Uniswap integration

.gitmodules

@@ -2,3 +2,7 @@
 	path = implementation/contracts/bitcoin-spv
 	url = [email protected]:summa-tx/bitcoin-spv.git
 	branch = 1.0.0-embedabble
+[submodule "implementation/uniswap/contracts-vyper"]
+	path = implementation/uniswap/contracts-vyper
+	url = https://github.com/Uniswap/contracts-vyper
+	branch = c10c08d81d6114f694baa8bd32f555a40f6264da

implementation/.babelrc

@@ -1,3 +1,15 @@
 {
-    "presets": ["es2015", "stage-2", "stage-3"]
+    "presets": [
+        [
+          "@babel/preset-env",
+          {
+            "useBuiltIns": "entry",
+            "corejs": 3,
+            "targets": {
+                "node": true
+            },
+          }
+        ]
+    ],
+    "sourceMaps": "inline"
 }

implementation/.gitignore

@@ -3,3 +3,5 @@ blocks/
 __pycache__/
 node_modules/
 .mypy_cache
+coverage/
+coverage.json

implementation/contracts/DepositLog.sol

@@ -94,6 +94,8 @@ contract DepositLog {
     /* solium-disable-next-line no-empty-blocks */
     function approvedToLog(address _caller) public view returns (bool) {
         /* TODO: auth via system */
+        _caller; 
+        return true;
     }
 
     ///

implementation/contracts/deposit/DepositFunding.sol

@@ -46,7 +46,7 @@ library DepositFunding {
         IKeep _keep = IKeep(_d.KeepBridge);
         bytes memory _pubkey = _keep.getKeepPubkey(_d.keepID);
         /* solium-disable-next-line */
-        require(_pubkey.length == 64);
+        require(_pubkey.length == 64, "public key not set or not 64-bytes long");
         return _pubkey;
     }
 

implementation/contracts/deposit/DepositLiquidation.sol

@@ -8,6 +8,9 @@ import {TBTCConstants} from "./TBTCConstants.sol";
 import {IKeep} from "../interfaces/IKeep.sol";
 import {OutsourceDepositLogging} from "./OutsourceDepositLogging.sol";
 import {IBurnableERC20} from "../interfaces/IBurnableERC20.sol";
+import {IUniswapFactory} from "../uniswap/IUniswapFactory.sol";
+import {IUniswapExchange} from "../uniswap/IUniswapExchange.sol";
+import {ITBTCSystem} from "../interfaces/ITBTCSystem.sol";
 
 library DepositLiquidation {
 
@@ -21,8 +24,32 @@ library DepositLiquidation {
     /// @notice     Tries to liquidate the position on-chain using the signer bond
     /// @dev        Calls out to other contracts, watch for re-entrance
     /// @return     True if Liquidated, False otherwise
-    function attemptToLiquidateOnchain() public pure returns (bool) {
-        return false;
+    // TODO(liamz): make attemptToLiquidateOnchain internal, check for re-entry
+    function attemptToLiquidateOnchain(
+        DepositUtils.Deposit storage _d
+    ) internal returns (bool) {
+        IUniswapFactory uniswapFactory = IUniswapFactory(ITBTCSystem(_d.TBTCSystem).getUniswapFactory());
+        IUniswapExchange exchange = IUniswapExchange(uniswapFactory.getExchange(_d.TBTCToken));
+        if(exchange == address(0x0)) {
+            return false;
+        }
+
+        // with collateralization = 125%, we can assume an order of
+        // 1.0005 TBTC (equivalent to will be filled
+        uint MIN_TBTC = TBTCConstants.getLotSize().add(DepositUtils.beneficiaryReward());
+
+        uint ethPrice = exchange.getTokenToEthInputPrice(MIN_TBTC);
+        uint uniswapFee = ethPrice * 1003 / 1000; // 0.3% fee
+        ethPrice += uniswapFee;
+
+        if(address(this).balance < ethPrice) {
+            return false;
+        }
+
+        uint deadline = block.timestamp + 1;
+        exchange.ethToTokenSwapOutput.value(ethPrice)(MIN_TBTC, deadline);
+
+        return true;
     }
 
     /// @notice                 Notifies the keep contract of fraud
@@ -72,58 +99,58 @@ library DepositLiquidation {
         return (_bondValue.mul(100).div(_lotValue));
     }
 
-    /// @notice         Starts signer liquidation due to fraud
-    /// @dev            We first attempt to liquidate on chain, then by auction
-    /// @param  _d      deposit storage pointer
-    function startSignerFraudLiquidation(DepositUtils.Deposit storage _d) public {
+    function startLiquidation(DepositUtils.Deposit storage _d) internal {
         _d.logStartedLiquidation(true);
-
         // Reclaim used state for gas savings
         _d.redemptionTeardown();
-        uint256 _seized = _d.seizeSignerBonds();
 
-        if (_d.auctionTBTCAmount() == 0) {
-            // we came from the redemption flow
-            _d.setLiquidated();
-            _d.requesterAddress.transfer(_seized);
-            _d.logLiquidated();
-            return;
-        }
-
-        bool _liquidated = attemptToLiquidateOnchain();
+        _d.seizeSignerBonds();
+        bool _liquidated = attemptToLiquidateOnchain(_d);
 
         if (_liquidated) {
-            _d.distributeBeneficiaryReward();
             _d.setLiquidated();
             _d.logLiquidated();
-            address(0).transfer(address(this).balance);  // burn it down
+
+            _d.distributeBeneficiaryReward();
+
+            IBurnableERC20 _tbtc = IBurnableERC20(_d.TBTCToken);
+
+            if (_d.requesterAddress != address(0)) { // redemption
+                _tbtc.transferFrom(address(this), _d.requesterAddress, TBTCConstants.getLotSize());
+            } else {
+                // maintain supply peg
+                _tbtc.burnFrom(address(this), TBTCConstants.getLotSize());
+            }
+
+        } else if (!_liquidated) {
+            _d.liquidationInitiated = block.timestamp;  // Store the timestamp for auction
         }
-        if (!_liquidated) {
+    }
+
+
+    /// @notice         Starts signer liquidation due to fraud
+    /// @dev            We first attempt to liquidate on chain, then by auction
+    /// @param  _d      deposit storage pointer
+    function startSignerFraudLiquidation(DepositUtils.Deposit storage _d) public {
+        startLiquidation(_d);
+        if(_d.inLiquidated()) {
+            // send remaining eth to maintainer
+            msg.sender.transfer(address(this).balance);
+        } else {
             _d.setFraudLiquidationInProgress();
-            _d.liquidationInitiated = block.timestamp;  // Store the timestamp for auction
         }
     }
 
     /// @notice         Starts signer liquidation due to abort or undercollateralization
     /// @dev            We first attempt to liquidate on chain, then by auction
     /// @param  _d      deposit storage pointer
     function startSignerAbortLiquidation(DepositUtils.Deposit storage _d) public {
-        _d.logStartedLiquidation(false);
-        // Reclaim used state for gas savings
-        _d.redemptionTeardown();
-        _d.seizeSignerBonds();
-
-        bool _liquidated = attemptToLiquidateOnchain();
-
-        if (_liquidated) {
-            _d.distributeBeneficiaryReward();
+        startLiquidation(_d);
+        if(_d.inLiquidated()) {
+            // send remaining eth to signers
             _d.pushFundsToKeepGroup(address(this).balance);
-            _d.setLiquidated();
-            _d.logLiquidated();
-        }
-        if (!_liquidated) {
-            _d.liquidationInitiated = block.timestamp;  // Store the timestamp for auction
-            _d.setFraudLiquidationInProgress();
+        } else {
+            _d.setLiquidationInProgress();
         }
     }
 

implementation/contracts/deposit/DepositUtils.sol

@@ -298,7 +298,7 @@ library DepositUtils {
     function distributeBeneficiaryReward(Deposit storage _d) public {
         IBurnableERC20 _tbtc = IBurnableERC20(_d.TBTCToken);
         /* solium-disable-next-line */
-        require(_tbtc.transfer(depositBeneficiary(_d), _tbtc.balanceOf(address(this))));
+        require(_tbtc.transfer(depositBeneficiary(_d), beneficiaryReward()));
     }
 
     /// @notice             pushes ether held by the deposit to the signer group

implementation/contracts/interfaces/ITBTCSystem.sol

@@ -6,6 +6,14 @@ pragma solidity 0.4.25;
 
 interface ITBTCSystem {
 
+    // Sets up the TBTC system
+    // - uniswap factory initialisation
+    // - TBTC uniswap exchange creation
+    function setExteroriorAddresses(
+        address _uniswapFactory,
+        address _tbtc
+    ) external;
+
     // expected behavior:
     // return the price of 1 sat in wei
     // these are the native units of the deposit contract
@@ -15,4 +23,5 @@ interface ITBTCSystem {
     function fetchRelayCurrentDifficulty() external view returns (uint256);
     function fetchRelayPreviousDifficulty() external view returns (uint256);
 
+    function getUniswapFactory() external view returns (address);
 }

implementation/contracts/interfaces/KeepBridge.sol

@@ -52,8 +52,10 @@ contract KeepBridge is IKeep {
     // should return a 64 byte packed pubkey (x and y)
     // error if not ready yet
     function getKeepPubkey(uint256 _keepID) external view returns (bytes){
-        //TODO: Implement
-        return "";
+        // TODO: keepID type should be changed from uint256 to addrress
+        address _keepAddress = address(_keepID);
+
+        return ECDSAKeepContract(_keepAddress).getPublicKey();
     }
 
 
@@ -74,9 +76,25 @@ contract KeepBridge is IKeep {
     }
 }
 
+/// @notice Interface for communication with `KeepRegistry` contract
+/// @dev It allows to call a function without the need of low-level call
 interface KeepRegistryContract {
+
+    /// @notice Create a new ECDSA keep
+    /// @param _groupSize Number of members in the keep
+    /// @param _honestThreshold Minimum number of honest keep members
+    /// @return Created keep address
     function createECDSAKeep(
         uint256 _groupSize,
         uint256 _honestThreshold
     ) external payable returns (address keep);
 }
+
+/// @notice Interface for communication with `ECDSAKeep` contract
+/// @dev It allows to call a function without the need of low-level call
+interface ECDSAKeepContract {
+
+    /// @notice Returns the keep signer's public key.
+    /// @return Signer's public key.
+    function getPublicKey() external view returns (bytes memory);
+}

implementation/contracts/interfaces/TBTCSystemStub.sol → implementation/contracts/system/TBTCSystem.sol

@@ -1,15 +1,29 @@
 pragma solidity 0.4.25;
 
-import {ITBTCSystem} from "./ITBTCSystem.sol";
-import {IERC721} from "./IERC721.sol";
+import {ITBTCSystem} from "../interfaces/ITBTCSystem.sol";
+import {IERC721} from "../interfaces/IERC721.sol";
+import {DepositLog} from "../DepositLog.sol";
+import {IUniswapFactory} from "../uniswap/IUniswapFactory.sol";
+import {TBTC} from "../tokens/TBTC.sol";
 
-contract TBTCSystemStub is ITBTCSystem, IERC721 {
+contract TBTCSystem is ITBTCSystem, IERC721, DepositLog {
 
     uint256 currentDifficulty = 1;
     uint256 previousDifficulty = 1;
     uint256 oraclePrice = 10 ** 12;
     address depositOwner = address(0);
 
+    address public uniswapFactory;
+    address public tbtc;
+
+    function setExteroriorAddresses(
+        address _uniswapFactory,
+        address _tbtc
+    ) external {
+        uniswapFactory = _uniswapFactory;
+        tbtc = _tbtc;
+    }
+
     // Price Oracle
     function fetchOraclePrice() external view returns (uint256) {return oraclePrice;}
 
@@ -23,6 +37,10 @@ contract TBTCSystemStub is ITBTCSystem, IERC721 {
         return previousDifficulty;
     }
 
+    function getUniswapFactory() external view returns (address) {
+        return uniswapFactory;
+    }
+
     function submitCurrentDifficulty(uint256 _currentDifficulty) public {
         if (currentDifficulty != _currentDifficulty) {
             previousDifficulty = currentDifficulty;

implementation/contracts/tokens/TBTC.sol

@@ -0,0 +1,48 @@
+pragma solidity 0.4.25;
+
+import "openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol";
+import "openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";
+
+contract TBTC is ERC20Detailed, ERC20 {
+    /// @dev Constructor, calls ERC20Detailed constructor to set Token info
+    ///      ERC20Detailed(TokenName, TokenSymbol, NumberOfDecimals)
+    constructor() ERC20Detailed("Trustless bitcoin", "TBTC", 18) public {
+        // solium-disable-previous-line no-empty-blocks
+    }
+
+    /// @dev             Mints an amount of the token and assigns it to an account.
+    ///                  Uses the internal _mint function
+    /// @param _account  The account that will receive the created tokens.
+    /// @param _amount   The amount of tokens that will be created.
+    function mint(address _account, uint256 _amount) public returns (bool){
+        // NOTE: this is a public function with unchecked minting.
+        // TODO: enforce calling authority.
+        _mint(_account, _amount);
+        return true;
+    }
+
+    /// @dev             Burns an amount of the token of a given account
+    ///                  deducting from the sender's allowance for said account.
+    ///                  Uses the internal _burn function.
+    /// @param _account  The account whose tokens will be burnt.
+    /// @param _amount   The amount of tokens that will be burnt.
+    function burnFrom(address _account, uint256 _amount) public {
+        // NOTE: this uses internal function _burn instead of _burnFrom.
+        // This will bypass allowance check for now.
+        // TODO: enforce calling authority.
+        _burn(_account, _amount);
+    }
+
+    /// @dev           Transfer tokens from one address to another
+    ///                Uses the internal _transfer function.
+    /// @param _from   The address to send tokens from
+    /// @param _to     The address to transfer tokens to
+    /// @param _value  The amount of tokens to be transferred
+    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
+        // NOTE: this overrides transferFrom in openZeppelin ERC20.sol
+        // in order to bypass allowance check for now.
+        // TODO: enforce calling authority.
+        _transfer(_from, _to, _value);
+        return true;
+    }
+}