Observe session database to be able to detect new user and removed user.

libraries/push/impl/src/main/kotlin/io/element/android/libraries/push/impl/userpushstore/UserPushStoreFactory.kt

@@ -17,16 +17,43 @@
 package io.element.android.libraries.push.impl.userpushstore
 
 import android.content.Context
+import io.element.android.libraries.di.AppScope
 import io.element.android.libraries.di.ApplicationContext
+import io.element.android.libraries.di.SingleIn
+import io.element.android.libraries.sessionstorage.api.observer.SessionListener
+import io.element.android.libraries.sessionstorage.api.observer.SessionObserver
 import javax.inject.Inject
 
+@SingleIn(AppScope::class)
 class UserPushStoreFactory @Inject constructor(
     @ApplicationContext private val context: Context,
-) {
+    private val sessionObserver: SessionObserver,
+) : SessionListener {
+    init {
+        observeSessions()
+    }
+
+    // We can have only one class accessing a single data store, so keep a cache of them.
+    private val cache = mutableMapOf<String, UserPushStore>()
     fun create(userId: String): UserPushStore {
-        return UserPushStoreDataStore(
-            context = context,
-            userId = userId
-        )
+        return cache.getOrPut(userId) {
+            UserPushStoreDataStore(
+                context = context,
+                userId = userId
+            )
+        }
+    }
+
+    private fun observeSessions() {
+        sessionObserver.addListener(this)
+    }
+
+    override suspend fun onSessionCreated(userId: String) {
+        // Nothing to do
+    }
+
+    override suspend fun onSessionDeleted(userId: String) {
+        // Delete the store
+        create(userId).reset()
     }
 }