ActivityPub: Include MimeType in profile picture attribute

activityStreams.go

@@ -69,8 +69,9 @@ type asPerson struct {
 }
 
 type asAttachment struct {
-	Type string `json:"type,omitempty"`
-	URL  string `json:"url,omitempty"`
+	Type      string `json:"type,omitempty"`
+	URL       string `json:"url,omitempty"`
+	MediaType string `json:"mediaType,omitempty"`
 }
 
 type asTag struct {
@@ -188,10 +189,11 @@ func (a *goBlog) toAsPerson(blog string) *asPerson {
 			})),
 		},
 	}
-	if a.cfg.User.Picture != "" {
+	if pic := a.cfg.User.Picture; pic != "" {
 		asBlog.Icon = &asAttachment{
-			Type: "Image",
-			URL:  a.cfg.User.Picture,
+			Type:      "Image",
+			URL:       pic,
+			MediaType: mimeTypeFromUrl(pic),
 		}
 	}
 	return asBlog

utils.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"math/rand"
+	"mime"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -403,3 +404,17 @@ func stringToInt(s string) int {
 func loStringNotEmpty(s string, _ int) bool {
 	return s != ""
 }
+
+func mimeTypeFromUrl(url string) string {
+	ext := path.Ext(url)
+	mimeType := mime.TypeByExtension(ext)
+	if mimeType == "" {
+		switch ext {
+		case ".jpg":
+			mimeType = "image/jpeg"
+		default:
+			mimeType = "image/" + strings.TrimPrefix(ext, ".")
+		}
+	}
+	return mimeType
+}

utils_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"strconv"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -167,3 +168,22 @@ func Test_groupStrings(t *testing.T) {
 	assert.Equal(t, "H", groups[3].Identifier)
 	assert.Equal(t, "🚴", groups[4].Identifier)
 }
+
+func Test_mimeTypeFromUrl(t *testing.T) {
+	type test struct {
+		url  string
+		want string
+	}
+	tests := []*test{
+		{url: "https://example.com/profile.jpg", want: "image/jpeg"},
+		{url: "https://example.com/profile.jpeg", want: "image/jpeg"},
+		{url: "https://example.com/profile.png", want: "image/png"},
+	}
+	for i, tt := range tests {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			if got := mimeTypeFromUrl(tt.url); got != tt.want {
+				t.Errorf("mimeTypeFromUrl() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}