Deposit to ERC4626 Vaults (#71)

- Added allocation functionality that deposits a single asset (tBTC) to
an authorized vault
- Added and adjusted deployment scripts
- Changed unit tests and added an integration test that validates the
flow of assets from Acre contract through Dispatcher that deposits
assets to an authorized ERC4626 Vault

core/contracts/Acre.sol

@@ -2,7 +2,9 @@
 pragma solidity ^0.8.21;
 
 import "@openzeppelin/contracts/token/ERC20/extensions/ERC4626.sol";
+import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
 import "@openzeppelin/contracts/access/Ownable.sol";
+import "./Dispatcher.sol";
 
 /// @title Acre
 /// @notice This contract implements the ERC-4626 tokenized vault standard. By
@@ -16,19 +18,41 @@ import "@openzeppelin/contracts/access/Ownable.sol";
 ///      burning of shares (stBTC), which are represented as standard ERC20
 ///      tokens, providing a seamless exchange with tBTC tokens.
 contract Acre is ERC4626, Ownable {
-    // Minimum amount for a single deposit operation.
+    using SafeERC20 for IERC20;
+
+    /// Dispatcher contract that routes tBTC from Acre to a given vault and back.
+    Dispatcher public dispatcher;
+    /// Minimum amount for a single deposit operation.
     uint256 public minimumDepositAmount;
-    // Maximum total amount of tBTC token held by Acre.
+    /// Maximum total amount of tBTC token held by Acre.
     uint256 public maximumTotalAssets;
 
+    /// Emitted when a referral is used.
+    /// @param referral Used for referral program.
+    /// @param assets Amount of tBTC tokens staked.
     event StakeReferral(bytes32 indexed referral, uint256 assets);
+
+    /// Emitted when deposit parameters are updated.
+    /// @param minimumDepositAmount New value of the minimum deposit amount.
+    /// @param maximumTotalAssets New value of the maximum total assets amount.
     event DepositParametersUpdated(
         uint256 minimumDepositAmount,
         uint256 maximumTotalAssets
     );
 
+    /// Emitted when the dispatcher contract is updated.
+    /// @param oldDispatcher Address of the old dispatcher contract.
+    /// @param newDispatcher Address of the new dispatcher contract.
+    event DispatcherUpdated(address oldDispatcher, address newDispatcher);
+
+    /// Reverts if the amount is less than the minimum deposit amount.
+    /// @param amount Amount to check.
+    /// @param min Minimum amount to check 'amount' against.
     error DepositAmountLessThanMin(uint256 amount, uint256 min);
 
+    /// Reverts if the address is zero.
+    error ZeroAddress();
+
     constructor(
         IERC20 tbtc
     ) ERC4626(tbtc) ERC20("Acre Staked Bitcoin", "stBTC") Ownable(msg.sender) {
@@ -59,6 +83,34 @@ contract Acre is ERC4626, Ownable {
         );
     }
 
+    // TODO: Implement a governed upgrade process that initiates an update and
+    //       then finalizes it after a delay.
+    /// @notice Updates the dispatcher contract and gives it an unlimited
+    ///         allowance to transfer staked tBTC.
+    /// @param newDispatcher Address of the new dispatcher contract.
+    function updateDispatcher(Dispatcher newDispatcher) external onlyOwner {
+        if (address(newDispatcher) == address(0)) {
+            revert ZeroAddress();
+        }
+
+        address oldDispatcher = address(dispatcher);
+
+        emit DispatcherUpdated(oldDispatcher, address(newDispatcher));
+        dispatcher = newDispatcher;
+
+        // TODO: Once withdrawal/rebalancing is implemented, we need to revoke the
+        // approval of the vaults share tokens from the old dispatcher and approve
+        // a new dispatcher to manage the share tokens.
+
+        if (oldDispatcher != address(0)) {
+            // Setting allowance to zero for the old dispatcher
+            IERC20(asset()).forceApprove(oldDispatcher, 0);
+        }
+
+        // Setting allowance to max for the new dispatcher
+        IERC20(asset()).forceApprove(address(dispatcher), type(uint256).max);
+    }
+
     /// @notice Mints shares to receiver by depositing exactly amount of
     ///         tBTC tokens.
     /// @dev Takes into account a deposit parameter, minimum deposit amount,

core/contracts/Dispatcher.sol

@@ -2,37 +2,91 @@
 pragma solidity ^0.8.21;
 
 import "@openzeppelin/contracts/access/Ownable.sol";
+import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+import "@openzeppelin/contracts/interfaces/IERC4626.sol";
+import "./Router.sol";
+import "./Acre.sol";
 
 /// @title Dispatcher
-/// @notice Dispatcher is a contract that routes TBTC from stBTC (Acre) to
-///         a given vault and back. Vaults supply yield strategies with TBTC that
+/// @notice Dispatcher is a contract that routes tBTC from Acre (stBTC) to
+///         yield vaults and back. Vaults supply yield strategies with tBTC that
 ///         generate yield for Bitcoin holders.
-contract Dispatcher is Ownable {
-    error VaultAlreadyAuthorized();
-    error VaultUnauthorized();
+contract Dispatcher is Router, Ownable {
+    using SafeERC20 for IERC20;
 
+    /// Struct holds information about a vault.
     struct VaultInfo {
         bool authorized;
     }
 
-    /// @notice Authorized Yield Vaults that implement ERC4626 standard. These
-    ///         vaults deposit assets to yield strategies, e.g. Uniswap V3
-    ///         WBTC/TBTC pool. Vault can be a part of Acre ecosystem or can be
-    ///         implemented externally. As long as it complies with ERC4626
-    ///         standard and is authorized by the owner it can be plugged into
-    ///         Acre.
+    /// The main Acre contract holding tBTC deposited by stakers.
+    Acre public immutable acre;
+    /// tBTC token contract.
+    IERC20 public immutable tbtc;
+    /// Address of the maintainer bot.
+    address public maintainer;
+
+    /// Authorized Yield Vaults that implement ERC4626 standard. These
+    /// vaults deposit assets to yield strategies, e.g. Uniswap V3
+    /// WBTC/TBTC pool. Vault can be a part of Acre ecosystem or can be
+    /// implemented externally. As long as it complies with ERC4626
+    /// standard and is authorized by the owner it can be plugged into
+    /// Acre.
     address[] public vaults;
+    /// Mapping of vaults to their information.
     mapping(address => VaultInfo) public vaultsInfo;
 
+    /// Emitted when a vault is authorized.
+    /// @param vault Address of the vault.
     event VaultAuthorized(address indexed vault);
+
+    /// Emitted when a vault is deauthorized.
+    /// @param vault Address of the vault.
     event VaultDeauthorized(address indexed vault);
 
-    constructor() Ownable(msg.sender) {}
+    /// Emitted when tBTC is routed to a vault.
+    /// @param vault Address of the vault.
+    /// @param amount Amount of tBTC.
+    /// @param sharesOut Amount of shares received by Acre.
+    event DepositAllocated(
+        address indexed vault,
+        uint256 amount,
+        uint256 sharesOut
+    );
+
+    /// Emitted when the maintainer address is updated.
+    /// @param maintainer Address of the new maintainer.
+    event MaintainerUpdated(address indexed maintainer);
+
+    /// Reverts if the vault is already authorized.
+    error VaultAlreadyAuthorized();
+
+    /// Reverts if the vault is not authorized.
+    error VaultUnauthorized();
+
+    /// Reverts if the caller is not the maintainer.
+    error NotMaintainer();
+
+    /// Reverts if the address is zero.
+    error ZeroAddress();
+
+    /// Modifier that reverts if the caller is not the maintainer.
+    modifier onlyMaintainer() {
+        if (msg.sender != maintainer) {
+            revert NotMaintainer();
+        }
+        _;
+    }
+
+    constructor(Acre _acre, IERC20 _tbtc) Ownable(msg.sender) {
+        acre = _acre;
+        tbtc = _tbtc;
+    }
 
     /// @notice Adds a vault to the list of authorized vaults.
     /// @param vault Address of the vault to add.
     function authorizeVault(address vault) external onlyOwner {
-        if (vaultsInfo[vault].authorized) {
+        if (isVaultAuthorized(vault)) {
             revert VaultAlreadyAuthorized();
         }
 
@@ -45,7 +99,7 @@ contract Dispatcher is Ownable {
     /// @notice Removes a vault from the list of authorized vaults.
     /// @param vault Address of the vault to remove.
     function deauthorizeVault(address vault) external onlyOwner {
-        if (!vaultsInfo[vault].authorized) {
+        if (!isVaultAuthorized(vault)) {
             revert VaultUnauthorized();
         }
 
@@ -63,7 +117,58 @@ contract Dispatcher is Ownable {
         emit VaultDeauthorized(vault);
     }
 
-    function getVaults() external view returns (address[] memory) {
+    /// @notice Updates the maintainer address.
+    /// @param newMaintainer Address of the new maintainer.
+    function updateMaintainer(address newMaintainer) external onlyOwner {
+        if (newMaintainer == address(0)) {
+            revert ZeroAddress();
+        }
+
+        maintainer = newMaintainer;
+
+        emit MaintainerUpdated(maintainer);
+    }
+
+    /// TODO: make this function internal once the allocation distribution is
+    /// implemented
+    /// @notice Routes tBTC from Acre to a vault. Can be called by the maintainer
+    ///         only.
+    /// @param vault Address of the vault to route the assets to.
+    /// @param amount Amount of tBTC to deposit.
+    /// @param minSharesOut Minimum amount of shares to receive by Acre.
+    function depositToVault(
+        address vault,
+        uint256 amount,
+        uint256 minSharesOut
+    ) public onlyMaintainer {
+        if (!isVaultAuthorized(vault)) {
+            revert VaultUnauthorized();
+        }
+
+        // slither-disable-next-line arbitrary-send-erc20
+        tbtc.safeTransferFrom(address(acre), address(this), amount);
+        tbtc.forceApprove(address(vault), amount);
+
+        uint256 sharesOut = deposit(
+            IERC4626(vault),
+            address(acre),
+            amount,
+            minSharesOut
+        );
+        // slither-disable-next-line reentrancy-events
+        emit DepositAllocated(vault, amount, sharesOut);
+    }
+
+    /// @notice Returns the list of authorized vaults.
+    function getVaults() public view returns (address[] memory) {
         return vaults;
     }
+
+    /// @notice Returns true if the vault is authorized.
+    /// @param vault Address of the vault to check.
+    function isVaultAuthorized(address vault) public view returns (bool) {
+        return vaultsInfo[vault].authorized;
+    }
+
+    /// TODO: implement redeem() / withdraw() functions
 }

core/contracts/Router.sol

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-3.0-only
+pragma solidity ^0.8.21;
+
+import "@openzeppelin/contracts/interfaces/IERC4626.sol";
+
+/// @title Router
+/// @notice Router is a contract that routes tBTC from stBTC (Acre) to
+///         a given vault and back. Vaults supply yield strategies with tBTC that
+///         generate yield for Bitcoin holders.
+abstract contract Router {
+    /// Thrown when amount of shares received is below the min set by caller.
+    /// @param vault Address of the vault.
+    /// @param sharesOut Amount of shares received by Acre.
+    /// @param minSharesOut Minimum amount of shares expected to receive.
+    error MinSharesError(
+        address vault,
+        uint256 sharesOut,
+        uint256 minSharesOut
+    );
+
+    /// @notice Routes funds from stBTC (Acre) to a vault. The amount of tBTC to
+    ///         Shares of deposited tBTC are minted to the stBTC contract.
+    /// @param vault Address of the vault to route the funds to.
+    /// @param receiver Address of the receiver of the shares.
+    /// @param amount Amount of tBTC to deposit.
+    /// @param minSharesOut Minimum amount of shares to receive.
+    function deposit(
+        IERC4626 vault,
+        address receiver,
+        uint256 amount,
+        uint256 minSharesOut
+    ) internal returns (uint256 sharesOut) {
+        if ((sharesOut = vault.deposit(amount, receiver)) < minSharesOut) {
+            revert MinSharesError(address(vault), sharesOut, minSharesOut);
+        }
+    }
+}

core/contracts/test/TestERC4626.sol

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-3.0-only
+pragma solidity ^0.8.21;
+
+import "@openzeppelin/contracts/token/ERC20/extensions/ERC4626.sol";
+
+contract TestERC4626 is ERC4626 {
+    constructor(
+        IERC20 asset,
+        string memory tokenName,
+        string memory tokenSymbol
+    ) ERC4626(asset) ERC20(tokenName, tokenSymbol) {}
+}

core/deploy/00_resolve_testing_erc4626.ts

@@ -0,0 +1,27 @@
+import type { HardhatRuntimeEnvironment } from "hardhat/types"
+import type { DeployFunction } from "hardhat-deploy/types"
+
+const func: DeployFunction = async (hre: HardhatRuntimeEnvironment) => {
+  const { getNamedAccounts, deployments } = hre
+  const { log } = deployments
+  const { deployer } = await getNamedAccounts()
+  const tBTC = await deployments.get("TBTC")
+
+  log("deploying Mock ERC4626 Vault")
+
+  await deployments.deploy("Vault", {
+    contract: "TestERC4626",
+    from: deployer,
+    args: [tBTC.address, "MockVault", "MV"],
+    log: true,
+    waitConfirmations: 1,
+  })
+}
+
+export default func
+
+func.tags = ["TestERC4626"]
+func.dependencies = ["TBTC"]
+
+func.skip = async (hre: HardhatRuntimeEnvironment): Promise<boolean> =>
+  hre.network.name === "mainnet"

core/deploy/02_deploy_acre_router.ts → core/deploy/02_deploy_dispatcher.ts

@@ -5,9 +5,12 @@ const func: DeployFunction = async (hre: HardhatRuntimeEnvironment) => {
   const { getNamedAccounts, deployments } = hre
   const { deployer } = await getNamedAccounts()
 
+  const tbtc = await deployments.get("TBTC")
+  const acre = await deployments.get("Acre")
+
   await deployments.deploy("Dispatcher", {
     from: deployer,
-    args: [],
+    args: [acre.address, tbtc.address],
     log: true,
     waitConfirmations: 1,
   })

core/deploy/11_acre_update_dispatcher.ts

@@ -0,0 +1,21 @@
+import type { HardhatRuntimeEnvironment } from "hardhat/types"
+import type { DeployFunction } from "hardhat-deploy/types"
+
+const func: DeployFunction = async (hre: HardhatRuntimeEnvironment) => {
+  const { getNamedAccounts, deployments } = hre
+  const { deployer } = await getNamedAccounts()
+
+  const dispatcher = await deployments.get("Dispatcher")
+
+  await deployments.execute(
+    "Acre",
+    { from: deployer, log: true, waitConfirmations: 1 },
+    "updateDispatcher",
+    dispatcher.address,
+  )
+}
+
+export default func
+
+func.tags = ["AcreUpdateDispatcher"]
+func.dependencies = ["Acre", "Dispatcher"]

core/deploy/12_dispatcher_update_maintainer.ts

@@ -0,0 +1,19 @@
+import type { HardhatRuntimeEnvironment } from "hardhat/types"
+import type { DeployFunction } from "hardhat-deploy/types"
+
+const func: DeployFunction = async (hre: HardhatRuntimeEnvironment) => {
+  const { getNamedAccounts, deployments } = hre
+  const { deployer, maintainer } = await getNamedAccounts()
+
+  await deployments.execute(
+    "Dispatcher",
+    { from: deployer, log: true, waitConfirmations: 1 },
+    "updateMaintainer",
+    maintainer,
+  )
+}
+
+export default func
+
+func.tags = ["DispatcherUpdateMaintainer"]
+func.dependencies = ["Dispatcher"]