| 1 | import 'dart:ffi'; |
| 2 | import 'package:ffi/ffi.dart'; |
| 3 | import 'dart:convert'; |
| 4 | |
| 5 | class PayloadResult { |
| 6 | final String payload; |
| 7 | final String err; |
| 8 | final int errCode; |
| 9 | |
| 10 | const PayloadResult(this.payload, this.err, this.errCode); |
| 11 | } |
| 12 | |
| 13 | // Executes the provided fn and converts the string response to a PayloadResult. |
| 14 | // Returns payload, error code, and error. |
| 15 | PayloadResult executePayloadFn({ |
| 16 | required Pointer<Char> fn(), |
| 17 | required List<Pointer> ptrsToFree, |
| 18 | bool skipErrorCheck = false, |
| 19 | }) { |
| 20 | final jsonStr = fn().toDartString(); |
| 21 | freePointers(ptrsToFree); |
| 22 | if (jsonStr == null) throw Exception("no json return from wallet library"); |
| 23 | final decoded = json.decode(jsonStr); |
| 24 | |
| 25 | final err = decoded["error"] ?? ""; |
| 26 | if (!skipErrorCheck) { |
| 27 | checkErr(err); |
| 28 | } |
| 29 | |
| 30 | final payload = decoded["payload"] ?? ""; |
| 31 | final errCode = decoded["errorcode"] ?? -1; |
| 32 | return new PayloadResult(payload, err, errCode); |
| 33 | } |
| 34 | |
| 35 | void freePointers(List<Pointer> ptrsToFree) { |
| 36 | for (final ptr in ptrsToFree) { |
| 37 | malloc.free(ptr); |
| 38 | } |
| 39 | } |
| 40 | |
| 41 | void checkErr(String err) { |
| 42 | if (err == "") return; |
| 43 | throw Exception(err); |
| 44 | } |
| 45 | |
| 46 | extension StringUtil on String { |
| 47 | Pointer<Char> toCString() => toNativeUtf8().cast<Char>(); |
| 48 | } |
| 49 | |
| 50 | extension CStringUtil on Pointer<Char> { |
| 51 | bool get isNull => address == nullptr.address; |
| 52 | |
| 53 | free() { |
| 54 | malloc.free(this); |
| 55 | } |
| 56 | |
| 57 | String? toDartString() { |
| 58 | if (isNull) return null; |
| 59 | |
| 60 | final str = cast<Utf8>().toDartString(); |
| 61 | free(); |
| 62 | return str; |
| 63 | } |
| 64 | } |