From 419e55010db1eeed1f5762f463f675d4a15b9244 Mon Sep 17 00:00:00 2001
From: Gustavo Inacio <gustavo@semiotic.ai>
Date: Mon, 7 Oct 2024 11:31:15 +0200
Subject: [PATCH] feat: check escrow balance before rav redeem

Signed-off-by: Gustavo Inacio <gustavo@semiotic.ai>
---
 .../src/allocations/escrow-accounts.ts        | 64 +++++++++++++++++++
 .../src/allocations/tap-collector.ts          | 27 +++++++-
 2 files changed, 90 insertions(+), 1 deletion(-)
 create mode 100644 packages/indexer-common/src/allocations/escrow-accounts.ts

diff --git a/packages/indexer-common/src/allocations/escrow-accounts.ts b/packages/indexer-common/src/allocations/escrow-accounts.ts
new file mode 100644
index 000000000..44d6060c2
--- /dev/null
+++ b/packages/indexer-common/src/allocations/escrow-accounts.ts
@@ -0,0 +1,64 @@
+import { Address, toAddress } from '@graphprotocol/common-ts'
+import { TAPSubgraph } from '../tap-subgraph'
+import gql from 'graphql-tag'
+
+type U256 = bigint
+
+type EscrowAccountResponse = {
+  escrowAccounts: {
+    balance: string
+    sender: {
+      id: string
+    }
+  }[]
+}
+
+export class EscrowAccounts {
+  constructor(private sendersBalances: Map<Address, U256>) {}
+
+  getBalanceForSender(sender: Address): U256 {
+    const balance = this.sendersBalances.get(sender)
+    if (balance === undefined) {
+      throw new Error(`No balance found for sender: ${sender}`)
+    }
+    return balance
+  }
+
+  subtractSenderBalance(sender: Address, ravValue: U256) {
+    const balance = this.getBalanceForSender(sender)
+    const newBalance = balance - ravValue
+    this.sendersBalances.set(sender, newBalance)
+  }
+
+  static fromResponse(response: EscrowAccountResponse): EscrowAccounts {
+    const sendersBalances = new Map<Address, U256>()
+    response.escrowAccounts.forEach((account) => {
+      sendersBalances.set(toAddress(account.sender.id), BigInt(account.balance))
+    })
+
+    return new EscrowAccounts(sendersBalances)
+  }
+}
+
+export const getEscrowAccounts = async (
+  tapSubgraph: TAPSubgraph,
+  indexer: Address,
+): Promise<EscrowAccounts> => {
+  const result = await tapSubgraph.query<EscrowAccountResponse>(
+    gql`
+      query EscrowAccountQuery($indexer: ID!) {
+        escrowAccounts(where: { receiver_: { id: $indexer } }) {
+          balance
+          sender {
+            id
+          }
+        }
+      }
+    `,
+    { indexer },
+  )
+  if (!result.data) {
+    throw `There was an error while querying Tap Subgraph. Errors: ${result.error}`
+  }
+  return EscrowAccounts.fromResponse(result.data)
+}
diff --git a/packages/indexer-common/src/allocations/tap-collector.ts b/packages/indexer-common/src/allocations/tap-collector.ts
index 95a51564e..67b683ad5 100644
--- a/packages/indexer-common/src/allocations/tap-collector.ts
+++ b/packages/indexer-common/src/allocations/tap-collector.ts
@@ -29,6 +29,7 @@ import pReduce from 'p-reduce'
 import { TAPSubgraph } from '../tap-subgraph'
 import { NetworkSubgraph } from '../network-subgraph'
 import gql from 'graphql-tag'
+import { getEscrowAccounts } from './escrow-accounts'
 
 const RAV_CHECK_INTERVAL_MS = 30_000
 
@@ -90,6 +91,7 @@ export class TapCollector {
   declare tapSubgraph: TAPSubgraph
   declare networkSubgraph: NetworkSubgraph
   declare finalityTime: number
+  declare indexerAddress: Address
 
   // eslint-disable-next-line @typescript-eslint/no-empty-function -- Private constructor to prevent direct instantiation
   private constructor() {}
@@ -119,10 +121,11 @@ export class TapCollector {
     collector.tapSubgraph = tapSubgraph
     collector.networkSubgraph = networkSubgraph
 
-    const { voucherRedemptionThreshold, finalityTime } =
+    const { voucherRedemptionThreshold, finalityTime, address } =
       networkSpecification.indexerOptions
     collector.ravRedemptionThreshold = voucherRedemptionThreshold
     collector.finalityTime = finalityTime
+    collector.indexerAddress = address
 
     collector.logger.info(`RAV processing is initiated`)
     collector.startRAVProcessing()
@@ -452,10 +455,28 @@ export class TapCollector {
     logger.info(`Redeem last RAVs on chain individually`, {
       signedRavs,
     })
+    const escrowAccounts = await getEscrowAccounts(this.tapSubgraph, this.indexerAddress)
 
     // Redeem RAV one-by-one as no plual version available
     for (const { rav: signedRav, allocation, sender } of signedRavs) {
       const { rav } = signedRav
+
+      // verify escrow balances
+      const ravValue = BigInt(rav.valueAggregate.toString())
+      const senderBalance = escrowAccounts.getBalanceForSender(sender)
+      if (senderBalance < ravValue) {
+        this.logger.warn(
+          'RAV was not sent to the blockchain \
+          because its value aggregate is lower than escrow balance.',
+          {
+            rav,
+            sender,
+            senderBalance,
+          },
+        )
+        continue
+      }
+
       const stopTimer = this.metrics.ravsRedeemDuration.startTimer({
         allocation: rav.allocationId,
       })
@@ -486,6 +507,10 @@ export class TapCollector {
           this.metrics.ravRedeemsInvalid.inc({ allocation: rav.allocationId })
           return
         }
+        // subtract from the escrow account
+        // THIS IS A MUT OPERATION
+        escrowAccounts.subtractSenderBalance(sender, ravValue)
+
         this.metrics.ravCollectedFees.set(
           { allocation: rav.allocationId },
           parseFloat(rav.valueAggregate.toString()),