From 919ddf569e8b5cd7db1e1bc2366c7b81fd3c6d7d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Rudowicz?= <michal.rudowicz@fl9.eu>
Date: Wed, 14 Feb 2024 21:34:16 +0100
Subject: [PATCH] FilterByLastSeen(); TODO: persistence

---
 filters.go      | 23 +++++++++++++++++++++++
 filters_test.go | 29 +++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/filters.go b/filters.go
index 62b78f0..9923d22 100644
--- a/filters.go
+++ b/filters.go
@@ -21,3 +21,26 @@ func FilterByType(ev <-chan satel.Event, allowedTypes []satel.ChangeType) <-chan
 
 	return returnChan
 }
+
+type EventKey struct {
+	ChangeType satel.ChangeType
+	Index      int
+}
+
+func FilterByLastSeen(ev <-chan satel.Event) <-chan satel.Event {
+	returnChan := make(chan satel.Event)
+
+	go func() {
+		lastSeen := make(map[EventKey]bool) // key: ChangeType/Index; value: Value
+		for e := range ev {
+			val, ok := lastSeen[EventKey{e.Type, e.Index}]
+			if !ok || val != e.Value {
+				lastSeen[EventKey{e.Type, e.Index}] = e.Value
+				returnChan <- e
+			}
+		}
+		close(returnChan)
+	}()
+
+	return returnChan
+}
diff --git a/filters_test.go b/filters_test.go
index b36f4dd..1058d40 100644
--- a/filters_test.go
+++ b/filters_test.go
@@ -35,3 +35,32 @@ func TestSatelEventTypeFiltering(t *testing.T) {
 	assert.Contains(t, receivedEvents, satel.Event{Type: satel.ArmedPartition, Index: 1, Value: true})
 	assert.Contains(t, receivedEvents, satel.Event{Type: satel.PartitionFireAlarm, Index: 4, Value: true})
 }
+
+func TestSatelLastSeenFiltering(t *testing.T) {
+	testEvents := make(chan satel.Event)
+	receivedEvents := make([]satel.Event, 0)
+	wg := sync.WaitGroup{}
+
+	go func() {
+		wg.Add(1)
+		for e := range FilterByLastSeen(testEvents) {
+			receivedEvents = append(receivedEvents, e)
+		}
+		wg.Done()
+	}()
+
+	testEvents <- satel.Event{Type: satel.ArmedPartition, Index: 1, Value: true}
+	testEvents <- satel.Event{Type: satel.ArmedPartition, Index: 2, Value: true}
+	testEvents <- satel.Event{Type: satel.ArmedPartition, Index: 1, Value: true}
+	testEvents <- satel.Event{Type: satel.ArmedPartition, Index: 1, Value: false}
+	testEvents <- satel.Event{Type: satel.ArmedPartition, Index: 2, Value: true}
+	testEvents <- satel.Event{Type: satel.ArmedPartition, Index: 1, Value: false}
+
+	close(testEvents)
+	wg.Wait()
+
+	assert.Len(t, receivedEvents, 3)
+	assert.Contains(t, receivedEvents, satel.Event{Type: satel.ArmedPartition, Index: 1, Value: true})
+	assert.Contains(t, receivedEvents, satel.Event{Type: satel.ArmedPartition, Index: 2, Value: true})
+	assert.Contains(t, receivedEvents, satel.Event{Type: satel.ArmedPartition, Index: 1, Value: false})
+}