package days

import (
	"fmt"
	"math"

	u "parnic.com/aoc2019/utilities"
)

var (
	day24AdjacentOffsets = []u.Vec2i{
		{X: -1, Y: 0},
		{X: 1, Y: 0},
		{X: 0, Y: -1},
		{X: 0, Y: 1},
	}
)

type Day24 struct {
	grid [][]bool
}

func (d *Day24) Parse() {
	lines := u.GetStringLines("24p")
	d.grid = make([][]bool, len(lines))
	for i, line := range lines {
		d.grid[i] = make([]bool, len(line))
		for j, ch := range line {
			d.grid[i][j] = ch == '#'
		}
	}
}

func (d Day24) Num() int {
	return 24
}

func (d Day24) calcActivatedNeighbors(grid [][]bool, i, j int) int {
	activatedNeighbors := 0
	for _, o := range day24AdjacentOffsets {
		newI := i + o.X
		newJ := j + o.Y
		if newI < 0 || newI >= len(grid) || newJ < 0 || newJ >= len(grid[i]) {
			continue
		}
		if grid[newI][newJ] {
			activatedNeighbors++
		}
	}

	return activatedNeighbors
}

func (d Day24) calcRating(grid [][]bool) int {
	rating := 0
	for i, r := range grid {
		for j := range r {
			pow := (i * len(r)) + j
			if grid[i][j] {
				result := int(math.Pow(2, float64(pow)))
				rating += result
			}
		}
	}
	return rating
}

func copy2d[T comparable](dest [][]T, src [][]T) {
	for i, r := range src {
		copy(dest[i], r)
	}
}

func (d Day24) Draw(grid [][]bool) {
	for _, r := range grid {
		for _, c := range r {
			if c {
				fmt.Print("#")
			} else {
				fmt.Print(".")
			}
		}
		fmt.Println()
	}
	fmt.Println()
}

func (d *Day24) Part1() string {
	grid := make([][]bool, len(d.grid))
	scratch := make([][]bool, len(grid))
	for i, g := range d.grid {
		grid[i] = make([]bool, len(g))
		scratch[i] = make([]bool, len(g))
		copy(grid[i], d.grid[i])
	}

	found := false
	answer := 0
	seenRatings := make([]int, 0)
	for i := 1; !found; i++ {
		// d.Draw(grid)
		for i, r := range grid {
			for j := range r {
				numActivated := d.calcActivatedNeighbors(grid, i, j)
				if grid[i][j] {
					scratch[i][j] = numActivated == 1
				} else {
					scratch[i][j] = numActivated == 1 || numActivated == 2
				}
			}
		}

		rating := d.calcRating(scratch)
		if u.ArrayContains(seenRatings, rating) {
			found = true
			d.Draw(scratch)
			answer = rating
		}
		seenRatings = append(seenRatings, rating)
		copy2d(grid, scratch)
	}

	return fmt.Sprintf("First repeated biodiversity rating is %s%d%s", u.TextBold, answer, u.TextReset)
}

func (d *Day24) Part2() string {
	return fmt.Sprintf("%s%d%s", u.TextBold, 0, u.TextReset)
}