using Core.Cpu;
using Core.Io;
using Core.Memory;
using System;
using System.IO;
using System.Collections.Generic;

namespace Core
{
    public class SmsMachine
    {
        public Z80 Cpu { get; private set; }
        public SmsMemoryBus MemoryBus { get; private set; }
        public SmsIoBus IoBus { get; private set; }
        public Core.Video.SmsVdp VideoProcessor { get; private set; }
        public ushort? Breakpoint { get; set; } = null;

        // NTSC SMS T-States per frame
        public const int TStatesPerFrame = 59736;

        public SmsMachine()
        {
            MemoryBus = new SmsMemoryBus();
            VideoProcessor = new Core.Video.SmsVdp();
            IoBus = new SmsIoBus { VideoProcessor = this.VideoProcessor };
            Cpu = new Z80(MemoryBus, IoBus);
        }

        public void LoadCartridge(byte[] romData)
        {
            MemoryBus.LoadCartridge(romData);
            Reset();
        }

        public void Reset()
        {
            MemoryBus.CleanRAMData();
            Cpu.Reset();
        }

        
        public void RunFrame()
        {
            int tStatesThisFrame = 0;
            while (tStatesThisFrame < 59736) // Standard NTSC frame time
            {
                // 1. Run one CPU instruction
                int cycles = Cpu.Step();
                tStatesThisFrame += cycles;

                // 2. Tell the VDP to catch up
                VideoProcessor.Update(cycles);

                // 3. Check if the VDP is begging for attention!
                if (VideoProcessor.InterruptPending && Cpu.IFF1)
                {
                    int intCycles = Cpu.RequestInterrupt();
                    tStatesThisFrame += intCycles;
                    VideoProcessor.Update(intCycles); // Keep VDP perfectly in sync
                }

                // 4. THE RESTORED BREAKPOINT TRAP
                if (Breakpoint.HasValue && Cpu.PC == Breakpoint.Value)
                {
                    break; // Instantly abort the frame so the debugger can take over!
                }
            }
        }
    }
}