package dungeon

import (
	"bytes"
	"compress/zlib"
	"encoding/binary"
	"image"
	"image/draw"
	"image/png"
	"io"
	"unsafe"
)

type TileType uint8

const (
	TileTypeNone TileType = iota
	TileTypeFloor
	TileTypeWall
)

type TileMap struct {
	Width  int
	Height int
	Tiles  []TileType
}

func NewTileMap(width, height int) TileMap {
	return TileMap{
		Width:  width,
		Height: height,
		Tiles:  make([]TileType, width*height),
	}
}

func (t *TileMap) Get(x int, y int) TileType {
	return t.Tiles[y*t.Width+x]
}

func (t *TileMap) Set(x int, y int, tile TileType) {
	t.Tiles[y*t.Width+x] = tile
}

func (t *TileMap) Draw(tileSet *TileSet) *image.RGBA {
	tileMapImage := image.NewRGBA(image.Rect(0, 0, t.Width*tileSize, t.Height*tileSize))
	for x := range t.Width {
		for y := range t.Height {
			tileType := t.Get(x, y)
			if tileType > 0 {

				tileRect := tileSet.TileBounds(tileType)
				draw.Draw(tileMapImage, image.Rect(x*tileSize, y*tileSize, (x*tileSize)+tileSize, (y*tileSize)+tileSize), tileSet.Image, image.Point{X: tileRect.Min.X, Y: tileRect.Min.Y}, draw.Src)
			}
		}
	}
	return tileMapImage
}

func (t *TileMap) ExportPNG(tileSet *TileSet, w io.Writer) error {
	return png.Encode(w, t.Draw(tileSet))
}

func (t *TileMap) ExportBytes(w io.Writer) {
	header := make([]byte, 4)
	binary.LittleEndian.PutUint16(header, uint16(t.Width))
	binary.LittleEndian.PutUint16(header[2:], uint16(t.Height))
	tileBytes := *(*[]byte)(unsafe.Pointer(&t.Tiles))

	zw := zlib.NewWriter(w)
	defer zw.Close()
	zw.Write(append(header, tileBytes...))
}

func TileMapFromBytes(compressedTileMapData []byte) TileMap {
	zr, err := zlib.NewReader(bytes.NewReader(compressedTileMapData))
	if err != nil {
		return TileMap{}
	}
	defer zr.Close()

	tileMapData, err := io.ReadAll(zr)
	if err != nil {
		return TileMap{}
	}

	if len(tileMapData) < 4 {
		return TileMap{}
	}

	width := int(binary.LittleEndian.Uint16(tileMapData[0:2]))
	height := int(binary.LittleEndian.Uint16(tileMapData[2:4]))

	if len(tileMapData[4:]) != width*height {
		return TileMap{}
	}

	tiles := make([]TileType, width*height)
	for i, b := range tileMapData[4:] {
		tiles[i] = TileType(b)
	}

	return TileMap{
		Width:  width,
		Height: height,
		Tiles:  tiles,
	}
}