// Copyright 2018 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//go:build example
// +build example

package main

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

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
	"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
)

const (
	screenWidth  = 240
	screenHeight = 240
)

const (
	tileSize = 16
)

var (
	tilesImage *ebiten.Image
)

func init() {
	// Decode an image from the image file's byte slice.
	img, _, err := image.Decode(bytes.NewReader(images.Tiles_png))
	if err != nil {
		log.Fatal(err)
	}
	tilesImage = ebiten.NewImageFromImage(img)
}

type Game struct {
	layers [][]int
}

func (g *Game) Update() error {
	return nil
}

func (g *Game) Draw(screen *ebiten.Image) {
	w, _ := tilesImage.Size()
	tileXCount := w / tileSize

	// Draw each tile with each DrawImage call.
	// As the source images of all DrawImage calls are always same,
	// this rendering is done very efficiently.
	// For more detail, see https://pkg.go.dev/github.com/hajimehoshi/ebiten/v2#Image.DrawImage
	const xCount = screenWidth / tileSize
	for _, l := range g.layers {
		for i, t := range l {
			op := &ebiten.DrawImageOptions{}
			op.GeoM.Translate(float64((i%xCount)*tileSize), float64((i/xCount)*tileSize))

			sx := (t % tileXCount) * tileSize
			sy := (t / tileXCount) * tileSize
			screen.DrawImage(tilesImage.SubImage(image.Rect(sx, sy, sx+tileSize, sy+tileSize)).(*ebiten.Image), op)
		}
	}

	ebitenutil.DebugPrint(screen, fmt.Sprintf("TPS: %0.2f", ebiten.ActualTPS()))
}

func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
	return screenWidth, screenHeight
}

func main() {
	g := &Game{
		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,
			},
		},
	}

	ebiten.SetWindowSize(screenWidth*2, screenHeight*2)
	ebiten.SetWindowTitle("Tiles (Ebitengine Demo)")
	if err := ebiten.RunGame(g); err != nil {
		log.Fatal(err)
	}
}