using PIEHidNetCore;
using System.IO;
using System.Windows.Media;

namespace PamhagenSysCtrl.Helpers {
    public class Xbe24Keyboard : IDisposable, PIEDataHandler, PIEErrorHandler {

        public enum LedBank { UPPER = 0, LOWER = 1 }

        public record struct KeyState(byte[] Rows) {
            public readonly bool GetKey(int n) => (Rows[n / 6] & (1 << (n % 6))) != 0;
        }

        protected readonly PIEDevice XbeDevice;

        private KeyState LastKeyState = new(new byte[4]);
        private readonly (Color Color, bool Flashing)[] LastStates = new (Color, bool)[48];

        public bool IsKeyPressed(int keyIndex) => LastKeyState.GetKey(keyIndex);

        public event EventHandler<int>? KeyDown;
        public event EventHandler<int>? KeyUp;
        public event EventHandler<KeyState>? KeysChanged;

        public Xbe24Keyboard(int pid = 0x0555) {
            foreach (var device in PIEDevice.EnumeratePIE()) {
                if (device.Pid == pid && device.HidUsagePage == 0x0C && device.HidUsage == 1 && device.WriteLength > 1) {
                    XbeDevice = device;
                    break;
                }
            }
            if (XbeDevice == null)
                throw new ArgumentException($"No XBE keyboard with id 05f3:{pid:x4}");

            int res;
            if ((res = XbeDevice.SetupInterface()) != 0)
                throw new IOException($"Unable to SetupInterface for XBE keyboard: {res}");
            if ((res = XbeDevice.SetDataCallback(this)) != 0)
                throw new IOException($"Unable to SetDataCallback for XBE keyboard: {res}");
            if ((res = XbeDevice.SetErrorCallback(this)) != 0)
                throw new IOException($"Unable to SetErrorCallback for XBE keyboard: {res}");
        }

        public void Dispose() {
            XbeDevice?.CloseInterface();
        }

        public void HandlePIEHidData(byte[] data, PIEDevice sourceDevice, int error) {
            if (sourceDevice != XbeDevice)
                return;
            var current = new KeyState(data[3..8]);
            var last = LastKeyState;
            LastKeyState = current;
            HandleKeyStateChange(current, last);
        }

        public void HandlePIEHidError(PIEDevice sourceDevice, int error) {
            if (sourceDevice != XbeDevice)
                return;
            // TODO
        }

        protected void HandleKeyStateChange(KeyState current, KeyState last) {
            for (int i = 0; i < 24; i++) {
                if (!last.GetKey(i) && current.GetKey(i)) {
                    KeyDown?.Invoke(this, i);
                } else if (last.GetKey(i) && !current.GetKey(i)) {
                    KeyUp?.Invoke(this, i);
                }
            }
            KeysChanged?.Invoke(this, current);
        }

        protected void SendCommand(byte command, byte[] payload) {
            byte[] data = new byte[XbeDevice.WriteLength];
            data[1] = command;
            Array.Copy(payload, 0, data, 2, Math.Min(payload.Length, data.Length - 2));

            int res;
            do {
                res = XbeDevice.WriteData(data);
            } while (res == 404);
            if (res != 0)
                throw new IOException($"Unable to WriteData for XBE keyboard: {res}");
        }

        public void SetBacklight(int keyIndex, Color color, bool flashing = false) {
            SetBacklight(keyIndex, LedBank.UPPER, color, flashing);
            SetBacklight(keyIndex, LedBank.LOWER, color, flashing);
        }

        public void SetBacklight(int keyIndex, LedBank bank, Color color, bool flashing = false) {
            if (LastStates[keyIndex * 2 + (int)bank] == (color, flashing))
                return;
            SendCommand(165, [(byte)keyIndex, (byte)bank, color.R, color.G, color.B, (byte)(flashing ? 1 : 0)]);
            LastStates[keyIndex * 2 + (int)bank] = (color, flashing);
        }

        public void SetBacklight(Color color) {
            SetBacklight(LedBank.UPPER, color);
            SetBacklight(LedBank.LOWER, color);
        }

        public void SetBacklight(LedBank bank, Color color) {
            SendCommand(166, [(byte)bank, color.R, color.G, color.B]);
            for (int i = 0; i < LastStates.Length; i++)
                LastStates[i] = (color, false);
        }

        public void SetFashFrequency(int ms) {
            SendCommand(180, [(byte)(ms / 16)]);
        }
    }
}