Handle permanently denied camera permission with Settings redirect

Detect when camera permission is permanently denied (not granted and
rationale not shown) and offer an "Open Settings" button instead of
a non-functional "Grant" button. Use centralized AppColors.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src/main/java/no/naiv/tiltshift/MainActivity.kt

@@ -1,7 +1,10 @@
 package no.naiv.tiltshift
 
 import android.Manifest
+import android.content.Intent
+import android.net.Uri
 import android.os.Bundle
+import android.provider.Settings
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
@@ -25,6 +28,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.text.font.FontWeight
@@ -38,7 +42,9 @@ import com.google.accompanist.permissions.ExperimentalPermissionsApi
 import com.google.accompanist.permissions.isGranted
 import com.google.accompanist.permissions.rememberMultiplePermissionsState
 import com.google.accompanist.permissions.rememberPermissionState
+import com.google.accompanist.permissions.shouldShowRationale
 import no.naiv.tiltshift.ui.CameraScreen
+import no.naiv.tiltshift.ui.theme.AppColors
 
 class MainActivity : ComponentActivity() {
 
@@ -96,12 +102,17 @@ private fun TiltShiftApp() {
                 }
             }
             else -> {
+                // Permanently denied: not granted AND rationale not shown
+                val cameraPermanentlyDenied = !cameraPermission.status.isGranted &&
+                    !cameraPermission.status.shouldShowRationale
+
                 // Show permission request UI
                 PermissionRequestScreen(
                     onRequestCamera = { cameraPermission.launchPermissionRequest() },
                     onRequestLocation = { locationPermissions.launchMultiplePermissionRequest() },
                     cameraGranted = cameraPermission.status.isGranted,
-                    locationGranted = locationPermissions.allPermissionsGranted
+                    locationGranted = locationPermissions.allPermissionsGranted,
+                    cameraPermanentlyDenied = cameraPermanentlyDenied
                 )
             }
         }
@@ -113,7 +124,8 @@ private fun PermissionRequestScreen(
     onRequestCamera: () -> Unit,
     onRequestLocation: () -> Unit,
     cameraGranted: Boolean,
-    locationGranted: Boolean
+    locationGranted: Boolean,
+    cameraPermanentlyDenied: Boolean
 ) {
     Column(
         modifier = Modifier
@@ -146,6 +158,7 @@ private fun PermissionRequestScreen(
             title = "Camera",
             description = "Required to take photos",
             isGranted = cameraGranted,
+            isPermanentlyDenied = cameraPermanentlyDenied,
             onRequest = onRequestCamera
         )
 
@@ -168,8 +181,10 @@ private fun PermissionItem(
     title: String,
     description: String,
     isGranted: Boolean,
+    isPermanentlyDenied: Boolean = false,
     onRequest: () -> Unit
 ) {
+    val context = LocalContext.current
     Box(
         modifier = Modifier
             .clip(RoundedCornerShape(16.dp))
@@ -182,7 +197,7 @@ private fun PermissionItem(
             Icon(
                 imageVector = icon,
                 contentDescription = null,
-                tint = if (isGranted) Color(0xFF4CAF50) else Color(0xFFFFB300),
+                tint = if (isGranted) AppColors.Success else AppColors.Accent,
                 modifier = Modifier.padding(bottom = 8.dp)
             )
 
@@ -201,10 +216,27 @@ private fun PermissionItem(
 
             if (!isGranted) {
                 Spacer(modifier = Modifier.height(12.dp))
+                if (isPermanentlyDenied) {
+                    Button(
+                        onClick = {
+                            context.startActivity(
+                                Intent(
+                                    Settings.ACTION_APPLICATION_DETAILS_SETTINGS,
+                                    Uri.fromParts("package", context.packageName, null)
+                                )
+                            )
+                        },
+                        colors = ButtonDefaults.buttonColors(
+                            containerColor = AppColors.Accent
+                        )
+                    ) {
+                        Text("Open Settings", color = Color.Black)
+                    }
+                } else {
                     Button(
                         onClick = onRequest,
                         colors = ButtonDefaults.buttonColors(
-                        containerColor = Color(0xFFFFB300)
+                            containerColor = AppColors.Accent
                         )
                     ) {
                         Text("Grant", color = Color.Black)
@@ -213,3 +245,4 @@ private fun PermissionItem(
             }
         }
     }
+}