package graphics

import (
	"image"
)

// Filter represents the type of filter to be used when a texture or a render
// target is maginified or minified.
type Filter int

const (
	FilterNearest Filter = iota
	FilterLinear
)

// TextureID represents an ID of a texture.
type TextureID int

// RenderTargetID represents an ID of a render target.
// A render target is essentially same as a texture, but it is assumed that the
// all alpha of a render target is maximum.
type RenderTargetID int

var currentTextureFactory TextureFactory

// A TextureFactory is the interface that creates a render target or a texture.
// This method is for the library and a game developer doesn't have to use this.
type TextureFactory interface {
	NewRenderTargetID(width, height int, filter Filter) (RenderTargetID, error)
	NewTextureID(img image.Image, filter Filter) (TextureID, error)
}

// SetTextureFactory sets the current texture factory.
// This method is for the library and a game developer doesn't have to use this.
func SetTextureFactory(textureFactory TextureFactory) {
	currentTextureFactory = textureFactory
}

// NewRenderTargetID returns an ID of a newly created render target.
func NewRenderTargetID(width, height int, filter Filter) (RenderTargetID, error) {
	if currentTextureFactory == nil {
		panic("graphics.NewRenderTarget: currentTextureFactory is not set.")
	}
	return currentTextureFactory.NewRenderTargetID(width, height, filter)
}

// NewRenderTargetID returns an ID of a newly created texture.
func NewTextureID(img image.Image, filter Filter) (TextureID, error) {
	if currentTextureFactory == nil {
		panic("graphics.NewTexture: currentTextureFactory is not set")
	}
	return currentTextureFactory.NewTextureID(img, filter)
}