ui: replace placeholder with RootScreen routing permission ↔ debug

app/src/main/java/de/jeanlucmakiola/calendula/MainActivity.kt

@@ -4,19 +4,10 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
-import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.foundation.layout.padding
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.Scaffold
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.res.stringResource
-import androidx.compose.ui.tooling.preview.Preview
 import dagger.hilt.android.AndroidEntryPoint
+import de.jeanlucmakiola.calendula.ui.RootScreen
 import de.jeanlucmakiola.calendula.ui.theme.CalendulaTheme
 
 @AndroidEntryPoint
@@ -26,34 +17,8 @@ class MainActivity : ComponentActivity() {
         enableEdgeToEdge()
         setContent {
             CalendulaTheme {
-                Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding ->
+                RootScreen(modifier = Modifier.fillMaxSize())
-                    PlaceholderScreen(modifier = Modifier.padding(innerPadding))
-                }
             }
         }
     }
 }
-
-@Composable
-private fun PlaceholderScreen(modifier: Modifier = Modifier) {
-    Column(
-        modifier = modifier.fillMaxSize(),
-        verticalArrangement = Arrangement.Center,
-        horizontalAlignment = Alignment.CenterHorizontally,
-    ) {
-        Text(
-            text = stringResource(R.string.app_name),
-            style = MaterialTheme.typography.displayMedium,
-        )
-        Text(
-            text = stringResource(R.string.app_tagline),
-            style = MaterialTheme.typography.bodyLarge,
-        )
-    }
-}
-
-@Preview(showBackground = true)
-@Composable
-private fun PlaceholderPreview() {
-    CalendulaTheme { PlaceholderScreen() }
-}

app/src/main/java/de/jeanlucmakiola/calendula/ui/RootScreen.kt

@@ -0,0 +1,55 @@
+package de.jeanlucmakiola.calendula.ui
+
+import android.Manifest
+import android.content.pm.PackageManager
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Scaffold
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
+import androidx.lifecycle.compose.LocalLifecycleOwner
+import androidx.core.content.ContextCompat
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.LifecycleEventObserver
+import de.jeanlucmakiola.calendula.ui.debug.DebugScreen
+import de.jeanlucmakiola.calendula.ui.permission.PermissionScreen
+
+@Composable
+fun RootScreen(modifier: Modifier = Modifier) {
+    val context = LocalContext.current
+    var hasPermission by remember {
+        mutableStateOf(
+            ContextCompat.checkSelfPermission(context, Manifest.permission.READ_CALENDAR)
+                == PackageManager.PERMISSION_GRANTED
+        )
+    }
+
+    val lifecycle = LocalLifecycleOwner.current.lifecycle
+    DisposableEffect(lifecycle) {
+        val obs = LifecycleEventObserver { _, event ->
+            if (event == Lifecycle.Event.ON_RESUME) {
+                hasPermission = ContextCompat.checkSelfPermission(
+                    context, Manifest.permission.READ_CALENDAR
+                ) == PackageManager.PERMISSION_GRANTED
+            }
+        }
+        lifecycle.addObserver(obs)
+        onDispose { lifecycle.removeObserver(obs) }
+    }
+
+    Scaffold(modifier = modifier) { innerPadding ->
+        if (hasPermission) {
+            DebugScreen(modifier = Modifier.padding(innerPadding))
+        } else {
+            PermissionScreen(
+                onGranted = { hasPermission = true },
+                modifier = Modifier.padding(innerPadding),
+            )
+        }
+    }
+}