From 8feea32a0aebce8b2770b2e679287b3294a64134 Mon Sep 17 00:00:00 2001
From: eric-volz <eric@volz.link>
Date: Fri, 6 Oct 2023 22:23:51 +0200
Subject: [PATCH] new method to estimate vSize of unsigned transactions

---
 .../transactions/rawtransactions/__init__.py  |  2 +-
 defichain/transactions/rawtransactions/fee.py | 43 ++++++++++++++++---
 2 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/defichain/transactions/rawtransactions/__init__.py b/defichain/transactions/rawtransactions/__init__.py
index 0ebcbb54..db19aa8a 100644
--- a/defichain/transactions/rawtransactions/__init__.py
+++ b/defichain/transactions/rawtransactions/__init__.py
@@ -11,4 +11,4 @@
 from .witness import WitnessHash, Witness
 
 # Fee
-from .fee import estimate_fee
+from .fee import estimate_size, estimate_fee, estimate_vsize
diff --git a/defichain/transactions/rawtransactions/fee.py b/defichain/transactions/rawtransactions/fee.py
index 7ffae2d4..0513c51a 100644
--- a/defichain/transactions/rawtransactions/fee.py
+++ b/defichain/transactions/rawtransactions/fee.py
@@ -1,27 +1,56 @@
+import math
+
 from defichain.transactions.constants import TxSize
 from .txinput import TxP2PKHInput, TxP2SHInput, TxP2WPKHInput
 from .tx import Transaction
 
 
-def estimate_fee(tx: Transaction, feePerByte: float):
+def estimate_size(tx: Transaction):
     """
-    Signes the transaction to find out the real size
+    Estimates the size of the later signed transaction.
 
-    :param tx: (required) the transaction object
+    :param tx: (required) the unsigned transaction object
     :type tx: Transaction
-    :param feePerByte: (required) the amount of fee to pay per byte
-    :type feePerByte: float
-    :return: "int" - the amount of fee to pay
+    :return: "int" - size of the signed transaction
     """
     # Current Size
     size = tx.size()
 
-    # Add witniss and signature size
+    # Add witness and signature size
     for input in tx.get_inputs():
         if isinstance(input, TxP2SHInput) or isinstance(input, TxP2WPKHInput):
             size += TxSize.WITNESS_SIGNATURE_LENGTH + TxSize.WITNESS_SIGNATURE + \
                     TxSize.PUBLIC_KEY_LENGTH + TxSize.PUBLIC_KEY
         elif isinstance(input, TxP2PKHInput):
             size += TxSize.SCRIPTSIG_SIGNATURE
+    return size
+
+
+def estimate_fee(tx: Transaction, feePerByte: float):
+    """
+    Estimates fees for unsigned transaction
+
+    :param tx: (required) the unsigned transaction object
+    :type tx: Transaction
+    :param feePerByte: (required) the amount of fee to pay per byte
+    :type feePerByte: float
+    :return: "int" - the amount of fee to pay
+    """
+
+    size = estimate_size(tx)
+
     return round(size * feePerByte)
 
+
+def estimate_vsize(tx: Transaction):
+    """
+    Estimates the vSize of the later signed transaction.
+
+    :param tx: (required) the unsigned transaction object
+    :type tx: Transaction
+    :return: "int" - vSize of the signed transaction
+    """
+    unsigned_size = tx.size()
+    signed_size = estimate_size(tx)
+
+    return math.ceil(unsigned_size + (signed_size - unsigned_size) / 4)