroll == 0 && deltaY != 0 {
		if deltaY > 0 {
			scroll = -120
		} else {
			scroll = 120
		}
	}
	flags := uint16(ptrFlagsWheel | 0x0001)
	if scroll < 0 {
		flags |= 0x0100
		scroll = -scroll
	}
	buf := []byte{byte(fastPathInputEventMouse << 5)}
	buf = append(buf, byte(flags), byte(flags>>8))
	buf = append(buf, byte(x), byte(x>>8), byte(y), byte(y>>8))
	buf = append(buf, byte(scroll), byte(scroll>>8))
	return s.Send(buf)
}

func (s *InputSender) mouseEvent(flags int, x, y int) error {
	buf := []byte{byte(fastPathInputEventMouse << 5)}
	buf = append(buf, byte(flags), byte(flags>>8))
	buf = append(buf, byte(x), byte(x>>8), byte(y), byte(y>>8))
	return s.Send(buf)
}

func (s *InputSender) TypeText(text string) error {
	for _, r := range utf16.Encode([]rune(text)) {
		if err := s.unicodeKey(uint16(r), true); err != nil {
			return err
		}
		if err := s.unicodeKey(uint16(r), false); err != nil {
			return err
		}
		time.Sleep(5 * time.Millisecond)
	}
	return nil
}

func (s *InputSender) unicodeKey(code uint16, down bool) error {
	flags := byte(0)
	if !down {
		flags |= fastPathInputKBRelease
	}
	buf := []byte{byte(fastPathInputEventUnicode<<5) | flags, byte(code), byte(code >> 8)}
	return s.Send(buf)
}

func (s *InputSender) AutoExec(command string) error {
	if err := s.Key(0xE05B, true); err != nil {
		return err
	}
	if err := s.Key(0x0013, true); err != nil {
		return err
	}
	if err := s.Key(0x0013, false); err != nil {
		return err
	}
	if err := s.Key(0xE05B, false); err != nil {
		return err
	}
	time.Sleep(200 * time.Millisecond)
	if err := s.TypeText(command); err != nil {
		return err
	}
	time.Sleep(80 * time.Millisecond)
	if err := s.Key(0x001C, true); err != nil {
		return err
	}
	time.Sleep(20 * time.Millisecond)
	return s.Key(0x001C, false)
}