// +build example jsgo

package main

import (
        "bytes"
        "fmt"
        "image"
        _ "image/png"
        "log"

        "github.com/hajimehoshi/ebiten"
        "github.com/hajimehoshi/ebiten/ebitenutil"
        "github.com/hajimehoshi/ebiten/examples/resources/images"
)

const (
        screenWidth  = 240
        screenHeight = 240
)

const (
        tileSize = 16
        tileXNum = 25
)

var (
        tilesImage *ebiten.Image
)

func init() {
        // Decode image from a byte slice instead of a file so that
        // this example works in any working directory.
        // If you want to use a file, there are some options:
        // 1) Use os.Open and pass the file to the image decoder.
        //    This is a very regular way, but doesn't work on browsers.
        // 2) Use ebitenutil.OpenFile and pass the file to the image decoder.
        //    This works even on browsers.
        // 3) Use ebitenutil.NewImageFromFile to create an ebiten.Image directly from a file.
        //    This also works on browsers.
        img, _, err := image.Decode(bytes.NewReader(images.Tiles_png))
        if err != nil {
                log.Fatal(err)
        }
        tilesImage, _ = ebiten.NewImageFromImage(img, ebiten.FilterDefault)
}

var (
        layers = [][]int{
                {
                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
                        243, 218, 243, 243, 243, 243, 243, 243, 243, 243, 243, 218, 243, 244, 243,
                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,

                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
                        243, 243, 244, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
                        243, 243, 243, 243, 243, 243, 243, 243, 243, 219, 243, 243, 243, 219, 243,
                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,

                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
                        243, 218, 243, 243, 243, 243, 243, 243, 243, 243, 243, 244, 243, 243, 243,
                        243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243, 243,
                },
                {
                        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 26, 27, 28, 29, 30, 31, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 51, 52, 53, 54, 55, 56, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 76, 77, 78, 79, 80, 81, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 101, 102, 103, 104, 105, 106, 0, 0, 0, 0,

                        0, 0, 0, 0, 0, 126, 127, 128, 129, 130, 131, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 303, 303, 245, 242, 303, 303, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 0, 0, 245, 242, 0, 0, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 0, 0, 245, 242, 0, 0, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 0, 0, 245, 242, 0, 0, 0, 0, 0, 0,

                        0, 0, 0, 0, 0, 0, 0, 245, 242, 0, 0, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 0, 0, 245, 242, 0, 0, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 0, 0, 245, 242, 0, 0, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 0, 0, 245, 242, 0, 0, 0, 0, 0, 0,
                        0, 0, 0, 0, 0, 0, 0, 245, 242, 0, 0, 0, 0, 0, 0,
                },
        }
)

func update(screen *ebiten.Image) error {
        if ebiten.IsRunningSlowly() {
                return nil
        }

        // Draw each tile with each DrawImage call.
        // As the source images of all DrawImage calls are always same,
        // this rendering is done very effectively.
        // For more detail, see https://godoc.org/github.com/hajimehoshi/ebiten#Image.DrawImage
        const xNum = screenWidth / tileSize
        for _, l := range layers {
                for i, t := range l {
                        op := &ebiten.DrawImageOptions{}
                        op.GeoM.Translate(float64((i%xNum)*tileSize), float64((i/xNum)*tileSize))

                        sx := (t % tileXNum) * tileSize
                        sy := (t / tileXNum) * tileSize
                        r := image.Rect(sx, sy, sx+tileSize, sy+tileSize)
                        op.SourceRect = &r
                        screen.DrawImage(tilesImage, op)
                }
        }

        ebitenutil.DebugPrint(screen, fmt.Sprintf("FPS: %0.2f", ebiten.CurrentFPS()))

        return nil
}

func main() {
        if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Tiles (Ebiten Demo)"); err != nil {
                log.Fatal(err)
        }
}