1 files changed, 96 insertions, 0 deletions
diff --git a/ui/src/main/java/com/wireguard/android/activity/BaseActivity.kt b/ui/src/main/java/com/wireguard/android/activity/BaseActivity.kt
new file mode 100644
index 00000000..5ff11062
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/activity/BaseActivity.kt
@@ -0,0 +1,96 @@
+/*
+ * Copyright © 2017-2025 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package com.wireguard.android.activity
+
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+import androidx.databinding.CallbackRegistry
+import androidx.databinding.CallbackRegistry.NotifierCallback
+import androidx.lifecycle.lifecycleScope
+import com.wireguard.android.Application
+import com.wireguard.android.model.ObservableTunnel
+import kotlinx.coroutines.launch
+
+/**
+ * Base class for activities that need to remember the currently-selected tunnel.
+ */
+abstract class BaseActivity : AppCompatActivity() {
+    private val selectionChangeRegistry = SelectionChangeRegistry()
+    private var created = false
+    var selectedTunnel: ObservableTunnel? = null
+        set(value) {
+            val oldTunnel = field
+            if (oldTunnel == value) return
+            field = value
+            if (created) {
+                if (!onSelectedTunnelChanged(oldTunnel, value)) {
+                    field = oldTunnel
+                } else {
+                    selectionChangeRegistry.notifyCallbacks(oldTunnel, 0, value)
+                }
+            }
+        }
+
+    fun addOnSelectedTunnelChangedListener(listener: OnSelectedTunnelChangedListener) {
+        selectionChangeRegistry.add(listener)
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        // Restore the saved tunnel if there is one; otherwise grab it from the arguments.
+        val savedTunnelName = when {
+            savedInstanceState != null -> savedInstanceState.getString(KEY_SELECTED_TUNNEL)
+            intent != null -> intent.getStringExtra(KEY_SELECTED_TUNNEL)
+            else -> null
+        }
+        if (savedTunnelName != null) {
+            lifecycleScope.launch {
+                val tunnel = Application.getTunnelManager().getTunnels()[savedTunnelName]
+                if (tunnel == null)
+                    created = true
+                selectedTunnel = tunnel
+                created = true
+            }
+        } else {
+            created = true
+        }
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        if (selectedTunnel != null) outState.putString(KEY_SELECTED_TUNNEL, selectedTunnel!!.name)
+        super.onSaveInstanceState(outState)
+    }
+
+    protected abstract fun onSelectedTunnelChanged(oldTunnel: ObservableTunnel?, newTunnel: ObservableTunnel?): Boolean
+
+    fun removeOnSelectedTunnelChangedListener(
+        listener: OnSelectedTunnelChangedListener
+    ) {
+        selectionChangeRegistry.remove(listener)
+    }
+
+    interface OnSelectedTunnelChangedListener {
+        fun onSelectedTunnelChanged(oldTunnel: ObservableTunnel?, newTunnel: ObservableTunnel?)
+    }
+
+    private class SelectionChangeNotifier : NotifierCallback<OnSelectedTunnelChangedListener, ObservableTunnel, ObservableTunnel>() {
+        override fun onNotifyCallback(
+            listener: OnSelectedTunnelChangedListener,
+            oldTunnel: ObservableTunnel?,
+            ignored: Int,
+            newTunnel: ObservableTunnel?
+        ) {
+            listener.onSelectedTunnelChanged(oldTunnel, newTunnel)
+        }
+    }
+
+    private class SelectionChangeRegistry :
+        CallbackRegistry<OnSelectedTunnelChangedListener, ObservableTunnel, ObservableTunnel>(SelectionChangeNotifier())
+
+    companion object {
+        private const val KEY_SELECTED_TUNNEL = "selected_tunnel"
+    }
+}