using BizHawk.Common;
using BizHawk.Emulation.Cores.Components.Z80A;

namespace BizHawk.Emulation.Cores.Computers.SinclairSpectrum
{
    /// <summary>
    /// The abstract class that all emulated models will inherit from
    /// * Main properties / fields / contruction*
    /// </summary>
    public abstract partial class SpectrumBase
    {
        #region Devices

        /// <summary>
        /// The calling ZXSpectrum class (piped in via constructor)
        /// </summary>
        public ZXSpectrum Spectrum { get; set; }

        /// <summary>
        /// Reference to the instantiated Z80 cpu (piped in via constructor)
        /// </summary>
        public Z80A CPU { get; set; }

        /// <summary>
        /// ROM and extended info
        /// </summary>
        public RomData RomData { get; set; }

        /// <summary>
        /// The emulated ULA device
        /// </summary>
        //public ULABase ULADevice { get; set; }
        public ULA ULADevice { get; set; }

        /// <summary>
        /// Monitors CPU cycles
        /// </summary>
        public CPUMonitor CPUMon { get; set; }

        /// <summary>
        /// The spectrum buzzer/beeper
        /// </summary>
        public IBeeperDevice BuzzerDevice { get; set; }

        /// <summary>
        /// A second beeper for the tape
        /// </summary>
        public IBeeperDevice TapeBuzzer { get; set; }

        /// <summary>
        /// Device representing the AY-3-8912 chip found in the 128k and up spectrums
        /// </summary>
        public IPSG AYDevice { get; set; }

        /// <summary>
        /// The spectrum keyboard
        /// </summary>
        public virtual IKeyboard KeyboardDevice { get; set; }

        /// <summary>
        /// The spectrum datacorder device
        /// </summary>
        public virtual DatacorderDevice TapeDevice { get; set; }

        /// <summary>
        /// The +3 built-in disk drive
        /// </summary>
        public virtual NECUPD765 UPDDiskDevice { get; set; }

        /// <summary>
        /// Holds the currently selected joysticks
        /// </summary>
        public virtual IJoystick[] JoystickCollection { get; set; }

        /// <summary>
        /// +3/2a printer port strobe
        /// </summary>
        protected bool PrinterPortStrobe;

        #endregion

        #region Emulator State

        /// <summary>
        /// Signs whether the frame has ended
        /// </summary>
        public bool FrameCompleted;

        /// <summary>
        /// Overflow from the previous frame (in Z80 cycles)
        /// </summary>
        public int OverFlow;

        /// <summary>
        /// The total number of frames rendered
        /// </summary>
        public int FrameCount;

        /// <summary>
        /// The current cycle (T-State) that we are at in the frame
        /// </summary>
        public long _frameCycles;

        /// <summary>
        /// Stores where we are in the frame after each CPU cycle
        /// </summary>
        public long LastFrameStartCPUTick;

        /// <summary>
        /// Gets the current frame cycle according to the CPU tick count
        /// </summary>
        public virtual long CurrentFrameCycle => CPU.TotalExecutedCycles - LastFrameStartCPUTick;

        /// <summary>
        /// Non-Deterministic bools
        /// </summary>
        public bool _render;
        public bool _renderSound;

        #endregion

        #region Constants

        /// <summary>
        /// Mask constants & misc
        /// </summary>
        protected const int BORDER_BIT = 0x07;
        protected const int EAR_BIT = 0x10;
        protected const int MIC_BIT = 0x08;
        protected const int TAPE_BIT = 0x40;
        protected const int AY_SAMPLE_RATE = 16;

        #endregion

        #region Emulation Loop

        /// <summary>
        /// Executes a single frame
        /// </summary>
        public virtual void ExecuteFrame(bool render, bool renderSound)
        {
            ULADevice.FrameEnd = false;
            ULADevice.ULACycleCounter = CurrentFrameCycle;

            InputRead = false;
            _render = render;
            _renderSound = renderSound;

            FrameCompleted = false;

            //if (UPDDiskDevice == null || !UPDDiskDevice.FDD_IsDiskLoaded)
                //TapeDevice.StartFrame();

            if (_renderSound)
            {
                if (AYDevice != null)
                    AYDevice.StartFrame();
            }

            PollInput();

            for (;;)
            {
                // run the CPU Monitor cycle
                CPUMon.ExecuteCycle();

                // cycle the tape device
                if (UPDDiskDevice == null || !UPDDiskDevice.FDD_IsDiskLoaded)
                    TapeDevice.TapeCycle();

                // has frame end been reached?
                if (ULADevice.FrameEnd)
                    break;
            }

            OverFlow = (int)CurrentFrameCycle - ULADevice.FrameLength;

            // we have reached the end of a frame
            LastFrameStartCPUTick = CPU.TotalExecutedCycles - OverFlow;

            ULADevice.LastTState = 0;

            if (AYDevice != null)
                AYDevice.EndFrame();

            FrameCount++;
                        
            if (UPDDiskDevice == null || !UPDDiskDevice.FDD_IsDiskLoaded)
                TapeDevice.EndFrame();

            FrameCompleted = true;

            // is this a lag frame?
            Spectrum.IsLagFrame = !InputRead;

            // FDC debug            
            if (UPDDiskDevice != null && UPDDiskDevice.writeDebug)
            {
                // only write UPD log every second
                if (FrameCount % 10 == 0)
                {
                    System.IO.File.AppendAllLines(UPDDiskDevice.outputfile, UPDDiskDevice.dLog);
                    UPDDiskDevice.dLog = new System.Collections.Generic.List<string>();
                    //System.IO.File.WriteAllText(UPDDiskDevice.outputfile, UPDDiskDevice.outputString);
                }                    
            }            
        }

        #endregion

        #region Reset Functions

        /// <summary>
        /// Hard reset of the emulated machine
        /// </summary>
        public virtual void HardReset()
        {
            //ULADevice.ResetInterrupt();
            ROMPaged = 0;
            SpecialPagingMode = false;
            RAMPaged = 0;
            CPU.RegPC = 0;

            Spectrum.SetCpuRegister("SP", 0xFFFF);
            Spectrum.SetCpuRegister("IY", 0xFFFF);
            Spectrum.SetCpuRegister("IX", 0xFFFF);
            Spectrum.SetCpuRegister("AF", 0xFFFF);
            Spectrum.SetCpuRegister("BC", 0xFFFF);
            Spectrum.SetCpuRegister("DE", 0xFFFF);
            Spectrum.SetCpuRegister("HL", 0xFFFF);
            Spectrum.SetCpuRegister("SP", 0xFFFF);
            Spectrum.SetCpuRegister("Shadow AF", 0xFFFF);
            Spectrum.SetCpuRegister("Shadow BC", 0xFFFF);
            Spectrum.SetCpuRegister("Shadow DE", 0xFFFF);
            Spectrum.SetCpuRegister("Shadow HL", 0xFFFF);

            CPU.Regs[CPU.I] = 0;
            CPU.Regs[CPU.R] = 0;

            TapeDevice.Reset();
            if (AYDevice != null)
                AYDevice.Reset();

            byte[][] rams = new byte[][]
            {
                RAM0,
                RAM1,
                RAM2,
                RAM3,
                RAM4,
                RAM5,
                RAM6,
                RAM7
            };

            foreach (var r in rams)
            {
                for (int i = 0; i < r.Length; i++)
                {
                    r[i] = 0x00;
                }
            }
        }

        /// <summary>
        /// Soft reset of the emulated machine
        /// </summary>
        public virtual void SoftReset()
        {
             //ULADevice.ResetInterrupt();
            ROMPaged = 0;
            SpecialPagingMode = false;
            RAMPaged = 0;
            CPU.RegPC = 0;

            Spectrum.SetCpuRegister("SP", 0xFFFF);
            Spectrum.SetCpuRegister("IY", 0xFFFF);
            Spectrum.SetCpuRegister("IX", 0xFFFF);
            Spectrum.SetCpuRegister("AF", 0xFFFF);
            Spectrum.SetCpuRegister("BC", 0xFFFF);
            Spectrum.SetCpuRegister("DE", 0xFFFF);
            Spectrum.SetCpuRegister("HL", 0xFFFF);
            Spectrum.SetCpuRegister("SP", 0xFFFF);
            Spectrum.SetCpuRegister("Shadow AF", 0xFFFF);
            Spectrum.SetCpuRegister("Shadow BC", 0xFFFF);
            Spectrum.SetCpuRegister("Shadow DE", 0xFFFF);
            Spectrum.SetCpuRegister("Shadow HL", 0xFFFF);

            CPU.Regs[CPU.I] = 0;
            CPU.Regs[CPU.R] = 0;

            TapeDevice.Reset();
            if (AYDevice != null)
                AYDevice.Reset();

            byte[][] rams = new byte[][]
            {
                RAM0,
                RAM1,
                RAM2,
                RAM3,
                RAM4,
                RAM5,
                RAM6,
                RAM7
            };

            foreach (var r in rams)
            {
                for (int i = 0; i < r.Length; i++)
                {
                    r[i] = 0x00;
                }
            }
        }

        #endregion

        #region IStatable

        public void SyncState(Serializer ser)
        {
            ser.BeginSection("ZXMachine");
            ser.Sync(nameof(FrameCompleted), ref FrameCompleted);
            ser.Sync(nameof(OverFlow), ref OverFlow);
            ser.Sync(nameof(FrameCount), ref FrameCount);
            ser.Sync(nameof(_frameCycles), ref _frameCycles);
            ser.Sync(nameof(inputRead), ref inputRead);
            ser.Sync(nameof(LastFrameStartCPUTick), ref LastFrameStartCPUTick);
            ser.Sync(nameof(LastULAOutByte), ref LastULAOutByte);
            ser.Sync(nameof(ROM0), ref ROM0, false);
            ser.Sync(nameof(ROM1), ref ROM1, false);
            ser.Sync(nameof(ROM2), ref ROM2, false);
            ser.Sync(nameof(ROM3), ref ROM3, false);
            ser.Sync(nameof(RAM0), ref RAM0, false);
            ser.Sync(nameof(RAM1), ref RAM1, false);
            ser.Sync(nameof(RAM2), ref RAM2, false);
            ser.Sync(nameof(RAM3), ref RAM3, false);
            ser.Sync(nameof(RAM4), ref RAM4, false);
            ser.Sync(nameof(RAM5), ref RAM5, false);
            ser.Sync(nameof(RAM6), ref RAM6, false);
            ser.Sync(nameof(RAM7), ref RAM7, false);
            ser.Sync(nameof(ROMPaged), ref ROMPaged);
            ser.Sync(nameof(SHADOWPaged), ref SHADOWPaged);
            ser.Sync(nameof(RAMPaged), ref RAMPaged);
            ser.Sync(nameof(PagingDisabled), ref PagingDisabled);
            ser.Sync(nameof(SpecialPagingMode), ref SpecialPagingMode);
            ser.Sync(nameof(PagingConfiguration), ref PagingConfiguration);
            ser.Sync(nameof(ROMhigh), ref ROMhigh);
            ser.Sync(nameof(ROMlow), ref ROMlow);
            ser.Sync(nameof(LastContendedReadByte), ref LastContendedReadByte);

            KeyboardDevice.SyncState(ser);
            BuzzerDevice.SyncState(ser);
            TapeBuzzer.SyncState(ser);
            ULADevice.SyncState(ser);
            CPUMon.SyncState(ser);

            if (AYDevice != null)
            {
                AYDevice.SyncState(ser);
                ((AY38912)AYDevice as AY38912).PanningConfiguration = Spectrum.Settings.AYPanConfig;
            }

            ser.Sync(nameof(tapeMediaIndex), ref tapeMediaIndex);
            if (ser.IsReader)
            {
                IsLoadState = true;
                TapeMediaIndex = tapeMediaIndex;
                IsLoadState = false;
            }
                

            TapeDevice.SyncState(ser);

            ser.Sync(nameof(diskMediaIndex), ref diskMediaIndex);
            if (ser.IsReader)
            {
                IsLoadState = true;
                DiskMediaIndex = diskMediaIndex;
                IsLoadState = false;
            }

            if (UPDDiskDevice != null)
            {
                UPDDiskDevice.SyncState(ser);
            }

            ser.EndSection();
        }

        #endregion
    }
}