From cadc159796d4c0addc36e9992286be677db71fcd Mon Sep 17 00:00:00 2001
From: AndreaScorza <atlantas95@gmail.com>
Date: Mon, 21 Mar 2022 14:45:35 +0100
Subject: [PATCH] Burn transaction

---
 src/lto/transactions/__init__.py |  3 ++
 src/lto/transactions/burn.py     | 71 ++++++++++++++++++++++++++++++++
 2 files changed, 74 insertions(+)
 create mode 100644 src/lto/transactions/burn.py

diff --git a/src/lto/transactions/__init__.py b/src/lto/transactions/__init__.py
index 4383b86..afea138 100644
--- a/src/lto/transactions/__init__.py
+++ b/src/lto/transactions/__init__.py
@@ -10,6 +10,7 @@
 from lto.transactions.transfer import Transfer
 from lto.transactions.register import Register
 from lto.transactions.data import Data
+from lto.transactions.burn import Burn
 
 def from_data(data):
     if data['type'] == 4:
@@ -36,5 +37,7 @@ def from_data(data):
         return CancelSponsorship.from_data(data)
     elif data['type'] == 20:
         return Register.from_data(data)
+    elif data['type'] == 21:
+        return Burn.from_data(data)
     else:
         raise Exception('Incorrect transaction Type')
diff --git a/src/lto/transactions/burn.py b/src/lto/transactions/burn.py
new file mode 100644
index 0000000..b935fcd
--- /dev/null
+++ b/src/lto/transactions/burn.py
@@ -0,0 +1,71 @@
+import base58
+import struct
+from lto import crypto
+from lto.transaction import Transaction
+
+
+class Burn(Transaction):
+    TYPE = 15
+    DEFAULT_FEE = 100000000
+    DEFAULT_VERSION = 3
+
+    def __init__(self, amount):
+        super().__init__()
+        if amount < 1:
+            raise Exception("Minimum burn amount = 1")
+        self.amount = amount
+        self.version = self.DEFAULT_VERSION
+        self.tx_fee = self.DEFAULT_FEE
+
+    def __to_binary_v3(self):
+        return (self.TYPE.to_bytes(1, 'big') +
+                b'\3' +
+                crypto.str2bytes(self.chain_id) +
+                struct.pack(">Q", self.timestamp) +
+                crypto.key_type_id(self.sender_key_type) +
+                base58.b58decode(self.sender_public_key) +
+                struct.pack(">Q", self.tx_fee) +
+                struct.pack(">Q", self.amount))
+
+    def to_binary(self):
+        if self.version == 3:
+            return self.__to_binary_v3()
+        else:
+            raise Exception('Incorrect Version')
+
+    def to_json(self):
+        return (crypto.merge_dicts({
+            "type": self.TYPE,
+            "version": self.version,
+            "id": self.id if self.id else "",
+            "sender": self.sender,
+            "senderKeyType": self.sender_key_type,
+            "senderPublicKey": self.sender_public_key,
+            "fee": self.tx_fee,
+            "timestamp": self.timestamp,
+            "amount": self.amount,
+            "proofs": self.proofs,
+            "height": self.height if self.height else ""
+        }, self._sponsor_json()))
+
+    @staticmethod
+    def from_data(data):
+        tx = Burn(data['amount'])
+        tx.type = data['type']
+        tx.version = data['version']
+        tx.id = data['id'] if 'id' in data else ''
+        tx.sender = data['sender'] if 'sender' in data else ''
+        tx.sender_key_type = data['senderKeyType'] if 'senderKeyType' in data else 'ed25519'
+        tx.sender_public_key = data['senderPublicKey']
+        tx.fee = data['fee']
+        tx.timestamp = data['timestamp']
+        tx.amount = data['amount']
+        tx.proofs = data['proofs'] if 'proofs' in data else []
+        tx.height = data['height'] if 'height' in data else ''
+
+        if "sponsor_public_key" in data:
+            tx.sponsor = data['sponsor']
+            tx.sponsor_public_key = data['sponsorPublicKey']
+            tx.sponsor_key_type = data['sponsorKeyType']
+
+        return tx