/*
 * 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.tephra.hbase;

import com.google.protobuf.Descriptors.MethodDescriptor;
import com.google.protobuf.Message;
import com.google.protobuf.Service;
import com.google.protobuf.ServiceException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.HColumnDescriptor;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Append;
import org.apache.hadoop.hbase.client.Delete;
import org.apache.hadoop.hbase.client.Durability;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HTableInterface;
import org.apache.hadoop.hbase.client.Increment;
import org.apache.hadoop.hbase.client.Mutation;
import org.apache.hadoop.hbase.client.OperationWithAttributes;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Row;
import org.apache.hadoop.hbase.client.RowMutations;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.client.coprocessor.Batch;
import org.apache.hadoop.hbase.client.coprocessor.Batch.Callback;
import org.apache.hadoop.hbase.filter.CompareFilter;
import org.apache.hadoop.hbase.ipc.CoprocessorRpcChannel;
import org.apache.tephra.AbstractTransactionAwareTable;
import org.apache.tephra.Transaction;
import org.apache.tephra.TransactionAware;
import org.apache.tephra.TxConstants;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.NavigableMap;
import java.util.Set;

/**
 * A Transaction Aware HTable implementation for HBase 1.3. Operations are committed as usual,
 * but upon a failed or aborted transaction, they are rolled back to the state before the transaction
 * was started.
 */
public class TransactionAwareHTable extends AbstractTransactionAwareTable
    implements HTableInterface, TransactionAware {

  private static final Logger LOG = LoggerFactory.getLogger(TransactionAwareHTable.class);
  private final HTableInterface hTable;

  /**
   * Create a transactional aware instance of the passed HTable
   *
   * @param hTable underlying HBase table to use
   */
  public TransactionAwareHTable(HTableInterface hTable) {
    this(hTable, false);
  }

  /**
   * Create a transactional aware instance of the passed HTable
   *
   * @param hTable underlying HBase table to use
   * @param conflictLevel level of conflict detection to perform (defaults to {@code COLUMN})
   */
  public TransactionAwareHTable(HTableInterface hTable, TxConstants.ConflictDetection conflictLevel) {
    this(hTable, conflictLevel, false);
  }

  /**
   * Create a transactional aware instance of the passed HTable, with the option
   * of allowing non-transactional operations.
   * @param hTable underlying HBase table to use
   * @param allowNonTransactional if true, additional operations (checkAndPut, increment, checkAndDelete)
   *                              will be available, though non-transactional
   */
  public TransactionAwareHTable(HTableInterface hTable, boolean allowNonTransactional) {
    this(hTable, TxConstants.ConflictDetection.COLUMN, allowNonTransactional);
  }

  /**
   * Create a transactional aware instance of the passed HTable, with the option
   * of allowing non-transactional operations.
   * @param hTable underlying HBase table to use
   * @param conflictLevel level of conflict detection to perform (defaults to {@code COLUMN})
   * @param allowNonTransactional if true, additional operations (checkAndPut, increment, checkAndDelete)
   *                              will be available, though non-transactional
   */
  public TransactionAwareHTable(HTableInterface hTable, TxConstants.ConflictDetection conflictLevel,
                                boolean allowNonTransactional) {
    super(conflictLevel, allowNonTransactional, 
        hTable.getConfiguration().getBoolean(
            TxConstants.TX_PRE_014_CHANGESET_KEY,
            TxConstants.DEFAULT_TX_PRE_014_CHANGESET_KEY));
    this.hTable = hTable;
  }

  /* AbstractTransactionAwareTable implementation */

  @Override
  protected byte[] getTableKey() {
    return getTableName();
  }

  @Override
  protected boolean doCommit() throws IOException {
    hTable.flushCommits();
    return true;
  }

  @Override
  protected boolean doRollback() throws Exception {
    try {
      // pre-size arraylist of deletes
      int size = 0;
      for (Set<ActionChange> cs : changeSets.values()) {
        size += cs.size();
      }
      List<Delete> rollbackDeletes = new ArrayList<>(size);
      for (Map.Entry<Long, Set<ActionChange>> entry : changeSets.entrySet()) {
        long transactionTimestamp = entry.getKey();
        for (ActionChange change : entry.getValue()) {
          byte[] row = change.getRow();
          byte[] family = change.getFamily();
          byte[] qualifier = change.getQualifier();
          Delete rollbackDelete = new Delete(row);
          makeRollbackOperation(rollbackDelete);
          switch (conflictLevel) {
            case ROW:
            case NONE:
              // issue family delete for the tx write pointer
              rollbackDelete.deleteFamilyVersion(change.getFamily(), transactionTimestamp);
              break;
            case COLUMN:
              if (family != null && qualifier == null) {
                rollbackDelete.deleteFamilyVersion(family, transactionTimestamp);
              } else if (family != null && qualifier != null) {
                rollbackDelete.deleteColumn(family, qualifier, transactionTimestamp);
              }
              break;
            default:
              throw new IllegalStateException("Unknown conflict detection level: " + conflictLevel);
          }
          rollbackDeletes.add(rollbackDelete);
        }
      }
      hTable.delete(rollbackDeletes);
      return true;
    } finally {
      try {
        hTable.flushCommits();
      } catch (Exception e) {
        LOG.error("Could not flush HTable commits", e);
      }
      tx = null;
      changeSets.clear();
    }
  }

  /* HTableInterface implementation */

  @Override
  public byte[] getTableName() {
    return hTable.getTableName();
  }

  @Override
  public TableName getName() {
    return hTable.getName();
  }

  @Override
  public Configuration getConfiguration() {
    return hTable.getConfiguration();
  }

  @Override
  public HTableDescriptor getTableDescriptor() throws IOException {
    return hTable.getTableDescriptor();
  }

  @Override
  public boolean exists(Get get) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    return hTable.exists(transactionalizeAction(get));
  }

  @Override
  public Boolean[] exists(List<Get> gets) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    List<Get> transactionalizedGets = new ArrayList<>(gets.size());
    for (Get get : gets) {
      transactionalizedGets.add(transactionalizeAction(get));
    }
    return hTable.exists(transactionalizedGets);
  }

  @Override
  public void batch(List<? extends Row> actions, Object[] results) throws IOException, InterruptedException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    hTable.batch(transactionalizeActions(actions), results);
  }

  @Override
  public Object[] batch(List<? extends Row> actions) throws IOException, InterruptedException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    return hTable.batch(transactionalizeActions(actions));
  }

  @Override
  public <R> void batchCallback(List<? extends Row> actions, Object[] results, Batch.Callback<R> callback) throws
    IOException, InterruptedException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    hTable.batchCallback(transactionalizeActions(actions), results, callback);
  }

  @Override
  public <R> Object[] batchCallback(List<? extends Row> actions, Batch.Callback<R> callback) throws IOException,
    InterruptedException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    return hTable.batchCallback(transactionalizeActions(actions), callback);
  }

  @Override
  public Result get(Get get) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    return hTable.get(transactionalizeAction(get));
  }

  @Override
  public Result[] get(List<Get> gets) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    ArrayList<Get> transactionalizedGets = new ArrayList<>();
    for (Get get : gets) {
      transactionalizedGets.add(transactionalizeAction(get));
    }
    return hTable.get(transactionalizedGets);
  }

  @Override
  public Result getRowOrBefore(byte[] row, byte[] family) throws IOException {
    if (allowNonTransactional) {
      return hTable.getRowOrBefore(row, family);
    } else {
      throw new UnsupportedOperationException("Operation is not supported transactionally");
    }
  }

  @Override
  public ResultScanner getScanner(Scan scan) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    return hTable.getScanner(transactionalizeAction(scan));
  }

  @Override
  public ResultScanner getScanner(byte[] family) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    Scan scan = new Scan();
    scan.addFamily(family);
    return hTable.getScanner(transactionalizeAction(scan));
  }

  @Override
  public ResultScanner getScanner(byte[] family, byte[] qualifier) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    Scan scan = new Scan();
    scan.addColumn(family, qualifier);
    return hTable.getScanner(transactionalizeAction(scan));
  }

  @Override
  public void put(Put put) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    Put txPut = transactionalizeAction(put);
    hTable.put(txPut);
  }

  @Override
  public void put(List<Put> puts) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    List<Put> transactionalizedPuts = new ArrayList<>(puts.size());
    for (Put put : puts) {
      Put txPut = transactionalizeAction(put);
      transactionalizedPuts.add(txPut);
    }
    hTable.put(transactionalizedPuts);
  }

  @Override
  public boolean checkAndPut(byte[] row, byte[] family, byte[] qualifier, byte[] value, Put put) throws IOException {
    if (allowNonTransactional) {
      return hTable.checkAndPut(row, family, qualifier, value, put);
    } else {
      throw new UnsupportedOperationException("Operation is not supported transactionally");
    }
  }

  @Override
  public void delete(Delete delete) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    hTable.delete(transactionalizeAction(delete));
  }

  @Override
  public void delete(List<Delete> deletes) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    List<Delete> transactionalizedDeletes = new ArrayList<>(deletes.size());
    for (Delete delete : deletes) {
      Delete txDelete = transactionalizeAction(delete);
      transactionalizedDeletes.add(txDelete);
    }
    hTable.delete(transactionalizedDeletes);
  }

  @Override
  public boolean checkAndDelete(byte[] row, byte[] family, byte[] qualifier, byte[] value, Delete delete)
    throws IOException {
    if (allowNonTransactional) {
      return hTable.checkAndDelete(row, family, qualifier, value, delete);
    } else {
      throw new UnsupportedOperationException("Operation is not supported transactionally");
    }
  }

  @Override
  public boolean checkAndDelete(byte[] bytes, byte[] bytes1, byte[] bytes2, CompareFilter.CompareOp compareOp,
                                byte[] bytes3, Delete delete) throws IOException {
    if (allowNonTransactional) {
      return hTable.checkAndDelete(bytes, bytes1, bytes2, compareOp, bytes3, delete);
    } else {
      throw new UnsupportedOperationException("Operation is not supported transactionally");
    }
  }

  @Override
  public boolean checkAndPut(byte[] bytes, byte[] bytes1, byte[] bytes2, CompareFilter.CompareOp compareOp,
                             byte[] bytes3, Put put) throws IOException {
    if (allowNonTransactional) {
      return hTable.checkAndPut(bytes, bytes1, bytes2, compareOp, bytes3, put);
    } else {
      throw new UnsupportedOperationException("Operation is not supported transactionally");
    }
  }

  @Override
  public boolean[] existsAll(List<Get> gets) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    List<Get> transactionalizedGets = new ArrayList<>(gets.size());
    for (Get get : gets) {
      transactionalizedGets.add(transactionalizeAction(get));
    }
    return hTable.existsAll(transactionalizedGets);
  }

  @Override
  public boolean checkAndMutate(byte[] row, byte[] family, byte[] qualifier,
                                CompareFilter.CompareOp compareOp, byte[] value, RowMutations rowMutations)
      throws IOException {
    if (allowNonTransactional) {
      return hTable.checkAndMutate(row, family, qualifier, compareOp, value, rowMutations);
    }

    throw new UnsupportedOperationException("checkAndMutate operation is not supported transactionally");
  }

  @Override
  public void setOperationTimeout(int operationTimeout) {
    hTable.setOperationTimeout(operationTimeout);
  }

  @Override
  public int getOperationTimeout() {
    return hTable.getOperationTimeout();
  }

  @Override
  public void setRpcTimeout(int rpcTimeout) {
    hTable.setRpcTimeout(rpcTimeout);
  }

  @Override
  public int getRpcTimeout() {
    return hTable.getRpcTimeout();
  }

  @Override
  public void mutateRow(RowMutations rm) throws IOException {
    if (tx == null) {
      throw new IOException("Transaction not started");
    }
    RowMutations transactionalMutations = new RowMutations();
    for (Mutation mutation : rm.getMutations()) {
      if (mutation instanceof Put) {
        transactionalMutations.add(transactionalizeAction((Put) mutation));
      } else if (mutation instanceof Delete) {
        transactionalMutations.add(transactionalizeAction((Delete) mutation));
      }
    }
    hTable.mutateRow(transactionalMutations);
  }

  @Override
  public Result append(Append append) throws IOException {
    if (allowNonTransactional) {
      return hTable.append(append);
    } else {
      throw new UnsupportedOperationException("Operation is not supported transactionally");
    }
  }

  @Override
  public Result increment(Increment increment) throws IOException {
    if (allowNonTransactional) {
      return hTable.increment(increment);
    } else {
      throw new UnsupportedOperationException("Operation is not supported transactionally");
    }
  }

  @Override
  public long incrementColumnValue(byte[] row, byte[] family, byte[] qualifier, long amount) throws IOException {
    if (allowNonTransactional) {
      return hTable.incrementColumnValue(row, family, qualifier, amount);
    } else {
      throw new UnsupportedOperationException("Operation is not supported transactionally");
    }
  }

  @Override
  public long incrementColumnValue(byte[] row, byte[] family, byte[] qualifier, long amount, Durability durability)
    throws IOException {
    if (allowNonTransactional) {
      return hTable.incrementColumnValue(row, family, qualifier, amount, durability);
    } else {
      throw new UnsupportedOperationException("Operation is not supported transactionally");
    }
  }

  @Override
  public long incrementColumnValue(byte[] row, byte[] family, byte[] qualifier, long amount, boolean writeToWAL)
    throws IOException {
    if (allowNonTransactional) {
      return hTable.incrementColumnValue(row, family, qualifier, amount, writeToWAL);
    } else {
      throw new UnsupportedOperationException("Operation is not supported transactionally");
    }
  }

  @Override
  public boolean isAutoFlush() {
    return hTable.isAutoFlush();
  }

  @Override
  public void flushCommits() throws IOException {
    hTable.flushCommits();
  }

  @Override
  public void close() throws IOException {
    hTable.close();
  }

  @Override
  public CoprocessorRpcChannel coprocessorService(byte[] row) {
    return hTable.coprocessorService(row);
  }

  @Override
  public <T extends Service, R> Map<byte[], R> coprocessorService(Class<T> service, byte[] startKey, byte[] endKey,
                                                                  Batch.Call<T, R> callable)
    throws ServiceException, Throwable {
    return hTable.coprocessorService(service, startKey, endKey, callable);
  }

  @Override
  public <T extends Service, R> void coprocessorService(Class<T> service, byte[] startKey, byte[] endKey,
                                                        Batch.Call<T, R> callable, Batch.Callback<R> callback)
    throws ServiceException, Throwable {
    hTable.coprocessorService(service, startKey, endKey, callable, callback);
  }

  @Override
  public <R extends Message> Map<byte[], R> batchCoprocessorService(
      MethodDescriptor methodDescriptor, Message request, byte[] startKey, byte[] endKey,
      R responsePrototype) throws ServiceException, Throwable {
    return hTable.batchCoprocessorService(methodDescriptor, request, startKey, endKey, responsePrototype);
  }

  @Override
  public <R extends Message> void batchCoprocessorService(MethodDescriptor methodDescriptor,
      Message request, byte[] startKey, byte[] endKey, R responsePrototype, Callback<R> callback)
      throws ServiceException, Throwable {
    hTable.batchCoprocessorService(methodDescriptor, request, startKey, endKey, responsePrototype, callback);
  }

  @Override
  public void setAutoFlush(boolean autoFlush) {
    setAutoFlushTo(autoFlush);
  }

  @Override
  public void setAutoFlush(boolean autoFlush, boolean clearBufferOnFail) {
    hTable.setAutoFlush(autoFlush, clearBufferOnFail);
  }

  @Override
  public void setAutoFlushTo(boolean autoFlush) {
    hTable.setAutoFlushTo(autoFlush);
  }

  @Override
  public long getWriteBufferSize() {
    return hTable.getWriteBufferSize();
  }

  @Override
  public void setWriteBufferSize(long writeBufferSize) throws IOException {
    hTable.setWriteBufferSize(writeBufferSize);
  }

  // Helpers to get copies of objects with the timestamp set to the current transaction timestamp.

  private Get transactionalizeAction(Get get) throws IOException {
    addToOperation(get, tx);
    return get;
  }

  private Scan transactionalizeAction(Scan scan) throws IOException {
    addToOperation(scan, tx);
    return scan;
  }

  private Put transactionalizeAction(Put put) throws IOException {
    Put txPut = new Put(put.getRow(), tx.getWritePointer());
    Set<Map.Entry<byte[], List<Cell>>> familyMap = put.getFamilyCellMap().entrySet();
    if (!familyMap.isEmpty()) {
      for (Map.Entry<byte[], List<Cell>> family : familyMap) {
        List<Cell> familyValues = family.getValue();
        if (!familyValues.isEmpty()) {
          for (Cell value : familyValues) {
            txPut.add(value.getFamily(), value.getQualifier(), tx.getWritePointer(), value.getValue());
            addToChangeSet(txPut.getRow(), value.getFamily(), value.getQualifier());
          }
        }
      }
    }
    for (Map.Entry<String, byte[]> entry : put.getAttributesMap().entrySet()) {
      txPut.setAttribute(entry.getKey(), entry.getValue());
    }
    txPut.setDurability(put.getDurability());
    addToOperation(txPut, tx);
    return txPut;
  }

  private Delete transactionalizeAction(Delete delete) throws IOException {
    long transactionTimestamp = tx.getWritePointer();

    byte[] deleteRow = delete.getRow();
    Delete txDelete = new Delete(deleteRow, transactionTimestamp);

    Map<byte[], List<Cell>> familyToDelete = delete.getFamilyCellMap();
    if (familyToDelete.isEmpty()) {
      // perform a row delete if we are using row-level conflict detection
      if (conflictLevel == TxConstants.ConflictDetection.ROW ||
        conflictLevel == TxConstants.ConflictDetection.NONE) {
        // Row delete leaves delete markers in all column families of the table
        // Therefore get all the column families of the hTable from the HTableDescriptor and add them to the changeSet
        for (HColumnDescriptor columnDescriptor : hTable.getTableDescriptor().getColumnFamilies()) {
          // no need to identify individual columns deleted
          addToChangeSet(deleteRow, columnDescriptor.getName(), null);
        }
      } else {
        Result result = get(new Get(delete.getRow()));
        // Delete everything
        NavigableMap<byte[], NavigableMap<byte[], byte[]>> resultMap = result.getNoVersionMap();
        for (Map.Entry<byte[], NavigableMap<byte[], byte[]>> familyEntry : resultMap.entrySet()) {
          NavigableMap<byte[], byte[]> familyColumns = result.getFamilyMap(familyEntry.getKey());
          for (Map.Entry<byte[], byte[]> column : familyColumns.entrySet()) {
            txDelete.deleteColumns(familyEntry.getKey(), column.getKey(), transactionTimestamp);
            addToChangeSet(deleteRow, familyEntry.getKey(), column.getKey());
          }
        }
      }
    } else {
      for (Map.Entry<byte [], List<Cell>> familyEntry : familyToDelete.entrySet()) {
        byte[] family = familyEntry.getKey();
        List<Cell> entries = familyEntry.getValue();
        boolean isFamilyDelete = false;
        if (entries.size() == 1) {
          Cell cell = entries.get(0);
          isFamilyDelete = CellUtil.isDeleteFamily(cell);
        }
        if (isFamilyDelete) {
          if (conflictLevel == TxConstants.ConflictDetection.ROW ||
              conflictLevel == TxConstants.ConflictDetection.NONE) {
            // no need to identify individual columns deleted
            txDelete.deleteFamily(family);
            addToChangeSet(deleteRow, family, null);
          } else {
            Result result = get(new Get(delete.getRow()).addFamily(family));
            // Delete entire family
            NavigableMap<byte[], byte[]> familyColumns = result.getFamilyMap(family);
            for (Map.Entry<byte[], byte[]> column : familyColumns.entrySet()) {
              txDelete.deleteColumns(family, column.getKey(), transactionTimestamp);
              addToChangeSet(deleteRow, family, column.getKey());
            }
          }
        } else {
          for (Cell value : entries) {
            txDelete.deleteColumns(value.getFamily(), value.getQualifier(), transactionTimestamp);
            addToChangeSet(deleteRow, value.getFamily(), value.getQualifier());
          }
        }
      }
    }
    for (Map.Entry<String, byte[]> entry : delete.getAttributesMap().entrySet()) {
        txDelete.setAttribute(entry.getKey(), entry.getValue());
    }
    txDelete.setDurability(delete.getDurability());
    addToOperation(txDelete, tx);
    return txDelete;
  }

  private List<? extends Row> transactionalizeActions(List<? extends Row> actions) throws IOException {
    List<Row> transactionalizedActions = new ArrayList<>(actions.size());
    for (Row action : actions) {
      if (action instanceof Get) {
        transactionalizedActions.add(transactionalizeAction((Get) action));
      } else if (action instanceof Put) {
        transactionalizedActions.add(transactionalizeAction((Put) action));
      } else if (action instanceof Delete) {
        transactionalizedActions.add(transactionalizeAction((Delete) action));
      } else {
        transactionalizedActions.add(action);
      }
    }
    return transactionalizedActions;
  }

  public void addToOperation(OperationWithAttributes op, Transaction tx) throws IOException {
    op.setAttribute(TxConstants.TX_OPERATION_ATTRIBUTE_KEY, txCodec.encode(tx));
  }

  protected void makeRollbackOperation(Delete delete) {
    delete.setAttribute(TxConstants.TX_ROLLBACK_ATTRIBUTE_KEY, new byte[0]);
  }
}