Create `InAppNotificationController` class

1 files changed, 78 insertions, 0 deletions

diff --git a/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/notification/InAppNotificationController.kt b/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/notification/InAppNotificationController.kt
new file mode 100644
index 0000000000..3c1a62d925
--- /dev/null
+++ b/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/notification/InAppNotificationController.kt
@@ -0,0 +1,78 @@
+package net.mullvad.mullvadvpn.ui.notification
+
+import kotlin.properties.Delegates.observable
+
+class InAppNotificationController(private val onNotificationChanged: (InAppNotification?) -> Unit) {
+    private val indices = HashMap<InAppNotification, Int>()
+    private val notifications = ArrayList<InAppNotification>()
+
+    private var currentIndex: Int? = null
+
+    var current by observable<InAppNotification?>(null) { _, _, notification ->
+        onNotificationChanged?.invoke(notification)
+    }
+
+    fun register(notification: InAppNotification) {
+        notification.controller = this
+
+        indices.put(notification, notifications.size)
+        notifications.add(notification)
+
+        notificationChanged(notification)
+    }
+
+    fun onResume() {
+        for (notification in notifications) {
+            notification.onResume()
+        }
+    }
+
+    fun onPause() {
+        for (notification in notifications) {
+            notification.onPause()
+        }
+    }
+
+    fun onDestroy() {
+        for (notification in notifications) {
+            notification.onDestroy()
+        }
+    }
+
+    fun notificationChanged(notification: InAppNotification) {
+        if (notification.shouldShow) {
+            maybeShowNotification(notification)
+        } else {
+            maybeHideNotification(notification)
+        }
+    }
+
+    private fun maybeShowNotification(notification: InAppNotification) {
+        indices.get(notification)?.let { index ->
+            if (index <= (currentIndex ?: Int.MAX_VALUE)) {
+                current = notification
+                currentIndex = index
+            }
+        }
+    }
+
+    private fun maybeHideNotification(notification: InAppNotification) {
+        if (current == notification) {
+            val start = currentIndex!! + 1
+            val end = notifications.size
+
+            for (index in start until end) {
+                val candidate = notifications.get(index)
+
+                if (candidate.shouldShow) {
+                    current = candidate
+                    currentIndex = index
+                    return
+                }
+            }
+
+            current = null
+            currentIndex = null
+        }
+    }
+}