Underlying amount in erc4626 client (#246)

* feat: getUnderlyingAmount in ERC4626 client

* chore: version bump

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@aztec/bridge-clients",
-  "version": "0.1.61",
+  "version": "0.1.62",
   "description": "This repo contains the solidity files and typescript helper class for all of the Aztec Connect Bridge Contracts",
   "repository": "[email protected]:AztecProtocol/aztec-connect-bridges.git",
   "license": "Apache-2.0",

src/client/erc4626/erc4626-bridge-data.test.ts

@@ -1,6 +1,6 @@
 import { EthAddress } from "@aztec/barretenberg/address";
 import { BigNumber } from "ethers";
-import { IERC4626, IERC4626__factory } from "../../../typechain-types";
+import { IERC20Metadata, IERC20Metadata__factory, IERC4626, IERC4626__factory } from "../../../typechain-types";
 import { AztecAsset, AztecAssetType } from "../bridge-data";
 import { ERC4626BridgeData } from "./erc4626-bridge-data";
 
@@ -14,18 +14,13 @@ type Mockify<T> = {
 
 describe("ERC4626 bridge data", () => {
   let erc4626Contract: Mockify<IERC4626>;
+  let erc2MetadataContract: Mockify<IERC20Metadata>;
 
-  let ethAsset: AztecAsset;
   let mplAsset: AztecAsset;
   let xmplAsset: AztecAsset;
   let emptyAsset: AztecAsset;
 
   beforeAll(() => {
-    ethAsset = {
-      id: 0,
-      assetType: AztecAssetType.ETH,
-      erc20Address: EthAddress.ZERO,
-    };
     mplAsset = {
       id: 10, // Asset has not yet been registered on RollupProcessor so this id is random
       assetType: AztecAssetType.ERC20,
@@ -121,4 +116,31 @@ describe("ERC4626 bridge data", () => {
     const asset = await erc4626BridgeData.getAsset(xmplAsset.erc20Address);
     expect(asset.toString()).toBe(mplAsset.erc20Address.toString());
   });
+
+  it("should correctly return underlying asset", async () => {
+    // Setup mocks
+    erc4626Contract = {
+      ...erc4626Contract,
+      asset: jest.fn().mockResolvedValue(mplAsset.erc20Address.toString()),
+      previewRedeem: jest.fn(() => BigNumber.from("100")),
+    };
+    IERC4626__factory.connect = () => erc4626Contract as any;
+
+    erc2MetadataContract = {
+      ...erc2MetadataContract,
+      name: jest.fn().mockResolvedValue("Maple Token"),
+      symbol: jest.fn().mockResolvedValue("MPL"),
+      decimals: jest.fn().mockResolvedValue(18),
+    };
+    IERC20Metadata__factory.connect = () => erc2MetadataContract as any;
+
+    const erc4626BridgeData = ERC4626BridgeData.create({} as any);
+    const underlyingAsset = await erc4626BridgeData.getUnderlyingAmount(xmplAsset, 10n ** 18n);
+
+    expect(underlyingAsset.address.toString()).toBe(mplAsset.erc20Address.toString());
+    expect(underlyingAsset.name).toBe("Maple Token");
+    expect(underlyingAsset.symbol).toBe("MPL");
+    expect(underlyingAsset.decimals).toBe(18);
+    expect(underlyingAsset.amount).toBe(100n);
+  });
 });

src/client/erc4626/erc4626-bridge-data.ts

@@ -1,12 +1,11 @@
 import { EthAddress } from "@aztec/barretenberg/address";
 import { EthereumProvider } from "@aztec/barretenberg/blockchain";
 import { Web3Provider } from "@ethersproject/providers";
-import { IERC4626__factory } from "../../../typechain-types";
+import { IERC20Metadata__factory, IERC4626__factory } from "../../../typechain-types";
 import { createWeb3Provider } from "../aztec/provider";
-import { AuxDataConfig, AztecAsset, BridgeDataFieldGetters, SolidityType } from "../bridge-data";
+import { AuxDataConfig, AztecAsset, BridgeDataFieldGetters, SolidityType, UnderlyingAsset } from "../bridge-data";
 
 export class ERC4626BridgeData implements BridgeDataFieldGetters {
-  readonly WETH = EthAddress.fromString("0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2");
   shareToAssetMap = new Map<EthAddress, EthAddress>();
 
   protected constructor(protected ethersProvider: Web3Provider) {}
@@ -97,4 +96,29 @@ export class ERC4626BridgeData implements BridgeDataFieldGetters {
     }
     return asset;
   }
+
+  /**
+   * @notice This function gets the underlying amount of asset corresponding to shares
+   * @param share Address of the share/vault
+   * @param amount Amount of shares to get underlying amount for
+   * @return Underlying amount of asset corresponding to the amount of shares
+   */
+  async getUnderlyingAmount(share: AztecAsset, amount: bigint): Promise<UnderlyingAsset> {
+    const vault = IERC4626__factory.connect(share.erc20Address.toString(), this.ethersProvider);
+    const assetAddress = EthAddress.fromString(await vault.asset());
+
+    const tokenContract = IERC20Metadata__factory.connect(assetAddress.toString(), this.ethersProvider);
+    const namePromise = tokenContract.name();
+    const symbolPromise = tokenContract.symbol();
+    const decimalsPromise = tokenContract.decimals();
+    const amountPromise = vault.previewRedeem(amount);
+
+    return {
+      address: assetAddress,
+      name: await namePromise,
+      symbol: await symbolPromise,
+      decimals: await decimalsPromise,
+      amount: (await amountPromise).toBigInt(),
+    };
+  }
 }