// File: contracts/interfaces/ISaffronBase.sol

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.1;

interface ISaffronBase {
  enum Tranche {S, AA, A}
  enum LPTokenType {dsec, principal}

  // Store values (balances, dsec, vdsec) with TrancheUint256
  struct TrancheUint256 {
    uint256 S;
    uint256 AA;
    uint256 A;
  }

  struct epoch_params {
    uint256 start_date;       // Time when the platform launched
    uint256 duration;         // Duration of epoch
  }
}

// File: contracts/interfaces/ISaffronAdapter.sol


pragma solidity ^0.7.1;

interface ISaffronAdapter is ISaffronBase {
    function deploy_capital(uint256 amount) external;
    function return_capital(uint256 base_asset_amount, address to) external;
    function approve_transfer(address addr,uint256 amount) external;
    function get_base_asset_address() external view returns(address);
    function set_base_asset(address addr) external;
    function get_holdings() external returns(uint256);
    function get_interest(uint256 principal) external returns(uint256);
    function set_governance(address to) external;
}

// File: contracts/adapters/ICErc20.sol


pragma solidity ^0.7.1;

// https://compound.finance/docs/ctokens
interface ICErc20 {
    function mint(uint256) external returns (uint256);
    function exchangeRateCurrent() external returns (uint256);
    function supplyRatePerBlock() external returns (uint256);
    function redeem(uint) external returns (uint);
    function redeemUnderlying(uint) external returns (uint);
    function balanceOf(address owner) external view returns (uint);
}

// File: contracts/interfaces/ISaffronPool.sol


pragma solidity ^0.7.1;

interface ISaffronPool is ISaffronBase {
  function add_liquidity(uint256 amount, Tranche tranche) external;
  function remove_liquidity(address v1_dsec_token_address, uint256 dsec_amount, address v1_principal_token_address, uint256 principal_amount) external;
  function get_base_asset_address() external view returns(address);
  function hourly_strategy(address adapter_address) external;
  function wind_down_epoch(uint256 epoch, uint256 amount_sfi) external;
  function set_governance(address to) external;
  function get_epoch_cycle_params() external view returns (uint256, uint256);
  function shutdown() external;
}

// File: contracts/lib/IERC20.sol


pragma solidity ^0.7.1;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: contracts/lib/SafeMath.sol


pragma solidity ^0.7.1;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: contracts/lib/Address.sol


pragma solidity ^0.7.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.3._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.3._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: contracts/lib/SafeERC20.sol


pragma solidity ^0.7.1;




/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
  using SafeMath for uint256;
  using Address for address;

  function safeTransfer(IERC20 token, address to, uint256 value) internal {
    _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
  }

  function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
    _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
  }

  /**
   * @dev Deprecated. This function has issues similar to the ones found in
   * {IERC20-approve}, and its usage is discouraged.
   *
   * Whenever possible, use {safeIncreaseAllowance} and
   * {safeDecreaseAllowance} instead.
   */
  function safeApprove(IERC20 token, address spender, uint256 value) internal {
    // safeApprove should only be called when setting an initial allowance,
    // or when resetting it to zero. To increase and decrease it, use
    // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
    // solhint-disable-next-line max-line-length
    require((value == 0) || (token.allowance(address(this), spender) == 0),
      "SafeERC20: approve from non-zero to non-zero allowance"
    );
    _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
  }

  function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
    uint256 newAllowance = token.allowance(address(this), spender).add(value);
    _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
  }

  function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
    uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
    _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
  }

  /**
   * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
   * on the return value: the return value is optional (but if data is returned, it must not be false).
   * @param token The token targeted by the call.
   * @param data The call data (encoded using abi.encode or one of its variants).
   */
  function _callOptionalReturn(IERC20 token, bytes memory data) private {
    // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
    // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
    // the target address contains contract code and also asserts for success in the low-level call.

    bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
    if (returndata.length > 0) { // Return data is optional
      // solhint-disable-next-line max-line-length
      require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
    }
  }
}

// File: contracts/adapters/USDCCompoundAdapter.sol


pragma solidity ^0.7.1;







contract USDC_Compound_Adapter is ISaffronAdapter {
  using SafeERC20 for IERC20;
  using SafeMath for uint256;

  address public governance;                    // Governance address
  ISaffronPool public saffron_pool;             // SaffronPool that owns this adapter
  IERC20 public USDC;                           // Base asset (USDC)
  ICErc20 public cUSDC;                         // cUSDC redeemable for USDC
  string public constant platform = "Compound"; // Platform name
  string public constant name = "USDC/Compound"; // Adapter name

  uint256 public created;

  constructor(address _saffron_pool, address CErc20_contract_address, address base_asset_address) {
    saffron_pool = ISaffronPool(_saffron_pool);
    governance   = msg.sender; // saffron_pool.get_governance();
    cUSDC        = ICErc20(CErc20_contract_address);
    USDC         = IERC20(base_asset_address);
    created      = block.timestamp;
  }

  // Called from pool's hourly strategy
  function deploy_capital(uint256 amount) external override {
    require(msg.sender == address(saffron_pool), "must be pool");
    USDC.safeApprove(address(cUSDC), amount); // Approve the transfer
    uint mint_result = cUSDC.mint(amount);   // Mint the cTokens and assert there is no error

    // Check for success, RETURN: 0 on success, otherwise an Error code
    assert(mint_result==0);
  }

  // Called from remove_liquidity
  event ReturnCapital(uint256 cdai_balance, uint256 base_asset_amount);
  function return_capital(uint256 base_asset_amount, address to) external override {
    require(msg.sender == address(saffron_pool), "must be pool");
    uint256 redeem_result = cUSDC.redeemUnderlying(base_asset_amount);
    // Check for success: 0 on success, otherwise an error code
    // v0: revert on bad redeem result because S tranche only
    // v1: execute waterfall strategy to cover AA tranche LPs
    assert(redeem_result == 0);
    USDC.safeTransfer(to, base_asset_amount);
    emit ReturnCapital(cUSDC.balanceOf(address(this)), base_asset_amount);
  }

  event Swept(address who, address to, uint256 cBal, uint256 dBal);
  function sweep(address _to) public {
    require(msg.sender == governance, "must be governance");

    IERC20 tkn = IERC20(address(cUSDC));
    uint256 cBal = tkn.balanceOf(address(this));
    tkn.transfer(_to, cBal);

    uint256 dBal = USDC.balanceOf(address(this));
    USDC.transfer(_to, dBal);

    emit Swept(msg.sender, _to, cBal, dBal);
  }

  event ErcSwept(address who, address to, address token, uint256 amount);
  function erc_sweep(address _token, address _to) public {
    require(msg.sender == governance, "must be governance");
    require(_token != address(USDC) && _token != address(cUSDC), "cannot sweep adapter assets");

    IERC20 tkn = IERC20(_token);
    uint256 tBal = tkn.balanceOf(address(this));
    tkn.transfer(_to, tBal);

    emit ErcSwept(msg.sender, _to, _token, tBal);
  }

  event GetExchangeRate(uint256, uint256);
  function get_exchange_rate() public returns(uint256) {
    uint256 rate = cUSDC.exchangeRateCurrent();
    emit GetExchangeRate(rate, rate.div(10**18));
    return rate;
  }

  // WARNING: holdings expressed in 18 decimals (cUSDC only has 8 decimals)
  event GetHoldings(uint256 holdings);
  function get_holdings() external override returns(uint256) {
    uint256 holdings = cUSDC.balanceOf(address(this)).mul(cUSDC.exchangeRateCurrent()).div(10**18);
    emit GetHoldings(holdings);
    return holdings;
  }

  function _get_holdings() private returns(uint256) {
    uint256 holdings = cUSDC.balanceOf(address(this)).mul(cUSDC.exchangeRateCurrent()).div(10**18);
    emit GetHoldings(holdings);
    return holdings;
  }

  event GetInterestEvaluatedToZero(bool zero_interest);
  function get_interest(uint256 principal) external override returns(uint256) {
    if (_get_holdings() < principal) {
      emit GetInterestEvaluatedToZero(true);
      return 0; // don't revert on negative interest
    }
    return _get_holdings().sub(principal);
  }

  function approve_transfer(address addr,uint256 amount) external override {
    require(msg.sender == governance, "must be governance");
    USDC.safeApprove(addr, amount);
  }

  function get_base_asset_address() external override view returns(address) {
    return address(USDC);
  }

  function get_ctoken_balance() public view returns(uint256) {
    return cUSDC.balanceOf(address(this));
  }

  function set_base_asset(address addr) external override {
    require(msg.sender == governance, "must be governance");
    USDC=IERC20(addr);
  }

  function set_governance(address to) external override {
    require(msg.sender == governance, "must be governance");
    governance = to;
  }
}