From ab3b0134b56ef4534e8ea239d512339cfe033b4a Mon Sep 17 00:00:00 2001
From: Lex Berezhny <lex@damoti.com>
Date: Tue, 14 Aug 2018 16:16:29 -0400
Subject: [PATCH] Purchase Transaction Type

---
 lbrynet/wallet/database.py    |  4 +++-
 lbrynet/wallet/script.py      | 31 +++++++++++++++++++++++++++++--
 lbrynet/wallet/transaction.py | 14 ++++++++++++++
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/lbrynet/wallet/database.py b/lbrynet/wallet/database.py
index 85eab2480..41adb2740 100644
--- a/lbrynet/wallet/database.py
+++ b/lbrynet/wallet/database.py
@@ -21,7 +21,8 @@ class WalletDatabase(BaseDatabase):
             claim_name text,
             is_claim boolean not null default 0,
             is_update boolean not null default 0,
-            is_support boolean not null default 0
+            is_support boolean not null default 0,
+            is_purchase boolean not null default 0
         );
     """
 
@@ -38,6 +39,7 @@ class WalletDatabase(BaseDatabase):
             'is_claim': txo.script.is_claim_name,
             'is_update': txo.script.is_update_claim,
             'is_support': txo.script.is_support_claim,
+            'is_purchase': txo.script.is_purchase_claim,
         })
         if txo.script.is_claim_involved:
             row['claim_id'] = txo.claim_id
diff --git a/lbrynet/wallet/script.py b/lbrynet/wallet/script.py
index af4723df2..68beeb5fc 100644
--- a/lbrynet/wallet/script.py
+++ b/lbrynet/wallet/script.py
@@ -12,6 +12,7 @@ class OutputScript(BaseOutputScript):
     OP_CLAIM_NAME = 0xb5
     OP_SUPPORT_CLAIM = 0xb6
     OP_UPDATE_CLAIM = 0xb7
+    OP_PURCHASE_CLAIM = 0xb8
 
     CLAIM_NAME_OPCODES = (
         OP_CLAIM_NAME, PUSH_SINGLE('claim_name'), PUSH_SINGLE('claim'),
@@ -46,13 +47,25 @@ class OutputScript(BaseOutputScript):
             UPDATE_CLAIM_OPCODES + BaseOutputScript.PAY_SCRIPT_HASH.opcodes
     ))
 
+    PURCHASE_CLAIM_OPCODES = (
+        OP_PURCHASE_CLAIM, PUSH_SINGLE('claim_id'), OP_2DROP
+    )
+    PURCHASE_CLAIM_PUBKEY = Template('purchase_claim+pay_pubkey_hash', (
+            PURCHASE_CLAIM_OPCODES + BaseOutputScript.PAY_PUBKEY_HASH.opcodes
+    ))
+    PURCHASE_CLAIM_SCRIPT = Template('purchase_claim+pay_script_hash', (
+            PURCHASE_CLAIM_OPCODES + BaseOutputScript.PAY_SCRIPT_HASH.opcodes
+    ))
+
     templates = BaseOutputScript.templates + [
         CLAIM_NAME_PUBKEY,
         CLAIM_NAME_SCRIPT,
         SUPPORT_CLAIM_PUBKEY,
         SUPPORT_CLAIM_SCRIPT,
         UPDATE_CLAIM_PUBKEY,
-        UPDATE_CLAIM_SCRIPT
+        UPDATE_CLAIM_SCRIPT,
+        PURCHASE_CLAIM_PUBKEY,
+        PURCHASE_CLAIM_SCRIPT
     ]
 
     @classmethod
@@ -63,6 +76,13 @@ class OutputScript(BaseOutputScript):
             'pubkey_hash': pubkey_hash
         })
 
+    @classmethod
+    def purchase_claim_pubkey_hash(cls, claim_id, pubkey_hash):
+        return cls(template=cls.PURCHASE_CLAIM_PUBKEY, values={
+            'claim_id': claim_id,
+            'pubkey_hash': pubkey_hash
+        })
+
     @classmethod
     def pay_update_claim_pubkey_hash(cls, claim_name, claim_id, claim, pubkey_hash):
         return cls(template=cls.UPDATE_CLAIM_PUBKEY, values={
@@ -84,6 +104,13 @@ class OutputScript(BaseOutputScript):
     def is_support_claim(self):
         return self.template.name.startswith('support_claim+')
 
+    @property
+    def is_purchase_claim(self):
+        return self.template.name.startswith('purchase_claim+')
+
     @property
     def is_claim_involved(self):
-        return self.is_claim_name or self.is_support_claim or self.is_update_claim
+        return any((
+            self.is_claim_name, self.is_support_claim,
+            self.is_update_claim, self.is_purchase_claim
+        ))
diff --git a/lbrynet/wallet/transaction.py b/lbrynet/wallet/transaction.py
index 18aa8a2d2..23644400f 100644
--- a/lbrynet/wallet/transaction.py
+++ b/lbrynet/wallet/transaction.py
@@ -54,6 +54,11 @@ class Output(BaseOutput):
             claim_name.encode(), claim, pubkey_hash)
         return cls(amount, script)
 
+    @classmethod
+    def purchase_claim_pubkey_hash(cls, amount: int, claim_id: str, pubkey_hash: bytes) -> 'Output':
+        script = cls.script_class.purchase_claim_pubkey_hash(unhexlify(claim_id)[::-1], pubkey_hash)
+        return cls(amount, script)
+
     @classmethod
     def pay_update_claim_pubkey_hash(
             cls, amount: int, claim_name: str, claim_id: str, claim: bytes, pubkey_hash: bytes) -> 'Output':
@@ -76,6 +81,15 @@ class Transaction(BaseTransaction):
         )
         return cls.create([], [claim_output], funding_accounts, change_account)
 
+    @classmethod
+    def purchase(cls, claim: Output, amount: int, merchant_address: bytes,
+              funding_accounts: List[Account], change_account: Account):
+        ledger = cls.ensure_all_have_same_ledger(funding_accounts, change_account)
+        claim_output = Output.purchase_claim_pubkey_hash(
+            amount, claim.claim_id, ledger.address_to_hash160(merchant_address)
+        )
+        return cls.create([], [claim_output], funding_accounts, change_account)
+
     @classmethod
     def update(cls, previous_claim: Output, meta: ClaimDict, amount: int, holding_address: bytes,
                funding_accounts: List[Account], change_account: Account):