Add read mark for channels

Fixes #12

components/channels.go

@@ -220,3 +220,7 @@ func (c *Channels) ClearNewMessageIndicator() {
 		c.List.Items[c.SelectedChannel] = channelName[0]
 	}
 }
+
+func (c *Channels) SetReadMark(svc *service.SlackService) {
+	svc.SetChannelReadMark(svc.SlackChannels[c.SelectedChannel])
+}

handlers/event.go

@@ -253,6 +253,9 @@ func actionChangeChannel(ctx *context.AppContext) {
 		ctx.Service.Channels[ctx.View.Channels.SelectedChannel].Name,
 	)
 
+	// Set read mark
+	ctx.View.Channels.SetReadMark(ctx.Service)
+
 	termui.Render(ctx.View.Channels)
 	termui.Render(ctx.View.Chat)
 }

service/slack.go

@@ -107,6 +107,18 @@ func (s *SlackService) GetChannels() []Channel {
 	return chans
 }
 
+// FIXME: timestamp is not yet correct
+func (s *SlackService) SetChannelReadMark(channel interface{}) {
+	switch channel := channel.(type) {
+	case slack.Channel:
+		s.Client.SetChannelReadMark(channel.ID, string(time.Now().UnixNano()))
+	case slack.Group:
+		s.Client.SetGroupReadMark(channel.ID, string(time.Now().UnixNano()))
+	case slack.IM:
+		s.Client.MarkIMChannel(channel.ID, string(time.Now().UnixNano()))
+	}
+}
+
 func (s *SlackService) SendMessage(channel string, message string) {
 	// https://godoc.org/github.com/nlopes/slack#PostMessageParameters
 	postParams := slack.PostMessageParameters{
@@ -135,7 +147,6 @@ func (s *SlackService) GetMessages(channel interface{}, count int) []string {
 			log.Fatal(err) // FIXME
 		}
 	case slack.Group:
-		// TODO: json: cannot unmarshal number into Go value of type string<Paste>
 		history, err = s.Client.GetGroupHistory(chnType.ID, historyParams)
 		if err != nil {
 			log.Fatal(err) // FIXME