package utio

import (
	"image"
	"image/png"
	"io"
)

// PNGer describes a PNG encoder/decoder.
type PNGer interface {
	Encoder
	Decoder
	Image() image.Image
}

// PNG creates a PNG encoder/decoder for m, m is only required for encoding.
func PNG(m image.Image) PNGer {
	return &pnger{m}
}

type pnger struct {
	m image.Image
}

func (p *pnger) Encode(w io.Writer) error {
	return png.Encode(w, p.m)
}

func (p *pnger) Decode(r io.Reader) error {
	var m, err = png.Decode(r)
	if nil != err {
		return err
	}
	p.m = m
	return nil
}

func (p *pnger) Image() image.Image {
	return p.m
}

// LoadPNG loads a PNG image from the supplied path.
func LoadPNG(path string) (image.Image, error) {
	var p = PNG(nil)
	var err = DecodeFile(path, p)
	if nil != err {
		return nil, err
	}
	return p.Image(), nil
}

// SavePNG writes an image as PNG to the supplied path.
func SavePNG(path string, m image.Image) error {
	return EncodeFile(path, PNG(m))
}