[MM-24714] Render markdown in email notifications (#18043)

Automatic Merge

app/notification_email.go

@@ -15,6 +15,7 @@ import (
 	"github.com/mattermost/mattermost-server/v6/model"
 	"github.com/mattermost/mattermost-server/v6/shared/i18n"
 	"github.com/mattermost/mattermost-server/v6/shared/mlog"
+	"github.com/mattermost/mattermost-server/v6/utils"
 	"github.com/pkg/errors"
 )
 
@@ -213,10 +214,16 @@ func (a *App) getNotificationEmailBody(recipient *model.User, post *model.Post,
 	if emailNotificationContentsType == model.EmailNotificationContentsFull {
 		postMessage := a.GetMessageForNotification(post, translateFunc)
 		postMessage = html.EscapeString(postMessage)
-		normalizedPostMessage, err := a.generateHyperlinkForChannels(postMessage, teamName, landingURL)
+		mdPostMessage, mdErr := utils.MarkdownToHTML(postMessage)
+		if mdErr != nil {
+			mlog.Warn("Encountered error while converting markdown to HTML", mlog.Err(mdErr))
+			mdPostMessage = postMessage
+		}
+
+		normalizedPostMessage, err := a.generateHyperlinkForChannels(mdPostMessage, teamName, landingURL)
 		if err != nil {
 			mlog.Warn("Encountered error while generating hyperlink for channels", mlog.String("team_name", teamName), mlog.Err(err))
-			normalizedPostMessage = postMessage
+			normalizedPostMessage = mdPostMessage
 		}
 		pData.Message = template.HTML(normalizedPostMessage)
 		pData.Time = translateFunc("app.notification.body.dm.time", messageTime)

app/notification_email_test.go

@@ -825,3 +825,112 @@ func TestLandingLinkPermalink(t *testing.T) {
 	require.NoError(t, err)
 	require.Contains(t, body, teamURL+"/pl/"+post.Id, fmt.Sprintf("Expected email text '%s'. Got %s", teamURL, body))
 }
+
+func TestMarkdownConversion(t *testing.T) {
+	tests := []struct {
+		name string
+		args string
+		want string
+	}{
+		{
+			name: "markdown: escape string test",
+			args: "<b>not bold</b>",
+			want: "&lt;b&gt;not bold&lt;/b&gt;",
+		},
+		{
+			name: "markdown: strong",
+			args: "This is **Mattermost**",
+			want: "This is <strong>Mattermost</strong>",
+		},
+		{
+			name: "markdown: blockquote",
+			args: "Below is blockquote\n" +
+				"> This is Mattermost blockquote\n" +
+				"> on multiple lines!",
+			want: "<blockquote>\n" +
+				"<p>This is Mattermost blockquote\n" +
+				"on multiple lines!</p>\n" +
+				"</blockquote>",
+		},
+		{
+			name: "markdown: emphasis",
+			args: "This is *Mattermost*",
+			want: "This is <em>Mattermost</em>",
+		},
+		{
+			name: "markdown: links",
+			args: "This is [Mattermost](https://mattermost.com)",
+			want: "This is <a href=\"https://mattermost.com\">Mattermost</a>",
+		},
+		{
+			name: "markdown: strikethrough",
+			args: "This is ~~Mattermost~~",
+			want: "This is <del>Mattermost</del>",
+		},
+		{
+			name: "markdown: table",
+			args: "| Tables        | Are           | Cool  |\n" +
+				"| ------------- |:-------------:| -----:|\n" +
+				"| col 3 is      | right-aligned | $1600 |\n" +
+				"| col 2 is      | centered      |   $12 |\n" +
+				"| zebra stripes | are neat      |    $1 |\n",
+			want: "<table>\n" +
+				"<thead>\n" +
+				"<tr>\n" +
+				"<th>Tables</th>\n" +
+				"<th style=\"text-align:center\">Are</th>\n" +
+				"<th style=\"text-align:right\">Cool</th>\n" +
+				"</tr>\n" +
+				"</thead>\n" +
+				"<tbody>\n" +
+				"<tr>\n" +
+				"<td>col 3 is</td>\n" +
+				"<td style=\"text-align:center\">right-aligned</td>\n" +
+				"<td style=\"text-align:right\">$1600</td>\n" +
+				"</tr>\n" +
+				"<tr>\n" +
+				"<td>col 2 is</td>\n" +
+				"<td style=\"text-align:center\">centered</td>\n" +
+				"<td style=\"text-align:right\">$12</td>\n" +
+				"</tr>\n" +
+				"<tr>\n" +
+				"<td>zebra stripes</td>\n" +
+				"<td style=\"text-align:center\">are neat</td>\n" +
+				"<td style=\"text-align:right\">$1</td>\n" +
+				"</tr>\n" +
+				"</tbody>\n" +
+				"</table>",
+		},
+		{
+			name: "markdown: multiline with header and links",
+			args: "###### H6 header\n[link 1](https://mattermost.com) - [link 2](https://mattermost.com)",
+			want: "<h6>H6 header</h6>\n" +
+				"<p><a href=\"https://mattermost.com\">link 1</a> - <a href=\"https://mattermost.com\">link 2</a></p>",
+		},
+	}
+
+	th := SetupWithStoreMock(t)
+	defer th.TearDown()
+
+	recipient := &model.User{}
+	storeMock := th.App.Srv().Store.(*mocks.Store)
+	teamStoreMock := mocks.TeamStore{}
+	teamStoreMock.On("GetByName", "testteam").Return(&model.Team{Name: "testteam"}, nil)
+	storeMock.On("Team").Return(&teamStoreMock)
+	channel := &model.Channel{
+		DisplayName: "ChannelName",
+		Type:        model.ChannelTypeOpen,
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			post := &model.Post{
+				Id:      "Test_id",
+				Message: tt.args,
+			}
+			got, err := th.App.getNotificationEmailBody(recipient, post, channel, "ChannelName", "sender", "testteam", "http://localhost:8065/landing#/testteam", model.EmailNotificationContentsFull, true, i18n.GetUserTranslations("en"), "user-avatar.png")
+			require.NoError(t, err)
+			require.Contains(t, got, tt.want)
+		})
+	}
+}

utils/markdown.go

@@ -4,6 +4,8 @@
 package utils
 
 import (
+	"html"
+	"regexp"
 	"strings"
 
 	"github.com/yuin/goldmark"
@@ -33,6 +35,28 @@ func StripMarkdown(markdown string) (string, error) {
 	return strings.TrimSpace(buf.String()), nil
 }
 
+// MarkdownToHTML takes a string containing Markdown and returns a string with HTML tagged version
+func MarkdownToHTML(markdown string) (string, error) {
+	// Unescape any blockquote text to be parsed by the markdown parser.
+	re := regexp.MustCompile(`^|\n(>)`)
+	markdownClean := re.ReplaceAllFunc([]byte(markdown), func(s []byte) []byte {
+		out := html.UnescapeString(string(s))
+		return []byte(out)
+	})
+
+	md := goldmark.New(
+		goldmark.WithExtensions(extension.GFM),
+	)
+
+	var b strings.Builder
+
+	err := md.Convert(markdownClean, &b)
+	if err != nil {
+		return "", err
+	}
+	return b.String(), nil
+}
+
 type notificationRenderer struct {
 }