client_api: Fix logging & add some comments

internal/icinga2/client_api.go

@@ -440,12 +440,7 @@ func (client *Client) listenEventStream() error {
 		case *StateChange:
 			// Ignore any state changes while in downtime
 			if respT.DowntimeDepth > 0 {
-				stateType := "HARD"
-				if respT.StateType == StateTypeSoft {
-					stateType = "SOFT"
-				}
-
-				client.Logger.Debugf("Skipping %q state change while in downtime, %#v", stateType, respT)
+				client.Logger.Debugf("Skipping state change, checkable is in downtime, %#v", respT)
 				continue
 			}
 
@@ -473,13 +468,17 @@ func (client *Client) listenEventStream() error {
 			evTime = respT.Timestamp.Time()
 		case *DowntimeStarted:
 			if !respT.Downtime.IsFixed {
+				// This may never happen, but Icinga 2 does the same thing, and we need to ignore the start
+				// event for flexible downtime, as there will definitely be a triggered event for it.
 				continue
 			}
 
 			ev, err = client.buildDowntimeEvent(client.Ctx, respT.Downtime, true)
 			evTime = respT.Timestamp.Time()
 		case *DowntimeTriggered:
 			if respT.Downtime.IsFixed {
+				// Fixed downtimes generate two events (start, triggered), the latter applies here and must
+				// be ignored, since we're going to process its start event to avoid duplicated notifications.
 				continue
 			}