From c20c6ecc569b3fcb99bd200896376cc4384c128a Mon Sep 17 00:00:00 2001
From: Haofan Zheng <hzheng6@ucsc.edu>
Date: Thu, 11 Jul 2024 12:25:55 -0700
Subject: [PATCH] Added helper for contract events

---
 PyEthHelper/ContractEventHelper.py | 77 ++++++++++++++++++++++++++++++
 PyEthHelper/_Meta.py               |  2 +-
 2 files changed, 78 insertions(+), 1 deletion(-)
 create mode 100644 PyEthHelper/ContractEventHelper.py

diff --git a/PyEthHelper/ContractEventHelper.py b/PyEthHelper/ContractEventHelper.py
new file mode 100644
index 0000000..ba986e8
--- /dev/null
+++ b/PyEthHelper/ContractEventHelper.py
@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+# -*- coding:utf-8 -*-
+###
+# Copyright (c) 2024 Haofan Zheng
+# Use of this source code is governed by an MIT-style
+# license that can be found in the LICENSE file or at
+# https://opensource.org/licenses/MIT.
+###
+
+
+import time
+from typing import List
+
+import web3
+
+from web3.contract import Contract
+from web3.contract.contract import ContractEvent
+
+
+class ContractEventHelper:
+
+	@classmethod
+	def GetBlockPeriod(
+		cls,
+		w3: web3.Web3,
+		probeBlkNum: int,
+	) -> int:
+		probeBlk = w3.eth.get_block(probeBlkNum)
+		prevBlk = w3.eth.get_block(probeBlkNum - 1)
+		return probeBlk.timestamp - prevBlk.timestamp
+
+	@classmethod
+	def WaitForEvent(
+		cls,
+		w3: web3.Web3,
+		event: ContractEvent,
+		fromBlock: int,
+		timeoutByBlkNum: int = -1,
+	) -> List[dict]:
+		blkPeriodHalf = cls.GetBlockPeriod(w3, fromBlock) / 2
+
+		queriedBlkNum = fromBlock - 1
+		currBlkNum = w3.eth.block_number
+		while True:
+			if queriedBlkNum >= currBlkNum:
+				# wait for new blocks
+				time.sleep(blkPeriodHalf)
+				currBlkNum = w3.eth.block_number
+				continue
+
+			queriedBlkNum += 1
+			logs = event.get_logs(fromBlock=queriedBlkNum, toBlock=queriedBlkNum)
+			if len(logs) > 0:
+				return logs
+
+			if (
+				(timeoutByBlkNum > 0) and
+				(queriedBlkNum >= (fromBlock + timeoutByBlkNum))
+			):
+				return []
+
+	@classmethod
+	def WaitForContractEvent(
+		cls,
+		w3: web3.Web3,
+		contract: Contract,
+		eventName: str,
+		fromBlock: int,
+		timeoutByBlkNum: int = -1,
+	) -> List[dict]:
+		return cls.WaitForEvent(
+			w3=w3,
+			event=contract.events[eventName](),
+			fromBlock=fromBlock,
+			timeoutByBlkNum=timeoutByBlkNum,
+		)
+
diff --git a/PyEthHelper/_Meta.py b/PyEthHelper/_Meta.py
index dbf8894..e1cf00a 100644
--- a/PyEthHelper/_Meta.py
+++ b/PyEthHelper/_Meta.py
@@ -9,7 +9,7 @@
 
 
 
-__version__ = '0.1.5'
+__version__ = '0.1.6'
 
 PKG_AUTHOR = 'Languages, Systems, and Data Lab at UC Santa Cruz'
 PKG_NAME = 'PyEthHelper'