org.fisco.bcos.web3j.abi.EventEncoder Maven / Gradle / Ivy

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package org.fisco.bcos.web3j.abi;

import java.util.List;
import java.util.stream.Collectors;
import org.fisco.bcos.web3j.abi.datatypes.Event;
import org.fisco.bcos.web3j.abi.datatypes.Type;
import org.fisco.bcos.web3j.crypto.Hash;
import org.fisco.bcos.web3j.utils.Numeric;

/**
 * Ethereum filter encoding. Further limited details are available here.
 */
public class EventEncoder {

  private EventEncoder() {}

  public static String encode(Event event) {

    String methodSignature = buildMethodSignature(event.getName(), event.getParameters());

    return buildEventSignature(methodSignature);
  }

  static  String buildMethodSignature(
      String methodName, List> parameters) {

    StringBuilder result = new StringBuilder();
    result.append(methodName);
    result.append("(");
    String params =
        parameters.stream().map(p -> Utils.getTypeName(p)).collect(Collectors.joining(","));
    result.append(params);
    result.append(")");
    return result.toString();
  }

  public static String buildEventSignature(String methodSignature) {
    byte[] input = methodSignature.getBytes();
    byte[] hash = Hash.sha3(input);
    return Numeric.toHexString(hash);
  }
}