util func to check if scriptpubkey is a fusion

lib/services/coins/bitcoincash/bch_utils.dart

@@ -2,8 +2,11 @@ import 'dart:typed_data';
 
 import 'package:bitcoindart/src/utils/constants/op.dart' as op;
 import 'package:bitcoindart/src/utils/script.dart' as bscript;
+import 'package:stackwallet/utilities/extensions/impl/string.dart';
 
 abstract final class BchUtils {
+  static const FUSE_ID = 'FUZ\x00';
+
   static bool isSLP(Uint8List scriptPubKey) {
     const id = [83, 76, 80, 0]; // 'SLP\x00'
     final decompiled = bscript.decompile(scriptPubKey);
@@ -26,4 +29,33 @@ abstract final class BchUtils {
 
     return false;
   }
+
+  static bool isFUZE(Uint8List scriptPubKey) {
+    final id = FUSE_ID.toUint8ListFromUtf8;
+    final decompiled = bscript.decompile(scriptPubKey);
+
+    if (decompiled != null &&
+        decompiled.length > 2 &&
+        decompiled.first == op.OPS["OP_RETURN"]) {
+      // check session hash length. Should be 32 bytes
+      final sessionHash = decompiled[2];
+      if (!(sessionHash is List<int> && sessionHash.length == 32)) {
+        return false;
+      }
+
+      final _id = decompiled[1];
+
+      if (_id is List<int> && _id.length == id.length) {
+        for (int i = 0; i < id.length; i++) {
+          if (_id[i] != id[i]) {
+            return false;
+          }
+        }
+        // lists match!
+        return true;
+      }
+    }
+
+    return false;
+  }
 }

test/services/coins/bitcoincash/bch_utils_test.dart

@@ -22,4 +22,25 @@ void main() {
       false,
     );
   });
+
+  test("script pub key check for fuze is true", () {
+    expect(
+      BchUtils.isFUZE("6a0446555a00204d662fb69f34dc23434a61c7bbb65c9f99a247f9c8"
+              "b377cb4de3cadf7542f8f0"
+          .toUint8ListFromHex),
+      true,
+    );
+  });
+
+  test("script pub key check for fuze is not true", () {
+    expect(
+      BchUtils.isFUZE(
+          "6a04534c500001010747454e45534953044d5430320f4d757461626c652054657374"
+                  "2030321668747470733a2f2f46756c6c537461636b2e63617368200e9a18"
+                  "8911ec0f2ac10cc9425b457d10ba14151a64eb4640f95ed7dab9e8f62601"
+                  "004c00080000000000000001"
+              .toUint8ListFromHex),
+      false,
+    );
+  });
 }