From 2ceb3a2b631fb220ce89fa0d9ff7c925ef8610f9 Mon Sep 17 00:00:00 2001
From: wilsoncusack <cusackw@gmail.com>
Date: Sat, 26 Aug 2023 22:08:18 -0400
Subject: [PATCH] add method to getWithdrawalMessages from a transaciton (#21)

---
 .../public/getL2HashesForDepositTx.test.ts}   |  2 +-
 .../public/getWithdrawalMessages.test.ts      | 24 +++++++++
 src/actions/public/getWithdrawalMessages.ts   | 49 +++++++++++++++++++
 src/decorators/publicOpStack.ts               |  7 ++-
 4 files changed, 80 insertions(+), 2 deletions(-)
 rename src/{_test/index.test.ts => actions/public/getL2HashesForDepositTx.test.ts} (89%)
 create mode 100644 src/actions/public/getWithdrawalMessages.test.ts
 create mode 100644 src/actions/public/getWithdrawalMessages.ts

diff --git a/src/_test/index.test.ts b/src/actions/public/getL2HashesForDepositTx.test.ts
similarity index 89%
rename from src/_test/index.test.ts
rename to src/actions/public/getL2HashesForDepositTx.test.ts
index 242f9b7e..44c8575d 100644
--- a/src/_test/index.test.ts
+++ b/src/actions/public/getL2HashesForDepositTx.test.ts
@@ -1,7 +1,7 @@
 import { test, expect } from 'vitest'
 import { createPublicClient, http } from 'viem'
 import { mainnet } from '@wagmi/chains'
-import { publicOpStackActions } from '../decorators/publicOpStack'
+import { publicOpStackActions } from '../../decorators/publicOpStack'
 
 test('correctly retrieves L2 hash', async () => {
   const client = createPublicClient({
diff --git a/src/actions/public/getWithdrawalMessages.test.ts b/src/actions/public/getWithdrawalMessages.test.ts
new file mode 100644
index 00000000..8dcd9485
--- /dev/null
+++ b/src/actions/public/getWithdrawalMessages.test.ts
@@ -0,0 +1,24 @@
+import { test, expect } from 'vitest'
+import { createPublicClient, http } from 'viem'
+import { base } from '@wagmi/chains'
+import { publicOpStackActions } from '../../decorators/publicOpStack'
+
+test('correctly retrieves L2 hash', async () => {
+  const client = createPublicClient({
+    chain: base,
+    transport: http(),
+  }).extend(publicOpStackActions)
+
+  const messages = await client.getWithdrawalMessages({
+    hash:
+      '0x999bab960dbdf600c51371ae819957063337a50cec2eb8032412739defadabe7',
+  })
+  expect(messages.length).toEqual(1)
+  expect(messages[0].nonce).toBeDefined()
+  expect(messages[0].gasLimit).toBeDefined()
+  expect(messages[0].data).toBeDefined()
+  expect(messages[0].value).toBeDefined()
+  expect(messages[0].sender).toBeDefined()
+  expect(messages[0].target).toBeDefined()
+  expect(messages[0].withdrawalHash).toBeDefined()
+})
diff --git a/src/actions/public/getWithdrawalMessages.ts b/src/actions/public/getWithdrawalMessages.ts
new file mode 100644
index 00000000..67d6ac43
--- /dev/null
+++ b/src/actions/public/getWithdrawalMessages.ts
@@ -0,0 +1,49 @@
+import { type PublicClient, Chain, Transport, Hash, Address, Hex, decodeEventLog } from 'viem'
+import { l2ToL1MessagePasserABI } from '@eth-optimism/contracts-ts'
+
+export type MessagePassedEvent = {
+  nonce: bigint, 
+  sender: Address,
+  target: Address,
+  value: bigint,
+  gasLimit: bigint,
+  data: Hex,
+  withdrawalHash: Hex
+}
+
+export type GetWithdrawalMessagesParameters = {
+  hash: Hash
+}
+
+export type GetWithdrawalMessagesReturnType = MessagePassedEvent[]
+
+/**
+ * Retrieves all MessagePassed events from a withdrawal transaction
+ *
+ * @param client - Public client to use
+ * @param parameters - {@link GetWithdrawalMessagesParameters}
+ * @returns An array of all MessagePassed events emitted in this transaction. {@link GetWithdrawalMessagesReturnType}
+ */
+export async function getWithdrawalMessages<TChain extends Chain | undefined>(
+  client: PublicClient<Transport, TChain>,
+  { hash }: GetWithdrawalMessagesParameters,
+): Promise<GetWithdrawalMessagesReturnType> {
+  const receipt = await client.getTransactionReceipt({ hash })
+  const events: MessagePassedEvent[] = []
+  for (const log of receipt.logs) {
+    /// These transactions will contain events from several contracts
+    /// this decode will revert for events not from l2ToL1MessagePasserABI
+    /// we are OK ignoring these events
+    try {
+      const event = decodeEventLog({
+        abi: l2ToL1MessagePasserABI,
+        data: log.data,
+        topics: log.topics,
+      })
+      if (event.eventName === 'MessagePassed') {
+        events.push(event.args)
+      }
+    } catch {}
+  }
+  return events;
+}
diff --git a/src/decorators/publicOpStack.ts b/src/decorators/publicOpStack.ts
index c579963a..682aaaed 100644
--- a/src/decorators/publicOpStack.ts
+++ b/src/decorators/publicOpStack.ts
@@ -1,9 +1,10 @@
-import { Account, Chain, Client, type PublicClient, Transport } from 'viem'
+import { Chain, type PublicClient, Transport } from 'viem'
 import {
   GetL2HashesForDepositTxParamters,
   GetL2HashesForDepositTxReturnType,
   getL2HashesForDepositTx,
 } from '../actions/public/getL2HashesForDepositTx'
+import { GetWithdrawalMessagesParameters, GetWithdrawalMessagesReturnType, getWithdrawalMessages } from '../actions/public/getWithdrawalMessages'
 
 /// NOTE We don't currently need account for exisiting actions but keeping in case
 export type PublicOpStackActions<
@@ -13,6 +14,9 @@ export type PublicOpStackActions<
   getL2HashesForDepositTx: (
     args: GetL2HashesForDepositTxParamters,
   ) => Promise<GetL2HashesForDepositTxReturnType>
+  getWithdrawalMessages: (
+    args: GetWithdrawalMessagesParameters,
+  ) => Promise<GetWithdrawalMessagesReturnType>
 }
 
 export function publicOpStackActions<
@@ -23,5 +27,6 @@ export function publicOpStackActions<
 ): PublicOpStackActions<TTransport, TChain> {
   return {
     getL2HashesForDepositTx: (args) => getL2HashesForDepositTx(client, args),
+    getWithdrawalMessages: (args) => getWithdrawalMessages(client, args),
   }
 }