From 2ae835e8b2b313de179a5d0c6d668bbcf510d325 Mon Sep 17 00:00:00 2001
From: Nikhil Thomas <nikhilthomas1@gmail.com>
Date: Sat, 25 Mar 2023 16:08:44 -0400
Subject: [PATCH] Minor Refactor for observer

Refactor removeFromSlice function

Add an example call to `deregister` in main

Signed-off-by: Nikhil Thomas <nikhilthomas1@gmail.com>
---
 observer/item.go | 21 ++++++++++++++-------
 observer/main.go |  4 ++++
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/observer/item.go b/observer/item.go
index 7130b62..4d4fa6d 100644
--- a/observer/item.go
+++ b/observer/item.go
@@ -23,7 +23,7 @@ func (i *Item) register(o Observer) {
 }
 
 func (i *Item) deregister(o Observer) {
-	i.observerList = removeFromslice(i.observerList, o)
+	i.observerList = removeFromSlice(i.observerList, o)
 }
 
 func (i *Item) notifyAll() {
@@ -32,13 +32,20 @@ func (i *Item) notifyAll() {
 	}
 }
 
-func removeFromslice(observerList []Observer, observerToRemove Observer) []Observer {
-	observerListLength := len(observerList)
+func removeFromSlice(observerList []Observer, observerToRemove Observer) []Observer {
+	idx := findIndex(observerList, observerToRemove)
+	if idx == -1 {
+		return observerList
+	}
+	observerList = append(observerList[:idx], observerList[idx+1:]...)
+	return observerList
+}
+
+func findIndex(observerList []Observer, observerToRemove Observer) int {
 	for i, observer := range observerList {
-		if observerToRemove.getID() == observer.getID() {
-			observerList[observerListLength-1], observerList[i] = observerList[i], observerList[observerListLength-1]
-			return observerList[:observerListLength-1]
+		if observer.getID() == observerToRemove.getID() {
+			return i
 		}
 	}
-	return observerList
+	return -1
 }
diff --git a/observer/main.go b/observer/main.go
index e022ea9..5b5e131 100644
--- a/observer/main.go
+++ b/observer/main.go
@@ -11,4 +11,8 @@ func main() {
 	shirtItem.register(observerSecond)
 
 	shirtItem.updateAvailability()
+
+	shirtItem.deregister(observerFirst)
+
+	shirtItem.updateAvailability()
 }