feat: Implement RevertDecoder for transaction revert reason decoding

lib/crypto_wallet_tool.rb

@@ -13,3 +13,4 @@ class Error < StandardError; end
 require_relative 'crypto_wallet_tool/transaction_debugger/receipt'
 require_relative 'crypto_wallet_tool/transaction_debugger/transaction'
 require_relative 'crypto_wallet_tool/transaction_debugger/fetcher'
+require_relative 'crypto_wallet_tool/transaction_debugger/revert_decoder'

lib/crypto_wallet_tool/transaction_debugger/revert_decoder.rb

@@ -0,0 +1,105 @@
+# frozen_string_literal: true
+
+module CryptoWalletTool
+  module TransactionDebugger
+    # Decoder for transaction revert reasons
+    class RevertDecoder
+      ERROR_STRING_SIGNATURE = '0x08c379a0'
+      PANIC_SIGNATURE = '0x4e487b71'
+
+      PANIC_CODES = {
+        0x01 => 'Assertion error',
+        0x11 => 'Arithmetic operation underflowed or overflowed',
+        0x12 => 'Division or modulo by zero',
+        0x21 => 'Enum conversion error',
+        0x31 => 'Pop on empty array',
+        0x32 => 'Array index out of bounds',
+        0x41 => 'Out of memory',
+        0x51 => 'Invalid internal function call'
+      }.freeze
+
+      def initialize(client: nil)
+        @client = client
+      end
+
+      def decode_from_receipt(receipt)
+        return nil if receipt.success?
+
+        if receipt.raw_data['revertReason']
+          decode_revert_data(receipt.raw_data['revertReason'])
+        else
+          decode_from_simulation(receipt)
+        end
+      end
+
+      def decode_revert_data(data)
+        return nil if data.nil? || data == '0x'
+
+        hex_data = normalize_hex(data)
+        signature = extract_signature(hex_data)
+
+        decode_by_signature(signature, hex_data)
+      end
+
+      private
+
+      def normalize_hex(data)
+        data.start_with?('0x') ? data[2..] : data
+      end
+
+      def extract_signature(hex_data)
+        "0x#{hex_data[0..7]}"
+      end
+
+      def decode_by_signature(signature, hex_data)
+        case signature
+        when ERROR_STRING_SIGNATURE
+          decode_error_string(hex_data)
+        when PANIC_SIGNATURE
+          decode_panic(hex_data)
+        else
+          "Unknown error (signature: #{signature})"
+        end
+      end
+
+      def decode_error_string(hex_data)
+        data_hex = hex_data[8..]
+        data_binary = [data_hex].pack('H*')
+        length = data_binary[32..63].unpack1('H*').to_i(16)
+        string_data = data_binary[64, length]
+        string_data.force_encoding('UTF-8')
+      rescue StandardError => e
+        "Failed to decode error string: #{e.message}"
+      end
+
+      def decode_panic(hex_data)
+        panic_code = hex_data[8..71].to_i(16)
+        description = PANIC_CODES[panic_code] || 'Unknown panic code'
+        "Panic: #{description} (code: 0x#{panic_code.to_s(16)})"
+      end
+
+      def decode_from_simulation(receipt)
+        raise ArgumentError, 'Client is required for simulation' if @client.nil?
+
+        tx_data = @client.eth_get_transaction_by_hash(receipt.transaction_hash)
+
+        call_params = {
+          from: tx_data['from'],
+          to: tx_data['to'],
+          data: tx_data['input'],
+          value: tx_data['value']
+        }
+
+        @client.eth_call(call_params, receipt.block_number - 1)
+        nil
+      rescue CryptoWalletTool::RPCError => e
+        extract_revert_from_error(e.message)
+      end
+
+      def extract_revert_from_error(error_message)
+        match = error_message.match(/(?:execution reverted:?\s*|revert\s+)(.+)/i)
+        match ? match[1].strip : error_message
+      end
+    end
+  end
+end