Support UI control via Item

Closes openhab#3540

Signed-off-by: mueller-ma <[email protected]>

mobile/src/main/java/org/openhab/habdroid/ui/MainActivity.kt

@@ -14,6 +14,7 @@
 package org.openhab.habdroid.ui
 
 import android.Manifest
+import android.app.Dialog
 import android.app.PendingIntent
 import android.content.ActivityNotFoundException
 import android.content.ComponentName
@@ -61,19 +62,24 @@ import androidx.core.view.isVisible
 import androidx.core.widget.ContentLoadingProgressBar
 import androidx.drawerlayout.widget.DrawerLayout
 import androidx.recyclerview.widget.RecyclerView
+import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import com.google.android.material.navigation.NavigationView
 import com.google.android.material.snackbar.Snackbar
 import de.duenndns.ssl.MemorizingTrustManager
 import java.nio.charset.Charset
 import java.util.concurrent.CancellationException
 import javax.jmdns.ServiceInfo
+import kotlin.time.Duration.Companion.milliseconds
 import kotlin.time.Duration.Companion.seconds
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.isActive
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
+import org.json.JSONException
+import org.json.JSONObject
 import org.openhab.habdroid.BuildConfig
 import org.openhab.habdroid.R
 import org.openhab.habdroid.background.BackgroundTasksManager
@@ -169,6 +175,9 @@ class MainActivity : AbstractBaseActivity(), ConnectionFactory.UpdateListener {
     private var inServerSelectionMode = false
     private var wifiSsidDuringLastOnStart: String? = null
 
+    private var uiCommandItemJob: Job? = null
+    private var uiCommandItemNotification: Dialog? = null
+
     private val permissionRequestNoActionCallback =
         registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions()) {}
 
@@ -1129,6 +1138,7 @@ class MainActivity : AbstractBaseActivity(), ConnectionFactory.UpdateListener {
         if (action != null && executeActionIfPossible(action)) {
             pendingAction = null
         }
+        setupUiCommandItem()
     }
 
     private fun executeActionIfPossible(action: PendingAction): Boolean = when {
@@ -1431,6 +1441,83 @@ class MainActivity : AbstractBaseActivity(), ConnectionFactory.UpdateListener {
         }
     }
 
+    private fun setupUiCommandItem () {
+        uiCommandItemJob?.cancel()
+        uiCommandItemJob = launch {
+            listenUiCommandItem()
+        }
+    }
+
+    private suspend fun listenUiCommandItem() {
+        val connection = connection ?: return
+        val eventSubscription = connection.httpClient.makeSse(
+            // Support for both the "openhab" and the older "smarthome" root topic by using a wildcard
+            // TODO: Limit to item
+            connection.httpClient.buildUrl("rest/events?topics=*/items/Command/command")
+        )
+
+        try {
+            while (isActive) {
+                try {
+                    val event = JSONObject(eventSubscription.getNextEvent())
+                    if (event.optString("type") == "ALIVE") {
+                        Log.d(TAG, "Got ALIVE event")
+                        continue
+                    }
+                    val topic = event.getString("topic")
+                    val topicPath = topic.split('/')
+                    // Possible formats:
+                    // - openhab/items/<item>/statechanged
+                    // - openhab/items/<group item>/<item>/statechanged
+                    // When an update for a group is sent, there's also one for the individual item.
+                    // Therefore always take the element on index two.
+                    if (topicPath.size !in 4..5) {
+                        throw JSONException("Unexpected topic path $topic")
+                    }
+                    val state = JSONObject(event.getString("payload")).getString("value")
+                    Log.e(TAG, "Got state by event: $state")
+                    handleUiCommand(state)
+                } catch (e: JSONException) {
+                    Log.e(TAG, "Failed parsing JSON of state change event", e)
+                }
+            }
+        } finally {
+            eventSubscription.cancel()
+        }
+    }
+
+    private fun handleUiCommand(command: String) {
+        val prefix = command.substringBefore(":")
+        val commandContent = command.removePrefix("$prefix:")
+        when (prefix) {
+            "notification" -> {
+                val split = commandContent.split(":")
+                val message = "${split.getOrNull(0).orEmpty()}\n" +
+                    "${split.getOrNull(2).orEmpty()}\n" +
+                    split.getOrNull(3).orEmpty()
+                val closeAfter = split.getOrNull(4)?.toIntOrNull()
+                uiCommandItemNotification?.dismiss()
+                uiCommandItemNotification = MaterialAlertDialogBuilder(this)
+                    .setTitle(split.getOrNull(1).orEmpty())
+                    .setMessage(message)
+                    .setPositiveButton(android.R.string.ok, null)
+                    .show()
+                closeAfter?.let {
+                    launch {
+                        delay(closeAfter.milliseconds)
+                        uiCommandItemNotification?.dismiss()
+                    }
+                }
+            }
+            "close" -> uiCommandItemNotification?.dismiss()
+            "back" -> onBackPressedCallback.handleOnBackPressed()
+            "reload" -> recreate()
+            else -> {
+                Log.d(TAG, "Command not implemented: $command")
+            }
+        }
+    }
+
     private fun manageHabPanelShortcut(visible: Boolean) {
         manageShortcut(visible, "habpanel", ACTION_HABPANEL_SELECTED,
             R.string.mainmenu_openhab_habpanel, R.mipmap.ic_shortcut_habpanel,