feat: approve methods for straight exchange

README.md

@@ -593,6 +593,12 @@ await pool.exchangeWrappedApprove("0x6c3F90f043a72FA612cbac8115EE7e52BDe6E490",
 ```
 **Note.** Removing wrapped does not require approve.
 
+### Exchange
+```ts
+await curve.exchangeisApproved("DAI", "0x99d8a9c45b2eca8864373a26d1459e3dff1e17f3", "1000"); // DAI -> MIM
+await curve.exchangeApprove("DAI", "0x99d8a9c45b2eca8864373a26d1459e3dff1e17f3", "1000"); // DAI -> MIM
+```
+
 ### Boosting
 ```ts
 await curve.boosting.isApproved('1000')

src/index.ts

@@ -4,6 +4,9 @@ import {
     Pool,
     getBestPoolAndOutput,
     exchangeExpected,
+    exchangeIsApproved,
+    exchangeApproveEstimateGas,
+    exchangeApprove,
     exchangeEstimateGas,
     exchange,
     crossAssetExchangeAvailable,
@@ -56,6 +59,8 @@ const curve = {
     hasAllowance,
     ensureAllowance,
     getBestPoolAndOutput,
+    exchangeIsApproved,
+    exchangeApprove,
     exchangeExpected,
     exchange,
     crossAssetExchangeAvailable,
@@ -64,6 +69,7 @@ const curve = {
     crossAssetExchange,
     estimateGas: {
         ensureAllowance: ensureAllowanceEstimateGas,
+        exchangeApprove: exchangeApproveEstimateGas,
         exchange: exchangeEstimateGas,
         crossAssetExchange: crossAssetExchangeEstimateGas,
     },

src/pools.ts

@@ -1684,6 +1684,25 @@ export const _getBestPoolAndOutput = async (
     return { poolAddress, output }
 }
 
+const _getExchangeData = async (inputCoin: string, outputCoin: string, amount: string): Promise<[string, number, number, boolean]> => {
+    const [inputCoinAddress, outputCoinAddress] = _getCoinAddresses(inputCoin, outputCoin);
+    const [inputCoinDecimals] = _getCoinDecimals(inputCoinAddress);
+    const addressProviderContract = curve.contracts[ALIASES.address_provider].contract;
+    const registryAddress = await addressProviderContract.get_registry();
+    const registryContract = new ethers.Contract(registryAddress, registryABI, curve.signer);
+
+    const { poolAddress } = await _getBestPoolAndOutput(inputCoinAddress, outputCoinAddress, inputCoinDecimals, amount);
+    if (poolAddress === "0x0000000000000000000000000000000000000000") {
+        throw new Error("This pair can't be exchanged");
+    }
+    const poolName = getPoolNameBySwapAddress(poolAddress);
+    const [_i, _j, isUnderlying] = await registryContract.get_coin_indices(poolAddress, inputCoinAddress, outputCoinAddress);
+    const i = Number(_i.toString());
+    const j = Number(_j.toString());
+
+    return [poolName, i, j, isUnderlying]
+}
+
 export const getBestPoolAndOutput = async (inputCoin: string, outputCoin: string, amount: string): Promise<{ poolAddress: string, output: string }> => {
     const [inputCoinAddress, outputCoinAddress] = _getCoinAddresses(inputCoin, outputCoin);
     const [inputCoinDecimals, outputCoinDecimals] = _getCoinDecimals(inputCoinAddress, outputCoinAddress);
@@ -1698,6 +1717,39 @@ export const exchangeExpected = async (inputCoin: string, outputCoin: string, am
     return (await getBestPoolAndOutput(inputCoin, outputCoin, amount))['output'];
 }
 
+export const exchangeIsApproved = async (inputCoin: string, outputCoin: string, amount: string): Promise<boolean> => {
+    const [poolName, i, , isUnderlying] = await _getExchangeData(inputCoin, outputCoin, amount);
+    const pool = new Pool(poolName);
+
+    if (isUnderlying) {
+        return await pool.exchangeIsApproved(i, amount);
+    } else {
+        return await pool.exchangeWrappedIsApproved(i, amount);
+    }
+}
+
+export const exchangeApproveEstimateGas = async (inputCoin: string, outputCoin: string, amount: string): Promise<number> => {
+    const [poolName, i, , isUnderlying] = await _getExchangeData(inputCoin, outputCoin, amount);
+    const pool = new Pool(poolName);
+
+    if (isUnderlying) {
+        return await pool.estimateGas.exchangeApprove(i, amount);
+    } else {
+        return await pool.estimateGas.exchangeWrappedApprove(i, amount);
+    }
+}
+
+export const exchangeApprove = async (inputCoin: string, outputCoin: string, amount: string): Promise<string[]> => {
+    const [poolName, i, , isUnderlying] = await _getExchangeData(inputCoin, outputCoin, amount);
+    const pool = new Pool(poolName);
+
+    if (isUnderlying) {
+        return await pool.exchangeApprove(i, amount);
+    } else {
+        return await pool.exchangeWrappedApprove(i, amount);
+    }
+}
+
 export const exchangeEstimateGas = async (inputCoin: string, outputCoin: string, amount: string, maxSlippage = 0.01): Promise<number> => {
     const [inputCoinAddress, outputCoinAddress] = _getCoinAddresses(inputCoin, outputCoin);
     const [inputCoinDecimals] = _getCoinDecimals(inputCoinAddress);