Merge pull request #2064 from hmhealey/plt882

PLT-882 Ephemeral Messages and Out-Of-Channel mentions

1 files changed, 334 insertions, 246 deletions

diff --git a/api/post.go b/api/post.go
index e8345b5e5..c17da262f 100644
--- a/api/post.go
+++ b/api/post.go
@@ -15,6 +15,7 @@ import (
 	"net/url"
 	"path/filepath"
 	"regexp"
+	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -231,6 +232,8 @@ func handlePostEventsAndForget(c *Context, post *model.Post, triggerWebhooks boo
 		tchan := Srv.Store.Team().Get(c.Session.TeamId)
 		cchan := Srv.Store.Channel().Get(post.ChannelId)
 		uchan := Srv.Store.User().Get(post.UserId)
+		pchan := Srv.Store.User().GetProfiles(c.Session.TeamId)
+		mchan := Srv.Store.Channel().GetMembers(post.ChannelId)
 
 		var team *model.Team
 		if result := <-tchan; result.Err != nil {
@@ -248,7 +251,24 @@ func handlePostEventsAndForget(c *Context, post *model.Post, triggerWebhooks boo
 			channel = result.Data.(*model.Channel)
 		}
 
-		sendNotificationsAndForget(c, post, team, channel)
+		var profiles map[string]*model.User
+		if result := <-pchan; result.Err != nil {
+			l4g.Error(utils.T("api.post.handle_post_events_and_forget.profiles.error"), c.Session.TeamId, result.Err)
+			return
+		} else {
+			profiles = result.Data.(map[string]*model.User)
+		}
+
+		var members []model.ChannelMember
+		if result := <-mchan; result.Err != nil {
+			l4g.Error(utils.T("api.post.handle_post_events_and_forget.members.error"), post.ChannelId, result.Err)
+			return
+		} else {
+			members = result.Data.([]model.ChannelMember)
+		}
+
+		go sendNotifications(c, post, team, channel, profiles, members)
+		go checkForOutOfChannelMentions(c, post, channel, profiles, members)
 
 		var user *model.User
 		if result := <-uchan; result.Err != nil {
@@ -413,311 +433,290 @@ func handleWebhookEventsAndForget(c *Context, post *model.Post, team *model.Team
 
 }
 
-func sendNotificationsAndForget(c *Context, post *model.Post, team *model.Team, channel *model.Channel) {
+func sendNotifications(c *Context, post *model.Post, team *model.Team, channel *model.Channel, profileMap map[string]*model.User, members []model.ChannelMember) {
+	var channelName string
+	var bodyText string
+	var subjectText string
 
-	go func() {
-		// Get a list of user names (to be used as keywords) and ids for the given team
-		uchan := Srv.Store.User().GetProfiles(c.Session.TeamId)
-		echan := Srv.Store.Channel().GetMembers(post.ChannelId)
+	var mentionedUsers []string
 
-		var channelName string
-		var bodyText string
-		var subjectText string
+	if _, ok := profileMap[post.UserId]; !ok {
+		l4g.Error(utils.T("api.post.send_notifications_and_forget.user_id.error"), post.UserId)
+		return
+	}
+	senderName := profileMap[post.UserId].Username
 
-		var mentionedUsers []string
+	toEmailMap := make(map[string]bool)
 
-		if result := <-uchan; result.Err != nil {
-			l4g.Error(utils.T("api.post.send_notifications_and_forget.retrive_profiles.error"), c.Session.TeamId, result.Err)
-			return
+	if channel.Type == model.CHANNEL_DIRECT {
+
+		var otherUserId string
+		if userIds := strings.Split(channel.Name, "__"); userIds[0] == post.UserId {
+			otherUserId = userIds[1]
+			channelName = profileMap[userIds[1]].Username
 		} else {
-			profileMap := result.Data.(map[string]*model.User)
+			otherUserId = userIds[0]
+			channelName = profileMap[userIds[0]].Username
+		}
 
-			if _, ok := profileMap[post.UserId]; !ok {
-				l4g.Error(utils.T("api.post.send_notifications_and_forget.user_id.error"), post.UserId)
-				return
-			}
-			senderName := profileMap[post.UserId].Username
+		otherUser := profileMap[otherUserId]
+		sendEmail := true
+		if _, ok := otherUser.NotifyProps["email"]; ok && otherUser.NotifyProps["email"] == "false" {
+			sendEmail = false
+		}
+		if sendEmail && (otherUser.IsOffline() || otherUser.IsAway()) {
+			toEmailMap[otherUserId] = true
+		}
 
-			toEmailMap := make(map[string]bool)
+	} else {
+		// Find out who is a member of the channel, only keep those profiles
+		tempProfileMap := make(map[string]*model.User)
+		for _, member := range members {
+			tempProfileMap[member.UserId] = profileMap[member.UserId]
+		}
 
-			if channel.Type == model.CHANNEL_DIRECT {
+		profileMap = tempProfileMap
 
-				var otherUserId string
-				if userIds := strings.Split(channel.Name, "__"); userIds[0] == post.UserId {
-					otherUserId = userIds[1]
-					channelName = profileMap[userIds[1]].Username
-				} else {
-					otherUserId = userIds[0]
-					channelName = profileMap[userIds[0]].Username
-				}
+		// Build map for keywords
+		keywordMap := make(map[string][]string)
+		for _, profile := range profileMap {
+			if len(profile.NotifyProps["mention_keys"]) > 0 {
 
-				otherUser := profileMap[otherUserId]
-				sendEmail := true
-				if _, ok := otherUser.NotifyProps["email"]; ok && otherUser.NotifyProps["email"] == "false" {
-					sendEmail = false
+				// Add all the user's mention keys
+				splitKeys := strings.Split(profile.NotifyProps["mention_keys"], ",")
+				for _, k := range splitKeys {
+					keywordMap[k] = append(keywordMap[strings.ToLower(k)], profile.Id)
 				}
-				if sendEmail && (otherUser.IsOffline() || otherUser.IsAway()) {
-					toEmailMap[otherUserId] = true
-				}
-
-			} else {
-
-				// Find out who is a member of the channel, only keep those profiles
-				if eResult := <-echan; eResult.Err != nil {
-					l4g.Error(utils.T("api.post.send_notifications_and_forget.members.error"), post.ChannelId, eResult.Err.Message)
-					return
-				} else {
-					tempProfileMap := make(map[string]*model.User)
-					members := eResult.Data.([]model.ChannelMember)
-					for _, member := range members {
-						tempProfileMap[member.UserId] = profileMap[member.UserId]
-					}
+			}
 
-					profileMap = tempProfileMap
-				}
+			// If turned on, add the user's case sensitive first name
+			if profile.NotifyProps["first_name"] == "true" {
+				keywordMap[profile.FirstName] = append(keywordMap[profile.FirstName], profile.Id)
+			}
 
-				// Build map for keywords
-				keywordMap := make(map[string][]string)
-				for _, profile := range profileMap {
-					if len(profile.NotifyProps["mention_keys"]) > 0 {
+			// Add @all to keywords if user has them turned on
+			// if profile.NotifyProps["all"] == "true" {
+			// 	keywordMap["@all"] = append(keywordMap["@all"], profile.Id)
+			// }
 
-						// Add all the user's mention keys
-						splitKeys := strings.Split(profile.NotifyProps["mention_keys"], ",")
-						for _, k := range splitKeys {
-							keywordMap[k] = append(keywordMap[strings.ToLower(k)], profile.Id)
-						}
-					}
+			// Add @channel to keywords if user has them turned on
+			if profile.NotifyProps["channel"] == "true" {
+				keywordMap["@channel"] = append(keywordMap["@channel"], profile.Id)
+			}
+		}
 
-					// If turned on, add the user's case sensitive first name
-					if profile.NotifyProps["first_name"] == "true" {
-						keywordMap[profile.FirstName] = append(keywordMap[profile.FirstName], profile.Id)
-					}
+		// Build a map as a list of unique user_ids that are mentioned in this post
+		splitF := func(c rune) bool {
+			return model.SplitRunes[c]
+		}
+		splitMessage := strings.Fields(post.Message)
+		for _, word := range splitMessage {
+			var userIds []string
 
-					// Add @all to keywords if user has them turned on
-					// if profile.NotifyProps["all"] == "true" {
-					// 	keywordMap["@all"] = append(keywordMap["@all"], profile.Id)
-					// }
+			// Non-case-sensitive check for regular keys
+			if ids, match := keywordMap[strings.ToLower(word)]; match {
+				userIds = append(userIds, ids...)
+			}
 
-					// Add @channel to keywords if user has them turned on
-					if profile.NotifyProps["channel"] == "true" {
-						keywordMap["@channel"] = append(keywordMap["@channel"], profile.Id)
-					}
-				}
+			// Case-sensitive check for first name
+			if ids, match := keywordMap[word]; match {
+				userIds = append(userIds, ids...)
+			}
 
-				// Build a map as a list of unique user_ids that are mentioned in this post
-				splitF := func(c rune) bool {
-					return model.SplitRunes[c]
-				}
-				splitMessage := strings.Fields(post.Message)
-				for _, word := range splitMessage {
-					var userIds []string
+			if len(userIds) == 0 {
+				// No matches were found with the string split just on whitespace so try further splitting
+				// the message on punctuation
+				splitWords := strings.FieldsFunc(word, splitF)
 
+				for _, splitWord := range splitWords {
 					// Non-case-sensitive check for regular keys
-					if ids, match := keywordMap[strings.ToLower(word)]; match {
+					if ids, match := keywordMap[strings.ToLower(splitWord)]; match {
 						userIds = append(userIds, ids...)
 					}
 
 					// Case-sensitive check for first name
-					if ids, match := keywordMap[word]; match {
+					if ids, match := keywordMap[splitWord]; match {
 						userIds = append(userIds, ids...)
 					}
-
-					if len(userIds) == 0 {
-						// No matches were found with the string split just on whitespace so try further splitting
-						// the message on punctuation
-						splitWords := strings.FieldsFunc(word, splitF)
-
-						for _, splitWord := range splitWords {
-							// Non-case-sensitive check for regular keys
-							if ids, match := keywordMap[strings.ToLower(splitWord)]; match {
-								userIds = append(userIds, ids...)
-							}
-
-							// Case-sensitive check for first name
-							if ids, match := keywordMap[splitWord]; match {
-								userIds = append(userIds, ids...)
-							}
-						}
-					}
-
-					for _, userId := range userIds {
-						if post.UserId == userId {
-							continue
-						}
-						sendEmail := true
-						if _, ok := profileMap[userId].NotifyProps["email"]; ok && profileMap[userId].NotifyProps["email"] == "false" {
-							sendEmail = false
-						}
-						if sendEmail && (profileMap[userId].IsAway() || profileMap[userId].IsOffline()) {
-							toEmailMap[userId] = true
-						} else {
-							toEmailMap[userId] = false
-						}
-					}
 				}
+			}
 
-				for id := range toEmailMap {
-					updateMentionCountAndForget(post.ChannelId, id)
+			for _, userId := range userIds {
+				if post.UserId == userId {
+					continue
+				}
+				sendEmail := true
+				if _, ok := profileMap[userId].NotifyProps["email"]; ok && profileMap[userId].NotifyProps["email"] == "false" {
+					sendEmail = false
+				}
+				if sendEmail && (profileMap[userId].IsAway() || profileMap[userId].IsOffline()) {
+					toEmailMap[userId] = true
+				} else {
+					toEmailMap[userId] = false
 				}
 			}
+		}
 
-			if len(toEmailMap) != 0 {
-				mentionedUsers = make([]string, 0, len(toEmailMap))
-				for k := range toEmailMap {
-					mentionedUsers = append(mentionedUsers, k)
-				}
+		for id := range toEmailMap {
+			updateMentionCountAndForget(post.ChannelId, id)
+		}
+	}
 
-				teamURL := c.GetSiteURL() + "/" + team.Name
+	if len(toEmailMap) != 0 {
+		mentionedUsers = make([]string, 0, len(toEmailMap))
+		for k := range toEmailMap {
+			mentionedUsers = append(mentionedUsers, k)
+		}
 
-				// Build and send the emails
-				tm := time.Unix(post.CreateAt/1000, 0)
+		teamURL := c.GetSiteURL() + "/" + team.Name
 
-				for id, doSend := range toEmailMap {
+		// Build and send the emails
+		tm := time.Unix(post.CreateAt/1000, 0)
 
-					if !doSend {
-						continue
-					}
+		for id, doSend := range toEmailMap {
 
-					// skip if inactive
-					if profileMap[id].DeleteAt > 0 {
-						continue
-					}
+			if !doSend {
+				continue
+			}
 
-					userLocale := utils.GetUserTranslations(profileMap[id].Locale)
+			// skip if inactive
+			if profileMap[id].DeleteAt > 0 {
+				continue
+			}
 
-					if channel.Type == model.CHANNEL_DIRECT {
-						bodyText = userLocale("api.post.send_notifications_and_forget.message_body")
-						subjectText = userLocale("api.post.send_notifications_and_forget.message_subject")
-					} else {
-						bodyText = userLocale("api.post.send_notifications_and_forget.mention_body")
-						subjectText = userLocale("api.post.send_notifications_and_forget.mention_subject")
-						channelName = channel.DisplayName
-					}
+			userLocale := utils.GetUserTranslations(profileMap[id].Locale)
 
-					month := userLocale(tm.Month().String())
-					day := fmt.Sprintf("%d", tm.Day())
-					year := fmt.Sprintf("%d", tm.Year())
-					zone, _ := tm.Zone()
-
-					subjectPage := NewServerTemplatePage("post_subject", c.Locale)
-					subjectPage.Props["Subject"] = userLocale("api.templates.post_subject",
-						map[string]interface{}{"SubjectText": subjectText, "TeamDisplayName": team.DisplayName,
-							"Month": month[:3], "Day": day, "Year": year})
-
-					bodyPage := NewServerTemplatePage("post_body", c.Locale)
-					bodyPage.Props["SiteURL"] = c.GetSiteURL()
-					bodyPage.Props["PostMessage"] = model.ClearMentionTags(post.Message)
-					bodyPage.Props["TeamLink"] = teamURL + "/channels/" + channel.Name
-					bodyPage.Props["BodyText"] = bodyText
-					bodyPage.Props["Button"] = userLocale("api.templates.post_body.button")
-					bodyPage.Html["Info"] = template.HTML(userLocale("api.templates.post_body.info",
-						map[string]interface{}{"ChannelName": channelName, "SenderName": senderName,
-							"Hour": fmt.Sprintf("%02d", tm.Hour()), "Minute": fmt.Sprintf("%02d", tm.Minute()),
-							"TimeZone": zone, "Month": month, "Day": day}))
-
-					// attempt to fill in a message body if the post doesn't have any text
-					if len(strings.TrimSpace(bodyPage.Props["PostMessage"])) == 0 && len(post.Filenames) > 0 {
-						// extract the filenames from their paths and determine what type of files are attached
-						filenames := make([]string, len(post.Filenames))
-						onlyImages := true
-						for i, filename := range post.Filenames {
-							var err error
-							if filenames[i], err = url.QueryUnescape(filepath.Base(filename)); err != nil {
-								// this should never error since filepath was escaped using url.QueryEscape
-								filenames[i] = filepath.Base(filename)
-							}
+			if channel.Type == model.CHANNEL_DIRECT {
+				bodyText = userLocale("api.post.send_notifications_and_forget.message_body")
+				subjectText = userLocale("api.post.send_notifications_and_forget.message_subject")
+			} else {
+				bodyText = userLocale("api.post.send_notifications_and_forget.mention_body")
+				subjectText = userLocale("api.post.send_notifications_and_forget.mention_subject")
+				channelName = channel.DisplayName
+			}
 
-							ext := filepath.Ext(filename)
-							onlyImages = onlyImages && model.IsFileExtImage(ext)
-						}
-						filenamesString := strings.Join(filenames, ", ")
+			month := userLocale(tm.Month().String())
+			day := fmt.Sprintf("%d", tm.Day())
+			year := fmt.Sprintf("%d", tm.Year())
+			zone, _ := tm.Zone()
+
+			subjectPage := NewServerTemplatePage("post_subject", c.Locale)
+			subjectPage.Props["Subject"] = userLocale("api.templates.post_subject",
+				map[string]interface{}{"SubjectText": subjectText, "TeamDisplayName": team.DisplayName,
+					"Month": month[:3], "Day": day, "Year": year})
+
+			bodyPage := NewServerTemplatePage("post_body", c.Locale)
+			bodyPage.Props["SiteURL"] = c.GetSiteURL()
+			bodyPage.Props["PostMessage"] = model.ClearMentionTags(post.Message)
+			bodyPage.Props["TeamLink"] = teamURL + "/channels/" + channel.Name
+			bodyPage.Props["BodyText"] = bodyText
+			bodyPage.Props["Button"] = userLocale("api.templates.post_body.button")
+			bodyPage.Html["Info"] = template.HTML(userLocale("api.templates.post_body.info",
+				map[string]interface{}{"ChannelName": channelName, "SenderName": senderName,
+					"Hour": fmt.Sprintf("%02d", tm.Hour()), "Minute": fmt.Sprintf("%02d", tm.Minute()),
+					"TimeZone": zone, "Month": month, "Day": day}))
+
+			// attempt to fill in a message body if the post doesn't have any text
+			if len(strings.TrimSpace(bodyPage.Props["PostMessage"])) == 0 && len(post.Filenames) > 0 {
+				// extract the filenames from their paths and determine what type of files are attached
+				filenames := make([]string, len(post.Filenames))
+				onlyImages := true
+				for i, filename := range post.Filenames {
+					var err error
+					if filenames[i], err = url.QueryUnescape(filepath.Base(filename)); err != nil {
+						// this should never error since filepath was escaped using url.QueryEscape
+						filenames[i] = filepath.Base(filename)
+					}
 
-						var attachmentPrefix string
-						if onlyImages {
-							attachmentPrefix = "Image"
-						} else {
-							attachmentPrefix = "File"
-						}
-						if len(post.Filenames) > 1 {
-							attachmentPrefix += "s"
-						}
+					ext := filepath.Ext(filename)
+					onlyImages = onlyImages && model.IsFileExtImage(ext)
+				}
+				filenamesString := strings.Join(filenames, ", ")
 
-						bodyPage.Props["PostMessage"] = userLocale("api.post.send_notifications_and_forget.sent",
-							map[string]interface{}{"Prefix": attachmentPrefix, "Filenames": filenamesString})
-					}
+				var attachmentPrefix string
+				if onlyImages {
+					attachmentPrefix = "Image"
+				} else {
+					attachmentPrefix = "File"
+				}
+				if len(post.Filenames) > 1 {
+					attachmentPrefix += "s"
+				}
 
-					if err := utils.SendMail(profileMap[id].Email, subjectPage.Render(), bodyPage.Render()); err != nil {
-						l4g.Error(utils.T("api.post.send_notifications_and_forget.send.error"), profileMap[id].Email, err)
-					}
+				bodyPage.Props["PostMessage"] = userLocale("api.post.send_notifications_and_forget.sent",
+					map[string]interface{}{"Prefix": attachmentPrefix, "Filenames": filenamesString})
+			}
 
-					if *utils.Cfg.EmailSettings.SendPushNotifications {
-						sessionChan := Srv.Store.Session().GetSessions(id)
-						if result := <-sessionChan; result.Err != nil {
-							l4g.Error(utils.T("api.post.send_notifications_and_forget.sessions.error"), id, result.Err)
-						} else {
-							sessions := result.Data.([]*model.Session)
-							alreadySeen := make(map[string]string)
-
-							for _, session := range sessions {
-								if len(session.DeviceId) > 0 && alreadySeen[session.DeviceId] == "" &&
-									(strings.HasPrefix(session.DeviceId, model.PUSH_NOTIFY_APPLE+":") || strings.HasPrefix(session.DeviceId, model.PUSH_NOTIFY_ANDROID+":")) {
-									alreadySeen[session.DeviceId] = session.DeviceId
-
-									msg := model.PushNotification{}
-									msg.Badge = 1
-									msg.ServerId = utils.CfgDiagnosticId
-
-									if strings.HasPrefix(session.DeviceId, model.PUSH_NOTIFY_APPLE+":") {
-										msg.Platform = model.PUSH_NOTIFY_APPLE
-										msg.DeviceId = strings.TrimPrefix(session.DeviceId, model.PUSH_NOTIFY_APPLE+":")
-									} else if strings.HasPrefix(session.DeviceId, model.PUSH_NOTIFY_ANDROID+":") {
-										msg.Platform = model.PUSH_NOTIFY_ANDROID
-										msg.DeviceId = strings.TrimPrefix(session.DeviceId, model.PUSH_NOTIFY_ANDROID+":")
-									}
+			if err := utils.SendMail(profileMap[id].Email, subjectPage.Render(), bodyPage.Render()); err != nil {
+				l4g.Error(utils.T("api.post.send_notifications_and_forget.send.error"), profileMap[id].Email, err)
+			}
 
-									if channel.Type == model.CHANNEL_DIRECT {
-										msg.Message = senderName + userLocale("api.post.send_notifications_and_forget.push_message")
-									} else {
-										msg.Message = senderName + userLocale("api.post.send_notifications_and_forget.push_mention") + channelName
-									}
+			if *utils.Cfg.EmailSettings.SendPushNotifications {
+				sessionChan := Srv.Store.Session().GetSessions(id)
+				if result := <-sessionChan; result.Err != nil {
+					l4g.Error(utils.T("api.post.send_notifications_and_forget.sessions.error"), id, result.Err)
+				} else {
+					sessions := result.Data.([]*model.Session)
+					alreadySeen := make(map[string]string)
+
+					for _, session := range sessions {
+						if len(session.DeviceId) > 0 && alreadySeen[session.DeviceId] == "" &&
+							(strings.HasPrefix(session.DeviceId, model.PUSH_NOTIFY_APPLE+":") || strings.HasPrefix(session.DeviceId, model.PUSH_NOTIFY_ANDROID+":")) {
+							alreadySeen[session.DeviceId] = session.DeviceId
+
+							msg := model.PushNotification{}
+							msg.Badge = 1
+							msg.ServerId = utils.CfgDiagnosticId
+
+							if strings.HasPrefix(session.DeviceId, model.PUSH_NOTIFY_APPLE+":") {
+								msg.Platform = model.PUSH_NOTIFY_APPLE
+								msg.DeviceId = strings.TrimPrefix(session.DeviceId, model.PUSH_NOTIFY_APPLE+":")
+							} else if strings.HasPrefix(session.DeviceId, model.PUSH_NOTIFY_ANDROID+":") {
+								msg.Platform = model.PUSH_NOTIFY_ANDROID
+								msg.DeviceId = strings.TrimPrefix(session.DeviceId, model.PUSH_NOTIFY_ANDROID+":")
+							}
 
-									httpClient := http.Client{}
-									request, _ := http.NewRequest("POST", *utils.Cfg.EmailSettings.PushNotificationServer+"/api/v1/send_push", strings.NewReader(msg.ToJson()))
+							if channel.Type == model.CHANNEL_DIRECT {
+								msg.Message = senderName + userLocale("api.post.send_notifications_and_forget.push_message")
+							} else {
+								msg.Message = senderName + userLocale("api.post.send_notifications_and_forget.push_mention") + channelName
+							}
 
-									l4g.Debug(utils.T("api.post.send_notifications_and_forget.push_notification.debug"), msg.DeviceId, msg.Message)
-									if _, err := httpClient.Do(request); err != nil {
-										l4g.Error(utils.T("api.post.send_notifications_and_forget.push_notification.error"), id, err)
-									}
-								}
+							httpClient := http.Client{}
+							request, _ := http.NewRequest("POST", *utils.Cfg.EmailSettings.PushNotificationServer+"/api/v1/send_push", strings.NewReader(msg.ToJson()))
+
+							l4g.Debug(utils.T("api.post.send_notifications_and_forget.push_notification.debug"), msg.DeviceId, msg.Message)
+							if _, err := httpClient.Do(request); err != nil {
+								l4g.Error(utils.T("api.post.send_notifications_and_forget.push_notification.error"), id, err)
 							}
 						}
 					}
 				}
 			}
 		}
+	}
 
-		message := model.NewMessage(c.Session.TeamId, post.ChannelId, post.UserId, model.ACTION_POSTED)
-		message.Add("post", post.ToJson())
-		message.Add("channel_type", channel.Type)
+	message := model.NewMessage(c.Session.TeamId, post.ChannelId, post.UserId, model.ACTION_POSTED)
+	message.Add("post", post.ToJson())
+	message.Add("channel_type", channel.Type)
 
-		if len(post.Filenames) != 0 {
-			message.Add("otherFile", "true")
+	if len(post.Filenames) != 0 {
+		message.Add("otherFile", "true")
 
-			for _, filename := range post.Filenames {
-				ext := filepath.Ext(filename)
-				if model.IsFileExtImage(ext) {
-					message.Add("image", "true")
-					break
-				}
+		for _, filename := range post.Filenames {
+			ext := filepath.Ext(filename)
+			if model.IsFileExtImage(ext) {
+				message.Add("image", "true")
+				break
 			}
 		}
+	}
 
-		if len(mentionedUsers) != 0 {
-			message.Add("mentions", model.ArrayToJson(mentionedUsers))
-		}
+	if len(mentionedUsers) != 0 {
+		message.Add("mentions", model.ArrayToJson(mentionedUsers))
+	}
 
-		PublishAndForget(message)
-	}()
+	PublishAndForget(message)
 }
 
 func updateMentionCountAndForget(channelId, userId string) {
@@ -728,6 +727,95 @@ func updateMentionCountAndForget(channelId, userId string) {
 	}()
 }
 
+func checkForOutOfChannelMentions(c *Context, post *model.Post, channel *model.Channel, allProfiles map[string]*model.User, members []model.ChannelMember) {
+	// don't check for out of channel mentions in direct channels
+	if channel.Type == model.CHANNEL_DIRECT {
+		return
+	}
+
+	mentioned := getOutOfChannelMentions(post, allProfiles, members)
+	if len(mentioned) == 0 {
+		return
+	}
+
+	usernames := make([]string, len(mentioned))
+	for i, user := range mentioned {
+		usernames[i] = user.Username
+	}
+	sort.Strings(usernames)
+
+	var message string
+	if len(usernames) == 1 {
+		message = c.T("api.post.check_for_out_of_channel_mentions.message.one", map[string]interface{}{
+			"Username": usernames[0],
+		})
+	} else {
+		message = c.T("api.post.check_for_out_of_channel_mentions.message.multiple", map[string]interface{}{
+			"Usernames":    strings.Join(usernames[:len(usernames)-1], ", "),
+			"LastUsername": usernames[len(usernames)-1],
+		})
+	}
+
+	SendEphemeralPost(
+		c.Session.TeamId,
+		post.UserId,
+		&model.Post{
+			ChannelId: post.ChannelId,
+			Message:   message,
+			CreateAt:  post.CreateAt + 1,
+		},
+	)
+}
+
+// Gets a list of users that were mentioned in a given post that aren't in the channel that the post was made in
+func getOutOfChannelMentions(post *model.Post, allProfiles map[string]*model.User, members []model.ChannelMember) []*model.User {
+	// copy the profiles map since we'll be removing items from it
+	profiles := make(map[string]*model.User)
+	for id, profile := range allProfiles {
+		profiles[id] = profile
+	}
+
+	// only keep profiles which aren't in the current channel
+	for _, member := range members {
+		delete(profiles, member.UserId)
+	}
+
+	var mentioned []*model.User
+
+	for _, profile := range profiles {
+		if pattern, err := regexp.Compile(`(\W|^)@` + regexp.QuoteMeta(profile.Username) + `(\W|$)`); err != nil {
+			l4g.Error(utils.T("api.post.get_out_of_channel_mentions.regex.error"), profile.Id, err)
+		} else if pattern.MatchString(post.Message) {
+			mentioned = append(mentioned, profile)
+		}
+	}
+
+	return mentioned
+}
+
+func SendEphemeralPost(teamId, userId string, post *model.Post) {
+	post.Type = model.POST_EPHEMERAL
+
+	// fill in fields which haven't been specified which have sensible defaults
+	if post.Id == "" {
+		post.Id = model.NewId()
+	}
+	if post.CreateAt == 0 {
+		post.CreateAt = model.GetMillis()
+	}
+	if post.Props == nil {
+		post.Props = model.StringInterface{}
+	}
+	if post.Filenames == nil {
+		post.Filenames = []string{}
+	}
+
+	message := model.NewMessage(teamId, post.ChannelId, userId, model.ACTION_EPHEMERAL_MESSAGE)
+	message.Add("post", post.ToJson())
+
+	PublishAndForget(message)
+}
+
 func updatePost(c *Context, w http.ResponseWriter, r *http.Request) {
 	post := model.PostFromJson(r.Body)