nft analysis, ipfs to HTTPS link

package com.odcchina.fai.util;

import com.alibaba.fastjson.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.client.RestTemplate;
import org.web3j.abi.FunctionEncoder;
import org.web3j.abi.FunctionReturnDecoder;
import org.web3j.abi.TypeReference;
import org.web3j.abi.datatypes.*;
import org.web3j.abi.datatypes.generated.Uint256;
import org.web3j.protocol.Web3j;
import org.web3j.protocol.core.DefaultBlockParameterName;
import org.web3j.protocol.core.methods.request.Transaction;
import org.web3j.protocol.core.methods.response.EthCall;
import org.web3j.protocol.http.HttpService;

import java.io.IOException;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.List;

import static com.ruoyi.common.config.datasource.DynamicDataSourceContextHolder.log;

/**
 * nft解析
 */
@Service
public class NftUtil {

    @Autowired
    private RestTemplate restTemplate;

    public JSONObject etherTokenURI(String contract, BigInteger tokenId) {
        String uri = tokenURI("https://mainnet.infura.io/v3/9aa3d95b3bc440fa88ea12eaa4456161", contract, tokenId);
        String jsonUrl = decodeUrl(uri);
        JSONObject resp = fetchUrl(jsonUrl);
        if (resp == null) {
            return new JSONObject();
        }
        //log.info(resp.toJSONString());
        String image = resp.getString("image");
        resp.put("image", decodeUrl(image));
        return resp;
    }

    private String tokenURI(String rpcUrl, String contract, BigInteger tokenId) {
        Web3j web3j = Web3j.build(new HttpService(rpcUrl));
        Function function = new Function("tokenURI",
            Arrays.asList(new Uint256(tokenId)),
            Arrays.asList(TypeReference.create(Utf8String.class))
        );

        Transaction transaction = Transaction.createEthCallTransaction(contract,
            contract, FunctionEncoder.encode(function));
        try {
            EthCall ethCall = web3j.ethCall(transaction, DefaultBlockParameterName.LATEST).send();
            if (ethCall.getError() != null) {
                log.error("tokenURI - {}", ethCall.getError().getMessage());
                return null;
            }
            List<Type> result = FunctionReturnDecoder.decode(ethCall.getValue(), function.getOutputParameters());
            Utf8String uri = (Utf8String) result.get(0);
            return uri.getValue();
        } catch (IOException | NullPointerException e) {
            log.error(e.getLocalizedMessage());
            //throw new RuntimeException(e);
        }
        return null;
    }

    //解析URL，IPFS url转为https链接
    //ipfs://QmeSjSinHpPnmXmspMjwiXyN6zS4E9zccariGR3jxcaWtq/18
    private String decodeUrl(String ipfsUrl) {
        if (ipfsUrl == null) {
            return null;
        }
        if (ipfsUrl.substring(0, 4).equalsIgnoreCase("http")) {
            return ipfsUrl;
        }
        if (ipfsUrl.substring(0, 12).equalsIgnoreCase("ipfs://ipfs/")) {
            return "https://ipfs.io/ipfs/" + ipfsUrl.substring(12);
        }
        if (ipfsUrl.substring(0, 7).equalsIgnoreCase("ipfs://")) {
            return "https://ipfs.io/ipfs/" + ipfsUrl.substring(7);
        }
        return null;
    }

    private JSONObject fetchUrl(String jsonUrl) {
        if (jsonUrl == null) {
            return null;
        }
        try {
            return restTemplate.getForObject(jsonUrl, JSONObject.class);
        } catch (Exception e) {
            e.getLocalizedMessage();
        }
        return null;
    }
}