feat(pool): add cumulative reward and fee factors

Add `cumulativeFeeFactor` and `cumulativeRewardFactor` fields to the Pool entity
to improve reward and fee calculations for delegators. This enables more precise
tracking and distribution of rewards and fees over time.

Author: rickstaa

schema.graphql

@@ -133,6 +133,10 @@ type Pool @entity {
   rewardCut: BigInt!
   "Transcoder's fee share during the earnings pool's round"
   feeShare: BigInt!
+  "Cumulative fee factor for delegator fees calculation"
+  cumulativeFeeFactor: BigDecimal
+  "Cumulative reward factor for delegator rewards calculation"
+  cumulativeRewardFactor: BigDecimal
 }
 
 """

src/mappings/bondingManager.ts

@@ -1,4 +1,4 @@
-import { store } from "@graphprotocol/graph-ts";
+import { store, Address } from "@graphprotocol/graph-ts";
 import {
   convertToDecimal,
   createOrLoadDelegator,
@@ -8,6 +8,7 @@ import {
   createOrLoadTranscoder,
   EMPTY_ADDRESS,
   getBlockNum,
+  integerFromString,
   makeEventId,
   makePoolId,
   makeUnbondingLockId,
@@ -500,6 +501,13 @@ export function reward(event: Reward): void {
   pool!.feeShare = transcoder.feeShare;
   pool!.rewardCut = transcoder.rewardCut;
 
+  let bondingManager = BondingManager.bind(event.address);
+  let earningsPool = bondingManager.getTranscoderEarningsPoolForRound(
+    Address.fromString(transcoder.id),
+    integerFromString(round.id)
+  );
+  pool!.cumulativeRewardFactor = convertToDecimal(earningsPool.cumulativeRewardFactor);
+
   transcoder.save();
   delegate.save();
   pool!.save();

src/mappings/ticketBroker.ts

@@ -10,6 +10,7 @@ import {
   createOrLoadTranscoderDay,
   getBlockNum,
   getEthPriceUsd,
+  integerFromString,
   makeEventId,
   makePoolId,
   ZERO_BD,
@@ -29,6 +30,9 @@ import {
   WinningTicketRedeemed,
   Withdrawal,
 } from "../types/TicketBroker/TicketBroker";
+import {
+  BondingManager,
+} from "../types/BondingManager/BondingManager";
 
 export function winningTicketRedeemed(event: WinningTicketRedeemed): void {
   let round = createOrLoadRound(getBlockNum());
@@ -97,9 +101,17 @@ export function winningTicketRedeemed(event: WinningTicketRedeemed): void {
   protocol.winningTicketCount = protocol.winningTicketCount + 1;
   protocol.save();
 
-  // update the transcoder pool fees
+  // update the transcoder pool fees and cummulative factors
   if (pool) {
     pool.fees = pool.fees.plus(faceValue);
+
+    let bondingManager = BondingManager.bind(event.address);
+    let earningsPool = bondingManager.getTranscoderEarningsPoolForRound(
+      Address.fromString(transcoder.id),
+      integerFromString(round.id)
+    );
+    pool.cumulativeFeeFactor = convertToDecimal(earningsPool.cumulativeFeeFactor);
+    
     pool.save();
   }