Add /v2/assets/ handler, with resizing

srv/src/api/api.go

@@ -27,6 +27,7 @@ type Params struct {
 	PowManager pow.Manager
 
 	PostStore      post.Store
+	PostAssetStore post.AssetStore
 
 	MailingList mailinglist.MailingList
 
@@ -192,6 +193,8 @@ func (a *api) handler() http.Handler {
 	mux.Handle("/v2/posts/", a.renderPostHandler())
 	mux.Handle("/v2/", a.renderIndexHandler())
 
+	mux.Handle("/v2/assets/", a.servePostAssetHandler())
+
 	var globalHandler http.Handler = mux
 	globalHandler = setLoggerMiddleware(a.params.Logger, globalHandler)
 

srv/src/api/assets.go

@@ -0,0 +1,113 @@
+package api
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"image"
+	"image/jpeg"
+	"image/png"
+	"io"
+	"net/http"
+	"path/filepath"
+	"strings"
+
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/api/apiutil"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/post"
+	"golang.org/x/image/draw"
+)
+
+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) servePostAssetHandler() http.Handler {
+
+	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+
+		id := filepath.Base(r.URL.Path)
+
+		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
+		}
+
+		switch ext := strings.ToLower(strings.TrimPrefix(filepath.Ext(id), ".")); ext {
+		case "jpg", "jpeg", "png":
+
+			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,
+					),
+				)
+			}
+
+		default:
+			apiutil.BadRequest(rw, r, fmt.Errorf("cannot resize file with extension %q", ext))
+			return
+		}
+
+	})
+}

srv/src/cmd/mediocre-blog/main.go

@@ -120,10 +120,12 @@ func main() {
 	defer postSQLDB.Close()
 
 	postStore := post.NewStore(postSQLDB)
+	postAssetStore := post.NewAssetStore(postSQLDB)
 
 	apiParams.Logger = logger.WithNamespace("api")
 	apiParams.PowManager = powMgr
 	apiParams.PostStore = postStore
+	apiParams.PostAssetStore = postAssetStore
 	apiParams.MailingList = ml
 	apiParams.GlobalRoom = chatGlobalRoom
 	apiParams.UserIDCalculator = chatUserIDCalc

srv/src/go.mod

@@ -17,6 +17,7 @@ require (
 	github.com/tilinna/clock v1.1.0
 	github.com/ziutek/mymysql v1.5.4 // indirect
 	golang.org/x/crypto v0.0.0-20210817164053-32db794688a5
+	golang.org/x/image v0.0.0-20220413100746-70e8d0d3baa9
 	golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e // indirect
 	golang.org/x/term v0.0.0-20210927222741-03fcf44c2211 // indirect
 )

srv/src/go.sum

@@ -184,6 +184,8 @@ golang.org/x/crypto v0.0.0-20191122220453-ac88ee75c92c/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/crypto v0.0.0-20200820211705-5c72a883971a/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20210817164053-32db794688a5 h1:HWj/xjIHfjYU5nVXpTM0s39J9CbLn7Cc5a7IC5rwsMQ=
 golang.org/x/crypto v0.0.0-20210817164053-32db794688a5/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/image v0.0.0-20220413100746-70e8d0d3baa9 h1:LRtI4W37N+KFebI/qV0OFiLUv4GLOWeEW5hn/KEJvxE=
+golang.org/x/image v0.0.0-20220413100746-70e8d0d3baa9/go.mod h1:023OzeP/+EPmXeapQh35lcL3II3LrY8Ic+EFFKVhULM=
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
 golang.org/x/lint v0.0.0-20190313153728-d0100b6bd8b3/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
 golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
@@ -218,6 +220,7 @@ golang.org/x/term v0.0.0-20210927222741-03fcf44c2211 h1:JGgROgKl9N8DuW20oFS5gxc+
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/tools v0.0.0-20180221164845-07fd8470d635/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=