// <copyright file="Board.cs" company="Adrian Conlon">
// Copyright (c) Adrian Conlon. All rights reserved.
// </copyright>

namespace Z80.Test
{
    using System.Text;
    using EightBit;

    internal class Board : Bus
    {
        private readonly Configuration configuration;
        private readonly Ram ram;
        private readonly InputOutput ports;
        private readonly Disassembler disassembler;
        private readonly MemoryMapping mapping;

        private int warmstartCount = 0;

        public Board(Configuration configuration)
        {
            this.configuration = configuration;
            this.ram = new Ram(0x10000);
            this.ports = new InputOutput();
            this.CPU = new Z80(this, this.ports);
            this.disassembler = new Disassembler(this);
            this.mapping = new MemoryMapping(this.ram, 0x0000, (ushort)Mask.Mask16, AccessLevel.ReadWrite);
        }

        public Z80 CPU { get; }

        public override void RaisePOWER()
        {
            base.RaisePOWER();
            this.CPU.RaisePOWER();
            this.CPU.RaiseRESET();
            this.CPU.RaiseINT();
            this.CPU.RaiseNMI();
        }

        public override void LowerPOWER()
        {
            this.CPU.LowerPOWER();
            base.LowerPOWER();
        }

        public override void Initialize()
        {
            var programFilename = this.configuration.Program;
            var programPath = this.configuration.RomDirectory + "/" + this.configuration.Program;
            var loadAddress = this.configuration.LoadAddress;
            this.ram.Load(programPath, loadAddress.Word);

            this.CPU.LoweredHALT += this.CPU_LoweredHALT;
            this.CPU.ExecutingInstruction += this.CPU_ExecutingInstruction_CPM;

            if (this.configuration.DebugMode)
            {
                this.CPU.ExecutingInstruction += this.CPU_ExecutingInstruction_Debug;
            }

            this.Poke(0, 0xc3);  // JMP
            this.CPU.PokeWord(1, this.configuration.StartAddress);
            this.Poke(5, 0xc9);	// ret
        }

        public override MemoryMapping Mapping(ushort absolute) => this.mapping;

        private void BDOS()
        {
            switch (CPU.C())
            {
                case 0x2:
                    System.Console.Out.Write(CPU.E().ToString());
                    break;
                case 0x9:
                    for (ushort i = CPU.DE().Word; Peek(i) != '$'; ++i)
                    {
                        System.Console.Out.Write((char)Peek(i));
                    }

                    break;
            }
        }

        private void CPU_ExecutingInstruction_CPM(object sender, System.EventArgs e)
        {
            switch (this.CPU.PC().Word)
            {
                case 0x0:   // CP/M warm start
                    if (++this.warmstartCount == 2)
                    {
                        this.LowerPOWER();
                    }

                    break;
                case 0x5:   // BDOS
                    BDOS();
                    break;
                default:
                    break;
            }
        }

        private void CPU_LoweredHALT(object sender, System.EventArgs e)
        {
            this.LowerPOWER();
        }

        private void CPU_ExecutingInstruction_Debug(object sender, System.EventArgs e)
        {
            System.Console.Error.WriteLine($"{EightBit.Disassembler.State(this.CPU)}\t{this.disassembler.Disassemble(this.CPU)}");
        }
    }
}