Fix message persistence

TODO.md

@@ -1,6 +1,6 @@
 Bugs:
 
-- [ ] when switching channels sometimes messages are persisted in the new
+- [x] when switching channels sometimes messages are persisted in the new
       channel, the Buffer() in Chat will probably not go further than the
       latest message. Could be that items are added to List and not cleared
       when switching channels

src/components/chat.go

@@ -12,6 +12,7 @@ type Chat struct {
 	SelectedChannel string
 }
 
+// CreateChat is the constructor for the Chat struct
 func CreateChat(svc *service.SlackService, inputHeight int, selectedChannel SlackChannel) *Chat {
 	chat := &Chat{
 		List: termui.NewList(),
@@ -129,6 +130,8 @@ func (c *Chat) SetY(y int) {
 	c.List.SetY(y)
 }
 
+// GetMessages will get an array of strings for a specific channel which will
+// contain messages in turn all these messages will be added to List.Items
 func (c *Chat) GetMessages(svc *service.SlackService, channel string) {
 	// Get the count of message that fit in the pane
 	count := c.List.InnerBounds().Max.Y - c.List.InnerBounds().Min.Y
@@ -139,15 +142,22 @@ func (c *Chat) GetMessages(svc *service.SlackService, channel string) {
 	}
 }
 
+// AddMessage adds a single message to List.Items
 func (c *Chat) AddMessage(message string) {
 	c.List.Items = append(c.List.Items, message)
 }
 
+// ClearMessages clear the List.Items
+func (c *Chat) ClearMessages() {
+	c.List.Items = []string{}
+}
+
 func (c *Chat) ScrollUp() {
 }
 
 func (c *Chat) ScrollDown() {}
 
+// SetBorderLabel will set Label of the Chat pane to the specified string
 func (c *Chat) SetBorderLabel(label string) {
 	c.List.BorderLabel = label
 }

src/handlers/event.go

@@ -197,28 +197,25 @@ func actionGetChannels(ctx *context.AppContext) {
 
 func actionMoveCursorUpChannels(ctx *context.AppContext) {
 	ctx.View.Channels.MoveCursorUp()
-
-	ctx.View.Chat.GetMessages(
-		ctx.Service,
-		ctx.View.Channels.SlackChannels[ctx.View.Channels.SelectedChannel].ID,
-	)
-
-	ctx.View.Chat.SetBorderLabel(
-		ctx.View.Channels.SlackChannels[ctx.View.Channels.SelectedChannel].Name,
-	)
-
-	termui.Render(ctx.View.Channels)
-	termui.Render(ctx.View.Chat)
+	actionChangeChannel(ctx)
 }
 
 func actionMoveCursorDownChannels(ctx *context.AppContext) {
 	ctx.View.Channels.MoveCursorDown()
+	actionChangeChannel(ctx)
+}
 
+func actionChangeChannel(ctx *context.AppContext) {
+	// Clear messages from Chat pane
+	ctx.View.Chat.ClearMessages()
+
+	// Get message for the new channel
 	ctx.View.Chat.GetMessages(
 		ctx.Service,
 		ctx.View.Channels.SlackChannels[ctx.View.Channels.SelectedChannel].ID,
 	)
 
+	// Set channel name for the Chat pane
 	ctx.View.Chat.SetBorderLabel(
 		ctx.View.Channels.SlackChannels[ctx.View.Channels.SelectedChannel].Name,
 	)