From 53e659fc9d8fa1b060936245c1f2749c1d217b75 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lukas=20F=C3=BCrderer?= <l.fuerderer@gmail.com>
Date: Sat, 16 Mar 2024 15:20:46 +0100
Subject: [PATCH] Fill computed fields during validation

---
 blockchain.py | 88 +++++++++++++++++++++++++++++----------------------
 1 file changed, 51 insertions(+), 37 deletions(-)

diff --git a/blockchain.py b/blockchain.py
index 807c560..26c8a7c 100644
--- a/blockchain.py
+++ b/blockchain.py
@@ -32,9 +32,16 @@ class Transaction:
         if balance is None:
             return False
         return balance >= self.amount + self.transaction_fee
+    def get_transaction_raw(self):
+        return self.id.to_bytes(4, "big") + \
+            self.sender + \
+            self.receiver + \
+            self.amount.to_bytes(8, "big") + \
+            self.transaction_fee.to_bytes(8, "big") + \
+            self.signature
 
 @dataclass
-class FullBlock:
+class Block:
     nonce: int
     timestamp: int
     previous_hash: bytes
@@ -45,14 +52,15 @@ class FullBlock:
     balances: dict
     # (sender_pubkey, id) tuples
     used_transaction_ids: set
+    valid: bool
 
-    def is_valid(self, blockchain):
+    def validate(self, blockchain):
         if self.transaction is not None:
             if not self.transaction.is_valid():
                 return False
         if self.previous_hash != 32 * b"\0":
             prev_block = blockchain.get_block(self.previous_hash)
-            if type(prev_block) is not FullBlock:
+            if not prev_block.valid:
                 return False
             if self.timestamp <= prev_block.timestamp:
                 return False
@@ -72,7 +80,35 @@ class FullBlock:
             return False
         block_raw = self.get_block_raw()
         block_hash = hashlib.sha256(block_raw).digest()
-        return int.from_bytes(block_hash, "big") * block_difficulty < 2**256
+        self.valid = int.from_bytes(block_hash, "big") * block_difficulty < 2**256
+        if self.valid:
+            self.calculate_balances(prev_block)
+            self.calculate_used_transaction_ids(prev_block)
+        return self.valid
+    def calculate_balances(self, prev_block):
+        if prev_block is None:
+            self.balances = {
+                self.miner_pubkey: 100,
+            }
+            return
+        balances = prev_block.balances.copy()
+        balances.setdefault(self.miner_pubkey, 0)
+        balances[miner_pubkey] += 100
+        t = self.transaction
+        if t is not None:
+            balances[miner_pubkey] += t.transaction_fee
+            balances[t.sender] -= (t.amount + t.transaction_fee)
+            balances[t.receiver] += t.amount
+        self.balances = balances
+    def calculate_used_transaction_ids(self, prev_block):
+        if prev_block is None:
+            self.used_transaction_ids = set()
+            return
+        used_transaction_ids = prev_block.used_transaction_ids.copy()
+        t = self.transaction
+        if t is not None:
+            used_transaction_ids.add((t.sender, t.id))
+        self.used_transaction_ids = used_transaction_ids
     def get_difficulty_info(self, steps, blockchain):
         if steps == 0:
             return self.difficulty_sum, self.timestamp
@@ -83,40 +119,18 @@ class FullBlock:
         else:
             previous_block = blockchain.get_block(self.previous_hash)
             return previous_block.get_difficulty_info(steps-1, blockchain)
-
-@dataclass
-class Datastructure:
-    nonce:int
-    timestamp: int
-    previous_hash: bytes
-    message: bytes
-    difficulty_sum: int
-    miner_pubkey: bytes
-    transaction: int
-
-
     def get_block_raw(self):
-            sender_pubkey_raw = Ed25519PublicKey.from_public_bytes(self.sender)
-            msg_raw =  self.nonce.to_bytes(8, "big") + \
-                        self.timestamp.to_bytes(8, "big") + \
-                        self.previous_hash + \
-                        self.message + \
-                        self.difficulty_sum.to_bytes(32, "big") + \
-                        self.miner_pubkey +\
-                        self.transaction.to_bytes(148, "big")      
-            try:
-                sender_pubkey_raw.verify(self.previous_hash,msg_raw)
-            except InvalidSignature:
-                return False
-            return self.transaction >=1
-    def is_valid_after_transaction(self.tansaction):
-        if(self.transaction is None):
-            return False
-        
-        
-
-
-
+        if self.transaction is None:
+            transaction = 148 * b"\0"
+        else:
+            transaction = self.transaction.get_transaction_raw()
+        return self.nonce.to_bytes(8, "big") + \
+            self.timestamp.to_bytes(8, "big") + \
+            self.previous_hash + \
+            self.message + \
+            self.difficulty_sum.to_bytes(32, "big") + \
+            self.miner_pubkey + \
+            transaction
 
 class Blockchain:
     def __init__(self):