com.org1.contract.StateReader Maven / Gradle / Ivy

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package com.org1.contract;

import com.scalar.dl.ledger.asset.Asset;
import com.scalar.dl.ledger.asset.InternalAsset;
import com.scalar.dl.ledger.contract.Contract;
import com.scalar.dl.ledger.exception.ContractContextException;
import com.scalar.dl.ledger.database.Ledger;
import java.util.Base64;
import java.util.Optional;
import javax.json.Json;
import javax.json.JsonObject;
import javax.json.JsonObjectBuilder;

public class StateReader extends Contract {

  @Override
  public JsonObject invoke(Ledger ledger, JsonObject argument, Optional properties) {
    if (!argument.containsKey("asset_id")) {
      // ContractContextException is the only throwable exception in a contract and
      // it should be thrown when a contract faces some non-recoverable error
      throw new ContractContextException("please set asset_id in the argument");
    }

    String assetId = argument.getString("asset_id");
    Optional asset = ledger.get(assetId);
    if (!asset.isPresent()) {
      return null;
    }
    InternalAsset internal = (InternalAsset) asset.get();

    Base64.Encoder encoder = Base64.getEncoder();
    JsonObjectBuilder builder =
        Json.createObjectBuilder()
            .add("age", internal.age())
            .add("input", internal.input())
            .add("output", internal.data())
            .add("contract_id", internal.contractId())
            .add("argument", internal.argument())
            .add("signature", encoder.encodeToString(internal.signature()))
            .add("hash", encoder.encodeToString(internal.hash()));
    if (internal.prevHash() != null) {
      builder.add("prev_hash", encoder.encodeToString(internal.prevHash()));
    } else {
      builder.add("prev_hash", "");
    }
    return builder.build();
  }
}