Staking

core/.solhint.json

@@ -1,5 +1,4 @@
 {
   "extends": "thesis",
-  "plugins": [],
-  "rules": {}
+  "plugins": []
 }

core/contracts/Acre.sol

@@ -1,9 +1,42 @@
 // SPDX-License-Identifier: GPL-3.0-only
 pragma solidity ^0.8.21;
 
-// Uncomment this line to use console.log
-// import "hardhat/console.sol";
+import "@openzeppelin/contracts/token/ERC20/extensions/ERC4626.sol";
 
-contract Acre {
-    // TODO: add your implementation
+/// @title Acre
+/// @notice Implementation of the ERR-4626 tokenized vault standard. ERC-4626 is
+///         a standard to optimize and unify the technical parameters of
+///         yield-bearing vaults. This contract allows the minting and burning
+///         of shares, represented as standard ERC20 token, in exchange for tBTC
+///         tokens.
+/// @dev ERC-4626 standard extends the ERC-20 token.
+contract Acre is ERC4626 {
+    event StakeReferral(bytes32 indexed referral, uint256 assets);
+
+    constructor(
+        IERC20 tbtc
+    ) ERC4626(tbtc) ERC20("Acre Staked Bitcoin", "stBTC") {}
+
+    /// @notice Stakes a given amount of tBTC token and mints shares to a
+    ///         receiver.
+    /// @dev This function calls `deposit` function from `ERC4626` contract. The
+    ///      amount of the assets has to be pre-approved in the tBTC contract.
+    /// @param assets Approved amount for the transfer and stake.
+    /// @param receiver The address to which the shares will be minted.
+    /// @param referral Data used for referral program.
+    /// @return shares Minted shares.
+    function stake(
+        uint256 assets,
+        address receiver,
+        bytes32 referral
+    ) public returns (uint256) {
+        // TODO: revisit the type of referral.
+        uint256 shares = deposit(assets, receiver);
+
+        if (referral != bytes32(0)) {
+            emit StakeReferral(referral, assets);
+        }
+
+        return shares;
+    }
 }

core/contracts/test/TestERC20.sol

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-3.0-only
+pragma solidity ^0.8.21;
+
+import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
+
+contract TestERC20 is ERC20 {
+    constructor() ERC20("Test Token", "TEST") {}
+
+    function mint(address account, uint256 value) external {
+        _mint(account, value);
+    }
+}

core/package.json

@@ -55,5 +55,8 @@
     "ts-node": "^10.9.1",
     "typechain": "^8.3.2",
     "typescript": "^5.3.2"
+  },
+  "dependencies": {
+    "@openzeppelin/contracts": "^5.0.0"
   }
 }