contract SevaLoveNFT is ContextMixin, ERC721Enumerable, NativeMetaTransaction, Ownable {
    using SafeMath for uint256;

    address proxyRegistryAddress;
    uint256 private _currentTokenId = 0;
    
    /**
     * @dev Mapping from NFT ID to metadata uri.
     */
    mapping (uint256 => string) internal idToUri;

    constructor(
        string memory _name,
        string memory _symbol,
        address _proxyRegistryAddress
    ) ERC721(_name, _symbol) {
        proxyRegistryAddress = _proxyRegistryAddress;
        _initializeEIP712(_name);
    }

    /**
     * @dev Returns contract-level metadata
     * based on https://docs.opensea.io/docs/contract-level-metadata
     */
    function contractURI() public pure returns (string memory) {
      return "https://infinite-seva.s3.amazonaws.com/contract-assets/seva-contract-metadata.json";
    }

    /**
     * @dev Mints a token to an address with a tokenURI.
     * @param _to address of the future owner of the token
     */
    function mintTo(address _to, string memory _uri) public onlyOwner {
        uint256 newTokenId = _getNextTokenId();
        _mint(_to, newTokenId);
        _incrementTokenId();
        _setTokenUri(newTokenId, _uri);
    }

    /**
     * @dev calculates the next token ID based on value of _currentTokenId
     * @return uint256 for the next token ID
     */
    function _getNextTokenId() private view returns (uint256) {
        return _currentTokenId.add(1);
    }

    /**
     * @dev increments the value of _currentTokenId
     */
    function _incrementTokenId() private {
        _currentTokenId++;
    }

    /**
     * Override isApprovedForAll to whitelist user's OpenSea proxy accounts to enable gas-less listings.
     */
    function isApprovedForAll(address owner, address operator)
        override
        public
        view
        returns (bool)
    {
        // Whitelist OpenSea proxy contract for easy trading.
        ProxyRegistry proxyRegistry = ProxyRegistry(proxyRegistryAddress);
        if (address(proxyRegistry.proxies(owner)) == operator) {
            return true;
        }

        return super.isApprovedForAll(owner, operator);
    }

    /**
     * This is used instead of msg.sender as transactions won't be sent by the original token owner, but by OpenSea.
     */
    function _msgSender()
        internal
        override
        view
        returns (address sender)
    {
        return ContextMixin.msgSender();
    }
    
      /**
   * @dev A distinct URI (RFC 3986) for a given NFT.
   * @param _tokenId Id for which we want uri.
   * @return URI of _tokenId.
   */
  function tokenURI(
    uint256 _tokenId
  )
    public
    override
    view
    returns (string memory)
  {
    return _tokenURI(_tokenId);
  }

  /**
   * @notice This is an internal function that can be overriden if you want to implement a different
   * way to generate token URI.
   * @param _tokenId Id for which we want uri.
   * @return URI of _tokenId.
   */
  function _tokenURI(
    uint256 _tokenId
  )
    internal
    virtual
    view
    returns (string memory)
  {
    return idToUri[_tokenId];
  }
    
      /**
   * @notice This is an internal function which should be called from user-implemented external
   * function. Its purpose is to show and properly initialize data structures when using this
   * implementation.
   * @dev Set a distinct URI (RFC 3986) for a given NFT ID.
   * @param _tokenId Id for which we want URI.
   * @param _uri String representing RFC 3986 URI.
   */
      function _setTokenUri(
        uint256 _tokenId,
        string memory _uri
      )
        internal
      {
        idToUri[_tokenId] = _uri;
      }
  
}
/**
 * @title SevaLoveNFT
 * SevaLoveNFT - NFT contract for https://seva.love
 * ERC721 contract that whitelists a trading address, and has minting functionality.
 * ProxyAddress depends on the network you're deploying to. 
 * It's 0xf57b2c51ded3a29e6891aba85459d600256cf317 on Rinkeby and 0xa5409ec958c83c3f309868babaca7c86dcb077c1 on mainnet. 
 * See https://github.com/ProjectOpenSea/opensea-creatures/blob/master/migrations/2_deploy_contracts.js#L7-L12 for an example of conditionally setting the proxy registry address.
 */
function tokenURI(
    uint256 _tokenId
  )
    public
    override
    view
    returns (string memory)
  {
    return _tokenURI(_tokenId);
  }
/**
 * @dev A distinct URI (RFC 3986) for a given NFT.
 * @param _tokenId Id for which we want uri.
 * @return URI of _tokenId.
 */