// 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.

// +build example

package main

import (
	"fmt"
	"image"
	"log"

	"github.com/hajimehoshi/ebiten"
	"github.com/hajimehoshi/ebiten/ebitenutil"
)

const (
	screenWidth  = 240
	screenHeight = 240
)

const (
	tileSize = 16
	tileXNum = 25
)

var (
	tilesImage *ebiten.Image
)

func init() {
	var err error
	tilesImage, _, err = ebitenutil.NewImageFromFile("_resources/images/tiles.png", ebiten.FilterNearest)
	if err != nil {
		log.Fatal(err)
	}
}

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)
	}
}