# SPA Buyback [Git Source](https://github.com/Sperax/USDs-v2/blob/ff71faf9d7e40d2b2764e5e8f2acc631f31489aa/contracts/buyback/SPABuyback.sol) **Inherits:** Initializable, OwnableUpgradeable, ReentrancyGuardUpgradeable **Author:** Sperax Foundation This contract allows users to exchange SPA tokens for USDs tokens. *Users can provide SPA tokens and receive USDs tokens in return based on the current exchange rate.* *A percentage of the provided SPA tokens are distributed as rewards, and the rest are burned.* ## **State Variables** ### **veSpaRewarder** ```solidity address public veSpaRewarder; ``` ### **rewardPercentage** ```solidity uint256 public rewardPercentage; ``` ### **oracle** ```solidity address public oracle; ``` ## **Functions** ### **constructor** ```solidity constructor(); ``` ### **initialize** *Contract initializer* ```solidity function initialize(address _veSpaRewarder, uint256 _rewardPercentage) external initializer; ``` **Parameters** | Name | Type | Description | | ------------------ | ------- | -------------------------------- | | \_veSpaRewarder | address | Rewarder's address | | \_rewardPercentage | uint256 | Percentage of SPA to be rewarded | ### **withdraw** Emergency withdrawal function for unexpected situations *Can only be called by the owner* ```solidity function withdraw(address _token, address _receiver, uint256 _amount) external onlyOwner; ``` **Parameters** | Name | Type | Description | | ---------- | ------- | ------------------------------------ | | \_token | address | Address of the asset to be withdrawn | | \_receiver | address | Address of the receiver of tokens | | \_amount | uint256 | Amount of tokens to be withdrawn | ### **updateRewardPercentage** Changes the reward percentage *Example value for \_newRewardPercentage = 5000 for 50%* ```solidity function updateRewardPercentage(uint256 _newRewardPercentage) external onlyOwner; ``` **Parameters** | Name | Type | Description | | --------------------- | ------- | --------------------- | | \_newRewardPercentage | uint256 | New Reward Percentage | ### **updateVeSpaRewarder** Update veSpaRewarder address ```solidity function updateVeSpaRewarder(address _newVeSpaRewarder) external onlyOwner; ``` **Parameters** | Name | Type | Description | | ------------------ | ------- | --------------------------------------- | | \_newVeSpaRewarder | address | is the address of desired veSpaRewarder | ### **updateOracle** Update oracle address ```solidity function updateOracle(address _newOracle) external onlyOwner; ``` **Parameters** | Name | Type | Description | | ----------- | ------- | -------------------------------- | | \_newOracle | address | is the address of desired oracle | ### **buyUSDs** Function to buy USDs for SPA for frontend ```solidity function buyUSDs(uint256 _spaIn, uint256 _minUSDsOut) external; ``` **Parameters** | Name | Type | Description | | ------------ | ------- | -------------------------- | | \_spaIn | uint256 | Amount of SPA tokens | | \_minUSDsOut | uint256 | Minimum amount out in USDs | ### **getSPAReqdForUSDs** Calculates and returns SPA amount required for \_usdsAmount ```solidity function getSPAReqdForUSDs(uint256 _usdsAmount) external view returns (uint256); ``` **Parameters** | Name | Type | Description | | ------------ | ------- | -------------------------- | | \_usdsAmount | uint256 | USDs amount the user wants | **Returns** | Name | Type | Description | | ---- | ------- | ---------------------- | | | uint256 | Amount of SPA required | ### **buyUSDs** Buy USDs for SPA if you want a different receiver ```solidity function buyUSDs(address _receiver, uint256 _spaIn, uint256 _minUSDsOut) public nonReentrant; ``` **Parameters** | Name | Type | Description | | ------------ | ------- | -------------------------- | | \_receiver | address | Receiver of USDs | | \_spaIn | uint256 | Amount of SPA tokens | | \_minUSDsOut | uint256 | Minimum amount out in USDs | ### **distributeAndBurnSPA** Sends available SPA in this contract to rewarder based on rewardPercentage and burns the rest ```solidity function distributeAndBurnSPA() public; ``` ### **getUsdsOutForSpa** Returns the amount of USDS for SPA amount in ```solidity function getUsdsOutForSpa(uint256 _spaIn) public view returns (uint256); ``` **Parameters** | Name | Type | Description | | ------- | ------- | -------------------- | | \_spaIn | uint256 | Amount of SPA tokens | **Returns** | Name | Type | Description | | ---- | ------- | ---------------------------- | | | uint256 | Amount of USDs user will get | ### **\_getUsdsOutForSpa** Returns the amount of USDS for SPA amount in ```solidity function _getUsdsOutForSpa(uint256 _spaIn) private view returns (uint256, uint256); ``` **Parameters** | Name | Type | Description | | ------- | ------- | -------------------- | | \_spaIn | uint256 | Amount of SPA tokens | **Returns** | Name | Type | Description | | ---- | ------- | ---------------------------- | | | uint256 | Amount of USDs user will get | | | uint256 | | ### **\_getOracleData** *Retrieves price data from the oracle contract for SPA and USDS tokens.* ```solidity function _getOracleData() private view returns (uint256, uint256, uint256, uint256); ``` **Returns** | Name | Type | Description | | ---- | ------- | ------------------------------------------------------------------------------------ | | | uint256 | The price of USDS in SPA, the price of SPA in USDS, and their respective precisions. | | | uint256 | | | | uint256 | | | | uint256 | | ### **\_isValidRewardPercentage** *Checks if the provided reward percentage is valid.* *The reward percentage must be a non-zero value and should not exceed the maximum percentage value.* ```solidity function _isValidRewardPercentage(uint256 _rewardPercentage) private pure; ``` **Parameters** | Name | Type | Description | | ------------------ | ------- | ---------------------------------- | | \_rewardPercentage | uint256 | The reward percentage to validate. | ## **Events** ### **BoughtBack** ```solidity event BoughtBack( address indexed receiverOfUSDs, address indexed senderOfSPA, uint256 spaPrice, uint256 spaAmount, uint256 usdsAmount ); ``` ### **Withdrawn** ```solidity event Withdrawn(address indexed token, address indexed receiver, uint256 amount); ``` ### **SPARewarded** ```solidity event SPARewarded(uint256 spaAmount); ``` ### **SPABurned** ```solidity event SPABurned(uint256 spaAmount); ``` ### **RewardPercentageUpdated** ```solidity event RewardPercentageUpdated(uint256 newRewardPercentage); ``` ### **VeSpaRewarderUpdated** ```solidity event VeSpaRewarderUpdated(address newVeSpaRewarder); ``` ### **OracleUpdated** ```solidity event OracleUpdated(address newOracle); ``` ## **Errors** ### **CannotWithdrawSPA** ```solidity error CannotWithdrawSPA(); ``` ### **InsufficientUSDsBalance** ```solidity error InsufficientUSDsBalance(uint256 toSend, uint256 bal); ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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