ERC1155SignatureMint

/**
 *  @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
    override
    returns (address signer)
{
    require(_req.quantity > 0, "Minting zero tokens.");
 
    uint256 tokenIdToMint;
    uint256 nextIdToMint = nextTokenIdToMint();
 
    if (_req.tokenId == type(uint256).max) {
        tokenIdToMint = nextIdToMint;
        nextTokenIdToMint_ += 1;
    } else {
        require(_req.tokenId < nextIdToMint, "invalid id");
        tokenIdToMint = _req.tokenId;
    }
 
    // Verify and process payload.
    signer = _processRequest(_req, _signature);
 
    address receiver = _req.to;
 
    // Collect price
    _collectPriceOnClaim(_req.primarySaleRecipient, _req.quantity, _req.currency, _req.pricePerToken);
 
    // Set royalties, if applicable.
    if (_req.royaltyRecipient != address(0)) {
        _setupRoyaltyInfoForToken(tokenIdToMint, _req.royaltyRecipient, _req.royaltyBps);
    }
 
    // Set URI
    if (_req.tokenId == type(uint256).max) {
        _setTokenURI(tokenIdToMint, _req.uri);
    }
 
    // Mint tokens.
    _mint(receiver, tokenIdToMint, _req.quantity, "");
 
    emit TokensMintedWithSignature(signer, receiver, tokenIdToMint, _req);
}

 /// @dev Collects and distributes the primary sale value of NFTs being claimed.
function _collectPriceOnClaim(
    address _primarySaleRecipient,
    uint256 _quantityToClaim,
    address _currency,
    uint256 _pricePerToken
) internal virtual {
    if (_pricePerToken == 0) {
        return;
    }
 
    uint256 totalPrice = _quantityToClaim * _pricePerToken;
 
    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);
}