package http import ( "bytes" "errors" "fmt" "image" "image/jpeg" "image/png" "io" "net/http" "path/filepath" "strings" "github.com/mediocregopher/blog.mediocregopher.com/srv/http/apiutil" "github.com/mediocregopher/blog.mediocregopher.com/srv/post" "golang.org/x/image/draw" ) func isImgResizable(id string) bool { switch strings.ToLower(filepath.Ext(id)) { case ".jpg", ".jpeg", ".png": return true default: return false } } func resizeImage(out io.Writer, in io.Reader, maxWidth float64) error { img, format, err := image.Decode(in) if err != nil { return fmt.Errorf("decoding image: %w", err) } imgRect := img.Bounds() imgW, imgH := float64(imgRect.Dx()), float64(imgRect.Dy()) if imgW > maxWidth { newH := imgH * maxWidth / imgW newImg := image.NewRGBA(image.Rect(0, 0, int(maxWidth), int(newH))) // Resize draw.BiLinear.Scale( newImg, newImg.Bounds(), img, img.Bounds(), draw.Over, nil, ) img = newImg } switch format { case "jpeg": return jpeg.Encode(out, img, nil) case "png": return png.Encode(out, img) default: return fmt.Errorf("unknown image format %q", format) } } func (a *api) renderPostAssetsIndexHandler() http.Handler { tpl := a.mustParseBasedTpl("assets.html") return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) { ids, err := a.params.PostAssetStore.List() if err != nil { apiutil.InternalServerError( rw, r, fmt.Errorf("getting list of asset ids: %w", err), ) return } tplPayload := struct { IDs []string }{ IDs: ids, } executeTemplate(rw, r, tpl, tplPayload) }) } func (a *api) getPostAssetHandler() http.Handler { renderIndexHandler := a.renderPostAssetsIndexHandler() return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) { id := filepath.Base(r.URL.Path) if id == "/" { renderIndexHandler.ServeHTTP(rw, r) return } maxWidth, err := apiutil.StrToInt(r.FormValue("w"), 0) if err != nil { apiutil.BadRequest(rw, r, fmt.Errorf("invalid w parameter: %w", err)) return } buf := new(bytes.Buffer) err = a.params.PostAssetStore.Get(id, buf) if errors.Is(err, post.ErrAssetNotFound) { http.Error(rw, "Asset not found", 404) return } else if err != nil { apiutil.InternalServerError( rw, r, fmt.Errorf("fetching asset with id %q: %w", id, err), ) return } if maxWidth == 0 { if _, err := io.Copy(rw, buf); err != nil { apiutil.InternalServerError( rw, r, fmt.Errorf( "copying asset with id %q to response writer: %w", id, err, ), ) } return } if !isImgResizable(id) { apiutil.BadRequest(rw, r, fmt.Errorf("cannot resize file %q", id)) return } if err := resizeImage(rw, buf, float64(maxWidth)); err != nil { apiutil.InternalServerError( rw, r, fmt.Errorf( "resizing image with id %q to size %d: %w", id, maxWidth, err, ), ) } }) } func (a *api) postPostAssetHandler() http.Handler { return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) { id := r.PostFormValue("id") if id == "/" { apiutil.BadRequest(rw, r, errors.New("id is required")) return } file, _, err := r.FormFile("file") if err != nil { apiutil.BadRequest(rw, r, fmt.Errorf("reading multipart file: %w", err)) return } defer file.Close() if err := a.params.PostAssetStore.Set(id, file); err != nil { apiutil.InternalServerError(rw, r, fmt.Errorf("storing file: %w", err)) return } a.executeRedirectTpl(rw, r, "assets/") }) } func (a *api) deletePostAssetHandler() http.Handler { return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) { id := filepath.Base(r.URL.Path) if id == "/" { apiutil.BadRequest(rw, r, errors.New("id is required")) return } err := a.params.PostAssetStore.Delete(id) if errors.Is(err, post.ErrAssetNotFound) { http.Error(rw, "Asset not found", 404) return } else if err != nil { apiutil.InternalServerError( rw, r, fmt.Errorf("deleting asset with id %q: %w", id, err), ) return } a.executeRedirectTpl(rw, r, "assets/") }) }