using Core.Audio;
using Core.Interfaces;
using Core.Memory;
using System.Diagnostics;
using static System.Runtime.InteropServices.JavaScript.JSType;

namespace Core.Io
{
    public class IO_Bus
    {
        public byte BorderColourIndex { get;  set; } = 7;
        public Ay38912 AyChip { get; private set; } = new Ay38912();
        public byte KempstonState { get; set; } = 0x00;
        public bool BeeperState { get; private set; } = false;
        public byte[] KeyboardRows = new byte[8] { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
        TapManager _tapManager = new TapManager();
        MemoryBus _memory;

        public IO_Bus(TapManager tapManager, MemoryBus memoryBus)
        {
            _tapManager = tapManager;
            _memory = memoryBus;
        }

        public byte ReadPort(ushort portAddress)
        {
            //ULA responds to any even port address (where the lowest bit is 0)
            if ((portAddress & 0x01) == 0) //Port 0xFE)
            {
                byte highByte = (byte)(portAddress >> 8); // The B register
                byte result = 0xFF; // Start assuming no keys are pressed

                
                if ((highByte & 0x01) == 0) result &= KeyboardRows[0]; // 0xFE: CAPS, Z, X, C, V
                if ((highByte & 0x02) == 0) result &= KeyboardRows[1]; // 0xFD: A, S, D, F, G
                if ((highByte & 0x04) == 0) result &= KeyboardRows[2]; // 0xFB: Q, W, E, R, T
                if ((highByte & 0x08) == 0) result &= KeyboardRows[3]; // 0xF7: 1, 2, 3, 4, 5
                if ((highByte & 0x10) == 0) result &= KeyboardRows[4]; // 0xEF: 0, 9, 8, 7, 6
                if ((highByte & 0x20) == 0) result &= KeyboardRows[5]; // 0xDF: P, O, I, U, Y
                if ((highByte & 0x40) == 0) result &= KeyboardRows[6]; // 0xBF: ENTER, L, K, J, H
                if ((highByte & 0x80) == 0) result &= KeyboardRows[7]; // 0x7F: SPACE, SYM, M, N, B
                if (_tapManager.EarBit) result |= 0x40; // Set Bit 6 high
                    else result &= 0xBF; // Set Bit 6 low
                
                //The top 3 bits (5, 6, 7) are unused by the keyboard and usually return 1 on a real Spectrum
                return (byte)(result | 0xA0);
            }

            //Kempston Joystick Port
            if ((portAddress & 0xFF) == 0x1F)
            {
                return KempstonState; 
            }
            // AY-3-8912 Data Read (Port 0xFFFD)
            if ((portAddress & 0xC002) == 0xC000)
            {
                return AyChip.ReadRegister();
            }

            return 0xFF; // Default floating bus
        }

        public void WritePort(ushort portAddress, byte portValue)
        {
            // The ULA intercepts any write to an even port address
            if ((portAddress & 0x01) == 0)
            {
                // The bottom 3 bits (0-2) define the border color
                BorderColourIndex = (byte)(portValue & 0x07);

                // Bit 4 controls the speaker
                BeeperState = (portValue & 0x10) != 0;

                // Bit 3 handles the cassette MIC output
            }
            // 128K Standard Paging Port (0x7FFD)
            // Mask 0xC002 checks A15=0, A14=1, A1=0 to prevent 0x1FFD from triggering this!
            if ((portAddress & 0xC002) == 0x4000)
            {
                _memory.HandlePaging(0x7FFD, portValue);
            }
            // +2A/+3 Extended Paging Port (0x1FFD)
            // Mask 0xF002 checks A15=0, A14=0, A13=0, A12=1, A1=0
            else if ((portAddress & 0xF002) == 0x1000)
            {
                _memory.HandlePaging(0x1FFD, portValue);
            }

            //// 128K Standard Paging Port (0x7FFD)
            //if ((portAddress & 0x8002) == 0)
            //{
            //    _memory.HandlePaging(0x7FFD, portValue);
            //}

            //// +2A/+3 Extended Paging Port (0x1FFD)
            //if ((portAddress & 0xF002) == 0x1000)
            //{
            //    _memory.HandlePaging(0x1FFD, portValue);
            //}
            // AY-3-8912 Register Select (Port 0xFFFD)
            if ((portAddress & 0xC002) == 0xC000)
            {
                AyChip.SelectRegister(portValue);
            }
            // AY-3-8912 Data Write (Port 0xBFFD)
            else if ((portAddress & 0xC002) == 0x8000)
            {
                AyChip.WriteRegister(portValue);
            }
        }
    }
}