From c1ef96ba2e7524a511d1ffe5bb86570d8565b0d5 Mon Sep 17 00:00:00 2001
From: Ashwin Phatak <ashwinpphatak@gmail.com>
Date: Mon, 19 Jul 2021 10:43:29 +0530
Subject: [PATCH] Handle Position Manager DecreaseLiquidity event. (#148)

Co-authored-by: nabarun <nabarun@deepstacksoft.com>
---
 packages/uni-info-watcher/src/events.ts | 47 +++++++++++++++++++++++--
 packages/uni-watcher/src/client.ts      |  7 ++++
 2 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/packages/uni-info-watcher/src/events.ts b/packages/uni-info-watcher/src/events.ts
index 9cb7cfb7..ad94359d 100644
--- a/packages/uni-info-watcher/src/events.ts
+++ b/packages/uni-info-watcher/src/events.ts
@@ -70,6 +70,14 @@ interface IncreaseLiquidityEvent {
   amount1: bigint;
 }
 
+interface DecreaseLiquidityEvent {
+  __typename: 'DecreaseLiquidityEvent';
+  tokenId: bigint;
+  liquidity: bigint;
+  amount0: bigint;
+  amount1: bigint;
+}
+
 interface Block {
   number: number;
   hash: string;
@@ -85,7 +93,7 @@ interface ResultEvent {
   block: Block;
   tx: Transaction;
   contract: string;
-  event: PoolCreatedEvent | InitializeEvent | MintEvent | BurnEvent | SwapEvent | IncreaseLiquidityEvent;
+  event: PoolCreatedEvent | InitializeEvent | MintEvent | BurnEvent | SwapEvent | IncreaseLiquidityEvent | DecreaseLiquidityEvent;
   proof: {
     data: string;
   }
@@ -153,6 +161,11 @@ export class EventWatcher {
         this._handleIncreaseLiquidity(block, contract, tx, event as IncreaseLiquidityEvent);
         break;
 
+      case 'DecreaseLiquidityEvent':
+        log('NFPM DecreaseLiquidity event', contract);
+        this._handleDecreaseLiquidity(block, contract, tx, event as DecreaseLiquidityEvent);
+        break;
+
       default:
         break;
     }
@@ -731,7 +744,7 @@ export class EventWatcher {
       return;
     }
 
-    // Temp fix.
+    // Temp fix from Subgraph mapping code.
     if (utils.getAddress(position.pool.id) === utils.getAddress('0x8fe8d9bb8eeba3ed688069c3d6b556c9ca258248')) {
       return;
     }
@@ -753,6 +766,36 @@ export class EventWatcher {
     await this._savePositionSnapshot(position, block, tx);
   }
 
+  async _handleDecreaseLiquidity (block: Block, contractAddress: string, tx: Transaction, event: DecreaseLiquidityEvent): Promise<void> {
+    const { number: blockNumber } = block;
+    const position = await this._getPosition(block, contractAddress, tx, BigInt(event.tokenId));
+
+    // Position was not able to be fetched.
+    if (position == null) {
+      return;
+    }
+
+    // Temp fix from Subgraph mapping code.
+    if (utils.getAddress(position.pool.id) === utils.getAddress('0x8fe8d9bb8eeba3ed688069c3d6b556c9ca258248')) {
+      return;
+    }
+
+    const token0 = position.token0;
+    const token1 = position.token1;
+    const amount0 = convertTokenToDecimal(BigInt(event.amount0), BigInt(token0.decimals));
+    const amount1 = convertTokenToDecimal(BigInt(event.amount1), BigInt(token1.decimals));
+
+    position.liquidity = BigInt(position.liquidity) - BigInt(event.liquidity);
+    position.depositedToken0 = position.depositedToken0.plus(amount0);
+    position.depositedToken1 = position.depositedToken1.plus(amount1);
+
+    await this._updateFeeVars(position, block, contractAddress, BigInt(event.tokenId));
+
+    await this._db.savePosition(position, blockNumber);
+
+    await this._savePositionSnapshot(position, block, tx);
+  }
+
   async _getPosition (block: Block, contractAddress: string, tx: Transaction, tokenId: bigint): Promise<Position | null> {
     const { number: blockNumber, hash: blockHash, timestamp: blockTimestamp } = block;
     const { hash: txHash } = tx;
diff --git a/packages/uni-watcher/src/client.ts b/packages/uni-watcher/src/client.ts
index 26ab3306..14322d13 100644
--- a/packages/uni-watcher/src/client.ts
+++ b/packages/uni-watcher/src/client.ts
@@ -81,6 +81,13 @@ export class Client {
                 amount0
                 amount1
               }
+
+              ... on DecreaseLiquidityEvent {
+                tokenId
+                liquidity
+                amount0
+                amount1
+              }
             }
           }
         }