refactor: Drop FlowUtils

This is a hangover from the UBA. Relocate the function to SpokeUtils
instead. This will make it easier to group functionality into evm/xvm.

src/clients/SpokePoolClient.ts

@@ -21,6 +21,7 @@ import {
   isValidEvmAddress,
   isZeroAddress,
   toAddress,
+  validateFillForDeposit,
 } from "../utils";
 import {
   duplicateEvent,
@@ -29,7 +30,6 @@ import {
   spreadEvent,
   spreadEventWithBlockNumber,
 } from "../utils/EventUtils";
-import { validateFillForDeposit } from "../utils/FlowUtils";
 import { ZERO_ADDRESS } from "../constants";
 import {
   Deposit,

src/utils/DepositUtils.ts

@@ -5,8 +5,7 @@ import { CachingMechanismInterface, Deposit, DepositWithBlock, Fill, SlowFillReq
 import { getNetworkName } from "./NetworkUtils";
 import { bnZero } from "./BigNumberUtils";
 import { getDepositInCache, getDepositKey, setDepositInCache } from "./CachingUtils";
-import { validateFillForDeposit } from "./FlowUtils";
-import { getMessageHash, isUnsafeDepositId } from "./SpokeUtils";
+import { getMessageHash, isUnsafeDepositId, validateFillForDeposit } from "./SpokeUtils";
 import { getCurrentTime } from "./TimeUtils";
 import { isDefined } from "./TypeGuards";
 import { isDepositFormedCorrectly } from "./ValidatorUtils";

src/utils/SpokeUtils.ts

@@ -1,6 +1,6 @@
 import assert from "assert";
 import { BytesLike, Contract, PopulatedTransaction, providers, utils as ethersUtils } from "ethers";
-import { CHAIN_IDs, MAX_SAFE_DEPOSIT_ID, ZERO_ADDRESS, ZERO_BYTES } from "../constants";
+import { CHAIN_IDs, MAX_SAFE_DEPOSIT_ID, UNDEFINED_MESSAGE_HASH, ZERO_ADDRESS, ZERO_BYTES } from "../constants";
 import { Deposit, FillStatus, FillWithBlock, RelayData } from "../interfaces";
 import { SpokePoolClient } from "../clients";
 import { chunk } from "./ArrayUtils";
@@ -88,6 +88,47 @@ export function getRelayEventKey(
     .join("-");
 }
 
+const RELAYDATA_KEYS = [
+  "depositId",
+  "originChainId",
+  "destinationChainId",
+  "depositor",
+  "recipient",
+  "inputToken",
+  "inputAmount",
+  "outputToken",
+  "outputAmount",
+  "fillDeadline",
+  "exclusivityDeadline",
+  "exclusiveRelayer",
+  "messageHash",
+] as const;
+
+// Ensure that each deposit element is included with the same value in the fill. This includes all elements defined
+// by the depositor as well as destinationToken, which are pulled from other clients.
+export function validateFillForDeposit(
+  relayData: Omit<RelayData, "message"> & { messageHash: string; destinationChainId: number },
+  deposit?: Omit<Deposit, "quoteTimestamp" | "fromLiteChain" | "toLiteChain">
+): { valid: true } | { valid: false; reason: string } {
+  if (deposit === undefined) {
+    return { valid: false, reason: "Deposit is undefined" };
+  }
+
+  // Note: this short circuits when a key is found where the comparison doesn't match.
+  // TODO: if we turn on "strict" in the tsconfig, the elements of FILL_DEPOSIT_COMPARISON_KEYS will be automatically
+  // validated against the fields in Fill and Deposit, generating an error if there is a discrepency.
+  let invalidKey = RELAYDATA_KEYS.find((key) => relayData[key].toString() !== deposit[key].toString());
+
+  // There should be no paths for `messageHash` to be unset, but mask it off anyway.
+  if (!isDefined(invalidKey) && [relayData.messageHash, deposit.messageHash].includes(UNDEFINED_MESSAGE_HASH)) {
+    invalidKey = "messageHash";
+  }
+
+  return isDefined(invalidKey)
+    ? { valid: false, reason: `${invalidKey} mismatch (${relayData[invalidKey]} != ${deposit[invalidKey]})` }
+    : { valid: true };
+}
+
 /**
  * Find the block range that contains the deposit ID. This is a binary search that searches for the block range
  * that contains the deposit ID.

src/utils/index.ts

@@ -9,7 +9,6 @@ export * from "./TypeGuards";
 export * from "./TypeUtils";
 export * from "./TokenUtils";
 export * from "./LogUtils";
-export * from "./FlowUtils";
 export * from "./BundleUtils";
 export * from "./JSONUtils";
 export * from "./IPFSUtils";