// 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.

package main

import (
	"bytes"
	"fmt"
	"image"
	"image/color"
	_ "image/jpeg"
	"log"
	"math"
	"runtime"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/examples/resources/fonts"
	"github.com/hajimehoshi/ebiten/v2/examples/resources/images"
	"github.com/hajimehoshi/ebiten/v2/inpututil"
	"github.com/hajimehoshi/ebiten/v2/text/v2"
)

var (
	gophersImage    *ebiten.Image
	mplusFaceSource *text.GoTextFaceSource
)

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

func init() {
	s, err := text.NewGoTextFaceSource(bytes.NewReader(fonts.MPlus1pRegular_ttf))
	if err != nil {
		log.Fatal(err)
	}
	mplusFaceSource = s
}

type Game struct {
	count int
}

func (g *Game) Update() error {
	g.count++

	if runtime.GOOS == "js" {
		if ebiten.IsKeyPressed(ebiten.KeyF) || len(inpututil.AppendJustPressedTouchIDs(nil)) > 0 {
			ebiten.SetFullscreen(true)
		}
	}
	if runtime.GOOS != "js" && ebiten.IsKeyPressed(ebiten.KeyQ) {
		return ebiten.Termination
	}
	return nil
}

func (g *Game) Draw(screen *ebiten.Image) {
	scale := ebiten.Monitor().DeviceScaleFactor()

	w, h := gophersImage.Bounds().Dx(), gophersImage.Bounds().Dy()
	op := &ebiten.DrawImageOptions{}

	op.GeoM.Translate(-float64(w)/2, -float64(h)/2)
	op.GeoM.Scale(scale, scale)
	op.GeoM.Rotate(float64(g.count%360) * 2 * math.Pi / 360)
	sw, sh := screen.Bounds().Dx(), screen.Bounds().Dy()
	op.GeoM.Translate(float64(sw)/2, float64(sh)/2)
	op.Filter = ebiten.FilterLinear
	screen.DrawImage(gophersImage, op)

	fw, fh := ebiten.Monitor().Size()
	msg := "This is an example of the finest fullscreen.\n"
	if runtime.GOOS == "js" {
		msg += "Press F or touch the screen to enter fullscreen (again).\n"
	} else {
		msg += "Press Q to quit.\n"
	}
	msg += fmt.Sprintf("Screen size in fullscreen: %d, %d\n", fw, fh)
	msg += fmt.Sprintf("Game's screen size: %d, %d\n", sw, sh)
	msg += fmt.Sprintf("Device scale factor: %0.2f\n", scale)

	textOp := &text.DrawOptions{}
	textOp.GeoM.Translate(50*scale, 50*scale)
	textOp.ColorScale.ScaleWithColor(color.White)
	textOp.LineSpacing = 12 * ebiten.Monitor().DeviceScaleFactor() * 1.5
	text.Draw(screen, msg, &text.GoTextFace{
		Source: mplusFaceSource,
		Size:   12 * ebiten.Monitor().DeviceScaleFactor(),
	}, textOp)
}

func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
	s := ebiten.Monitor().DeviceScaleFactor()
	return int(float64(outsideWidth) * s), int(float64(outsideHeight) * s)
}

func main() {
	ebiten.SetFullscreen(true)
	ebiten.SetWindowTitle("Fullscreen (Ebitengine Demo)")
	if err := ebiten.RunGame(&Game{}); err != nil {
		log.Fatal(err)
	}
}