From fb64c00d9cfb31972b996c21353aed47a224c425 Mon Sep 17 00:00:00 2001
From: Jonald Fyookball <jonaldfyookball@outlook.com>
Date: Sat, 26 Aug 2023 19:19:25 -0400
Subject: [PATCH] Add cashtokens.dart for initial class implementation.

---
 .../coins/bitcoincash/cashtokens.dart         | 345 ++++++++++++++++++
 1 file changed, 345 insertions(+)
 create mode 100644 lib/services/coins/bitcoincash/cashtokens.dart

diff --git a/lib/services/coins/bitcoincash/cashtokens.dart b/lib/services/coins/bitcoincash/cashtokens.dart
new file mode 100644
index 000000000..aaddb8c8a
--- /dev/null
+++ b/lib/services/coins/bitcoincash/cashtokens.dart
@@ -0,0 +1,345 @@
+import 'dart:typed_data';
+import 'package:hex/hex.dart';
+import 'package:convert/convert.dart';
+
+// The Structure enum
+enum Structure {
+  HasAmount,
+  HasNFT,
+  HasCommitmentLength,
+}
+
+// The Capability enum
+enum Capability {
+  NoCapability,
+  Mutable,
+  Minting,
+}
+
+// Used as a "custom tuple"
+class CompactSizeResult {
+  final int amount;
+  final int bytesRead;
+
+  CompactSizeResult({required this.amount, required this.bytesRead});
+}
+
+
+class ParsedOutput {
+  List<int>? script_pub_key;
+  TokenOutputData? token_data;
+  ParsedOutput({this.script_pub_key, this.token_data});
+}
+
+class TokenOutputData {
+  Uint8List? id;
+  int? amount;
+  Uint8List? commitment;
+  Uint8List? bitfield; // A byte (Uint8List of length 1)
+
+  // Constructor
+  TokenOutputData({
+    this.id,
+    this.amount,
+    this.commitment,
+    this.bitfield,
+  });
+
+  int getCapability() {
+    if (bitfield != null) {
+      return bitfield![0] & 0x0f;
+    }
+    return 0;
+  }
+
+  bool hasCommitmentLength() {
+    if (bitfield != null) {
+      return (bitfield![0] & 0x40) != 0;
+    }
+    return false;
+  }
+
+  bool hasAmount() {
+    if (bitfield != null) {
+      return (bitfield![0] & 0x10) != 0;
+    }
+    return false;
+  }
+
+  bool hasNFT() {
+    if (bitfield != null) {
+      return (bitfield![0] & 0x20) != 0;
+    }
+    return false;
+  }
+
+  bool isMintingNFT() {
+    return hasNFT() && getCapability() == Capability.Minting.index;
+  }
+
+  bool isMutableNFT() {
+    return hasNFT() && getCapability() == Capability.Mutable.index;
+  }
+
+  bool isImmutableNFT() {
+    return hasNFT() && getCapability() == Capability.NoCapability.index;
+  }
+
+  bool isValidBitfield() {
+    if (bitfield == null) {
+      return false;
+    }
+
+    int s = bitfield![0] & 0xf0;
+    if (s >= 0x80 || s == 0x00) {
+      return false;
+    }
+    if (bitfield![0] & 0x0f > 2) {
+      return false;
+    }
+    if (!hasNFT() && !hasAmount()) {
+      return false;
+    }
+    if (!hasNFT() && (bitfield![0] & 0x0f) != 0) {
+      return false;
+    }
+    if (!hasNFT() && hasCommitmentLength()) {
+      return false;
+    }
+    return true;
+  }
+
+
+
+  int deserialize(Uint8List buffer, {int cursor = 0, bool strict = false}) {
+    try {
+
+      this.id = buffer.sublist(cursor, cursor + 32);
+      cursor += 32;
+
+
+      this.bitfield = Uint8List.fromList([buffer[cursor]]);
+      cursor += 1;
+
+      if (this.hasCommitmentLength()) {
+
+        // Read the first byte to determine the length of the commitment data
+        int commitmentLength = buffer[cursor];
+
+        // Move cursor to the next byte
+        cursor += 1;
+
+        // Read 'commitmentLength' bytes for the commitment data
+        this.commitment = buffer.sublist(cursor, cursor + commitmentLength);
+
+        // Adjust the cursor by the length of the commitment data
+        cursor += commitmentLength;
+      } else {
+        this.commitment = null;
+      }
+
+
+      if (this.hasAmount()) {
+        // Use readCompactSize that returns CompactSizeResult
+        CompactSizeResult result = readCompactSize(buffer, cursor, strict: strict);
+        this.amount = result.amount;
+        cursor += result.bytesRead;
+      } else {
+        this.amount = 0;
+      }
+
+
+      if (!this.isValidBitfield() ||
+          (this.hasAmount() && this.amount == 0) ||
+          (this.amount! < 0 || this.amount! > (1 << 63) - 1) ||
+          (this.hasCommitmentLength() && this.commitment!.isEmpty) ||
+          (this.amount! == 0 && !this.hasNFT())
+      ) {
+        throw Exception('Unable to parse token data or token data is invalid');
+      }
+
+      return cursor;  // Return the number of bytes read
+
+    } catch (e) {
+      throw Exception('Deserialization failed: $e');
+    }
+  }
+
+
+  // Serialize method
+  Uint8List serialize() {
+    var buffer = BytesBuilder();
+
+    // write ID and bitfield
+    buffer.add(this.id!);
+    buffer.addByte(this.bitfield![0]);
+
+    // Write optional fields
+    if (this.hasCommitmentLength()) {
+      buffer.add(this.commitment!);
+    }
+
+    if (this.hasAmount()) {
+      List<int> compactSizeBytes = writeCompactSize(this.amount!);
+      buffer.add(compactSizeBytes);
+    }
+
+    return buffer.toBytes();
+  }
+
+}  //END OF OUTPUTDATA CLASS
+
+final List<int> PREFIX_BYTE = [0xef];
+
+ParsedOutput wrap_spk(TokenOutputData? token_data, Uint8List script_pub_key) {
+  ParsedOutput parsedOutput = ParsedOutput();
+
+  if (token_data == null) {
+    parsedOutput.script_pub_key = script_pub_key;
+    return parsedOutput;
+  }
+
+  final buf = BytesBuilder();
+
+  buf.add(PREFIX_BYTE);
+  buf.add(token_data.serialize());
+  buf.add(script_pub_key);
+
+  parsedOutput.script_pub_key = buf.toBytes();
+  parsedOutput.token_data = token_data;
+
+  return parsedOutput;
+}
+
+
+
+
+ParsedOutput unwrap_spk(Uint8List wrapped_spk) {
+  ParsedOutput parsedOutput = ParsedOutput();
+
+
+  if (wrapped_spk.isEmpty || wrapped_spk[0] != PREFIX_BYTE[0]) {
+    parsedOutput.script_pub_key = wrapped_spk;
+    return parsedOutput;
+  }
+
+
+  int read_cursor = 1; // Start after the PREFIX_BYTE
+  TokenOutputData token_data = TokenOutputData();
+
+  Uint8List wrapped_spk_without_prefix_byte;
+  try {
+    // Deserialize updates read_cursor by the number of bytes read
+
+    wrapped_spk_without_prefix_byte= wrapped_spk.sublist(read_cursor);
+    int bytesRead = token_data.deserialize(wrapped_spk_without_prefix_byte);
+
+
+    read_cursor += bytesRead;
+    parsedOutput.token_data = token_data;
+    parsedOutput.script_pub_key = wrapped_spk.sublist(read_cursor);
+
+  } catch (e) {
+    // If unable to deserialize, return all bytes as the full scriptPubKey
+    parsedOutput.script_pub_key = wrapped_spk;
+  }
+
+  return parsedOutput;
+}
+
+
+void testUnwrapSPK() {
+
+
+  // Example Hex format string
+  String var1 = "YOUR-SCRIPT-PUBKEY-AS-HEX-STRING-FOR-TESTING-GOES-HERE";
+  // Convert the Hex string to Uint8List
+  Uint8List wrapped_spk = Uint8List.fromList(HEX.decode(var1));
+
+  // Call unwrap_spk
+  ParsedOutput parsedOutput = unwrap_spk(wrapped_spk);
+
+  print("Parsed Output: $parsedOutput");
+
+  // Access token_data inside parsedOutput
+  TokenOutputData? tokenData = parsedOutput.token_data;
+
+  // Check if tokenData is null
+  if (tokenData != null) {
+  // Print specific fields
+  if (tokenData.id != null) {
+  print("ID: ${hex.encode(tokenData.id!)}");  // hex is imported
+  } else {
+  print("ID: null");
+  }
+  print ("amount of tokens");
+  print (tokenData.amount);
+  print("Is it an NFT?: ${tokenData.hasNFT()}");
+  } else {
+  print("Token data is null.");
+  }
+
+} //end function
+
+
+// HELPER FUNCTIONS
+CompactSizeResult readCompactSize(Uint8List buffer, int cursor, {bool strict = false}) {
+
+
+  int bytesRead = 0; // Variable to count bytes read
+  int val;
+  try {
+    val = buffer[cursor];
+    cursor += 1;
+    bytesRead += 1;
+    int minVal;
+    if (val == 253) {
+      val = buffer.buffer.asByteData().getUint16(cursor, Endian.little);
+      cursor += 2;
+      bytesRead += 2;
+      minVal = 253;
+    } else if (val == 254) {
+      val = buffer.buffer.asByteData().getUint32(cursor, Endian.little);
+      cursor += 4;
+      bytesRead += 4;
+      minVal = 1 << 16;
+    } else if (val == 255) {
+      val = buffer.buffer.asByteData().getInt64(cursor, Endian.little);
+      cursor += 8;
+      bytesRead += 8;
+      minVal = 1 << 32;
+    } else {
+      minVal = 0;
+    }
+    if (strict && val < minVal) {
+      throw Exception("CompactSize is not minimally encoded");
+    }
+
+    return CompactSizeResult(amount: val, bytesRead: bytesRead);
+  } catch (e) {
+    throw Exception("attempt to read past end of buffer");
+  }
+}
+Uint8List writeCompactSize(int size) {
+  var buffer = ByteData(9); // Maximum needed size for compact size is 9 bytes
+  if (size < 0) {
+    throw Exception("attempt to write size < 0");
+  } else if (size < 253) {
+    return Uint8List.fromList([size]);
+  } else if (size < (1 << 16)) {
+    buffer.setUint8(0, 253);
+    buffer.setUint16(1, size, Endian.little);
+    return buffer.buffer.asUint8List(0, 3);
+  } else if (size < (1 << 32)) {
+    buffer.setUint8(0, 254);
+    buffer.setUint32(1, size, Endian.little);
+    return buffer.buffer.asUint8List(0, 5);
+  } else if (size < (1 << 64)) {
+    buffer.setUint8(0, 255);
+    buffer.setInt64(1, size, Endian.little);
+    return buffer.buffer.asUint8List(0, 9);
+  } else {
+    throw Exception("Size too large to represent as CompactSize");
+  }
+}
+