--- Day 4: Ceres Search ---

"Looks like the Chief's not here. Next!" One of The Historians pulls out a device and pushes the only button on it. After a brief flash, you recognize the interior of the Ceres monitoring station!

As the search for the Chief continues, a small Elf who lives on the station tugs on your shirt; she'd like to know if you could help her with her word search (your puzzle input). She only has to find one word: XMAS.

This word search allows words to be horizontal, vertical, diagonal, written backwards, or even overlapping other words. It's a little unusual, though, as you don't merely need to find one instance of XMAS - you need to find all of them. Here are a few ways XMAS might appear, where irrelevant characters have been replaced with .:

..X...
.SAMX.
.A..A.
XMAS.S
.X....
The actual word search will be full of letters instead. For example:

MMMSXXMASM
MSAMXMSMSA
AMXSXMAAMM
MSAMASMSMX
XMASAMXAMM
XXAMMXXAMA
SMSMSASXSS
SAXAMASAAA
MAMMMXMMMM
MXMXAXMASX
In this word search, XMAS occurs a total of 18 times; here's the same word search again, but where letters not involved in any XMAS have been replaced with .:

....XXMAS.
.SAMXMS...
...S..A...
..A.A.MS.X
XMASAMX.MM
X.....XA.A
S.S.S.S.SS
.A.A.A.A.A
..M.M.M.MM
.X.X.XMASX
Take a look at the little Elf's word search. How many times does XMAS appear?

Your puzzle answer was 2434.

--- Part Two ---

The Elf looks quizzically at you. Did you misunderstand the assignment?

Looking for the instructions, you flip over the word search to find that this isn't actually an XMAS puzzle; it's an X-MAS puzzle in which you're supposed to find two MAS in the shape of an X. One way to achieve that is like this:

M.S
.A.
M.S
Irrelevant characters have again been replaced with . in the above diagram. Within the X, each MAS can be written forwards or backwards.

Here's the same example from before, but this time all of the X-MASes have been kept instead:

.M.S......
..A..MSMS.
.M.S.MAA..
..A.ASMSM.
.M.S.M....
..........
S.S.S.S.S.
.A.A.A.A..
M.M.M.M.M.
..........
In this example, an X-MAS appears 9 times.

Flip the word search from the instructions back over to the word search side and try again. How many times does an X-MAS appear?
let fs = require('fs');
let rows = fs.readFileSync('input.txt').toString().split("\n");

// We need a Width and a Height - we will assume it is a rectangular wordsearch and that all rows are the same length
const WIDTH = rows[0].length;
const HEIGHT = rows.length;

// Keep a running total of how many times we have found the Search Word
let runningTotal = 0;

rows.forEach((row, rowIndex) => {
    if (row.length > 0) {
        [...row].forEach((letter, colIndex) => {
            if (letter === 'A') {
                if (
                    rowIndex > 0 && rowIndex < HEIGHT - 1 &&
                    colIndex > 0 && colIndex < WIDTH - 1 &&
                    (
                        (rows[rowIndex + 1][colIndex + 1] === 'M' && rows[rowIndex - 1][colIndex - 1] === 'S') ||
                        (rows[rowIndex + 1][colIndex + 1] === 'S' && rows[rowIndex - 1][colIndex - 1] === 'M')
                    ) &&
                    (
                        (rows[rowIndex + 1][colIndex - 1] === 'M' && rows[rowIndex - 1][colIndex + 1] === 'S') ||
                        (rows[rowIndex + 1][colIndex - 1] === 'S' && rows[rowIndex - 1][colIndex + 1] === 'M')
                    )
                ) {
                    runningTotal++;
                }
            }
        });
    }
});

console.log(runningTotal);