[MM-41185]: new API to mark thread as unread (#19951)

* [MM-41185]: new API to mark thread as unread

Until now we mark a thread as read/unread by sending a timestamp to the
server. This created some issues when marking a thread as unread from a
post. We needed to send the post.create_at - 1 as a timestamp but we
didn't do so consistently.

This commit adds a new API to set a thread as unread by post id.
Making all clients agnostic of the timestamp, and thus solving consistency issues.

Endpoint: /api/v4/users/{user_id}/teams/{team_id}/threads/{thread_id}/set_unread/{post_id}

* Updates client.go adding SetThreadUnreadByPostId

* Guards endpoint behind read channel permission

* Returns status 400 if post_id not belong in thread

* Root post as post_id should be permitted

app/app_iface.go

@@ -1077,6 +1077,7 @@ type AppIface interface {
 	UpdateThreadFollowForUser(userID, teamID, threadID string, state bool) *model.AppError
 	UpdateThreadFollowForUserFromChannelAdd(userID, teamID, threadID string) *model.AppError
 	UpdateThreadReadForUser(currentSessionId, userID, teamID, threadID string, timestamp int64) (*model.ThreadResponse, *model.AppError)
+	UpdateThreadReadForUserByPost(currentSessionId, userID, teamID, threadID, postID string) (*model.ThreadResponse, *model.AppError)
 	UpdateThreadsReadForUser(userID, teamID string) *model.AppError
 	UpdateUser(user *model.User, sendNotifications bool) (*model.User, *model.AppError)
 	UpdateUserActive(c *request.Context, userID string, active bool) *model.AppError

app/opentracing/opentracing_layer.go

@@ -16964,6 +16964,28 @@ func (a *OpenTracingAppLayer) UpdateThreadReadForUser(currentSessionId string, u
 	return resultVar0, resultVar1
 }
 
+func (a *OpenTracingAppLayer) UpdateThreadReadForUserByPost(currentSessionId string, userID string, teamID string, threadID string, postID string) (*model.ThreadResponse, *model.AppError) {
+	origCtx := a.ctx
+	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.UpdateThreadReadForUserByPost")
+
+	a.ctx = newCtx
+	a.app.Srv().Store.SetContext(newCtx)
+	defer func() {
+		a.app.Srv().Store.SetContext(origCtx)
+		a.ctx = origCtx
+	}()
+
+	defer span.Finish()
+	resultVar0, resultVar1 := a.app.UpdateThreadReadForUserByPost(currentSessionId, userID, teamID, threadID, postID)
+
+	if resultVar1 != nil {
+		span.LogFields(spanlog.Error(resultVar1))
+		ext.Error.Set(span, true)
+	}
+
+	return resultVar0, resultVar1
+}
+
 func (a *OpenTracingAppLayer) UpdateThreadsReadForUser(userID string, teamID string) *model.AppError {
 	origCtx := a.ctx
 	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.UpdateThreadsReadForUser")

app/user.go

@@ -2476,6 +2476,19 @@ func (a *App) UpdateThreadFollowForUserFromChannelAdd(userID, teamID, threadID s
 	return nil
 }
 
+func (a *App) UpdateThreadReadForUserByPost(currentSessionId, userID, teamID, threadID, postID string) (*model.ThreadResponse, *model.AppError) {
+	post, err := a.GetSinglePost(postID)
+	if err != nil {
+		return nil, err
+	}
+
+	if post.RootId != threadID && postID != threadID {
+		return nil, model.NewAppError("UpdateThreadReadForUser", "app.user.update_thread_read_for_user_by_post.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	return a.UpdateThreadReadForUser(currentSessionId, userID, teamID, threadID, post.CreateAt-1)
+}
+
 func (a *App) UpdateThreadReadForUser(currentSessionId, userID, teamID, threadID string, timestamp int64) (*model.ThreadResponse, *model.AppError) {
 	user, err := a.GetUser(userID)
 	if err != nil {