// 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 graphicsdriver

import (
	"errors"

	"github.com/hajimehoshi/ebiten/v2/internal/graphics"
	"github.com/hajimehoshi/ebiten/v2/internal/shaderir"
)

type Region struct {
	X      float32
	Y      float32
	Width  float32
	Height float32
}

const (
	InvalidImageID  = 0
	InvalidShaderID = 0
)

type ColorM interface {
	IsIdentity() bool
	At(i, j int) float32
	Elements(body *[16]float32, translate *[4]float32)
}

type Graphics interface {
	Initialize() error
	Begin() error
	End(present bool) error
	SetTransparent(transparent bool)
	SetVertices(vertices []float32, indices []uint16) error
	NewImage(width, height int) (Image, error)
	NewScreenFramebufferImage(width, height int) (Image, error)
	SetVsyncEnabled(enabled bool)
	SetFullscreen(fullscreen bool)
	FramebufferYDirection() YDirection
	NDCYDirection() YDirection
	NeedsRestoring() bool
	NeedsClearingScreen() bool
	IsGL() bool
	IsDirectX() bool
	HasHighPrecisionFloat() bool
	MaxImageSize() int

	NewShader(program *shaderir.Program) (Shader, error)

	// DrawTriangles draws an image onto another image with the given parameters.
	//
	// uniforms represents a colletion of uniform variables. The values must be one of these types:
	//
	//   * float32
	//   * []float32
	DrawTriangles(dst ImageID, srcs [graphics.ShaderImageNum]ImageID, offsets [graphics.ShaderImageNum - 1][2]float32, shader ShaderID, indexLen int, indexOffset int, mode CompositeMode, colorM ColorM, filter Filter, address Address, dstRegion, srcRegion Region, uniforms [][]float32, evenOdd bool) error
}

// GraphicsNotReady represents that the graphics driver is not ready for recovering from the context lost.
var GraphicsNotReady = errors.New("graphics not ready")

type Image interface {
	ID() ImageID
	Dispose()
	IsInvalidated() bool
	ReadPixels(buf []byte) error
	ReplacePixels(args []*ReplacePixelsArgs) error
}

type ImageID int

type ReplacePixelsArgs struct {
	Pixels []byte
	Mask   []byte
	X      int
	Y      int
	Width  int
	Height int
}

type YDirection int

const (
	Upward YDirection = iota
	Downward
)

type Shader interface {
	ID() ShaderID
	Dispose()
}

type ShaderID int