var lines = File.ReadAllLines("input.txt");
var charArray = new char[lines.Length, lines[0].Length];

for (var i = 0; i < charArray.GetLength(0); i++)
for (var j = 0; j < charArray.GetLength(1); j++)
{
    charArray[i, j] = lines[i][j];
}

Console.WriteLine($"Part1: {FindXmas(charArray)}\nPart2: {FindMas(charArray)}");

int FindMas(char[,] grid)
{
    var rows = grid.GetLength(0);
    var cols = grid.GetLength(1);

    var directions = new[,]
    {
        { -1, 1 }, // diagonal up right
        { 1, 1 }, // diagonal down right
        { -1, -1 }, // diagonal up left
        { 1, -1 } // diagonal down left
    };

    List<string> masCenterCoordinates = new();

    for (var r = 0; r < rows; r++)
    {
        for (var c = 0; c < cols; c++)
        {
            for (var d = 0; d < directions.GetLength(0); d++)
            {
                var masCoordinates = CheckWord(r, c, directions[d, 0], directions[d, 1], grid, "MAS");
                if (masCoordinates != null)
                {
                    masCenterCoordinates.Add($"{masCoordinates[1][0]},{masCoordinates[1][1]}");
                }
            }
        }
    }

    var masCountDict = masCenterCoordinates.GroupBy(item => item).ToDictionary(group => group.Key, group => group.Count()).Where(x => x.Value > 1);

    return masCountDict.Count();
}

int FindXmas(char[,] grid)
{
    var rows = grid.GetLength(0);
    var cols = grid.GetLength(1);
    var xmasCount = 0;

    var directions = new[,]
    {
        { -1, 0 }, // up
        { 0, 1 }, // right
        { 0, -1 }, // left
        { 1, 0 }, // down
        { -1, 1 }, // diagonal up right
        { 1, 1 }, // diagonal down right
        { -1, -1 }, // diagonal up left
        { 1, -1 } // diagonal down left
    };

    for (var r = 0; r < rows; r++)
    {
        for (var c = 0; c < cols; c++)
        {
            for (var d = 0; d < directions.GetLength(0); d++)
            {
                if (CheckWord(r, c, directions[d, 0], directions[d, 1], grid, "XMAS") != null)
                {
                    xmasCount++;
                }
            }
        }
    }

    return xmasCount;
}

List<int[]>? CheckWord(int r, int c, int dr, int dc, char[,] grid, string word)
{
    var characterCoordinates = new List<int[]>();

    for (var i = 0; i < word.Length; i++)
    {
        var newR = r + i * dr;
        var newC = c + i * dc;
        if (!IsValid(newR, newC, grid) || grid[newR, newC] != word[i]) return null;

        characterCoordinates.Add([newR, newC]);
    }

    return characterCoordinates;
}

bool IsValid(int r, int c, char[,] grid) => r >= 0 && r < grid.GetLength(0) && c >= 0 && c < grid.GetLength(1);