Create chain.py

blockchain/chain.py

@@ -0,0 +1,35 @@
+import hashlib
+
+class Blockchain:
+    def __init__(self):
+        self.chain = [self.create_genesis_block()]
+        self.difficulty = 2
+
+    def create_genesis_block(self):
+        return Block(0, '0' * 64, int(time.time()), 'Genesis Block', self.calculate_hash(0, '0' * 64, int(time.time()), 'Genesis Block'))
+
+    def calculate_hash(self, index, previous_hash, timestamp, data):
+        value = str(index) + str(previous_hash) + str(timestamp) + str(data)
+        return hashlib.sha256(value.encode('utf-8')).hexdigest()
+
+    def is_chain_valid(self, chain):
+        for i in range(1, len(chain)):
+            current_block = chain[i]
+            previous_block = chain[i - 1]
+
+            if current_block.hash != self.calculate_hash(current_block.index, current_block.previous_hash, current_block.timestamp, current_block.data):
+                return False
+
+            if current_block.previous_hash != previous_block.hash:
+                return False
+
+        return True
+
+    def add_block(self, data):
+        new_block = Block(len(self.chain), self.chain[-1].hash, int(time.time()), data, None)
+        new_block.hash = self.calculate_hash(new_block.index, new_block.previous_hash, new_block.timestamp, new_block.data)
+        self.chain.append(new_block)
+
+    def replace_chain(self, chain):
+        if self.is_chain_valid(chain) and len(chain) > len(self.chain):
+            self.chain = chain