pub fn answer(text : String) -> ( u16, u16 ) {
    let grid : Vec<Vec<char>> = from_string(text);

    let rows = grid.len();
    let cols = grid[0].len();

    ( find_xmas(&grid, rows as isize, cols as isize), find_x_mas(&grid, rows, cols) )
}

fn find_x_mas(grid : &Vec<Vec<char>>, rows : usize, cols : usize) -> u16 {
    let mut total : u16 = 0;

    for y in 1..rows-1 {
        for x in 1..cols-1 {
            if grid[y][x] == 'A' {
                total = total + inspect_x_mas_location(&grid, x, y)
            }
        }
    }

    total
}

fn find_xmas(grid : &Vec<Vec<char>>, rows : isize, cols : isize) -> u16 {
    let mut total : u16 = 0;

    for y in 0..rows {
        for x in 0..cols {
            if grid[y as usize][x as usize] == 'X' {
                total = total + inspect_xmas_location(&grid, x, y, rows, cols)
            }
        }
    }

    total
}

fn from_string(s : String) -> Vec<Vec<char>> {
    s.split("\n").map(|s| s.chars().collect()).collect()
}

fn inspect_x_mas_location(grid : &Vec<Vec<char>>, x : usize, y : usize) -> u16 {
    let c1 = grid[y-1][x-1];
    let c2 = grid[y-1][x+1];
    let c3 = grid[y+1][x-1];
    let c4 = grid[y+1][x+1];

    let horizontal = c1 == c2 && c3 == c4 && c1 != c3;
    let vertical = c1 == c3 && c2 == c4 && c1 != c2;
    let letters_match = (c1 == 'M' && c4 == 'S') || (c1 == 'S' && c4 == 'M');

    if letters_match && (horizontal || vertical) {
        1
    } else {
        0
    }
}

fn inspect_xmas_location(grid : &Vec<Vec<char>>, x : isize, y : isize, rows : isize, cols : isize) -> u16 {
    let mut total : u16 = 0;

    for dx in -1..=1 {
        for dy in -1..=1 {
            if dx == 0 && dy == 0 {
                continue;
            }

            let (s_x, s_y) = ( x + 3 * dx, y + 3 * dy );

            if s_x < 0 || s_x >= rows || s_y < 0 || s_y >= cols {
                continue;
            }

            let m = grid[(y + 1 * dy) as usize][(x + 1 * dx) as usize];
            let a = grid[(y + 2 * dy) as usize][(x + 2 * dx) as usize];
            let s = grid[(y + 3 * dy) as usize][(x + 3 * dx) as usize];

            if m == 'M' && a == 'A'  && s == 'S' {
                total = total + 1;
            }
        }
    };

    total
}