contented/thumb.go

package contented

import (
	"errors"
	"fmt"
	"log"
	"net/http"
	"path/filepath"

	"code.ivysaur.me/thumbnail"
)

func thumbnailer(t byte) (*thumbnail.Thumbnailer, error) {
	// Modelled on what imgur.com offers
	// @ref https://api.imgur.com/models/image#thumbs

	const (
		cacheSize = 1
		outputFmt = thumbnail.OUTPUT_JPG
		scaleFmt  = thumbnail.SCALEFMT_BILINEAR
	)

	switch t {
	case 's':
		return thumbnail.NewThumbnailerEx(90, 90, cacheSize, outputFmt, thumbnail.ASPECT_CROP_TO_DIMENSIONS, scaleFmt), nil
	case 'b':
		return thumbnail.NewThumbnailerEx(160, 160, cacheSize, outputFmt, thumbnail.ASPECT_CROP_TO_DIMENSIONS, scaleFmt), nil
	case 't':
		return thumbnail.NewThumbnailerEx(160, 160, cacheSize, outputFmt, thumbnail.ASPECT_RESPECT_MAX_DIMENSION_ONLY, scaleFmt), nil
	case 'm':
		return thumbnail.NewThumbnailerEx(340, 340, cacheSize, outputFmt, thumbnail.ASPECT_RESPECT_MAX_DIMENSION_ONLY, scaleFmt), nil
	case 'l':
		return thumbnail.NewThumbnailerEx(640, 640, cacheSize, outputFmt, thumbnail.ASPECT_RESPECT_MAX_DIMENSION_ONLY, scaleFmt), nil
	case 'h':
		return thumbnail.NewThumbnailerEx(1024, 1024, cacheSize, outputFmt, thumbnail.ASPECT_RESPECT_MAX_DIMENSION_ONLY, scaleFmt), nil
	default:
		return nil, errors.New("Unsupported thumbnail type (should be s/b/t/m/l/h)")
	}
}

func (this *Server) handleThumb(w http.ResponseWriter, r *http.Request, thumbnailType byte, fileId string) {
	t, err := thumbnailer(thumbnailType)
	if err != nil {
		log.Printf("%s Thumbnail failed: %s\n", this.remoteIP(r), err.Error())
		http.Error(w, err.Error(), 400)
		return
	}

	err = this.handleThumbInternal(w, t, fileId)
	if err != nil {
		log.Printf("%s Thumbnail failed: %s\n", this.remoteIP(r), err.Error())

		w.Header().Set(`Location`, fmt.Sprintf(`/nothumb_%d.png`, t.Height()))
		w.WriteHeader(302)
	}
}

func (this *Server) handleThumbInternal(w http.ResponseWriter, t *thumbnail.Thumbnailer, fileId string) error {

	// Load metadata
	m, err := this.Metadata(fileId)
	if err != nil {
		return err
	}

	filePath := filepath.Join(this.opts.DataDirectory, m.FileHash)
	thumb, err := t.RenderFile_NoCache_MimeType(filePath, m.MimeType)
	if err != nil {
		return err
	}

	w.Header().Set(`Content-Length`, fmt.Sprintf("%d", len(thumb)))
	w.Header().Set(`Content-Type`, `image/jpeg`)
	w.WriteHeader(200)
	w.Write(thumb)

	return nil
}