save fix (#176)

Author: 0xodia

hub/providers/Defi/plans/save.tsx

@@ -10,9 +10,8 @@ import {
   createAssociatedTokenAccountIdempotentInstruction,
   getAssociatedTokenAddressSync,
 } from '@solana/spl-token-new';
-import { useConnection } from '@solana/wallet-adapter-react';
-import { Connection, Keypair, PublicKey } from '@solana/web3.js';
-import { SolendActionCore } from '@solendprotocol/solend-sdk';
+import { Connection, Keypair, PublicKey, AccountInfo, TransactionMessage, VersionedTransaction } from '@solana/web3.js';
+import { parseReserve, SolendActionCore } from '@solendprotocol/solend-sdk';
 import {
   InstructionWithSigners,
   LendingInstruction,
@@ -32,6 +31,19 @@ import useWalletOnePointOh from '@hooks/useWalletOnePointOh';
 import { sendTransactionsV3, SequenceType } from '@utils/sendTransactions';
 import tokenPriceService from '@utils/services/tokenPrice';
 
+// simulatedAccount is one element from simulated.value.accounts
+function simulatedToAccountInfo(simulatedAccount: any): AccountInfo<Buffer> {
+  const [base64Data, _encoding] = simulatedAccount.data;
+  return {
+    data: Buffer.from(base64Data, 'base64'),
+    executable: simulatedAccount.executable,
+    lamports: simulatedAccount.lamports,
+    owner: new PublicKey(simulatedAccount.owner),
+    rentEpoch: simulatedAccount.rentEpoch,
+  };
+}
+
+
 export const PROTOCOL_SLUG = 'Save';
 
 const SAVE_TRANSACTIONS_ENDPOINT = 'https://api.save.finance/transactions';
@@ -358,7 +370,66 @@ export const useSavePlans = (
         },
       );
 
-    const solendIxs = await solendAction.getInstructions();
+      const solendIxs = await solendAction.getInstructions();
+
+
+    const ixs = [
+      ...solendIxs.oracleIxs,
+      ...solendIxs.preLendingIxs,
+      ...solendIxs.lendingIxs,
+      ...solendIxs.postLendingIxs,
+    ] as InstructionWithSigners[];
+
+    // Get Transaction Message 
+    const message = new TransactionMessage({
+      payerKey: wallet.publicKey,
+      recentBlockhash: (await connection.current.getLatestBlockhash()).blockhash,
+      instructions: ixs.map((ix) => ix.instruction),
+    }).compileToV0Message();
+    
+    // Get Versioned Transaction
+    const vtx = new VersionedTransaction(message);
+
+    const res = await connection.current.simulateTransaction(
+      vtx,
+      {
+        commitment: 'processed',
+        sigVerify: false,
+        accounts: {
+          encoding: 'base64',
+          addresses: [reserveAddress],
+        }
+      }
+    );
+
+    const accountInfo = res?.value.accounts?.map(simulatedToAccountInfo);
+    let cTokenExchangeRate = new BigNumber(reserve.cTokenExchangeRate);
+    let buffer = 0.02;
+    if (accountInfo?.[0]) {
+      const simulatedReserve = parseReserve(new PublicKey(reserveAddress), accountInfo?.[0], 'base64');
+
+
+    const decimals = simulatedReserve.info.liquidity.mintDecimals;
+    const availableAmount = new BigNumber(
+      simulatedReserve.info.liquidity.availableAmount.toString()
+    ).shiftedBy(-decimals);
+    const totalBorrow = new BigNumber(
+      simulatedReserve.info.liquidity.borrowedAmountWads.toString()
+    ).shiftedBy(-18 - decimals);
+    const accumulatedProtocolFees = new BigNumber(
+      simulatedReserve.info.liquidity.accumulatedProtocolFeesWads.toString()
+    ).shiftedBy(-18 - decimals);
+    const totalSupply = totalBorrow
+      .plus(availableAmount)
+      .minus(accumulatedProtocolFees);
+
+      cTokenExchangeRate = new BigNumber(totalSupply).dividedBy(
+        new BigNumber(simulatedReserve.info.collateral.mintTotalSupply.toString()).shiftedBy(
+          -decimals
+        )
+      );
+      buffer = 0;
+    }
 
     const userAta = await SplToken.getAssociatedTokenAddress(
       ASSOCIATED_TOKEN_PROGRAM_ID,
@@ -375,16 +446,10 @@ export const useSavePlans = (
       true,
     );
 
-    const ixs = [
-      ...solendIxs.oracleIxs,
-      ...solendIxs.preLendingIxs,
-      ...solendIxs.lendingIxs,
-      ...solendIxs.postLendingIxs,
-    ] as InstructionWithSigners[];
-
     const transferAmountBase = new BigNumber(amount)
-      .shiftedBy(reserve?.mintDecimals ?? 0)
-      .div(reserve.cTokenExchangeRate)
+      .shiftedBy(reserve.mintDecimals)
+      .times(1-buffer)
+      .div(cTokenExchangeRate)
       .dp(0, BigNumber.ROUND_DOWN)
       .toNumber();