// Copyright 2022 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 ui

import (
	"errors"
	"image"

	"github.com/hajimehoshi/ebiten/v2/internal/atlas"
	"github.com/hajimehoshi/ebiten/v2/internal/mipmap"
)

// RegularTermination represents a regular termination.
// Run can return this error, and if this error is received,
// the game loop should be terminated as soon as possible.
var RegularTermination = errors.New("regular termination")

type FPSModeType int

const (
	FPSModeVsyncOn FPSModeType = iota
	FPSModeVsyncOffMaximum
	FPSModeVsyncOffMinimum
)

type CursorMode int

const (
	CursorModeVisible CursorMode = iota
	CursorModeHidden
	CursorModeCaptured
)

type CursorShape int

const (
	CursorShapeDefault CursorShape = iota
	CursorShapeText
	CursorShapeCrosshair
	CursorShapePointer
	CursorShapeEWResize
	CursorShapeNSResize
	CursorShapeNESWResize
	CursorShapeNWSEResize
	CursorShapeMove
	CursorShapeNotAllowed
)

type WindowResizingMode int

const (
	WindowResizingModeDisabled WindowResizingMode = iota
	WindowResizingModeOnlyFullscreenEnabled
	WindowResizingModeEnabled
)

type UserInterface struct {
	userInterfaceImpl
}

var theUI = &UserInterface{}

func Get() *UserInterface {
	// TODO: Get is a legacy API to access this package. Remove this.
	return theUI
}

func (u *UserInterface) readPixels(mipmap *mipmap.Mipmap, pixels []byte, region image.Rectangle) error {
	return mipmap.ReadPixels(u.graphicsDriver, pixels, region)
}

func (u *UserInterface) dumpScreenshot(mipmap *mipmap.Mipmap, name string, blackbg bool) (string, error) {
	return mipmap.DumpScreenshot(u.graphicsDriver, name, blackbg)
}

func (u *UserInterface) dumpImages(dir string) (string, error) {
	return atlas.DumpImages(u.graphicsDriver, dir)
}

type RunOptions struct {
	GraphicsLibrary   GraphicsLibrary
	InitUnfocused     bool
	ScreenTransparent bool
	SkipTaskbar       bool
}

// InitialWindowPosition returns the position for centering the given second width/height pair within the first width/height pair.
func InitialWindowPosition(mw, mh, ww, wh int) (x, y int) {
	return (mw - ww) / 2, (mh - wh) / 3
}