Add ActiveRoomsHolder to manage the active rooms for a session (#4758)

services/appnavstate/api/src/main/kotlin/io/element/android/services/appnavstate/api/ActiveRoomsHolder.kt

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.services.appnavstate.api
+
+import io.element.android.libraries.di.AppScope
+import io.element.android.libraries.di.SingleIn
+import io.element.android.libraries.matrix.api.core.RoomId
+import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.matrix.api.room.JoinedRoom
+import java.util.concurrent.ConcurrentHashMap
+import javax.inject.Inject
+
+/**
+ * Holds the active rooms for a given session so they can be reused instead of instantiating new ones.
+ */
+@SingleIn(AppScope::class)
+class ActiveRoomsHolder @Inject constructor() {
+    private val rooms = ConcurrentHashMap<SessionId, MutableSet<JoinedRoom>>()
+
+    /**
+     * Adds a new held room for the given sessionId.
+     */
+    fun addRoom(room: JoinedRoom) {
+        val roomsForSessionId = rooms.getOrPut(key = room.sessionId, defaultValue = { mutableSetOf() })
+        if (roomsForSessionId.none { it.roomId == room.roomId }) {
+            // We don't want to add the same room multiple times
+            roomsForSessionId.add(room)
+        }
+    }
+
+    /**
+     * Returns the last room added for the given [sessionId] or null if no room was added.
+     */
+    fun getActiveRoom(sessionId: SessionId): JoinedRoom? {
+        return rooms[sessionId]?.lastOrNull()
+    }
+
+    /**
+     * Returns an active room associated to the given [sessionId], with the given [roomId], or null if none match.
+     */
+    fun getActiveRoomMatching(sessionId: SessionId, roomId: RoomId): JoinedRoom? {
+        return rooms[sessionId]?.find { it.roomId == roomId }
+    }
+
+    /**
+     * Removes any room matching the provided [sessionId] and [roomId].
+     */
+    fun removeRoom(sessionId: SessionId, roomId: RoomId) {
+        val roomsForSessionId = rooms[sessionId] ?: return
+        roomsForSessionId.removeIf { it.roomId == roomId }
+    }
+
+    /**
+     * Clears all the rooms for the given sessionId.
+     */
+    fun clear(sessionId: SessionId) {
+        val activeRooms = rooms.remove(sessionId) ?: return
+        for (room in activeRooms) {
+            // Destroy the room to reset the live timelines
+            room.destroy()
+        }
+    }
+}