Adding deposit and redeem functionality

Renamed AcreRouter to Dispatcher and introduced an abstract contract
called Router that will handle moving funds between Acre and Vaults.

In order to deposit / redeem assets, Acre contract should approve assets
for Dispatcher to spend and call depositToVault or redeemFromVault
functions. These Acre's functions can be also called by a bot for
rebalancing purposes.

core/contracts/AcreRouter.sol → core/contracts/Dispatcher.sol

@@ -2,16 +2,25 @@
 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";
 
-/// @title AcreRouter
-/// @notice AcreRouter is a contract that routes TBTC from stBTC (Acre) to
+/// @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
 ///         generate yield for Bitcoin holders.
-contract AcreRouter is Ownable {
+///         TODO: add more description around vaults.
+contract Dispatcher is Router, Ownable {
+    using SafeERC20 for IERC20;
+
     struct Vault {
         bool approved;
     }
 
+    IERC20 public immutable stBTC; // Acre contract
+    IERC20 public immutable tBTC;
+
     /// @notice Approved vaults within the Yiern Modules 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
@@ -24,7 +33,10 @@ contract AcreRouter is Ownable {
     event VaultAdded(address indexed vault);
     event VaultRemoved(address indexed vault);
 
-    constructor() Ownable(msg.sender) {}
+    constructor(IERC20 _stBTC, IERC20 _tBTC) Ownable(msg.sender) {
+        stBTC = _stBTC;
+        tBTC = _tBTC;
+    }
 
     /// @notice Adds a vault to the list of approved vaults.
     /// @param vault Address of the vault to add.
@@ -59,4 +71,28 @@ contract AcreRouter is Ownable {
     function vaultsLength() external view returns (uint256) {
         return vaults.length;
     }
+
+    // TODO: add documentation
+    function depositToVault(
+        address vault,
+        uint256 amount,
+        uint256 minSharesOut
+    ) public {
+        require(msg.sender == address(stBTC), "stBTC only");
+        require(vaultsInfo[vault].approved, "Vault is not approved");
+
+        deposit(IERC4626(vault), address(stBTC), amount, minSharesOut);
+    }
+
+    // TODO: add documentation
+    function redeemFromVault(
+        address vault,
+        uint256 shares,
+        uint256 minAssetsOut
+    ) public {
+        require(msg.sender == address(stBTC), "stBTC only");
+        require(vaultsInfo[vault].approved, "Vault is not approved");
+
+        redeem(IERC4626(vault), address(stBTC), shares, minAssetsOut);
+    }
 }

core/contracts/Router.sol

@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-3.0-only
+pragma solidity ^0.8.21;
+
+import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
+import "@openzeppelin/contracts/interfaces/IERC20.sol";
+import "@openzeppelin/contracts/interfaces/IERC4626.sol";
+
+/// TODO: Add documentation
+abstract contract Router {
+    using SafeERC20 for IERC20;
+
+    /// @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 to 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 to,
+        uint256 amount,
+        uint256 minSharesOut
+    ) public returns (uint256 sharesOut) {
+        IERC20(vault.asset()).safeTransferFrom(
+            msg.sender,
+            address(this),
+            amount
+        );
+        IERC20(vault.asset()).safeIncreaseAllowance(address(vault), amount);
+        if ((sharesOut = vault.deposit(amount, to)) < minSharesOut) {
+            revert("Not enough shares received");
+        }
+    }
+
+    /// @notice Redeem tBTC from a vault and approve tokens to be transferred
+    ///         by stBTC (Acre)
+    /// @param vault Address of the vault to collect the assets from.
+    /// @param to Address of the receiver of the assets.
+    /// @param shares Amount of shares to collect. Shares are the internal representation
+    ///               of the underlying asset in the vault. Concrete amount of the
+    ///               underlying asset is calculated by calling `convertToAssets` on
+    ///               the vault and the shares are burned.
+    /// @param minAssetsOut Minimum amount of TBTC to receive.
+    function redeem(
+        IERC4626 vault,
+        address to,
+        uint256 shares,
+        uint256 minAssetsOut
+    ) public returns (uint256 assetsOut) {
+        if (
+            (assetsOut = vault.redeem(shares, address(this), to)) < minAssetsOut
+        ) {
+            revert("Not enough assets received");
+        }
+        IERC20(vault.asset()).safeIncreaseAllowance(to, assetsOut);
+    }
+}