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/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 +8,8 @@ import {TBTCConstants} from "./TBTCConstants.sol";
 import {IKeep} from "../interfaces/IKeep.sol";
 import {OutsourceDepositLogging} from "./OutsourceDepositLogging.sol";
 import {IBurnableERC20} from "../interfaces/IBurnableERC20.sol";
+import {IUniswapExchange} from "../uniswap/IUniswapExchange.sol";
+import {ITBTCSystem} from "../interfaces/ITBTCSystem.sol";
 
 library DepositLiquidation {
 
@@ -21,8 +23,28 @@ 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
+    ) public returns (bool) {
+        require(address(this).balance > 0, "no ether to liquidate");
+
+        IUniswapExchange exchange = IUniswapExchange(ITBTCSystem(_d.TBTCSystem).getTBTCUniswapExchange());
+
+        // 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 ethSold = address(this).balance;
+        uint tbtcBought = exchange.getEthToTokenInputPrice(ethSold);
+        if(tbtcBought < MIN_TBTC) {
+            return false;
+        }
+
+        uint deadline = block.timestamp + 1;
+        exchange.ethToTokenSwapOutput.value(ethSold)(tbtcBought, deadline);
+
+        return true;
     }
 
     /// @notice                 Notifies the keep contract of fraud
@@ -77,28 +99,30 @@ library DepositLiquidation {
     /// @param  _d      deposit storage pointer
     function startSignerFraudLiquidation(DepositUtils.Deposit storage _d) public {
         _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();
+        bool _liquidated = attemptToLiquidateOnchain(_d);
 
         if (_liquidated) {
-            _d.distributeBeneficiaryReward();
             _d.setLiquidated();
             _d.logLiquidated();
-            address(0).transfer(address(this).balance);  // burn it down
-        }
-        if (!_liquidated) {
+
+            _d.distributeBeneficiaryReward();
+
+            if (_d.auctionTBTCAmount() == 0) { // redemption
+                IBurnableERC20 _tbtc = IBurnableERC20(_d.TBTCToken);
+                _tbtc.transferFrom(address(this), _d.requesterAddress, TBTCConstants.getLotSize());
+                address(_d.requesterAddress).transfer(address(this).balance);
+            } else {
+                // maintain supply peg
+                _tbtc.burnFrom(address(this), TBTCConstants.getLotSize());
+                address(0).transfer(address(this).balance); // burn down eth
+            }
+
+
+        } else if (!_liquidated) {
             _d.setFraudLiquidationInProgress();
             _d.liquidationInitiated = block.timestamp;  // Store the timestamp for auction
         }
@@ -111,9 +135,17 @@ library DepositLiquidation {
         _d.logStartedLiquidation(false);
         // Reclaim used state for gas savings
         _d.redemptionTeardown();
-        _d.seizeSignerBonds();
+        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();
+        bool _liquidated = attemptToLiquidateOnchain(_d);
 
         if (_liquidated) {
             _d.distributeBeneficiaryReward();
@@ -122,8 +154,8 @@ library DepositLiquidation {
             _d.logLiquidated();
         }
         if (!_liquidated) {
-            _d.liquidationInitiated = block.timestamp;  // Store the timestamp for auction
             _d.setFraudLiquidationInProgress();
+            _d.liquidationInitiated = block.timestamp;  // Store the timestamp for auction
         }
     }
 

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 getTBTCUniswapExchange() 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

@@ -1,14 +1,31 @@
 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);
+    IUniswapFactory public uniswapFactory;
+    TBTC public tbtc;
+
+    function setExteroriorAddresses(
+        address _uniswapFactory,
+        address _tbtc
+    ) external {
+        uniswapFactory = IUniswapFactory(_uniswapFactory);
+        tbtc = TBTC(_tbtc);
+    }
+
+    function getTBTCUniswapExchange() external view returns (address) {
+        return uniswapFactory.getExchange(address(tbtc));
+    }
 
     // Price Oracle
     function fetchOraclePrice() external view returns (uint256) {return oraclePrice;}

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;
+    }
+}

implementation/contracts/uniswap/IUniswapExchange.sol

@@ -0,0 +1,57 @@
+pragma solidity 0.4.25;
+
+/* solium-disable */
+
+contract IUniswapExchange {
+    event TokenPurchase(address indexed buyer, uint256 indexed eth_sold, uint256 indexed tokens_bought);
+    event EthPurchase(address indexed buyer, uint256 indexed tokens_sold, uint256 indexed eth_bought);
+    event AddLiquidity(address indexed provider, uint256 indexed eth_amount, uint256 indexed token_amount);
+    event RemoveLiquidity(address indexed provider, uint256 indexed eth_amount, uint256 indexed token_amount);
+    event Transfer(address indexed _from, uint256 indexed _value);
+    event Approval(address indexed _owner, uint256 indexed _value);
+
+    // Address of ERC20 token sold on this exchange
+    function tokenAddress() external view returns (address token);
+    // Address of Uniswap Factory
+    function factoryAddress() external view returns (address factory);
+    // Provide Liquidity
+    function addLiquidity(uint256 min_liquidity, uint256 max_tokens, uint256 deadline) external payable returns (uint256);
+    function removeLiquidity(uint256 amount, uint256 min_eth, uint256 min_tokens, uint256 deadline) external returns (uint256, uint256);
+    // Get Prices
+    function getEthToTokenInputPrice(uint256 eth_sold) external view returns (uint256 tokens_bought);
+    function getEthToTokenOutputPrice(uint256 tokens_bought) external view returns (uint256 eth_sold);
+    function getTokenToEthInputPrice(uint256 tokens_sold) external view returns (uint256 eth_bought);
+    function getTokenToEthOutputPrice(uint256 eth_bought) external view returns (uint256 tokens_sold);
+    // Trade ETH to ERC20
+    function ethToTokenSwapInput(uint256 min_tokens, uint256 deadline) external payable returns (uint256  tokens_bought);
+    function ethToTokenTransferInput(uint256 min_tokens, uint256 deadline, address recipient) external payable returns (uint256  tokens_bought);
+    function ethToTokenSwapOutput(uint256 tokens_bought, uint256 deadline) external payable returns (uint256  eth_sold);
+    function ethToTokenTransferOutput(uint256 tokens_bought, uint256 deadline, address recipient) external payable returns (uint256  eth_sold);
+    // Trade ERC20 to ETH
+    function tokenToEthSwapInput(uint256 tokens_sold, uint256 min_eth, uint256 deadline) external returns (uint256  eth_bought);
+    function tokenToEthTransferInput(uint256 tokens_sold, uint256 min_eth, uint256 deadline, address recipient) external returns (uint256  eth_bought);
+    function tokenToEthSwapOutput(uint256 eth_bought, uint256 max_tokens, uint256 deadline) external returns (uint256  tokens_sold);
+    function tokenToEthTransferOutput(uint256 eth_bought, uint256 max_tokens, uint256 deadline, address recipient) external returns (uint256  tokens_sold);
+    // Trade ERC20 to ERC20
+    function tokenToTokenSwapInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address token_addr) external returns (uint256  tokens_bought);
+    function tokenToTokenTransferInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address recipient, address token_addr) external returns (uint256  tokens_bought);
+    function tokenToTokenSwapOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address token_addr) external returns (uint256  tokens_sold);
+    function tokenToTokenTransferOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address recipient, address token_addr) external returns (uint256  tokens_sold);
+    // Trade ERC20 to Custom Pool
+    function tokenToExchangeSwapInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address exchange_addr) external returns (uint256  tokens_bought);
+    function tokenToExchangeTransferInput(uint256 tokens_sold, uint256 min_tokens_bought, uint256 min_eth_bought, uint256 deadline, address recipient, address exchange_addr) external returns (uint256  tokens_bought);
+    function tokenToExchangeSwapOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address exchange_addr) external returns (uint256  tokens_sold);
+    function tokenToExchangeTransferOutput(uint256 tokens_bought, uint256 max_tokens_sold, uint256 max_eth_sold, uint256 deadline, address recipient, address exchange_addr) external returns (uint256  tokens_sold);
+    // ERC20 comaptibility for liquidity tokens
+    bytes32 public name;
+    bytes32 public symbol;
+    uint256 public decimals;
+    function transfer(address _to, uint256 _value) external returns (bool);
+    function transferFrom(address _from, address _to, uint256 value) external returns (bool);
+    function approve(address _spender, uint256 _value) external returns (bool);
+    function allowance(address _owner, address _spender) external view returns (uint256);
+    function balanceOf(address _owner) external view returns (uint256);
+    function totalSupply() external view returns (uint256);
+    // Never use
+    function setup(address token_addr) external;
+}

implementation/contracts/uniswap/IUniswapFactory.sol

@@ -0,0 +1,17 @@
+pragma solidity 0.4.25;
+
+/* solium-disable */
+
+contract IUniswapFactory {
+    // Public Variables
+    address public exchangeTemplate;
+    uint256 public tokenCount;
+    // Create Exchange
+    function createExchange(address token) external returns (address exchange);
+    // Get Exchange and Token Info
+    function getExchange(address token) external view returns (address exchange);
+    function getToken(address exchange) external view returns (address token);
+    function getTokenWithId(uint256 tokenId) external view returns (address token);
+    // Never use
+    function initializeFactory(address template) external;
+}

implementation/contracts/uniswap/UniswapDeployment.sol

@@ -0,0 +1,16 @@
+pragma solidity 0.4.25;
+
+/// @notice A contract for tracking the location of Uniswap testnet deployments
+/// @dev useful for usage in tests/migrations, but SHOULD NOT be used by other contracts
+contract UniswapDeployment {
+    address public factory;
+    address public exchange;
+
+    constructor(
+        address _factory,
+        address _exchange
+    ) public {
+        factory = _factory;
+        exchange = _exchange;
+    }
+}