package device

import (
	"encoding/binary"
	"fmt"
	"time"
)

// Touch immediately forwards an event on the persistent scrcpy connection.
// It never launches an adb shell or waits for a complete gesture.
func (s *Service) Touch(req TouchRequest) error {
	if req.Action < 0 || req.Action > 3 || req.Width < 1 || req.Height < 1 || req.Width > 65535 || req.Height > 65535 || req.X < 0 || req.Y < 0 || req.X >= req.Width || req.Y >= req.Height {
		return fmt.Errorf("触摸事件或画面坐标无效")
	}
	st := s.ensureStream()
	st.mu.Lock()
	defer st.mu.Unlock()
	if !st.running || st.serial != req.DeviceID || st.controlConn == nil {
		return fmt.Errorf("控制通道未连接，请重新开始预览")
	}
	if req.Action != 0 && !st.touchDown {
		return nil
	}
	if req.Action == 0 && st.touchDown {
		cancel := st.lastTouch
		cancel.Action = 3
		if err := st.writeTouchLocked(cancel); err != nil {
			return err
		}
	}
	if err := st.writeTouchLocked(req); err != nil {
		return fmt.Errorf("发送触摸事件失败，请重新开始预览: %w", err)
	}
	st.lastTouch = req
	st.touchDown = req.Action == 0 || req.Action == 2
	return nil
}

// scrcpy 5 INJECT_TOUCH_EVENT: 32 bytes, big endian. Generic finger id=-2.
func encodeTouch(req TouchRequest) []byte {
	packet := make([]byte, 32)
	packet[0] = 2
	packet[1] = byte(req.Action)
	binary.BigEndian.PutUint64(packet[2:10], ^uint64(1))
	binary.BigEndian.PutUint32(packet[10:14], uint32(req.X))
	binary.BigEndian.PutUint32(packet[14:18], uint32(req.Y))
	binary.BigEndian.PutUint16(packet[18:20], uint16(req.Width))
	binary.BigEndian.PutUint16(packet[20:22], uint16(req.Height))
	if req.Action == 0 || req.Action == 2 {
		binary.BigEndian.PutUint16(packet[22:24], 65535)
	}
	return packet
}

func (st *previewStream) writeTouchLocked(req TouchRequest) error {
	return st.writeControlLocked(encodeTouch(req))
}

func (st *previewStream) writeControlLocked(data []byte) error {
	_ = st.controlConn.SetWriteDeadline(time.Now().Add(500 * time.Millisecond))
	for len(data) > 0 {
		n, err := st.controlConn.Write(data)
		if err != nil {
			return err
		}
		if n == 0 {
			return fmt.Errorf("控制通道写入中断")
		}
		data = data[n:]
	}
	return nil
}

// SetScreenOff changes physical display power while keeping mirroring active.
func (s *Service) SetScreenOff(deviceID string, screenOff bool) error {
	st := s.ensureStream()
	st.lifecycle.Lock()
	defer st.lifecycle.Unlock()
	st.mu.Lock()
	defer st.mu.Unlock()
	if !st.running || st.serial != deviceID || st.controlConn == nil {
		return fmt.Errorf("控制通道未连接，请重新开始预览")
	}
	return st.setScreenOffLocked(screenOff)
}

func (st *previewStream) setScreenOffLocked(screenOff bool) error {
	if st.screenOff == screenOff {
		return nil
	}
	// scrcpy 5 SET_DISPLAY_POWER: type=10, boolean on (not Android sleep).
	on := byte(1)
	if screenOff {
		on = 0
	}
	if err := st.writeControlLocked([]byte{10, on}); err != nil {
		return fmt.Errorf("调整手机屏幕失败，请重新开始预览: %w", err)
	}
	st.screenOff = screenOff
	return nil
}