extensions: Strip out logic for shared pref callback into extension

Signed-off-by: Aayush Gupta <aayushgupta219@gmail.com>

app/src/main/java/com/aurora/extensions/SharedPreferences.kt

@@ -0,0 +1,41 @@
+/*
+ * SPDX-FileCopyrightText: 2025 The Calyx Institute
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+package com.aurora.extensions
+
+import android.content.SharedPreferences
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.callbackFlow
+import kotlinx.coroutines.flow.stateIn
+
+/**
+ * Extension method to observe changes in shared preferences as a flow
+ */
+fun <T> SharedPreferences.observeAsStateFlow(
+    key: String,
+    scope: CoroutineScope,
+    started: SharingStarted = SharingStarted.Eagerly,
+    initial: T,
+    valueProvider: () -> T
+): StateFlow<T> =
+    callbackFlow {
+        val listener =
+            SharedPreferences.OnSharedPreferenceChangeListener { _, changedKey ->
+                if (changedKey == key) {
+                    trySend(valueProvider())
+                }
+            }
+
+        // Emit the initial value
+        trySend(valueProvider())
+
+        registerOnSharedPreferenceChangeListener(listener)
+        awaitClose {
+            unregisterOnSharedPreferenceChangeListener(listener)
+        }
+    }.stateIn(scope, started, initial)