/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hdds.utils;

import com.google.common.base.Preconditions;
import org.apache.hadoop.hdds.StringUtils;

import java.io.IOException;
import java.util.Objects;

import org.apache.hadoop.ozone.common.ha.ratis.RatisSnapshotInfo;
import org.apache.ratis.server.protocol.TermIndex;
import org.apache.ratis.statemachine.SnapshotInfo;

import static org.apache.hadoop.ozone.OzoneConsts.TRANSACTION_INFO_KEY;
import static org.apache.hadoop.ozone.OzoneConsts.TRANSACTION_INFO_SPLIT_KEY;

/**
 * TransactionInfo which is persisted to DB.
 */
public final class TransactionInfo {

  // Term associated with Ratis Log index in Ratis enabled cluster. In
  // non-Ratis cluster, term is set to -1.
  private long term; // term associated with the ratis log index.
  // Ratis Log index in Ratis enabled cluster or the unique transaction
  // index {@link OzoneManagerServerSideTransalatorPB#transactionIndex} in
  // non-Ratis cluster
  private long transactionIndex;

  private TransactionInfo(String transactionInfo) {
    String[] tInfo =
        transactionInfo.split(TRANSACTION_INFO_SPLIT_KEY);
    Preconditions.checkState(tInfo.length==2,
        "Incorrect TransactionInfo value");

    term = Long.parseLong(tInfo[0]);
    transactionIndex = Long.parseLong(tInfo[1]);
  }

  private TransactionInfo(long currentTerm, long transactionIndex) {
    this.term = currentTerm;
    this.transactionIndex = transactionIndex;
  }

  public boolean isDefault() {
    return transactionIndex == -1 && term == 0;
  }

  public int compareTo(TransactionInfo info) {
    if (info.getTerm() == this.getTerm()) {
      return (int)(this.getTransactionIndex() - info.getTransactionIndex());
    } else {
      return (int)(this.getTerm() - info.getTerm());
    }
  }

  /**
   * Get current term.
   * @return currentTerm
   */
  public long getTerm() {
    return term;
  }

  /**
   * Get current transaction index.
   * @return transactionIndex
   */
  public long getTransactionIndex() {
    return transactionIndex;
  }

  public TermIndex getTermIndex() {
    return TermIndex.valueOf(term, transactionIndex);
  }

  /**
   * Generate String form of transaction info which need to be persisted in OM
   * DB finally in byte array.
   * @return transaction info.
   */
  private String generateTransactionInfo() {
    StringBuilder stringBuilder = new StringBuilder();
    stringBuilder.append(term);
    stringBuilder.append(TRANSACTION_INFO_SPLIT_KEY);
    stringBuilder.append(transactionIndex);

    return stringBuilder.toString();
  }

  /**
   * Convert OMTransactionInfo to byteArray to be persisted to OM DB.
   * @return byte[]
   */
  public byte[] convertToByteArray() {
    return StringUtils.string2Bytes(generateTransactionInfo());
  }

  /**
   * Convert byte array persisted in DB to OMTransactionInfo.
   * @param bytes
   * @return OMTransactionInfo
   */
  public static TransactionInfo getFromByteArray(byte[] bytes) {
    String tInfo = StringUtils.bytes2String(bytes);
    return new TransactionInfo(tInfo);
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    TransactionInfo that = (TransactionInfo) o;
    return term == that.term &&
        transactionIndex == that.transactionIndex;
  }

  public static TransactionInfo fromTermIndex(TermIndex termIndex) {
    return new Builder().setCurrentTerm(termIndex.getTerm())
        .setTransactionIndex(termIndex.getIndex()).build();
  }

  @Override
  public int hashCode() {
    return Objects.hash(term, transactionIndex);
  }

  @Override
  public String toString() {
    return generateTransactionInfo();
  }

  /**
   * Return transaction info persisted in OM DB.
   * @param metadataManager
   * @return
   * @throws IOException
   */
  public static TransactionInfo readTransactionInfo(
      DBStoreHAManager metadataManager) throws IOException {
    return metadataManager.getTransactionInfoTable().get(TRANSACTION_INFO_KEY);
  }

  public SnapshotInfo toSnapshotInfo() {
    return new RatisSnapshotInfo(term, transactionIndex);
  }

  public static Builder builder() {
    return new Builder();
  }
  /**
   * Builder to build {@link TransactionInfo}.
   */
  public static class Builder {
    private long currentTerm = 0;
    private long transactionIndex = -1;

    public Builder setCurrentTerm(long term) {
      this.currentTerm = term;
      return this;
    }

    public Builder setTransactionIndex(long tIndex) {
      this.transactionIndex = tIndex;
      return this;
    }

    public TransactionInfo build() {
      return new TransactionInfo(currentTerm, transactionIndex);
    }
  }
}