ERC20SignatureMintVote

/**
 *  @notice           Mints tokens according to the provided mint request.
 *
 *  @param _req       The payload / mint request.
 *  @param _signature The signature produced by an account signing the mint request.
 */
function mintWithSignature(MintRequest calldata _req, bytes calldata _signature)
    external
    payable
    virtual
    returns (address signer)
{
    require(_req.quantity > 0, "Minting zero tokens.");
 
    // Verify and process payload.
    signer = _processRequest(_req, _signature);
 
    /**
        *  Get receiver of tokens.
        *
        *  Note: If `_req.to == address(0)`, a `mintWithSignature` transaction sitting in the
        *        mempool can be frontrun by copying the input data, since the minted tokens
        *        will be sent to the `_msgSender()` in this case.
        */
    address receiver = _req.to == address(0) ? msg.sender : _req.to;
 
    // Collect price
    _collectPriceOnClaim(_req.primarySaleRecipient, _req.quantity, _req.currency, _req.pricePerToken);
 
    // Mint tokens.
    _mint(receiver, _req.quantity);
 
    emit TokensMintedWithSignature(signer, receiver, _req);
}

/// @dev Collects and distributes the primary sale value of tokens being claimed.
function _collectPriceOnClaim(
    address _primarySaleRecipient,
    uint256 _quantityToClaim,
    address _currency,
    uint256 _pricePerToken
) internal virtual {
    if (_pricePerToken == 0) {
        return;
    }
 
    uint256 totalPrice = (_quantityToClaim * _pricePerToken) / 1 ether;
    require(totalPrice > 0, "quantity too low");
 
    if (_currency == CurrencyTransferLib.NATIVE_TOKEN) {
        require(msg.value == totalPrice, "Must send total price.");
    }
 
    address saleRecipient = _primarySaleRecipient == address(0) ? primarySaleRecipient() : _primarySaleRecipient;
    CurrencyTransferLib.transferCurrency(_currency, msg.sender, saleRecipient, totalPrice);
}