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DemurrageNFT.sol

//SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;

import {RedirectAll, ISuperToken, IConstantFlowAgreementV1, ISuperfluid} from "./RedirectAll.sol";

import {ERC721} from "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.2.0-solc-0.7/contracts/token/ERC721/ERC721.sol";
import {ERC1155} from "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/release-v3.2.0-solc-0.7/contracts/token/ERC1155/ERC1155.sol";

/* Hello and welcome to your first Super App!
* In order to deploy this contract, you'll need a few things
* Get the deployed SF addresses here: https://docs.superfluid.finance/superfluid/resources/networks
* or using the js-sdk as shown here https://docs.superfluid.finance/superfluid/protocol-tutorials/setup-local-environment
*/


contract DemurrageNFT is ERC721, RedirectAll {

 address private _author;
 address private _ipfsPinningProviderWallet;
 address private _storageTrust;
 uint256 private _royaltyFee;
 uint256 private constant _storageFee = 5; //TODO: adjust to filecoin market price
 
  constructor (
     address author, // This allows someone other than an author to mint an NFT
    // Holds wrapped tokens to be streamed to provider wallet (fDAIx, for example)
    address ipfsPinningProviderWallet, //Holds the address to the wallet that will be deposited with an IPFS streaming provider, eventually using filecoin market for storage
    address storageTrust,
    string memory _name,
    string memory _symbol,
    uint256 royaltyFee,
    ISuperfluid host,
    IConstantFlowAgreementV1 cfa,
    ISuperToken acceptedToken
  )
    ERC721 ( _name, _symbol )
    RedirectAll (
      host,
      cfa,
      acceptedToken,
      ipfsPinningProviderWallet
     )
      {
          assert(host != ISuperfluid(address(0)));
          assert(ipfsPinningProviderWallet != address(0));
          assert(author != address(0));
          assert(storageTrust != address(0));
          _author = author;
          _royaltyFee = royaltyFee;
          _storageTrust = storageTrust;
          _ipfsPinningProviderWallet = ipfsPinningProviderWallet;
          _mint(author, 1);
  }

  function transferPinningProviderWallet( address to) public {
      //Only the author can chamge where the storage fee is being paid
      
      if(msg.sender == _author) {
          _changeReceiver(to);
      }
  }
  
 //approve(sender, tokenId) in ERC721
  
   function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual override {
       assert(from == address(0) || from == this.ownerOf(tokenId)); //from address is 0 when token minted
       if(_author == to) return;
       if(_acceptedToken.balanceOf(to) < _royaltyFee + _storageFee ){
           revert("Not enough money sent to cover royalty + storage costs.");
       }
       // assert(_acceptedToken.increaseAllowance(to, _royaltyFee + _storageFee));
       assert(_acceptedToken.transferFrom(to,_author, _royaltyFee));
       assert(_acceptedToken.transferFrom(to, _storageTrust, _storageFee));
    }

}