PLT-7824 Added support for mentions with <@userid> and <!here> (#7615) (#7737)

4 files changed, 166 insertions, 0 deletions

diff --git a/app/command.go b/app/command.go
index 96dd2656c..8bd025c8e 100644
--- a/app/command.go
+++ b/app/command.go
@@ -275,6 +275,10 @@ func (a *App) HandleCommandResponse(command *model.Command, args *model.CommandA
 		}
 	}
 
+	// Process Slack text replacements
+	response.Text = a.ProcessSlackText(response.Text)
+	response.Attachments = a.ProcessSlackAttachments(response.Attachments)
+
 	if _, err := a.CreateCommandPost(post, args.TeamId, response); err != nil {
 		l4g.Error(err.Error())
 	}
diff --git a/app/slack.go b/app/slack.go
new file mode 100644
index 000000000..f05c27478
--- /dev/null
+++ b/app/slack.go
@@ -0,0 +1,76 @@
+// Copyright (c) 2017-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package app
+
+import (
+	"regexp"
+
+	"fmt"
+	"strings"
+
+	"github.com/mattermost/mattermost-server/model"
+	"github.com/mattermost/mattermost-server/store"
+)
+
+func (a *App) ProcessSlackText(text string) string {
+	text = expandAnnouncement(text)
+	text = replaceUserIds(a.Srv.Store.User(), text)
+
+	return text
+}
+
+// Expand announcements in incoming webhooks from Slack. Those announcements
+// can be found in the text attribute, or in the pretext, text, title and value
+// attributes of the attachment structure. The Slack attachment structure is
+// documented here: https://api.slack.com/docs/attachments
+func (app *App) ProcessSlackAttachments(a []*model.SlackAttachment) []*model.SlackAttachment {
+	var nonNilAttachments = model.StringifySlackFieldValue(a)
+	for _, attachment := range a {
+		attachment.Pretext = app.ProcessSlackText(attachment.Pretext)
+		attachment.Text = app.ProcessSlackText(attachment.Text)
+		attachment.Title = app.ProcessSlackText(attachment.Title)
+
+		for _, field := range attachment.Fields {
+			if field.Value != nil {
+				// Ensure the value is set to a string if it is set
+				field.Value = app.ProcessSlackText(fmt.Sprintf("%v", field.Value))
+			}
+		}
+	}
+	return nonNilAttachments
+}
+
+// To mention @channel or @here via a webhook in Slack, the message should contain
+// <!channel> or <!here>, as explained at the bottom of this article:
+// https://get.slack.help/hc/en-us/articles/202009646-Making-announcements
+func expandAnnouncement(text string) string {
+	a1 := [3]string{"<!channel>", "<!here>", "<!all>"}
+	a2 := [3]string{"@channel", "@here", "@all"}
+
+	for i, a := range a1 {
+		text = strings.Replace(text, a, a2[i], -1)
+	}
+	return text
+}
+
+// Replaces user IDs mentioned like this <@userID> to a normal username (eg. @bob)
+// This is required so that Mattermost maintains Slack compatibility
+// Refer to: https://api.slack.com/changelog/2017-09-the-one-about-usernames
+func replaceUserIds(userStore store.UserStore, text string) string {
+	rgx, err := regexp.Compile("<@([a-zA-Z0-9]+)>")
+	if err == nil {
+		userIds := make([]string, 0)
+		matches := rgx.FindAllStringSubmatch(text, -1)
+		for _, match := range matches {
+			userIds = append(userIds, match[1])
+		}
+
+		if res := <-userStore.GetProfileByIds(userIds, true); res.Err == nil {
+			for _, user := range res.Data.([]*model.User) {
+				text = strings.Replace(text, "<@"+user.Id+">", "@"+user.Username, -1)
+			}
+		}
+	}
+	return text
+}
diff --git a/app/slack_test.go b/app/slack_test.go
new file mode 100644
index 000000000..370942ba0
--- /dev/null
+++ b/app/slack_test.go
@@ -0,0 +1,83 @@
+package app
+
+import (
+	"testing"
+
+	"github.com/mattermost/mattermost-server/model"
+)
+
+func TestProcessSlackText(t *testing.T) {
+	th := Setup().InitBasic()
+	defer th.TearDown()
+
+	if th.App.ProcessSlackText("<!channel> foo <!channel>") != "@channel foo @channel" {
+		t.Fail()
+	}
+
+	if th.App.ProcessSlackText("<!here> bar <!here>") != "@here bar @here" {
+		t.Fail()
+	}
+
+	if th.App.ProcessSlackText("<!all> bar <!all>") != "@all bar @all" {
+		t.Fail()
+	}
+
+	userId := th.BasicUser.Id
+	username := th.BasicUser.Username
+	if th.App.ProcessSlackText("<@"+userId+"> hello") != "@"+username+" hello" {
+		t.Fail()
+	}
+}
+
+func TestProcessSlackAnnouncement(t *testing.T) {
+	th := Setup().InitBasic()
+	defer th.TearDown()
+
+	userId := th.BasicUser.Id
+	username := th.BasicUser.Username
+
+	attachments := []*model.SlackAttachment{
+		{
+			Pretext: "<!channel> pretext <!here>",
+			Text:    "<!channel> text <!here>",
+			Title:   "<!channel> title <!here>",
+			Fields: []*model.SlackAttachmentField{
+				{
+					Title: "foo",
+					Value: "<!channel> bar <!here>",
+					Short: true,
+				},
+			},
+		},
+		{
+			Pretext: "<@" + userId + "> pretext",
+			Text:    "<@" + userId + "> text",
+			Title:   "<@" + userId + "> title",
+			Fields: []*model.SlackAttachmentField{
+				{
+					Title: "foo",
+					Value: "<@" + userId + "> bar",
+					Short: true,
+				},
+			},
+		},
+	}
+	attachments = th.App.ProcessSlackAttachments(attachments)
+	if len(attachments) != 2 || len(attachments[0].Fields) != 1 || len(attachments[1].Fields) != 1 {
+		t.Fail()
+	}
+
+	if attachments[0].Pretext != "@channel pretext @here" ||
+		attachments[0].Text != "@channel text @here" ||
+		attachments[0].Title != "@channel title @here" ||
+		attachments[0].Fields[0].Value != "@channel bar @here" {
+		t.Fail()
+	}
+
+	if attachments[1].Pretext != "@"+username+" pretext" ||
+		attachments[1].Text != "@"+username+" text" ||
+		attachments[1].Title != "@"+username+" title" ||
+		attachments[1].Fields[0].Value != "@"+username+" bar" {
+		t.Fail()
+	}
+}
diff --git a/app/webhook.go b/app/webhook.go
index f7efd3af0..5ce56aa88 100644
--- a/app/webhook.go
+++ b/app/webhook.go
@@ -537,6 +537,9 @@ func (a *App) HandleIncomingWebhook(hookId string, req *model.IncomingWebhookReq
 	channelName := req.ChannelName
 	webhookType := req.Type
 
+	text = a.ProcessSlackText(text)
+	req.Attachments = a.ProcessSlackAttachments(req.Attachments)
+
 	// attachments is in here for slack compatibility
 	if len(req.Attachments) > 0 {
 		if len(req.Props) == 0 {