using System;
using System.Collections.Generic;

namespace MCEmuCore.GBMonolith
{
    class CpuRegisters
    {
        enum Register { A, B, C, D, E, H, L };
        private readonly byte[] Registers = new byte[7];
        public readonly FlagRegister Flags = new FlagRegister();

        #region Register Accessors
        public byte A
        {
            get
            {
                return Registers[(int)Register.A];
            }
            set
            {
                Registers[(int)Register.A] = value;
            }
        }
        public byte B
        {
            get
            {
                return Registers[(int)Register.B];
            }
            set
            {
                Registers[(int)Register.B] = value;
            }
        }
        public byte D
        {
            get
            {
                return Registers[(int)Register.D];
            }
            set
            {
                Registers[(int)Register.D] = value;
            }
        }
        public byte H
        {
            get
            {
                return Registers[(int)Register.H];
            }
            set
            {
                Registers[(int)Register.H] = value;
            }
        }
        public byte F
        {
            get
            {
                return Flags.Value;
            }
            set
            {
                Flags.Value = value;
            }
        }
        public byte C
        {
            get
            {
                return Registers[(int)Register.C];
            }
            set
            {
                Registers[(int)Register.C] = value;
            }
        }
        public byte E
        {
            get
            {
                return Registers[(int)Register.E];
            }
            set
            {
                Registers[(int)Register.E] = value;
            }
        }
        public byte L
        {
            get
            {
                return Registers[(int)Register.L];
            }
            set
            {
                Registers[(int)Register.L] = value;
            }
        }
        #endregion

        #region Wide Register Accessors
        public ushort AF
        {
            get
            {
                ushort retVal = Flags.Value;
                retVal += (ushort)((Registers[(int)Register.A]) << 8);
                return retVal;
            }
            set
            {
                Flags.Value = (byte)(value & 0x00FF);
                Registers[(int)Register.A] = (byte)((value & 0xFF00) >> 8);
            }
        }
        public ushort BC
        {
            get
            {
                ushort retVal = Registers[(int)Register.C];
                retVal += (ushort)((Registers[(int)Register.B]) << 8);
                return retVal;
            }
            set
            {
                Registers[(int)Register.C] = (byte)(value & 0x00FF);
                Registers[(int)Register.B] = (byte)((value & 0xFF00) >> 8);
            }
        }
        public ushort DE
        {
            get
            {
                ushort retVal = Registers[(int)Register.E];
                retVal += (ushort)((Registers[(int)Register.D]) << 8);
                return retVal;
            }
            set
            {
                Registers[(int)Register.E] = (byte)(value & 0x00FF);
                Registers[(int)Register.D] = (byte)((value & 0xFF00) >> 8);
            }
        }
        public ushort HL
        {
            get
            {
                ushort retVal = Registers[(int)Register.L];
                retVal += (ushort)((Registers[(int)Register.H]) << 8);
                return retVal;
            }
            set
            {
                Registers[(int)Register.L] = (byte)(value & 0x00FF);
                Registers[(int)Register.H] = (byte)((value & 0xFF00) >> 8);
            }
        }
        #endregion

        public ushort SP { get; set; }
        public ushort PC { get; set; }

        #region Constructors
        public CpuRegisters()
        {
            AF = 0x01B0;
            BC = 0x0013;
            DE = 0x00D8;
            HL = 0x014D;
        }
        public CpuRegisters(ushort initValue) : base()
        {
            AF = initValue;
            BC = initValue;
            DE = initValue;
            HL = initValue;
        }
        public CpuRegisters(byte A, byte F, ushort SP, ushort PC)
        {
            this.A = A;
            this.F = F;
            this.SP = SP;
            this.PC = PC;
        }
        public CpuRegisters(byte A, byte F, byte B, byte C, byte D, byte E, byte H, byte L, ushort SP, ushort PC) : this(A, F, SP, PC)
        {
            this.B = B;
            this.C = C;
            this.D = D;
            this.E = E;
            this.H = H;
            this.L = L;
        }
        public CpuRegisters(byte A, byte F, ushort BC, ushort DE, ushort HL, ushort SP, ushort PC) : this(A, F, SP, PC)
        {
            this.BC = BC;
            this.DE = DE;
            this.HL = HL;
        }
        #endregion

        public Dictionary<string, ushort> DumpRegisters()
        {
            return new Dictionary<string, ushort>
            {
                { "A", A },
                { "F", F },
                { "B", B },
                { "C", C },
                { "D", D },
                { "E", E },
                { "H", H },
                { "L", L },
                { "AF", AF },
                { "BC", BC },
                { "DE", DE },
                { "HL", HL },
                { "PC", PC },
                { "SP", SP }
            };
        }

        #region Print Functions
        public void PrintSingleStatus()
        {
            Console.WriteLine("Register status:");
            Console.WriteLine($"A:\t{A}\tF:\t{F}");
            Console.WriteLine($"B:\t{B}\tC:\t{C}");
            Console.WriteLine($"D:\t{D}\tE:\t{E}");
            Console.WriteLine($"H:\t{H}\tL:\t{L}\r\n");
        }
        public void PrintWideStatus()
        {
            Console.WriteLine("Wide Register status:");
            Console.WriteLine($"AF:\t{AF}");
            Console.WriteLine($"BC:\t{BC}");
            Console.WriteLine($"DE:\t{DE}");
            Console.WriteLine($"HL:\t{HL}");
        }
        public void PrintFlags()
        {
            Console.WriteLine("Flag status:");
            Console.WriteLine($"Zero:\t\t{Flags.Zero}");
            Console.WriteLine($"Subtract:\t{Flags.Subtract}");
            Console.WriteLine($"Half Carry:\t{Flags.HalfCarry}");
            Console.WriteLine($"Carry:\t\t{Flags.Carry}");
            Console.WriteLine($"Raw Register:\t{Convert.ToString(Flags.Value, 2)}");
        }
        #endregion

        public class FlagRegister
        {
            protected internal byte Value { get; set; }
            #region Boolean Flag Properties
            public bool Zero
            {
                get { return (Value & 0b1000_0000) != 0; }
                set
                {
                    if (value)
                        Value |= 0b1000_0000;
                    else
                        Value &= 0b0111_1111;
                }
            }
            public bool Subtract
            {
                get { return (Value & 0b0100_0000) != 0; }
                set
                {
                    if (value)
                        Value |= 0b0100_0000;
                    else
                        Value &= 0b1011_1111;
                }
            }
            public bool HalfCarry
            {
                get { return (Value & 0b0010_0000) != 0; }
                set
                {
                    if (value)
                        Value |= 0b0010_0000;
                    else
                        Value &= 0b1101_1111;
                }
            }
            public bool Carry
            {
                get { return (Value & 0b0001_0000) != 0; }
                set
                {
                    if (value)
                        Value |= 0b0001_0000;
                    else
                        Value &= 0b1110_1111;
                }
            }
            #endregion
            public bool IsValid
            {
                get { return (Value & 0b0000_1111) == 0; }
            }
        }
    }
}