// Copyright 2016 Hajime Hoshi
//
// 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 android ios

// Package ebitenmobileview offers functions for OpenGL/Metal view of mobiles.
//
// The functions are not intended for public usages.
// There is no guarantee of backward compatibility.
package ebitenmobileview

import (
	"math"
	"runtime"

	"github.com/hajimehoshi/ebiten"
	"github.com/hajimehoshi/ebiten/internal/uidriver/mobile"
)

type ViewRectSetter interface {
	SetViewRect(x, y, width, height int)
}

func Layout(viewWidth, viewHeight int, viewRectSetter ViewRectSetter) {
	theState.m.Lock()
	defer theState.m.Unlock()
	layout(viewWidth, viewHeight, viewRectSetter)
}

func layout(viewWidth, viewHeight int, viewRectSetter ViewRectSetter) {
	if theState.game == nil {
		// It is fine to override the existing function since only the last layout result matters.
		theState.delayedLayout = func() {
			layout(viewWidth, viewHeight, viewRectSetter)
		}
		return
	}

	w, h := theState.game.Layout(int(viewWidth), int(viewHeight))
	scaleX := float64(viewWidth) / float64(w)
	scaleY := float64(viewHeight) / float64(h)
	scale := math.Min(scaleX, scaleY)

	// To convert a logical offscreen size to the actual screen size, use Math.floor to use smaller and safer
	// values, or glitches can appear (#956).
	width := int(math.Floor(float64(w) * scale))
	height := int(math.Floor(float64(h) * scale))
	x := (viewWidth - width) / 2
	y := (viewHeight - height) / 2

	if theState.isRunning() {
		mobile.Get().SetScreenSize(w, h)
		mobile.Get().SetScreenScale(scale)
	} else {
		// The last argument 'title' is not used on mobile platforms, so just pass an empty string.
		theState.errorCh = ebiten.RunWithoutMainLoop(theState.game.Update, w, h, scale, "")
	}

	if viewRectSetter != nil {
		viewRectSetter.SetViewRect(x, y, width, height)
	}
}

func Update() error {
	runtime.LockOSThread()
	defer runtime.UnlockOSThread()

	theState.m.Lock()
	defer theState.m.Unlock()

	return update()
}