Add OS permissions request helper

Author: abnegate

templates/android/library/src/main/java/io/package/OS.kt.twig

@@ -0,0 +1,52 @@
+package {{ sdk.namespace | caseDot }}
+
+import android.Manifest
+import android.content.pm.PackageManager
+import android.os.Build
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.content.ContextCompat
+
+object OS {
+    fun requestPermission(
+        activity: AppCompatActivity,
+        permission: String,
+        onGranted: () -> Unit = {},
+        onDenied: () -> Unit = {},
+        onShowRationale: () -> Unit = {},
+    ) {
+        if (
+            Build.VERSION.SDK_INT < Build.VERSION_CODES.M ||
+            (permission == Manifest.permission.POST_NOTIFICATIONS && Build.VERSION.SDK_INT < Build.VERSION_CODES.TIRAMISU)
+        ) {
+            onGranted()
+            return
+        }
+
+        if (ContextCompat.checkSelfPermission(
+                activity,
+                permission
+            ) == PackageManager.PERMISSION_GRANTED
+        ) {
+            onGranted()
+        } else if (activity.shouldShowRequestPermissionRationale(Manifest.permission.POST_NOTIFICATIONS)) {
+            onShowRationale()
+        } else {
+            requestPermissionLauncher(activity, onGranted, onDenied).launch(permission)
+        }
+    }
+
+    private fun requestPermissionLauncher(
+        activity: AppCompatActivity,
+        onGranted: () -> Unit,
+        onDenied: () -> Unit,
+    ) = activity.registerForActivityResult(
+        ActivityResultContracts.RequestPermission(),
+    ) { isGranted: Boolean ->
+        if (isGranted) {
+            onGranted()
+        } else {
+            onDenied()
+        }
+    }
+}