feat: Implement mint and burn (#106)

Signed-off-by: Victor Yanev <[email protected]>
Signed-off-by: Victor Yanev <[email protected]>

@hts-forking/test/data/MFCT/getBalanceOfToken_0.0.2669675.json

@@ -0,0 +1,13 @@
+{
+    "timestamp": "1727813254.582754397",
+    "balances": [
+        {
+            "account": "0.0.2669675",
+            "balance": 5000,
+            "decimals": 0
+        }
+    ],
+    "links": {
+        "next": null
+    }
+}

@hts-forking/test/data/USDC/getBalanceOfToken_0.0.5176.json

@@ -0,0 +1,13 @@
+{
+    "timestamp": "1724799522.972495003",
+    "balances": [
+        {
+            "account": "0.0.5176",
+            "balance": 5000000,
+            "decimals": 6
+        }
+    ],
+    "links": {
+        "next": null
+    }
+}

@hts-forking/test/data/getAccount_0xa3612a87022a4706fc9452c50abd2703ac4fd7d9.json

@@ -0,0 +1,36 @@
+{
+    "account": "0.0.2669675",
+    "alias": "HIQQEAMJCQN7IZLRPU6I53Q7VFOINWOXBZM365CNKLKTBQ5RXPYUKLWH",
+    "auto_renew_period": 7776000,
+    "balance": {
+        "balance": 99981012856,
+        "timestamp": "1727813254.582754397",
+        "tokens": [
+            {
+                "token_id": "0.0.4730999",
+                "balance": 5000
+            }
+        ]
+    },
+    "created_timestamp": "1707161970.469792002",
+    "decline_reward": false,
+    "deleted": false,
+    "ethereum_nonce": 802,
+    "evm_address": "0xa3612a87022a4706fc9452c50abd2703ac4fd7d9",
+    "expiry_timestamp": "1714937970.469792002",
+    "key": {
+        "_type": "ECDSA_SECP256K1",
+        "key": "020189141bf465717d3c8eee1fa95c86d9d70e59bf744d52d530c3b1bbf1452ec7"
+    },
+    "max_automatic_token_associations": 0,
+    "memo": "auto-created account",
+    "pending_reward": 0,
+    "receiver_sig_required": false,
+    "staked_account_id": null,
+    "staked_node_id": null,
+    "stake_period_start": null,
+    "transactions": [],
+    "links": {
+        "next": "/api/v1/accounts/0.0.2669675?timestamp=lt:1726314195.875000001"
+    }
+}

scripts/curl

@@ -46,13 +46,23 @@ for (const [re, fn] of /** @type {const} */([
 
         return require(`../@hts-forking/test/data/${token.symbol}/getBalanceOfToken_${accountId}.json`);
     }],
-    [/^accounts\/(0x[0-9a-fA-F]{40})$/, address => {
-        assert(typeof address === 'string');
+    [/^accounts\/((0x[0-9a-fA-F]{40})|(0\.0\.\d+))$/, idOrAliasOrEvmAddress => {
+        assert(typeof idOrAliasOrEvmAddress === 'string');
         try {
-            return require(`../@hts-forking/test/data/getAccount_${address.toLowerCase()}.json`);
+            return require(`../@hts-forking/test/data/getAccount_${idOrAliasOrEvmAddress.toLowerCase()}.json`);
         } catch {
-            if (address.startsWith(LONG_ZERO_PREFIX)) {
-                return { account: '0.0.' + parseInt(address, 16) };
+            if (idOrAliasOrEvmAddress.startsWith(LONG_ZERO_PREFIX)) {
+                return {
+                    account: '0.0.' + parseInt(idOrAliasOrEvmAddress, 16),
+                    evm_address: idOrAliasOrEvmAddress,
+                };
+            }
+            if (idOrAliasOrEvmAddress.startsWith('0.0.')) {
+                const accountNumber = parseInt(idOrAliasOrEvmAddress.slice(4));
+                return {
+                    account: idOrAliasOrEvmAddress,
+                    evm_address: `0x${accountNumber.toString(16).padStart(40, '0')}`
+                };
             }
             return undefined;
         }

src/HtsSystemContract.sol

@@ -40,18 +40,54 @@ contract HtsSystemContract is IHederaTokenService, IERC20Events {
         assembly { accountId := sload(slot) }
     }
 
-    /**
-     * Query token info
-     * @param token - The token address to check
-     * @return responseCode - the response code for the status of the request. SUCCESS is `22`.
-     * @return tokenInfo - token info for `token`
-     */
     function getTokenInfo(address token) htsCall external returns (int64 responseCode, TokenInfo memory tokenInfo) {
         require(token != address(0), "getTokenInfo: invalid token");
 
         (responseCode, tokenInfo) = IHederaTokenService(token).getTokenInfo(token);
     }
 
+    function mintToken(address token, int64 amount, bytes[] memory) htsCall external returns (
+        int64 responseCode,
+        int64 newTotalSupply,
+        int64[] memory serialNumbers
+    ) {
+        require(token != address(0), "mintToken: invalid token");
+        require(amount > 0, "mintToken: invalid amount");
+
+        (int64 tokenInfoResponseCode, TokenInfo memory tokenInfo) = IHederaTokenService(token).getTokenInfo(token);
+        require(tokenInfoResponseCode == 22, "mintToken: failed to get token info");
+
+        address treasuryAccount = tokenInfo.token.treasury;
+        require(treasuryAccount != address(0), "mintToken: invalid account");
+
+        HtsSystemContract(token)._update(address(0), treasuryAccount, uint256(uint64(amount)));
+
+        responseCode = 22; // HederaResponseCodes.SUCCESS
+        newTotalSupply = int64(uint64(IERC20(token).totalSupply()));
+        serialNumbers = new int64[](0);
+        require(newTotalSupply >= 0, "mintToken: invalid total supply");
+    }
+
+    function burnToken(address token, int64 amount, int64[] memory) htsCall external returns (
+        int64 responseCode,
+        int64 newTotalSupply
+    ) {
+        require(token != address(0), "burnToken: invalid token");
+        require(amount > 0, "burnToken: invalid amount");
+
+        (int64 tokenInfoResponseCode, TokenInfo memory tokenInfo) = IHederaTokenService(token).getTokenInfo(token);
+        require(tokenInfoResponseCode == 22, "burnToken: failed to get token info");
+
+        address treasuryAccount = tokenInfo.token.treasury;
+        require(treasuryAccount != address(0), "burnToken: invalid account");
+
+        HtsSystemContract(token)._update(treasuryAccount, address(0), uint256(uint64(amount)));
+
+        responseCode = 22; // HederaResponseCodes.SUCCESS
+        newTotalSupply = int64(uint64(IERC20(token).totalSupply()));
+        require(newTotalSupply >= 0, "burnToken: invalid total supply");
+    }
+
     /**
      * @dev Validates `redirectForToken(address,bytes)` dispatcher arguments.
      *
@@ -194,6 +230,15 @@ contract HtsSystemContract is IHederaTokenService, IERC20Events {
             require(msg.sender == HTS_ADDRESS, "getTokenInfo: unauthorized");
             _initTokenData();
             return abi.encode(22, _tokenInfo);
+        } else if (selector == this._update.selector) {
+            require(msg.data.length >= 124, "update: Not enough calldata");
+            require(msg.sender == HTS_ADDRESS, "update: unauthorized");
+            address from = address(bytes20(msg.data[40:60]));
+            address to = address(bytes20(msg.data[72:92]));
+            uint256 amount = uint256(bytes32(msg.data[92:124]));
+            _initTokenData();
+            _update(from, to, amount);
+            return abi.encode(true);
         }
         revert ("redirectForToken: not supported");
     }
@@ -236,22 +281,32 @@ contract HtsSystemContract is IHederaTokenService, IERC20Events {
     function _transfer(address from, address to, uint256 amount) private {
         require(from != address(0), "hts: invalid sender");
         require(to != address(0), "hts: invalid receiver");
+        _update(from, to, amount);
+        emit Transfer(from, to, amount);
+    }
 
-        bytes32 fromSlot = _balanceOfSlot(from);
-        uint256 fromBalance;
-        assembly { fromBalance := sload(fromSlot) }
-        require(fromBalance >= amount, "_transfer: insufficient balance");
-        assembly { sstore(fromSlot, sub(fromBalance, amount)) }
-
-        bytes32 toSlot = _balanceOfSlot(to);
-        uint256 toBalance;
-        assembly { toBalance := sload(toSlot) }
-        // Solidity's checked arithmetic will revert if this overflows
-        // https://soliditylang.org/blog/2020/12/16/solidity-v0.8.0-release-announcement
-        uint256 newToBalance = toBalance + amount;
-        assembly { sstore(toSlot, newToBalance) }
+    function _update(address from, address to, uint256 amount) public {
+        if (from == address(0)) {
+            totalSupply += amount;
+        } else {
+            bytes32 fromSlot = _balanceOfSlot(from);
+            uint256 fromBalance;
+            assembly { fromBalance := sload(fromSlot) }
+            require(fromBalance >= amount, "_transfer: insufficient balance");
+            assembly { sstore(fromSlot, sub(fromBalance, amount)) }
+        }
 
-        emit Transfer(from, to, amount);
+        if (to == address(0)) {
+            totalSupply -= amount;
+        } else {
+            bytes32 toSlot = _balanceOfSlot(to);
+            uint256 toBalance;
+            assembly { toBalance := sload(toSlot) }
+            // Solidity's checked arithmetic will revert if this overflows
+            // https://soliditylang.org/blog/2020/12/16/solidity-v0.8.0-release-announcement
+            uint256 newToBalance = toBalance + amount;
+            assembly { sstore(toSlot, newToBalance) }
+        }
     }
 
     function _approve(address owner, address spender, uint256 amount) private {

src/HtsSystemContractJson.sol

@@ -46,11 +46,21 @@ contract HtsSystemContractJson is HtsSystemContract {
 
     /**
      * @dev Reading Smart Contract's data into it's storage directly from the MirrorNode.
+     * @dev Both `initialized` and `_mirrorNode` are stored in the same slot (with different offsets).
+     * Given how `initialized` is written to (see at the end of the method), it would seem that the
+     * instance variable `_mirrorNode` is overwritten.
+     * However, this is not the case because the slot space for each access is different:
+     * - `_mirrorNode` is accessed through the `0x167` address.
+     * - `initialized` is accessed through the address of the token.
      */
     function _initTokenData() internal override {
-        if (initialized) return;
-
         bytes32 slot;
+        assembly { slot := initialized.slot }
+        if (vm.load(address(this), slot) == bytes32(uint256(1))) {
+            // Already initialized
+            return;
+        }
+
         string memory json = mirrorNode().fetchTokenData(address(this));
 
         assembly { slot := name.slot }

src/IHederaTokenService.sol

@@ -216,4 +216,35 @@ interface IHederaTokenService {
     /// @return responseCode The response code for the status of the request. SUCCESS is 22.
     /// @return tokenInfo TokenInfo info for `token`
     function getTokenInfo(address token) external returns (int64 responseCode, TokenInfo memory tokenInfo);
+
+    /// Mints an amount of the token to the defined treasury account
+    /// @param token The token for which to mint tokens. If token does not exist, transaction results in
+    ///              INVALID_TOKEN_ID
+    /// @param amount Applicable to tokens of type FUNGIBLE_COMMON. The amount to mint to the Treasury Account.
+    ///               Amount must be a positive non-zero number represented in the lowest denomination of the
+    ///               token. The new supply must be lower than 2^63.
+    /// @param metadata Applicable to tokens of type NON_FUNGIBLE_UNIQUE. A list of metadata that are being created.
+    ///                 Maximum allowed size of each metadata is 100 bytes
+    /// @return responseCode The response code for the status of the request. SUCCESS is 22.
+    /// @return newTotalSupply The new supply of tokens. For NFTs it is the total count of NFTs
+    /// @return serialNumbers If the token is an NFT the newly generate serial numbers, othersise empty.
+    function mintToken(address token, int64 amount, bytes[] memory metadata) external returns (
+        int64 responseCode,
+        int64 newTotalSupply,
+        int64[] memory serialNumbers
+    );
+
+    /// Burns an amount of the token from the defined treasury account
+    /// @param token The token for which to burn tokens. If token does not exist, transaction results in
+    ///              INVALID_TOKEN_ID
+    /// @param amount  Applicable to tokens of type FUNGIBLE_COMMON. The amount to burn from the Treasury Account.
+    ///                Amount must be a positive non-zero number, not bigger than the token balance of the treasury
+    ///                account (0; balance], represented in the lowest denomination.
+    /// @param serialNumbers Applicable to tokens of type NON_FUNGIBLE_UNIQUE. The list of serial numbers to be burned.
+    /// @return responseCode The response code for the status of the request. SUCCESS is 22.
+    /// @return newTotalSupply The new supply of tokens. For NFTs it is the total count of NFTs
+    function burnToken(address token, int64 amount, int64[] memory serialNumbers) external returns (
+        int64 responseCode,
+        int64 newTotalSupply
+    );
 }