// See https://aka.ms/new-console-template for more information
using System.Collections.Generic;
using System.Runtime.CompilerServices;

var exParsed = new Day07Parsed("example-input.txt");

Console.WriteLine("Example Part01: {0}", exParsed.GetPart01());
Console.WriteLine("Example Part02: {0}", exParsed.GetPart02());

var pzParsed = new Day07Parsed("puzzle-input.txt");

Console.WriteLine("Puzzle Part01: {0}", pzParsed.GetPart01());
Console.WriteLine("Puzzle Part02: {0}", pzParsed.GetPart02());

class Day07Parsed : AdventCommon.ParsedInput
{
    class Equation
    {
        public long LeftHandSide { get; set; }
        public List<long> RightHandSide { get; set; } = new List<int>();

        public int MaxOpCount 
        { 
            get
            {
                return RightHandSide.Count - 1;
            }
        }

        List<long> ValidOps { get; set; } = new List<long>();

        public bool IsValid()
        {
            for (int i = 0; i < (int)Math.Pow(2,MaxOpCount); i++)
            {
                long eqTotal = RightHandSide[0];

                // a value of 0 for a given bit is +, 1 is *
                for (int opIndex = 0; opIndex < MaxOpCount; opIndex++)
                {
                    if ((i & (1 << opIndex)) == 0)
                    {
                        eqTotal += RightHandSide[opIndex + 1];
                    } else
                    {
                        eqTotal *= RightHandSide[opIndex + 1];
                    }

                    if (eqTotal > LeftHandSide)
                    {
                        break;
                    }
                }

                if (eqTotal == LeftHandSide)
                {
                    ValidOps.Add(i);
                    return true;
                }
            }
            return false;
        }

    }

    public override int GetPart01()
    {
        int sum = 0;
        foreach (var equation in Equations)
        {
            if (equation.IsValid())
            {
                sum += equation.LeftHandSide;
            }
        }
        return 0;
    }

    List<Equation> Equations { get; set; } = new List<Equation>();

    public Day07Parsed(string fileName) : base(fileName) { }

    public override bool ParseLine(string line, object? context = null)
    {
        Equation equation = new Equation();

        equation.LeftHandSide = Int32.Parse(line.Split(':')[0].Trim());

        foreach (var v in line.Split(':')[1].Split(' ', StringSplitOptions.RemoveEmptyEntries))
        {
            equation.RightHandSide.Add(Int32.Parse(v));
        }

        Equations.Add(equation);

        return true;
    }
}