package day_04

import "strings"

// task:https://adventofcode.com/2024/day/2
// short summary - count all instances of XMAS in the 2d array
func SolveBasic(input string) int {
	grid := toGrid(input)
	found := 0
	for y := 0; y < len(grid); y++ {
		for x := 0; x < len(grid[y]); x++ {
			if grid[y][x] == 'X' {
				found += checkForXMAS(grid, x, y)
			}
		}
	}
	return found
}

// task:https://adventofcode.com/2024/day/2#part2
// short summary -
func SolveComplex(input string) int {
	grid := toGrid(input)
	found := 0
	for y := 1; y < len(grid)-1; y++ {
		for x := 1; x < len(grid[y])-1; x++ {
			if grid[y][x] == 'A' {
				if checkForX_MAS(grid, x, y) {
					found++
				}
			}
		}
	}
	return found
}

// helper methods
func toGrid(input string) [][]rune {
	substrings := strings.Split(input, "\n")
	var grid [][]rune
	for _, line := range substrings {
		grid = append(grid, []rune(line))
	}
	return grid
}

func checkForXMAS(grid [][]rune, x int, y int) int {
	found := 0
	// going clockwise from top left
	if x >= 3 && y >= 3 {
		if checkLineForXMAS(grid, x, y, -1, -1) {
			found++
		}
	}
	if y >= 3 {
		if checkLineForXMAS(grid, x, y, 0, -1) {
			found++
		}
	}
	if y >= 3 && x < len(grid[y])-3 {
		if checkLineForXMAS(grid, x, y, 1, -1) {
			found++
		}
	}
	if x < len(grid[y])-3 {
		if checkLineForXMAS(grid, x, y, 1, 0) {
			found++
		}
	}
	if y < len(grid)-3 && x < len(grid[y])-3 {
		if checkLineForXMAS(grid, x, y, 1, 1) {
			found++
		}
	}
	if y < len(grid)-3 {
		if checkLineForXMAS(grid, x, y, 0, 1) {
			found++
		}
	}
	if x >= 3 && y < len(grid)-3 {
		if checkLineForXMAS(grid, x, y, -1, 1) {
			found++
		}
	}
	if x >= 3 {
		if checkLineForXMAS(grid, x, y, -1, 0) {
			found++
		}
	}
	return found
}

func checkForX_MAS(grid [][]rune, x int, y int) bool {
	// M.M
	// .A.
	// S.S
	if grid[y-1][x-1] == 'M' && grid[y-1][x+1] == 'M' &&
		grid[y+1][x-1] == 'S' && grid[y+1][x+1] == 'S' {
		return true
	}
	// S.M
	// .A.
	// S.M
	if grid[y-1][x-1] == 'S' && grid[y-1][x+1] == 'M' &&
		grid[y+1][x-1] == 'S' && grid[y+1][x+1] == 'M' {
		return true
	}
	// M.S
	// .A.
	// M.S
	if grid[y-1][x-1] == 'M' && grid[y-1][x+1] == 'S' &&
		grid[y+1][x-1] == 'M' && grid[y+1][x+1] == 'S' {
		return true
	}
	// S.S
	// .A.
	// M.M
	if grid[y-1][x-1] == 'S' && grid[y-1][x+1] == 'S' &&
		grid[y+1][x-1] == 'M' && grid[y+1][x+1] == 'M' {
		return true
	}

	return false
}

func checkLineForXMAS(grid [][]rune, x int, y int, xStep int, yStep int) bool {
	return grid[y+yStep][x+xStep] == 'M' &&
		grid[y+2*yStep][x+2*xStep] == 'A' &&
		grid[y+3*yStep][x+3*xStep] == 'S'
}