aave-protocol-v2/contracts/fees/FeeProvider.sol

// SPDX-License-Identifier: agpl-3.0
pragma solidity ^0.6.8;

import '../libraries/openzeppelin-upgradeability/VersionedInitializable.sol';
import '../interfaces/IFeeProvider.sol';
import '../libraries/WadRayMath.sol';

/**
 * @title FeeProvider contract
 * @notice Implements calculation for the fees applied by the protocol
 * @author Aave
 **/
contract FeeProvider is IFeeProvider, VersionedInitializable {
  using WadRayMath for uint256;

  // percentage of the fee to be calculated on the loan amount
  uint256 public originationFeePercentage;

  uint256 public constant FEE_PROVIDER_REVISION = 0x1;

  function getRevision() internal override pure returns (uint256) {
    return FEE_PROVIDER_REVISION;
  }

  /**
   * @dev initializes the FeeProvider after it's added to the proxy
   * @param _addressesProvider the address of the LendingPoolAddressesProvider
   */
  function initialize(address _addressesProvider) public initializer {
    /// @notice origination fee is set as default as 25 basis points of the loan amount (0.0025%)
    originationFeePercentage = 0.0025 * 1e18;
  }

  /**
   * @dev calculates the origination fee for every loan executed on the platform.
   * @param _user can be used in the future to apply discount to the origination fee based on the
   * _user account (eg. stake AAVE tokens in the lending pool, or deposit > 1M USD etc.)
   * @param _amount the amount of the loan
   **/
  function calculateLoanOriginationFee(address _user, uint256 _amount)
    external
    override
    view
    returns (uint256)
  {
    return _amount.wadMul(originationFeePercentage);
  }

  /**
   * @dev returns the origination fee percentage
   **/
  function getLoanOriginationFeePercentage() external override view returns (uint256) {
    return originationFeePercentage;
  }
}