more refactoring, media handler => manager

internal/media/processing.go

@@ -1,190 +0,0 @@
-package media
-
-import (
-	"bytes"
-	"errors"
-	"fmt"
-	"image"
-	"image/gif"
-	"image/jpeg"
-	"image/png"
-
-	"github.com/buckket/go-blurhash"
-	"github.com/nfnt/resize"
-	"github.com/superseriousbusiness/exifremove/pkg/exifremove"
-)
-
-// purgeExif is a little wrapper for the action of removing exif data from an image.
-// Only pass pngs or jpegs to this function.
-func purgeExif(data []byte) ([]byte, error) {
-	if len(data) == 0 {
-		return nil, errors.New("passed image was not valid")
-	}
-
-	clean, err := exifremove.Remove(data)
-	if err != nil {
-		return nil, fmt.Errorf("could not purge exif from image: %s", err)
-	}
-
-	if len(clean) == 0 {
-		return nil, errors.New("purged image was not valid")
-	}
-	
-	return clean, nil
-}
-
-func deriveGif(b []byte, extension string) (*imageAndMeta, error) {
-	var g *gif.GIF
-	var err error
-	switch extension {
-	case mimeGif:
-		g, err = gif.DecodeAll(bytes.NewReader(b))
-		if err != nil {
-			return nil, err
-		}
-	default:
-		return nil, fmt.Errorf("extension %s not recognised", extension)
-	}
-
-	// use the first frame to get the static characteristics
-	width := g.Config.Width
-	height := g.Config.Height
-	size := width * height
-	aspect := float64(width) / float64(height)
-
-	return &imageAndMeta{
-		image:  b,
-		width:  width,
-		height: height,
-		size:   size,
-		aspect: aspect,
-	}, nil
-}
-
-func deriveImage(b []byte, contentType string) (*imageAndMeta, error) {
-	var i image.Image
-	var err error
-
-	switch contentType {
-	case mimeImageJpeg:
-		i, err = jpeg.Decode(bytes.NewReader(b))
-		if err != nil {
-			return nil, err
-		}
-	case mimeImagePng:
-		i, err = png.Decode(bytes.NewReader(b))
-		if err != nil {
-			return nil, err
-		}
-	default:
-		return nil, fmt.Errorf("content type %s not recognised", contentType)
-	}
-
-	width := i.Bounds().Size().X
-	height := i.Bounds().Size().Y
-	size := width * height
-	aspect := float64(width) / float64(height)
-
-	return &imageAndMeta{
-		image:  b,
-		width:  width,
-		height: height,
-		size:   size,
-		aspect: aspect,
-	}, nil
-}
-
-// deriveThumbnail returns a byte slice and metadata for a thumbnail of width x and height y,
-// of a given jpeg, png, or gif, or an error if something goes wrong.
-//
-// Note that the aspect ratio of the image will be retained,
-// so it will not necessarily be a square, even if x and y are set as the same value.
-func deriveThumbnail(b []byte, contentType string, x uint, y uint) (*imageAndMeta, error) {
-	var i image.Image
-	var err error
-
-	switch contentType {
-	case mimeImageJpeg:
-		i, err = jpeg.Decode(bytes.NewReader(b))
-		if err != nil {
-			return nil, err
-		}
-	case mimeImagePng:
-		i, err = png.Decode(bytes.NewReader(b))
-		if err != nil {
-			return nil, err
-		}
-	case mimeImageGif:
-		i, err = gif.Decode(bytes.NewReader(b))
-		if err != nil {
-			return nil, err
-		}
-	default:
-		return nil, fmt.Errorf("content type %s not recognised", contentType)
-	}
-
-	thumb := resize.Thumbnail(x, y, i, resize.NearestNeighbor)
-	width := thumb.Bounds().Size().X
-	height := thumb.Bounds().Size().Y
-	size := width * height
-	aspect := float64(width) / float64(height)
-
-	tiny := resize.Thumbnail(32, 32, thumb, resize.NearestNeighbor)
-	bh, err := blurhash.Encode(4, 3, tiny)
-	if err != nil {
-		return nil, err
-	}
-
-	out := &bytes.Buffer{}
-	if err := jpeg.Encode(out, thumb, &jpeg.Options{
-		Quality: 75,
-	}); err != nil {
-		return nil, err
-	}
-	return &imageAndMeta{
-		image:    out.Bytes(),
-		width:    width,
-		height:   height,
-		size:     size,
-		aspect:   aspect,
-		blurhash: bh,
-	}, nil
-}
-
-// deriveStaticEmojji takes a given gif or png of an emoji, decodes it, and re-encodes it as a static png.
-func deriveStaticEmoji(b []byte, contentType string) (*imageAndMeta, error) {
-	var i image.Image
-	var err error
-
-	switch contentType {
-	case mimeImagePng:
-		i, err = png.Decode(bytes.NewReader(b))
-		if err != nil {
-			return nil, err
-		}
-	case mimeImageGif:
-		i, err = gif.Decode(bytes.NewReader(b))
-		if err != nil {
-			return nil, err
-		}
-	default:
-		return nil, fmt.Errorf("content type %s not allowed for emoji", contentType)
-	}
-
-	out := &bytes.Buffer{}
-	if err := png.Encode(out, i); err != nil {
-		return nil, err
-	}
-	return &imageAndMeta{
-		image: out.Bytes(),
-	}, nil
-}
-
-type imageAndMeta struct {
-	image    []byte
-	width    int
-	height   int
-	size     int
-	aspect   float64
-	blurhash string
-}