feat: calculate transaction size

lib/ckb/serializers/serializers.rb

@@ -26,6 +26,8 @@
 require_relative "out_point_serializer"
 require_relative "output_data_serializer"
 require_relative "raw_transaction_serializer"
+require_relative "witness_serializer"
+require_relative "transaction_serializer"
 
 module CKB
   module Serializers

lib/ckb/serializers/transaction_serializer.rb

@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module CKB
+  module Serializers
+    class TransactionSerializer
+      include TableSerializer
+
+      # @param transaction [CKB::Types::Transaction]
+      def initialize(transaction)
+        @raw_serializer = RawTransactionSerializer.new(transaction)
+        @witnesses_serializer = DynVecSerializer.new(transaction.witnesses, WitnessSerializer)
+        @items_count = 2
+      end
+
+      private
+
+      attr_reader :raw_serializer, :witnesses_serializer, :items_count
+
+      def body
+        raw_layout + witnesses_layout
+      end
+
+      def offsets
+        offset0 = (items_count + 1) * UINT32_CAPACITY
+        offset1 = offset0 + raw_capacity
+
+        [offset0, offset1]
+      end
+
+      def raw_layout
+        raw_serializer.serialize[2..-1]
+      end
+
+      def raw_capacity
+        raw_serializer.capacity
+      end
+
+      def witnesses_layout
+        witnesses_serializer.serialize[2..-1]
+      end
+    end
+  end
+end

lib/ckb/serializers/witness_serializer.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module CKB
+  module Serializers
+    class WitnessSerializer
+      include BaseSerializer
+
+      # @param witness [String]
+      def initialize(witness)
+        witness ||= ""
+        witness = witness.start_with?("0x") ? witness[2..-1] : witness
+        items = witness.scan(/../)
+        @bytes_serializer = FixVecSerializer.new(items, ByteSerializer)
+      end
+
+      private
+
+      attr_reader :bytes_serializer
+
+      def layout
+        bytes_serializer.serialize[2..-1]
+      end
+    end
+  end
+end

lib/ckb/types/transaction.rb

@@ -114,6 +114,11 @@ def compute_hash
         blake2b.hexdigest
       end
 
+      def size
+        transaction_serializer = CKB::Serializers::TransactionSerializer.new(self)
+        Utils.hex_to_bin(transaction_serializer.serialize).bytesize + 4
+      end
+
       def self.from_h(hash)
         return if hash.nil?