Extract SharedPreferences extensions to a file

app/src/main/java/gq/kirmanak/mealient/data/auth/impl/AuthStorageImpl.kt

@@ -2,13 +2,11 @@ package gq.kirmanak.mealient.data.auth.impl
 
 import android.content.SharedPreferences
 import gq.kirmanak.mealient.data.auth.AuthStorage
-import kotlinx.coroutines.Dispatchers
+import gq.kirmanak.mealient.data.impl.util.changesFlow
+import gq.kirmanak.mealient.data.impl.util.getStringOrNull
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.channels.awaitClose
-import kotlinx.coroutines.channels.onFailure
 import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.callbackFlow
+import kotlinx.coroutines.flow.map
-import kotlinx.coroutines.withContext
 import timber.log.Timber
 import javax.inject.Inject
 
@@ -29,43 +27,21 @@ class AuthStorageImpl @Inject constructor(
     }
 
     override suspend fun getBaseUrl(): String? {
-        val baseUrl = getString(BASE_URL_KEY)
+        val baseUrl = sharedPreferences.getStringOrNull(BASE_URL_KEY)
         Timber.d("getBaseUrl: base url is $baseUrl")
         return baseUrl
     }
 
     override suspend fun getToken(): String? {
         Timber.v("getToken() called")
-        val token = getString(TOKEN_KEY)
+        val token = sharedPreferences.getStringOrNull(TOKEN_KEY)
         Timber.d("getToken: token is $token")
         return token
     }
 
-    private suspend fun getString(key: String): String? = withContext(Dispatchers.Default) {
-        sharedPreferences.getString(key, null)
-    }
-
     override fun tokenObservable(): Flow<String?> {
         Timber.v("tokenObservable() called")
-        return callbackFlow {
+        return sharedPreferences.changesFlow().map { it.first.getStringOrNull(TOKEN_KEY) }
-            val listener = SharedPreferences.OnSharedPreferenceChangeListener { prefs, key ->
-                Timber.v("tokenObservable: listener called with key $key")
-                val token = when (key) {
-                    null -> null
-                    TOKEN_KEY -> prefs.getString(key, null)
-                    else -> return@OnSharedPreferenceChangeListener
-                }
-                Timber.d("tokenObservable: New token: $token")
-                trySend(token).onFailure { Timber.e(it, "Can't send new token") }
-            }
-            Timber.v("tokenObservable: registering listener")
-            send(getToken())
-            sharedPreferences.registerOnSharedPreferenceChangeListener(listener)
-            awaitClose {
-                Timber.v("tokenObservable: flow has been closed")
-                sharedPreferences.unregisterOnSharedPreferenceChangeListener(listener)
-            }
-        }
     }
 
     override fun clearAuthData() {

app/src/main/java/gq/kirmanak/mealient/data/disclaimer/DisclaimerStorageImpl.kt

@@ -1,8 +1,7 @@
 package gq.kirmanak.mealient.data.disclaimer
 
 import android.content.SharedPreferences
-import kotlinx.coroutines.Dispatchers
+import gq.kirmanak.mealient.data.impl.util.getBooleanOrFalse
-import kotlinx.coroutines.withContext
 import timber.log.Timber
 import javax.inject.Inject
 
@@ -14,9 +13,7 @@ class DisclaimerStorageImpl @Inject constructor(
 
     override suspend fun isDisclaimerAccepted(): Boolean {
         Timber.v("isDisclaimerAccepted() called")
-        val isAccepted = withContext(Dispatchers.IO) {
+        val isAccepted = sharedPreferences.getBooleanOrFalse(IS_DISCLAIMER_ACCEPTED_KEY)
-            sharedPreferences.getBoolean(IS_DISCLAIMER_ACCEPTED_KEY, false)
-        }
         Timber.v("isDisclaimerAccepted() returned: $isAccepted")
         return isAccepted
     }

app/src/main/java/gq/kirmanak/mealient/data/impl/util/SharedPrefExtensions.kt

@@ -0,0 +1,36 @@
+package gq.kirmanak.mealient.data.impl.util
+
+import android.content.SharedPreferences
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.channels.onClosed
+import kotlinx.coroutines.channels.onFailure
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.callbackFlow
+import kotlinx.coroutines.withContext
+import timber.log.Timber
+
+suspend fun SharedPreferences.getStringOrNull(key: String) =
+    withContext(Dispatchers.IO) { getString(key, null) }
+
+suspend fun SharedPreferences.getBooleanOrFalse(key: String) =
+    withContext(Dispatchers.IO) { getBoolean(key, false) }
+
+@ExperimentalCoroutinesApi
+fun SharedPreferences.changesFlow(): Flow<Pair<SharedPreferences, String?>> = callbackFlow {
+    val listener = SharedPreferences.OnSharedPreferenceChangeListener { prefs, key ->
+        Timber.v("watchChanges: listener called with key $key")
+        trySend(prefs to key)
+            .onFailure { Timber.e(it, "watchChanges: can't send preference change, key $key") }
+            .onClosed { Timber.e(it, "watchChanges: flow has been closed") }
+    }
+    Timber.v("watchChanges: registering listener")
+    registerOnSharedPreferenceChangeListener(listener)
+    send(this@changesFlow to null)
+    awaitClose {
+        Timber.v("watchChanges: flow has been closed")
+        unregisterOnSharedPreferenceChangeListener(listener)
+    }
+}
+