// See https://aka.ms/new-console-template for more information
Console.WriteLine("Hello, World!");

var exampleInstructions01 = Instruction.LoadInstructions("example-input1.txt");
var exampleInstructions02 = Instruction.LoadInstructions("example-input2.txt");
var puzzleInstructions = Instruction.LoadInstructions("puzzle-input.txt");

// Part 01
outputSignalStrength(exampleInstructions02, 20, 40);
outputSignalStrength(puzzleInstructions, 20, 40);

// Part 02
Console.Write(" === Writing Example Output === ");
renderOnCrt(exampleInstructions02);
Console.WriteLine();

Console.WriteLine();
Console.Write(" === Writing Puzzle Output === ");
renderOnCrt(puzzleInstructions);
Console.WriteLine();

bool ShouldDrawSprite(int position, int cycle)
{
    return (position + 0) % 40 == cycle % 40
        || (position - 1) % 40 == cycle % 40
        || (position + 1) % 40 == cycle % 40;
}

void Draw(int spritePosition, CPU cpu)
{
    if (cpu.Cycle % 40 == 0) Console.WriteLine();
    
    if (ShouldDrawSprite(spritePosition, cpu.Cycle))
    {
        Console.Write('#');
    }
    else
    {
        Console.Write('.');
    }
}

void renderOnCrt(List<Instruction> instructions)
{
    int spritePosition;
    CPU cpu = new CPU();

    foreach (var i in instructions)
    {
        spritePosition = cpu.GetRegisterValue('X');

        if (i.CycleCount() == 1)
        {
            Draw(spritePosition, cpu);
            cpu.Execute(i);
        } 
        else if (i.CycleCount() == 2)
        {
            Draw(spritePosition, cpu);
            cpu.Cycle++;
            Draw(spritePosition, cpu);
            cpu.Execute(i);
            cpu.Cycle--;
        }
        else throw new InvalidDataException();
        
    }


}

void outputSignalStrength(List<Instruction> list, int init, int step)
{
    CPU cpu = new CPU();
    int nextSignal = init;
    List<int> strengthList = new List<int>();

    Console.WriteLine(" === Listing signals ===");
    foreach (var l in list)
    {
        int oldValue = cpu.GetRegisterValue('X');

        cpu.Execute(l);

        if (cpu.Cycle >= nextSignal)
        {
            int strength = nextSignal * oldValue;

            Console.WriteLine(String.Format("Cycle({0}): SignalStrength({1})", nextSignal, strength));
            strengthList.Add(strength);
            nextSignal += step;
        }
    }

    int strengthSum = 0;
    foreach (var s in strengthList)
    {
        strengthSum += s;
    }
    Console.WriteLine("Strength Sum: " + strengthSum);
    Console.WriteLine();
}

class CPU
{
    public int Cycle
    {
        get; set;
    }
    private int registerX;

    public CPU()
    {
        Cycle = 0;
        registerX = 1;
    }

    public int GetRegisterValue(char registerName)
    {
        switch (registerName)
        {
            case 'X':
                return registerX;
            default:
                throw new ArgumentException();
        }
    }

    public void SetRegisterValue(char registerName, int value)
    {
        switch (registerName) 
        {
            case 'X':
                registerX = value;
                break;
            default: throw new ArgumentException();
        }
    }

    public void Execute(Instruction i)
    {
        i.Execute(this);
    }
}

abstract class Instruction
{
    public virtual void Execute(CPU cpu, params int[] list)
    {
        cpu.Cycle += CycleCount();
    }

    public abstract int CycleCount();

    static Instruction ParseInstruction(string line)
    {
        if (line.StartsWith("noop"))
        {
            return new NoopInstruction();
        }
        if (line.StartsWith("addx"))
        {
            var split = line.Split(' ');

            return new AddInstruction('X', Int32.Parse(split[1]));
        }

        throw new InvalidDataException();
    }

    public static List<Instruction> LoadInstructions(string filename)
    {
        List<Instruction> list = new List<Instruction>();

        using (StreamReader reader = System.IO.File.OpenText(filename))
        {
            while (!reader.EndOfStream)
            {
                string? line = reader.ReadLine();
                if (line == null) throw new InvalidDataException();
                
                list.Add(ParseInstruction(line));
            }
        }

        return list;
    }
}

class NoopInstruction : Instruction
{
    public override void Execute(CPU cpu, params int[] list)
    {
        base.Execute(cpu, list);
    }

    public override int CycleCount()
    {
        return 1;
    }
}

class AddInstruction : Instruction
{
    public AddInstruction(char register, int value)
    {
        Value = value;
        Register = register;
    }
    public int Value
    {
        get; set;
    }

    public char Register
    {
        get; set;
    }

    public override void Execute(CPU cpu, params int[] list)
    {
        base.Execute(cpu, list);

        cpu.SetRegisterValue(Register, cpu.GetRegisterValue(Register) + Value);
    }

    public override int CycleCount()
    {
        return 2;
    }
}