package day04

import (
	"adventofcode2025/utils/grid2d"
	"adventofcode2025/utils/inputs"
)

func Part1(input string) int {
	adj := 0
	rolls := 0
	grid := inputs.ToGrid2D(input, "\n", "", "", func(c string) string { return c })
	directions := [][]int{{0, 1}, {0, -1}, {1, 0}, {-1, 0}, {-1, 1}, {1, 1}, {-1, -1}, {1, -1}}
	for j := 0; j < grid.SizeY(); j++ {
		for i := 0; i < grid.SizeX(); i++ {
			if !checkChar(i, j, grid, "@") {
				continue
			}
			for _, dir := range directions {
				x := i + dir[0]
				y := j + dir[1]
				if checkChar(x, y, grid, "@") {
					adj++
				}
			}
			if adj < 4 {
				rolls++
			}
			adj = 0
		}
	}
	return rolls
}

func Part2(input string) int {
	grid := inputs.ToGrid2D(input, "\n", "", "", func(c string) string { return c })
	rolls := countRolls(grid)
	total := rolls

	for rolls > 0 {
		removeRolls(grid)        // modifies grid
		rolls = countRolls(grid) // compute only once per loop
		total += rolls
	}

	return total
}

func checkChar(x int, y int, grid *grid2d.Grid[string], c string) bool {
	if x < 0 || x >= grid.SizeX() || y < 0 || y >= grid.SizeY() {
		return false
	}
	if grid.Get(x, y) == c {
		return true
	}
	return false
}

func countRolls(grid *grid2d.Grid[string]) int {
	adj := 0
	rolls := 0
	directions := [][]int{{0, 1}, {0, -1}, {1, 0}, {-1, 0}, {-1, 1}, {1, 1}, {-1, -1}, {1, -1}}
	for j := 0; j < grid.SizeY(); j++ {
		for i := 0; i < grid.SizeX(); i++ {
			if checkChar(i, j, grid, ".") {
				continue
			}
			for _, dir := range directions {
				x := i + dir[0]
				y := j + dir[1]
				if checkChar(x, y, grid, "@") || checkChar(x, y, grid, "x") {
					adj++
				}
			}
			if adj < 4 {
				grid.Set(i, j, "x")
				rolls++
			}
			adj = 0
		}
	}
	return rolls
}
func removeRolls(grid *grid2d.Grid[string]) {
	for j := 0; j < grid.SizeY(); j++ {
		for i := 0; i < grid.SizeX(); i++ {
			if checkChar(i, j, grid, "x") {
				grid.Set(i, j, ".")
			}
		}
	}

}