From 1a12a4bd894c03d6f4dbe8d0f88087e223dec926 Mon Sep 17 00:00:00 2001
From: mihaisc <mihai@oceanprotocol.com>
Date: Tue, 22 Feb 2022 18:37:41 +0200
Subject: [PATCH] Calculating max swap/liquidity (#1306)

* calc max

* more  max checks

* fix description
---
 src/pools/balancer/Pool.ts | 53 +++++++++++++++++++++++++++++++++-----
 src/utils/PoolHelpers.ts   | 47 +++++++++++++++++++++++++++++++++
 2 files changed, 93 insertions(+), 7 deletions(-)
 create mode 100644 src/utils/PoolHelpers.ts

diff --git a/src/pools/balancer/Pool.ts b/src/pools/balancer/Pool.ts
index 4c90af18..b8161d54 100644
--- a/src/pools/balancer/Pool.ts
+++ b/src/pools/balancer/Pool.ts
@@ -21,6 +21,13 @@ import {
   PoolPriceAndFees
 } from '../../@types'
 import { Config } from '../../models'
+import {
+  getMaxAddLiquidity,
+  getMaxRemoveLiquidity,
+  getMaxSwapExactIn,
+  getMaxSwapExactOut
+} from '../../utils/PoolHelpers'
+import Decimal from 'decimal.js'
 const MaxUint256 =
   '115792089237316195423570985008687907853269984665640564039457584007913129639934'
 
@@ -847,6 +854,11 @@ export class Pool {
       this.config
     )
 
+    const maxSwap = await getMaxSwapExactIn(this, poolAddress, tokenInOutMarket.tokenIn)
+    if (new Decimal(amountsInOutMaxFee.tokenAmountIn).greaterThan(maxSwap)) {
+      throw new Error(`tokenAmountIn is greater than ${maxSwap.toString()}`)
+    }
+
     amountsInOutMaxFee.tokenAmountIn = await amountToUnits(
       this.web3,
       tokenInOutMarket.tokenIn,
@@ -971,6 +983,11 @@ export class Pool {
     )
     let result = null
 
+    const maxSwap = await getMaxSwapExactOut(this, poolAddress, tokenInOutMarket.tokenIn)
+    if (new Decimal(amountsInOutMaxFee.tokenAmountOut).greaterThan(maxSwap)) {
+      throw new Error(`tokenAmountOut is greater than ${maxSwap.toString()}`)
+    }
+
     amountsInOutMaxFee.maxAmountIn = await amountToUnits(
       this.web3,
       tokenInOutMarket.tokenIn,
@@ -1233,7 +1250,6 @@ export class Pool {
    * Pay tokenAmountIn of baseToken to join the pool, getting poolAmountOut of the pool shares.
    * @param {String} account
    * @param {String} poolAddress
-   * @param {String} tokenIn
    * @param {String} tokenAmountIn exact number of base tokens to spend
    * @param {String} minPoolAmountOut minimum of pool shares expectex
    * @return {TransactionReceipt}
@@ -1249,12 +1265,13 @@ export class Pool {
       this.config
     )
     let result = null
+    const tokenIn = await this.getBaseToken(poolAddress)
+    const maxSwap = await getMaxAddLiquidity(this, poolAddress, tokenIn)
+    if (new Decimal(tokenAmountIn).greaterThan(maxSwap)) {
+      throw new Error(`tokenAmountOut is greater than ${maxSwap.toString()}`)
+    }
 
-    const amountInFormatted = await amountToUnits(
-      this.web3,
-      await this.getBaseToken(poolAddress),
-      tokenAmountIn
-    )
+    const amountInFormatted = await amountToUnits(this.web3, tokenIn, tokenAmountIn)
     const estGas = await this.estJoinswapExternAmountIn(
       account,
       poolAddress,
@@ -1321,7 +1338,6 @@ export class Pool {
    * Pay poolAmountIn pool shares into the pool, getting minTokenAmountOut of the baseToken
    * @param {String} account
    * @param {String} poolAddress
-   * @param {String} tokenOut
    * @param {String} poolAmountIn exact number of pool shares to spend
    * @param {String} minTokenAmountOut minimum amount of basetokens expected
    * @return {TransactionReceipt}
@@ -1337,6 +1353,18 @@ export class Pool {
       this.config
     )
     let result = null
+    const tokenOut = await this.getBaseToken(poolAddress)
+
+    const tokenAmountOut = await this.calcSingleOutGivenPoolIn(
+      poolAddress,
+      tokenOut,
+      poolAmountIn
+    )
+
+    const maxSwap = await getMaxRemoveLiquidity(this, poolAddress, tokenOut)
+    if (new Decimal(tokenAmountOut).greaterThan(maxSwap)) {
+      throw new Error(`tokenAmountOut is greater than ${maxSwap.toString()}`)
+    }
 
     const minTokenOutFormatted = await amountToUnits(
       this.web3,
@@ -1451,6 +1479,12 @@ export class Pool {
       this.config
     )
 
+    const maxSwap = await getMaxSwapExactOut(this, poolAddress, tokenIn)
+
+    if (new Decimal(tokenAmountOut).greaterThan(maxSwap)) {
+      throw new Error(`tokenAmountOut is greater than ${maxSwap.toString()}`)
+    }
+
     const amountOutFormatted = await amountToUnits(this.web3, tokenOut, tokenAmountOut)
 
     let amount = null
@@ -1509,6 +1543,11 @@ export class Pool {
       this.config
     )
 
+    const maxSwap = await getMaxSwapExactIn(this, poolAddress, tokenIn)
+    if (new Decimal(tokenAmountIn).greaterThan(maxSwap)) {
+      throw new Error(`tokenAmountIn is greater than ${maxSwap.toString()}`)
+    }
+
     const amountInFormatted = await amountToUnits(this.web3, tokenIn, tokenAmountIn)
 
     let amount = null
diff --git a/src/utils/PoolHelpers.ts b/src/utils/PoolHelpers.ts
new file mode 100644
index 00000000..c817d64d
--- /dev/null
+++ b/src/utils/PoolHelpers.ts
@@ -0,0 +1,47 @@
+import Decimal from 'decimal.js'
+import { Pool } from '..'
+
+export function calcMaxExactOut(balance: string): Decimal {
+  return new Decimal(balance).div(3.01)
+}
+
+export function calcMaxExactIn(balance: string): Decimal {
+  return new Decimal(balance).div(2.01)
+}
+export async function getMaxSwapExactOut(
+  poolInstance: Pool,
+  poolAddress: string,
+  tokenAddress: string
+): Promise<Decimal> {
+  const reserve = await poolInstance.getReserve(poolAddress, tokenAddress)
+  return calcMaxExactOut(reserve)
+}
+
+export async function getMaxSwapExactIn(
+  poolInstance: Pool,
+  poolAddress: string,
+  tokenAddress: string
+): Promise<Decimal> {
+  const reserve = await poolInstance.getReserve(poolAddress, tokenAddress)
+  return calcMaxExactIn(reserve)
+}
+
+export async function getMaxAddLiquidity(
+  poolInstance: Pool,
+  poolAddress: string,
+  tokenAddress: string
+): Promise<Decimal> {
+  const reserve = await poolInstance.getReserve(poolAddress, tokenAddress)
+
+  return calcMaxExactIn(reserve)
+}
+
+export async function getMaxRemoveLiquidity(
+  poolInstance: Pool,
+  poolAddress: string,
+  tokenAddress: string
+): Promise<Decimal> {
+  const reserve = await poolInstance.getReserve(poolAddress, tokenAddress)
+
+  return calcMaxExactIn(reserve)
+}