Improve native error handling (#10)

android/src/main/kotlin/com/navideck/universal_ble/UniversalBleHelper.kt

@@ -106,6 +106,33 @@ fun Int.parseBluetoothStatusCodeError(): String? {
     }
 }
 
+fun Int.parseGattErrorCode(): String? {
+    return when (this) {
+        BluetoothGatt.GATT_SUCCESS -> null
+        BluetoothGatt.GATT_READ_NOT_PERMITTED -> "GATT_READ_NOT_PERMITTED"
+        BluetoothGatt.GATT_WRITE_NOT_PERMITTED -> "GATT_WRITE_NOT_PERMITTED"
+        BluetoothGatt.GATT_INSUFFICIENT_AUTHENTICATION -> "GATT_INSUFFICIENT_AUTHENTICATION"
+        BluetoothGatt.GATT_REQUEST_NOT_SUPPORTED -> "GATT_REQUEST_NOT_SUPPORTED"
+        BluetoothGatt.GATT_INVALID_OFFSET -> "GATT_INVALID_OFFSET"
+        BluetoothGatt.GATT_INSUFFICIENT_AUTHORIZATION -> "GATT_INSUFFICIENT_AUTHORIZATION"
+        BluetoothGatt.GATT_INVALID_ATTRIBUTE_LENGTH -> "GATT_INVALID_ATTRIBUTE_LENGTH"
+        BluetoothGatt.GATT_INSUFFICIENT_ENCRYPTION -> "GATT_INSUFFICIENT_ENCRYPTION"
+        BluetoothGatt.GATT_CONNECTION_CONGESTED -> "GATT_CONNECTION_CONGESTED"
+        BluetoothGatt.GATT_FAILURE -> "GATT_FAILURE"
+        0x01 -> "GATT_INVALID_HANDLE"
+        0x04 -> "GATT_INVALID_PDU"
+        0x09 -> "GATT_PREPARE_QUEUE_FULL"
+        0x0a -> "GATT_ATTR_NOT_FOUND"
+        0x0b -> "GATT_ATTR_NOT_LONG"
+        0x0c -> "GATT_INSUFFICIENT_KEY_SIZE"
+        0x0e -> "GATT_UNLIKELY"
+        0x10 -> "GATT_UNSUPPORTED_GROUP"
+        0x11 -> "GATT_INSUFFICIENT_RESOURCES"
+        else -> "Unknown Error: $this"
+    }
+}
+
+
 val ScanResult.manufacturerDataHead: ByteArray?
     get() {
         val sparseArray = scanRecord?.manufacturerSpecificData ?: return null

android/src/main/kotlin/com/navideck/universal_ble/UniversalBlePlugin.kt

@@ -267,7 +267,20 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
                     it.serviceId == characteristic.service.uuid.toString()
         }.forEach {
             bleCharacteristicFutureList.remove(it)
-            it.result(Result.success(value))
+            if (status == BluetoothGatt.GATT_SUCCESS) {
+                it.result(Result.success(value))
+            } else {
+                it.result(
+                    Result.failure(
+                        FlutterError(
+                            status.toString(),
+                            "Failed to read: (${status.parseGattErrorCode()})",
+                            null,
+                        )
+                    )
+                )
+            }
+
         }
     }
 
@@ -374,9 +387,9 @@ class UniversalBlePlugin : UniversalBlePlatformChannel, BluetoothGattCallback(),
                 it.result(
                     Result.failure(
                         FlutterError(
-                            "Failed",
-                            "Failed to write ($status)",
-                            "status $status"
+                            status.toString(),
+                            "Failed to write: (${status.parseGattErrorCode()})",
+                            null,
                         )
                     )
                 )