From 21eb783d70de94eff552c0bb9e43e7a89b5e5772 Mon Sep 17 00:00:00 2001
From: Derek Chiang <me@derekchiang.com>
Date: Mon, 29 Jan 2024 18:32:53 -0500
Subject: [PATCH] Support ERC20 paymaster in presets

---
 packages/presets/package.json     |  2 +-
 packages/presets/zerodev/index.ts | 64 +++++++++++++++++++++++--------
 2 files changed, 48 insertions(+), 18 deletions(-)

diff --git a/packages/presets/package.json b/packages/presets/package.json
index 9a3cca21..de0137f1 100644
--- a/packages/presets/package.json
+++ b/packages/presets/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@zerodev/presets",
-  "version": "5.0.1",
+  "version": "5.1.0",
   "author": "ZeroDev",
   "main": "./_cjs/index.js",
   "module": "./_esm/index.js",
diff --git a/packages/presets/zerodev/index.ts b/packages/presets/zerodev/index.ts
index d0de276e..6ef260af 100644
--- a/packages/presets/zerodev/index.ts
+++ b/packages/presets/zerodev/index.ts
@@ -3,12 +3,12 @@ import type { KernelAccountClient, KernelSmartAccount } from "@zerodev/sdk"
 import {
     createKernelAccount,
     createKernelAccountClient,
-    createZeroDevPaymasterClient
+    createZeroDevPaymasterClient,
 } from "@zerodev/sdk"
 import type { UserOperation } from "permissionless"
 import type { SmartAccountSigner } from "permissionless/accounts"
 import type { Address, Chain, HttpTransport } from "viem"
-import { http, createPublicClient } from "viem"
+import { http, createPublicClient, isAddress } from "viem"
 
 export type Provider = "STACKUP" | "PIMLICO" | "ALCHEMY" | "GELATO"
 
@@ -34,6 +34,17 @@ const getZeroDevPaymasterRPC = (
     return rpc
 }
 
+// An enum type called "PAYMASTER" with the following values:
+// - "NONE"
+// - "SPONSOR"
+// - "ERC20", which should wrap a string
+type ERC20Paymaster = Address
+type PaymasterType = "NONE" | "SPONSOR" | ERC20Paymaster
+
+function isERC20(value: PaymasterType): value is ERC20Paymaster {
+    return isAddress(value)
+}
+
 export async function createEcdsaKernelAccountClient<
     TChain extends Chain | undefined = Chain | undefined,
     TSource extends string = "custom",
@@ -44,14 +55,14 @@ export async function createEcdsaKernelAccountClient<
     signer,
     provider,
     index,
-    usePaymaster = true
+    paymaster = 'SPONSOR',
 }: {
     chain: TChain
     projectId: string
     signer: SmartAccountSigner<TSource, TAddress>
     provider?: Provider
     index?: bigint
-    usePaymaster?: boolean
+    paymaster?: PaymasterType
 }): Promise<
     KernelAccountClient<
         HttpTransport,
@@ -74,23 +85,42 @@ export async function createEcdsaKernelAccountClient<
         index
     })
 
+    let sponsorUserOperation: ((args: {
+        userOperation: UserOperation
+        entryPoint: Address
+    }) => Promise<UserOperation>) | undefined = undefined
+
+    if (paymaster !== undefined) {
+        const zerodevPaymaster = createZeroDevPaymasterClient({
+            chain: chain,
+            transport: http(
+                getZeroDevPaymasterRPC(projectId, provider)
+            )
+        })
+
+        if (isERC20(paymaster)) {
+            sponsorUserOperation = async ({ userOperation }): Promise<UserOperation> => {
+                return zerodevPaymaster.sponsorUserOperation({
+                    userOperation,
+                    gasToken: paymaster,
+                })
+            }
+        } else if (paymaster === "SPONSOR") {
+            sponsorUserOperation = async ({ userOperation }): Promise<UserOperation> => {
+                return zerodevPaymaster.sponsorUserOperation({
+                    userOperation
+                })
+            }
+        } else if (paymaster !== "NONE") {
+            throw new Error('Invalid paymaster type')
+        }
+    }
+
     const kernelClient = createKernelAccountClient({
         account,
         chain,
         transport: http(getZeroDevBundlerRPC(projectId, provider)),
-        sponsorUserOperation: usePaymaster
-            ? async ({ userOperation }): Promise<UserOperation> => {
-                  const zerodevPaymaster = createZeroDevPaymasterClient({
-                      chain: chain,
-                      transport: http(
-                          getZeroDevPaymasterRPC(projectId, provider)
-                      )
-                  })
-                  return zerodevPaymaster.sponsorUserOperation({
-                      userOperation
-                  })
-              }
-            : undefined
+        sponsorUserOperation,
     })
 
     return kernelClient as unknown as KernelAccountClient<