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contracts...NFTNotSimple.sol

pragma solidity >=0.4.24 <0.5.6;

//0.5.6
contract NFTSimple { //Simple NFG

    string public name = "KlayLion";
    string public symbol = "KL"; // 단위

    //mint 발행 (tokenId, uri, owner) 
    //transform 전송 (from, to , uri)

    mapping (uint256 => address) public tokenOwner;
    mapping (uint256 => string) public tokenURIs; //map

    //배열 소유한 토큰 리스트 
    mapping(address => uint256[]) private _ownedTokens;

    //onKIP17Received bytes value
    bytes4 private constant _KIP17_RECEIVED = 0x6745782b;

    function  mintWithTokenUri(address to, uint256 tokenId, string memory tokenURI) public returns (bool) {
        tokenOwner[tokenId] = to; //msg.sender 에게 토큰 id 발행
        tokenURIs[tokenId] = tokenURI; //글자  

        _ownedTokens[to].push(tokenId); //add Token to the list
        return true;
    } 

    function safeTransferform(address from, address to, uint256 tokenId, bytes memory _data) public {
        require(from == msg.sender, "from != msg.sender"); //조건
        require(from == tokenOwner[tokenId], "you are not the owner of the token");
        

        _removeTokenFromList(from, tokenId);
        _ownedTokens[to].push(tokenId);
        
        tokenOwner[tokenId] = to;

        //전송했을 때 받는 쪽이 실행할 코드가 있는 스마트컨트랙트라면 코드를 실행할 것 
        require(
            _checkOnKIP17Received(from, to, tokenId, _data), "KIP17: transfer to non KIP17Receiver implementer"
        );

    }
    
    function _checkOnKIP17Received(address from , address to, uint256 tokenId, bytes memory _data) internal returns (bool){
        bool success;
        bytes memory returndata;
        //스마트 컨트랙트인지 확인 
        if (!isContract(to)){
            return true;
        }
        //to //NFTMarket의 onKIP17Received
        (success, returndata) = to.call( 
            abi.encodeWithSelector( 
                _KIP17_RECEIVED, 
                msg.sender,
                from,
                tokenId,
                _data
            )
        );
        if (
            returndata.length != 0 && 
            abi.decode(returndata, (bytes4)) == _KIP17_RECEIVED
        ) {
            return true;
        }
        return false;
    }
    
    //주소에 code 가 있으면 스마트 컨트랙트
    function isContract(address account) internal view returns (bool){
        uint256 size;
        assembly { size := extcodesize(account) }
        return size > 0;
    }


    function _removeTokenFromList(address from, uint256 tokenId) private{
       
         //_ownedTokens[from] 
        //맨 뒤랑 바꾸고, 자르기
        uint256 lastTokenIdex = _ownedTokens[from].length-1;
        for (uint256 i = 0 ; i <= _ownedTokens[from].length; i ++){
            if (tokenId == _ownedTokens[from][i]) {
               // var temp = _ownedTokens[from][i]; //swap
                _ownedTokens[from][i] = _ownedTokens[from][lastTokenIdex];
                _ownedTokens[from][lastTokenIdex] = tokenId ;
                break;
            }
        }
        _ownedTokens[from].length--;
    }

    function ownedTokens(address owner) public view returns (uint256[] memory) {
        return _ownedTokens[owner];
    }


    function setTokenUri(uint256 id, string memory uri) public {
        tokenURIs[id] = uri;
    }
}


contract NFTMarket {
    //nft 미술품

     //판매자(누가 NFT를 마켓에 보냈는가) 기록 sell
    mapping(uint256 => address) public seller;

    function buyNFT(uint256 tokenId, address NFTAddress) public payable returns (bool) {

        //구매? 판매? 사람한테 0.01 klay 보내야, 전송
        address payable receiver = address(uint160(seller[tokenId]));
        
        receiver.transfer(10 ** 16); //buyNFT실행한 사람이 보내야 
        // // // 10 ** 18 PEB = 1 Klay
        // 10 ** 16 PEB = 0.01  


        NFTSimple(NFTAddress).safeTransferform(address(this), msg.sender, tokenId, "0x00");
        return true; //구매자 (token이 구매자에게 간다. (buy) 
    }    

    //Market이 Token을 받았을 때(판매대에 올라왔을 때), 판매자가 누구인지 기록해야 
    function onKIP17Received(address operator, address from, uint256 tokenId, bytes memory data) public returns (bytes4){
        seller[tokenId] = from;
        return bytes4(keccak256("onKIP17Received(address,address,uint256,bytes)")); //실행 할 함수 0x6745782b 를 보면 토큰 받았을 경우 실행할 함수 가 존재함을확인?
    }

}