using System;

namespace DS4Windows
{
    public class TouchpadEventArgs : EventArgs
    {
        public readonly Touch[] touches = null;
        public readonly DateTime timeStamp;
        public readonly bool touchButtonPressed;
        public TouchpadEventArgs(DateTime utcTimestamp, bool tButtonDown, Touch t0, Touch t1 = null)
        {
            if (t1 != null)
            {
                touches = new Touch[2];
                touches[0] = t0;
                touches[1] = t1;
            }
            else if (t0 != null)
            {
                touches = new Touch[1];
                touches[0] = t0;
            }

            touchButtonPressed = tButtonDown;
            timeStamp = utcTimestamp;
        }
    }

    public class Touch
    {
        public readonly int hwX, hwY, deltaX, deltaY;
        public readonly byte touchID;
        public readonly Touch previousTouch;
        public Touch(int X, int Y, byte tID, Touch prevTouch = null)
        {
            hwX = X;
            hwY = Y;
            touchID = tID;
            previousTouch = prevTouch;
            if (previousTouch != null)
            {
                deltaX = X - previousTouch.hwX;
                deltaY = Y - previousTouch.hwY;
            }
        }
    }

    public class DS4Touchpad
    {
        public event EventHandler<TouchpadEventArgs> TouchesBegan = null; // finger one or two landed (or both, or one then two, or two then one; any touches[] count increase)
        public event EventHandler<TouchpadEventArgs> TouchesMoved = null; // deltaX/deltaY are set because one or both fingers were already down on a prior sensor reading
        public event EventHandler<TouchpadEventArgs> TouchesEnded = null; // all fingers lifted
        public event EventHandler<TouchpadEventArgs> TouchButtonDown = null; // touchpad pushed down until the button clicks
        public event EventHandler<TouchpadEventArgs> TouchButtonUp = null; // touchpad button released
        public event EventHandler<EventArgs> TouchUnchanged = null; // no status change for the touchpad itself... but other sensors may have changed, or you may just want to do some processing
        public event EventHandler<EventArgs> PreTouchProcess = null; // used to publish that a touch packet is about to be processed

        public readonly static int TOUCHPAD_DATA_OFFSET = 35;
        internal int lastTouchPadX1, lastTouchPadY1,
            lastTouchPadX2, lastTouchPadY2; // tracks 0, 1 or 2 touches; we maintain touch 1 and 2 separately
        internal bool lastTouchPadIsDown;
        internal bool lastIsActive1, lastIsActive2;
        internal byte lastTouchID1, lastTouchID2;
        internal byte[] previousPacket = new byte[8];

        // We check everything other than the not bothering with not-very-useful TouchPacketCounter.
        private bool PacketChanged(byte[] data, int touchPacketOffset)
        {
            bool changed = false;
            for (int i = 0, arLen = previousPacket.Length; !changed && i < arLen; i++)
            {
                byte oldValue = previousPacket[i];
                previousPacket[i] = data[i + TOUCHPAD_DATA_OFFSET + touchPacketOffset];
                if (previousPacket[i] != oldValue)
                    changed = true;
            }

            return changed;
        }

        public void handleTouchpad(byte[] data, DS4State sensors, int touchPacketOffset = 0)
        {
            PreTouchProcess?.Invoke(this, EventArgs.Empty);

            bool touchPadIsDown = sensors.TouchButton;
            if (!PacketChanged(data, touchPacketOffset) && touchPadIsDown == lastTouchPadIsDown)
            {
                if (TouchUnchanged != null)
                    TouchUnchanged(this, EventArgs.Empty);
                return;
            }

            byte touchID1 = (byte)(data[0 + TOUCHPAD_DATA_OFFSET + touchPacketOffset] & 0x7F);
            byte touchID2 = (byte)(data[4 + TOUCHPAD_DATA_OFFSET + touchPacketOffset] & 0x7F);
            int currentX1 = ((data[2 + TOUCHPAD_DATA_OFFSET + touchPacketOffset] & 0x0F) << 8) | data[1 + TOUCHPAD_DATA_OFFSET + touchPacketOffset];
            int currentY1 = (data[3 + TOUCHPAD_DATA_OFFSET + touchPacketOffset] << 4) | ((data[2 + TOUCHPAD_DATA_OFFSET + touchPacketOffset] & 0xF0) >> 4);
            int currentX2 = ((data[6 + TOUCHPAD_DATA_OFFSET + touchPacketOffset] & 0x0F) << 8) | data[5 + TOUCHPAD_DATA_OFFSET + touchPacketOffset];
            int currentY2 = (data[7 + TOUCHPAD_DATA_OFFSET + touchPacketOffset] << 4) | ((data[6 + TOUCHPAD_DATA_OFFSET + touchPacketOffset] & 0xF0) >> 4);

            TouchpadEventArgs args;
            if (sensors.Touch1 || sensors.Touch2)
            {
                if ((sensors.Touch1 && !lastIsActive1) || (sensors.Touch2 && !lastIsActive2))
                {
                    if (TouchesBegan != null)
                    {
                        if (sensors.Touch1 && sensors.Touch2)
                            args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(currentX1, currentY1, touchID1), new Touch(currentX2, currentY2, touchID2));
                        else if (sensors.Touch1)
                            args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(currentX1, currentY1, touchID1));
                        else
                            args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(currentX2, currentY2, touchID2));

                        TouchesBegan(this, args);
                    }
                }
                else if (sensors.Touch1 == lastIsActive1 && sensors.Touch2 == lastIsActive2 && TouchesMoved != null)
                {
                    Touch tPrev, t0, t1;

                    if (sensors.Touch1 && sensors.Touch2)
                    {
                        tPrev = new Touch(lastTouchPadX1, lastTouchPadY1, lastTouchID1);
                        t0 = new Touch(currentX1, currentY1, touchID1, tPrev);
                        tPrev = new Touch(lastTouchPadX2, lastTouchPadY2, lastTouchID2);
                        t1 = new Touch(currentX2, currentY2, touchID2, tPrev);
                    }
                    else if (sensors.Touch1)
                    {
                        tPrev = new Touch(lastTouchPadX1, lastTouchPadY1, lastTouchID1);
                        t0 = new Touch(currentX1, currentY1, touchID1, tPrev);
                        t1 = null;
                    }
                    else
                    {
                        tPrev = new Touch(lastTouchPadX2, lastTouchPadY2, lastTouchID2);
                        t0 = new Touch(currentX2, currentY2, touchID2, tPrev);
                        t1 = null;
                    }

                    args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, t0, t1);

                    TouchesMoved(this, args);
                }

                if (!lastTouchPadIsDown && touchPadIsDown && TouchButtonDown != null)
                {
                    if (sensors.Touch1 && sensors.Touch2)
                        args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(currentX1, currentY1, touchID1), new Touch(currentX2, currentY2, touchID2));
                    else if (sensors.Touch1)
                        args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(currentX1, currentY1, touchID1));
                    else
                        args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(currentX2, currentY2, touchID2));

                    TouchButtonDown(this, args);
                }
                else if (lastTouchPadIsDown && !touchPadIsDown && TouchButtonUp != null)
                {
                    if (sensors.Touch1 && sensors.Touch2)
                        args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(currentX1, currentY1, touchID1), new Touch(currentX2, currentY2, touchID2));
                    else if (sensors.Touch1)
                        args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(currentX1, currentY1, touchID1));
                    else
                        args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(currentX2, currentY2, touchID2));

                    TouchButtonUp(this, args);
                }

                if (sensors.Touch1)
                {
                    lastTouchPadX1 = currentX1;
                    lastTouchPadY1 = currentY1;
                }
                if (sensors.Touch2)
                {
                    lastTouchPadX2 = currentX2;
                    lastTouchPadY2 = currentY2;
                }

                lastTouchPadIsDown = touchPadIsDown;
            }
            else
            {
                if (touchPadIsDown && !lastTouchPadIsDown)
                {
                    if (TouchButtonDown != null)
                        TouchButtonDown(this, new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, null, null));
                }
                else if (!touchPadIsDown && lastTouchPadIsDown)
                {
                    if (TouchButtonUp != null)
                        TouchButtonUp(this, new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, null, null));
                }

                if ((lastIsActive1 || lastIsActive2) && TouchesEnded != null)
                {
                    if (lastIsActive1 && lastIsActive2)
                        args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(lastTouchPadX1, lastTouchPadY1, touchID1), new Touch(lastTouchPadX2, lastTouchPadY2, touchID2));
                    else if (lastIsActive1)
                        args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(lastTouchPadX1, lastTouchPadY1, touchID1));
                    else
                        args = new TouchpadEventArgs(sensors.ReportTimeStamp, sensors.TouchButton, new Touch(lastTouchPadX2, lastTouchPadY2, touchID2));

                    TouchesEnded(this, args);
                }
            }

            lastIsActive1 = sensors.Touch1;
            lastIsActive2 = sensors.Touch2;
            lastTouchID1 = touchID1;
            lastTouchID2 = touchID2;
            lastTouchPadIsDown = touchPadIsDown;
        }
    }
}