Android Permissions and Privacy Best Practices

@Composable
fun CameraFeatureButton(onCameraReady: () -> Unit) {
    val context = LocalContext.current
    var showRationale by remember { mutableStateOf(false) }
    var showSettingsHint by remember { mutableStateOf(false) }

    val launcher = rememberLauncherForActivityResult(ActivityResultContracts.RequestPermission()) { granted ->
        if (granted) onCameraReady()
        else {
            val activity = context.findActivity()
            // If the system won't show a rationale after a denial, the user chose "don't ask again".
            showSettingsHint = activity != null &&
                !ActivityCompat.shouldShowRequestPermissionRationale(activity, Manifest.permission.CAMERA)
        }
    }

    Button(onClick = {
        when {
            ContextCompat.checkSelfPermission(context, Manifest.permission.CAMERA) ==
                PackageManager.PERMISSION_GRANTED -> onCameraReady()
            else -> showRationale = true
        }
    }) { Text("Scan receipt") }

    if (showRationale) AlertDialog(
        onDismissRequest = { showRationale = false },
        title = { Text("Camera access") },
        text = { Text("We use the camera only to scan receipts. Photos stay on your device unless you choose to upload them.") },
        confirmButton = { TextButton(onClick = { showRationale = false; launcher.launch(Manifest.permission.CAMERA) }) { Text("Continue") } },
        dismissButton = { TextButton(onClick = { showRationale = false }) { Text("Not now") } },
    )

    if (showSettingsHint) TextButton(onClick = {
        context.startActivity(Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS, Uri.fromParts("package", context.packageName, null)))
    }) { Text("Enable camera in Settings") }
}

fun Context.findActivity(): Activity? = when (this) {
    is Activity -> this
    is ContextWrapper -> baseContext.findActivity()
    else -> null
}

val pickImage = rememberLauncherForActivityResult(ActivityResultContracts.PickVisualMedia()) { uri ->
    uri?.let(onImagePicked)
}
// pickImage.launch(PickVisualMediaRequest(ActivityResultContracts.PickVisualMedia.ImageOnly))