/// AdvancedTokenAdapters.sol

// Copyright (C) 2018 Rain <rainbreak@riseup.net>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

pragma solidity 0.6.7;

abstract contract SAFEEngineLike {
    function modifyCollateralBalance(bytes32,address,int) virtual public;
}

// CollateralJoin1
abstract contract CollateralLike {
    function decimals() virtual public view returns (uint);
    function transfer(address,uint) virtual public returns (bool);
    function transferFrom(address,address,uint) virtual public returns (bool);
}

contract CollateralJoin1 {
    // --- Auth ---
    mapping (address => uint) public authorizedAccounts;
    /**
     * @notice Add auth to an account
     * @param account Account to add auth to
     */
    function addAuthorization(address account) external isAuthorized {
        authorizedAccounts[account] = 1;
        emit AddAuthorization(account);
    }
    /**
     * @notice Remove auth from an account
     * @param account Account to remove auth from
     */
    function removeAuthorization(address account) external isAuthorized {
        authorizedAccounts[account] = 0;
        emit RemoveAuthorization(account);
    }
    /**
    * @notice Checks whether msg.sender can call an authed function
    **/
    modifier isAuthorized {
        require(authorizedAccounts[msg.sender] == 1, "CollateralJoin1/account-not-authorized");
        _;
    }

    SAFEEngineLike public safeEngine;
    bytes32        public collateralType;
    CollateralLike public collateral;
    uint           public decimals;
    uint           public contractEnabled;  // Access Flag

    // --- Events ---
    event AddAuthorization(address account);
    event RemoveAuthorization(address account);
    event DisableContract();
    event Join(address sender, address usr, uint wad);
    event Exit(address sender, address usr, uint wad);

    constructor(address safeEngine_, bytes32 collateralType_, address collateral_) public {
        authorizedAccounts[msg.sender] = 1;
        contractEnabled = 1;
        safeEngine = SAFEEngineLike(safeEngine_);
        collateralType = collateralType_;
        collateral = CollateralLike(collateral_);
        decimals = collateral.decimals();
        require(decimals == 18, "CollateralJoin1/not-18-decimals");
        emit AddAuthorization(msg.sender);
    }

    // --- Math ---
    function addition(uint x, int y) internal pure returns (uint z) {
        z = x + uint(y);
        require(y >= 0 || z <= x);
        require(y <= 0 || z >= x);
    }

    // --- Administration ---
    function disableContract() external isAuthorized {
        contractEnabled = 0;
        emit DisableContract();
    }

    // --- Collateral Gateway ---
    function join(address usr, uint wad) external {
        require(contractEnabled == 1, "CollateralJoin1/not-contractEnabled");
        require(int(wad) >= 0, "CollateralJoin1/overflow");
        safeEngine.modifyCollateralBalance(collateralType, usr, int(wad));
        require(collateral.transferFrom(msg.sender, address(this), wad), "CollateralJoin1/failed-transfer");
        emit Join(msg.sender, usr, wad);
    }
    function exit(address usr, uint wad) external {
        require(wad <= 2 ** 255, "CollateralJoin1/overflow");
        safeEngine.modifyCollateralBalance(collateralType, msg.sender, -int(wad));
        require(collateral.transfer(usr, wad), "CollateralJoin1/failed-transfer");
        emit Exit(msg.sender, usr, wad);
    }
}

{
  "compilationTarget": {
    "CollateralJoin1.sol": "CollateralJoin1"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}