/*
 * ToroDB
 * Copyright © 2014 8Kdata Technology (www.8kdata.com)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

package com.torodb.torod.impl.sql;

import com.google.common.base.Preconditions;
import com.torodb.core.backend.BackendConnection;
import com.torodb.torod.TorodConnection;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import javax.annotation.concurrent.NotThreadSafe;

/**
 *
 */
@NotThreadSafe
public class SqlTorodConnection implements TorodConnection {

  private static final Logger LOGGER = LogManager.getLogger(SqlTorodConnection.class);

  private final SqlTorodServer server;
  private final int connectionid;
  private final BackendConnection backendConnection;
  private boolean closed = false;
  private SqlTorodTransaction<?> currentTransaction = null;

  SqlTorodConnection(SqlTorodServer server, int connectionId) {
    this.server = server;
    this.connectionid = connectionId;
    this.backendConnection = server.getBackend().openConnection();
  }

  @Override
  public SqlReadOnlyTorodTransaction openReadOnlyTransaction() {
    Preconditions.checkState(!closed, "This connection is closed");
    Preconditions.checkState(currentTransaction == null,
        "Another transaction is currently under execution. Transaction is " + currentTransaction);

    SqlReadOnlyTorodTransaction transaction = new SqlReadOnlyTorodTransaction(this);
    currentTransaction = transaction;

    return transaction;
  }

  @Override
  public SqlSharedWriteTorodTransaction openWriteTransaction(boolean concurrent) {
    Preconditions.checkState(!closed, "This connection is closed");
    Preconditions.checkState(currentTransaction == null,
        "Another transaction is currently under execution. Transaction is " + currentTransaction);

    SqlSharedWriteTorodTransaction transaction =
        new SqlSharedWriteTorodTransaction(this, concurrent);
    currentTransaction = transaction;

    return transaction;
  }

  @Override
  public SqlExclusiveWriteTorodTransaction openExclusiveWriteTransaction(boolean concurrent) {
    Preconditions.checkState(!closed, "This connection is closed");
    Preconditions.checkState(currentTransaction == null,
        "Another transaction is currently under execution. Transaction is " + currentTransaction);

    SqlExclusiveWriteTorodTransaction transaction = new SqlExclusiveWriteTorodTransaction(this,
        concurrent);
    currentTransaction = transaction;

    return transaction;
  }

  @Override
  public int getConnectionId() {
    return connectionid;
  }

  @Override
  public void close() {
    if (!closed) {
      closed = true;
      if (currentTransaction != null) {
        currentTransaction.close();
      }
      assert currentTransaction == null;
      server.onConnectionClosed(this);

      backendConnection.close();
    }
  }

  void onTransactionClosed(SqlTorodTransaction<?> transaction) {
    if (currentTransaction == null) {
      LOGGER.debug(
          "Recived an on transaction close notification, but there is no current transaction");
      return;
    }
    if (currentTransaction != transaction) {
      LOGGER.debug(
          "Recived an on transaction close notification, but the recived transaction is not the "
              + "same as the current one");
      return;
    }
    currentTransaction = null;
  }

  @Override
  public SqlTorodServer getServer() {
    return server;
  }

  BackendConnection getBackendConnection() {
    return backendConnection;
  }

}