The following code snippets show an example of how you can integrate the Spirals vault contracts into your smart contracts. Please create a new file GreenTokenVaultInterface.sol in your project to import the interface in your contract files and get started on these code examples 👇

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Depositing into vault

Once again, we start with a simple example where the contract being integrated deposit _amount of token into the vault.

contract MyContract {
    ImpactVaultInterface gTokenVault;

    constructor(address _gTokenVaultAddress) {
        gTokenVault = ImpactVaultInterface(_gTokenVaultAddress);
    }

    /**
     * @dev Deposits tokens into gToken vault on behalf of receiver.
     *  Assumes that the contract has enough tokens already.
     */
    function gTokenDeposit(uint256 _amount, address _receiver) {
        require(gTokenVault.asset().balanceOf(address(this)) >= _amount, "AMOUNT_EXCEEDS_TOKEN_BALANCE");
        gTokenVault.asset().approve(address(gTokenVault), _amount);
        gTokenVault.deposit(_amount, address(this));
    }
}

For native tokens like ETH and Celo, use depositETH(address _receiver) payable

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Reading gToken balances

Similarly, we can also pretty easily read the gToken balances using the method that’s available on the interface.

contract MyContract {
    ImpactVaultInterface gTokenVault;

    constructor(address _gTokenVaultAddress) {
        gTokenVault = ImpactVaultInterface(_gTokenVaultAddress);
    }

    /**
     * @dev Returns the gToken balance of the user.
     */
    function getGTokenBalance(address _user) {
        return gTokenVault.balanceOf(_user);
    }
}

Now let’s put the 2 snippets together so that on deposit we return the amount of gTokens the receiver gets through a deposit function call.

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Putting it together

contract MyContract {
    ImpactVaultInterface gTokenVault;

    constructor(address _gTokenVaultAddress) {
        gTokenVault = ImpactVaultInterface(_gTokenVaultAddress);
    }

    /**
     * @dev Deposits tokens into gToken vault on behalf of receiver.
     *  Assumes that the contract has enough tokens already to support this.
     *  Returns the number of gTokens recieved by the user.
     */
    function gTokenDeposit(uint256 _amount, address _receiver) returns (uint256) {
        require(gTokenVault.asset().balanceOf(address(this)) >= _amount, "AMOUNT_EXCEEDS_TOKEN_BALANCE");
        gTokenVault.asset().approve(address(gTokenVault), _amount);

        uint256 gTokenPreDepositBalance = getGTokenBalance(_receiver);
        gTokenVault.deposit(_amount, address(this));
        return getGTokenBalance(_receiver) - gTokenPreDepositBalance;
    }

    /**
     * @dev Returns the gToken balance of the user.
     */
    function getGTokenBalance(address _user) {
        return gTokenVault.balanceOf(_user);
    }
}

Sweet! Now we have a full end-to-end example of a smart contract that deposits an ERC-20 token into the gToken vault on behalf of a receiver and returns the amount of gTokens received 😤

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