// Genererar placeholder-grafik tills riktig pixel art finns:
//
//	go run ./tools/genart
//
// Skriver resources/sprites/tiles.png (en remsa 16×16-rutor i ordningen
// vägg, golv, start, perrong, spärr, automat, skylt) och
// resources/sprites/player.png (3 bildrutor × 4 riktningar: ner, upp,
// vänster, höger; kolumn 0 = stilla, 1–2 = gå). Ritas med enkla rektanglar
// så att allt är deterministiskt och lätt att justera.
package main

import (
	"fmt"
	"image"
	"image/color"
	"image/png"
	"os"
	"path/filepath"
)

const T = 16

func rgb(r, g, b uint8) color.RGBA { return color.RGBA{r, g, b, 255} }

var (
	wallDark, wallMid, wallLight = rgb(38, 43, 68), rgb(58, 68, 102), rgb(90, 105, 136)
	floorA, floorB, grout        = rgb(139, 155, 180), rgb(128, 143, 168), rgb(108, 121, 146)
	yellow, yellowDark           = rgb(254, 174, 52), rgb(200, 130, 30)
	metal, metalDark             = rgb(190, 198, 208), rgb(120, 130, 145)
	screenC, boxDark             = rgb(44, 232, 245), rgb(50, 60, 80)
	signBoard, white             = rgb(24, 60, 120), rgb(255, 255, 255)
	green, greenDark             = rgb(99, 199, 77), rgb(60, 140, 50)
	skin, hair, capC, capDark    = rgb(240, 200, 160), rgb(60, 40, 30), rgb(228, 59, 68), rgb(170, 40, 50)
	jacket, jacketDark           = rgb(44, 232, 245), rgb(30, 170, 185)
	pants, shoe, eye             = rgb(38, 43, 68), rgb(255, 255, 255), rgb(38, 43, 68)
)

type canvas struct {
	img    *image.NRGBA
	ox, oy int
}

func (c canvas) rect(x, y, w, h int, col color.RGBA) {
	for yy := y; yy < y+h; yy++ {
		for xx := x; xx < x+w; xx++ {
			c.img.SetNRGBA(c.ox+xx, c.oy+yy, color.NRGBA{col.R, col.G, col.B, col.A})
		}
	}
}

func floor(c canvas) {
	c.rect(0, 0, 7, 7, floorA)
	c.rect(8, 0, 7, 7, floorB)
	c.rect(0, 8, 7, 7, floorB)
	c.rect(8, 8, 7, 7, floorA)
	c.rect(7, 0, 1, 16, grout)
	c.rect(15, 0, 1, 16, grout)
	c.rect(0, 7, 16, 1, grout)
	c.rect(0, 15, 16, 1, grout)
}

var tiles = []func(canvas){
	func(c canvas) { // vägg
		c.rect(0, 0, 16, 16, wallMid)
		c.rect(0, 0, 16, 2, wallLight)
		c.rect(0, 14, 16, 2, wallDark)
		c.rect(0, 7, 16, 1, wallDark)
		c.rect(7, 2, 1, 5, wallDark)
		c.rect(3, 8, 1, 6, wallDark)
		c.rect(11, 8, 1, 6, wallDark)
	},
	floor, // golv
	func(c canvas) { // start: golv + dörrmatta
		floor(c)
		c.rect(3, 10, 10, 4, green)
		c.rect(3, 10, 10, 1, greenDark)
		c.rect(3, 13, 10, 1, greenDark)
	},
	func(c canvas) { // perrong: golv + gul ledlinje + kant
		floor(c)
		c.rect(0, 11, 16, 3, yellow)
		for x := 1; x < 16; x += 4 {
			c.rect(x, 12, 2, 1, yellowDark)
		}
		c.rect(0, 15, 16, 1, wallDark)
	},
	func(c canvas) { // spärr: två stolpar med grön lampa
		floor(c)
		for _, x := range []int{1, 11} {
			c.rect(x, 1, 4, 13, metal)
			c.rect(x, 1, 4, 1, white)
			c.rect(x, 13, 4, 1, metalDark)
			c.rect(x+1, 3, 2, 2, green)
		}
	},
	func(c canvas) { // automat
		floor(c)
		c.rect(3, 1, 10, 13, boxDark)
		c.rect(4, 2, 8, 5, screenC)
		c.rect(5, 9, 6, 1, metal)
		c.rect(5, 11, 2, 1, yellow)
		c.rect(8, 11, 2, 1, green)
	},
	func(c canvas) { // skylt
		floor(c)
		c.rect(7, 7, 2, 9, boxDark)
		c.rect(2, 1, 12, 7, signBoard)
		c.rect(2, 1, 12, 1, white)
		c.rect(3, 3, 10, 1, white)
		c.rect(3, 5, 6, 1, white)
	},
}

// player ritar en figur som tittar åt facing (0 ner, 1 upp, 2 vänster, 3 höger)
// i bildruta frame (0 stilla, 1–2 gå).
func player(c canvas, facing, frame int) {
	// ben + skor
	ly, ry := 11, 11
	lx, rx := 5, 9
	switch frame {
	case 1:
		ly = 10
	case 2:
		ry = 10
	}
	if facing >= 2 { // sidovy: benen närmare varandra, växelvis fram
		lx, rx = 6, 8
		if frame == 1 {
			lx, rx = 5, 8
		} else if frame == 2 {
			lx, rx = 6, 9
		}
	}
	c.rect(lx, ly, 2, 14-ly, pants)
	c.rect(rx, ry, 2, 14-ry, pants)
	c.rect(lx, 14, 2, 1, shoe)
	c.rect(rx, 14, 2, 1, shoe)
	// kropp + armar
	c.rect(4, 6, 8, 5, jacket)
	c.rect(4, 6, 8, 1, jacketDark)
	c.rect(3, 7, 1, 3, jacket)
	c.rect(12, 7, 1, 3, jacket)
	// huvud
	switch facing {
	case 0: // ner
		c.rect(4, 1, 8, 5, skin)
		c.rect(3, 0, 10, 2, capC)
		c.rect(3, 2, 10, 1, capDark)
		c.rect(6, 4, 1, 1, eye)
		c.rect(9, 4, 1, 1, eye)
	case 1: // upp: bakhuvud
		c.rect(4, 1, 8, 5, hair)
		c.rect(3, 0, 10, 2, capC)
		c.rect(3, 2, 10, 1, capDark)
	case 2: // vänster
		c.rect(4, 1, 8, 5, skin)
		c.rect(9, 1, 3, 5, hair)
		c.rect(3, 0, 10, 2, capC)
		c.rect(1, 2, 8, 1, capDark)
		c.rect(5, 4, 1, 1, eye)
	case 3: // höger
		c.rect(4, 1, 8, 5, skin)
		c.rect(4, 1, 3, 5, hair)
		c.rect(3, 0, 10, 2, capC)
		c.rect(7, 2, 8, 1, capDark)
		c.rect(10, 4, 1, 1, eye)
	}
}

func main() {
	out := filepath.Join(repoRoot(), "resources", "sprites")

	tilesImg := image.NewNRGBA(image.Rect(0, 0, T*len(tiles), T))
	for i, draw := range tiles {
		draw(canvas{tilesImg, i * T, 0})
	}
	save(filepath.Join(out, "tiles.png"), tilesImg)

	playerImg := image.NewNRGBA(image.Rect(0, 0, T*3, T*4))
	for facing := 0; facing < 4; facing++ {
		for frame := 0; frame < 3; frame++ {
			player(canvas{playerImg, frame * T, facing * T}, facing, frame)
		}
	}
	save(filepath.Join(out, "player.png"), playerImg)
}

func save(path string, img image.Image) {
	f, err := os.Create(path)
	if err != nil {
		fail(err)
	}
	defer f.Close()
	if err := png.Encode(f, img); err != nil {
		fail(err)
	}
	fmt.Println("skrev", path)
}

func repoRoot() string {
	dir, _ := os.Getwd()
	for {
		if _, err := os.Stat(filepath.Join(dir, "go.mod")); err == nil {
			return dir
		}
		parent := filepath.Dir(dir)
		if parent == dir {
			fail(fmt.Errorf("hittade ingen go.mod"))
		}
		dir = parent
	}
}

func fail(err error) {
	fmt.Fprintln(os.Stderr, "genart:", err)
	os.Exit(1)
}