Implement on-demand updating of room & user pictures

2 files changed, 80 insertions, 22 deletions

diff --git a/connector/mattermost/mattermost.go b/connector/mattermost/mattermost.go
index 73ea66b..6282831 100644
--- a/connector/mattermost/mattermost.go
+++ b/connector/mattermost/mattermost.go
@@ -314,17 +314,21 @@ func (mm *Mattermost) handleConnected() {
 				} else {
 					room_info.Name = t.Team.Name + " / " + room_info.Name
 				}
-				// TODO: cache last update time so we don't do this needlessly
 				if t.Team.LastTeamIconUpdate > 0 {
-					team_img, resp := mm.conn.Client.GetTeamIcon(t.Id, "")
-					if resp.Error == nil {
-						room_info.Picture = &BlobMediaObject{
-							ObjectFilename: t.Team.Name,
-							ObjectMimetype: http.DetectContentType(team_img),
-							ObjectData: team_img,
-						}
-					} else {
-						log.Warnf("Could not get team image: %s", resp.Error)
+					room_info.Picture = &LazyBlobMediaObject{
+						ObjectFilename: fmt.Sprintf("%s-%d",
+							t.Team.Name,
+							t.Team.LastTeamIconUpdate),
+						GetFn: func(o *LazyBlobMediaObject) error {
+							team_img, resp := mm.conn.Client.GetTeamIcon(t.Id, "")
+							if resp.Error == nil {
+								log.Warnf("Could not get team image: %s", resp.Error)
+								return resp.Error
+							}
+							o.ObjectData = team_img
+							o.ObjectMimetype = http.DetectContentType(team_img)
+							return nil
+						},
 					}
 				}
 				break
@@ -378,20 +382,24 @@ func (mm *Mattermost) updateUserInfo(user *model.User) {
 			DisplayName: userDisp,
 		}
 		if user.LastPictureUpdate > 0 {
-			// TODO: cache last update time so we don't do this needlessly
-			img, resp := mm.conn.Client.GetProfileImage(user.Id, "")
-			if resp.Error == nil {
-				ui.Avatar = &BlobMediaObject{
-					ObjectFilename: user.Username,
-					ObjectMimetype: http.DetectContentType(img),
-					ObjectData: img,
-				}
-			} else {
-				log.Warnf("Could not get profile picture: %s", resp.Error)
+			ui.Avatar = &LazyBlobMediaObject{
+				ObjectFilename: fmt.Sprintf("%s-%d",
+					user.Username,
+					user.LastPictureUpdate),
+				GetFn: func(o *LazyBlobMediaObject) error {
+					img, resp := mm.conn.Client.GetProfileImage(user.Id, "")
+					if resp.Error == nil {
+						log.Warnf("Could not get profile picture: %s", resp.Error)
+						return resp.Error
+					}
+					o.ObjectData = img
+					o.ObjectMimetype = http.DetectContentType(img)
+					return nil
+				},
 			}
-			mm.handler.UserInfoUpdated(userId, ui)
-			mm.userdisplaynamemap[userId] = userDisp
 		}
+		mm.handler.UserInfoUpdated(userId, ui)
+		mm.userdisplaynamemap[userId] = userDisp
 	}
 }
 
diff --git a/connector/mediaobject.go b/connector/mediaobject.go
index a8d6f9a..244e571 100644
--- a/connector/mediaobject.go
+++ b/connector/mediaobject.go
@@ -132,3 +132,53 @@ type nullCloseReader struct {
 func (ncr nullCloseReader) Close() error {
 	return nil
 }
+
+// ----
+
+type LazyBlobMediaObject struct {
+	ObjectFilename string
+	ObjectMimetype string
+	ObjectImageSize *ImageSize
+	ObjectData []byte
+
+	GetFn func(o *LazyBlobMediaObject) error
+}
+
+func (m *LazyBlobMediaObject) Filename() string {
+	return m.ObjectFilename
+}
+
+func (m *LazyBlobMediaObject) Size() int64 {
+	if m.ObjectData == nil {
+		m.GetFn(m)
+	}
+	return int64(len(m.ObjectData))
+}
+
+func (m *LazyBlobMediaObject) Mimetype() string {
+	if m.ObjectData == nil {
+		m.GetFn(m)
+	}
+	return m.ObjectMimetype
+}
+
+func (m *LazyBlobMediaObject) ImageSize() *ImageSize {
+	if m.ObjectData == nil {
+		m.GetFn(m)
+	}
+	return m.ObjectImageSize
+}
+
+func (m *LazyBlobMediaObject) Read() (io.ReadCloser, error) {
+	if m.ObjectData == nil {
+		err := m.GetFn(m)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return nullCloseReader{bytes.NewBuffer(m.ObjectData)}, nil
+}
+
+func (m *LazyBlobMediaObject) URL() string {
+	return ""
+}