/*
 * 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.mongodb.core;

import com.eightkdata.mongowp.server.api.CommandsExecutor;
import com.eightkdata.mongowp.server.api.Connection;
import com.google.common.base.Preconditions;
import com.torodb.torod.TorodConnection;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import javax.annotation.Nullable;
import javax.annotation.concurrent.NotThreadSafe;

@NotThreadSafe
public class MongodConnection implements Connection, AutoCloseable {

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

  private final MongodServer server;
  private final TorodConnection torodConnection;
  private final LastErrorManager lastErrorManager;
  private final CommandsExecutor<? super MongodConnection> commandsExecutor;
  private MongodTransaction currentTransaction;
  private boolean closed = false;
  private final StackTraceElement[] stack;

  public MongodConnection(MongodServer server) {
    this.server = server;
    this.torodConnection = server.getTorodServer().openConnection();
    this.lastErrorManager = new LastErrorManager();
    this.commandsExecutor = server.getCommandsExecutorClassifier().getConnectionCommandsExecutor();
    stack = Thread.currentThread().getStackTrace();
  }

  public MongodServer getServer() {
    return server;
  }

  public TorodConnection getTorodConnection() {
    return torodConnection;
  }

  public LastErrorManager getLastErrorManager() {
    return lastErrorManager;
  }

  public ReadOnlyMongodTransaction openReadOnlyTransaction() {
    Preconditions.checkState(!closed, "This connection is closed");
    Preconditions.checkState(currentTransaction == null,
        "Another transaction is currently under execution. Transaction is " + currentTransaction);
    ReadOnlyMongodTransaction trans = new ReadOnlyMongodTransactionImpl(this);
    currentTransaction = trans;
    return trans;
  }

  public WriteMongodTransaction openWriteTransaction() {
    return openWriteTransaction(false);
  }

  public WriteMongodTransaction openWriteTransaction(boolean concurrent) {
    Preconditions.checkState(!closed, "This connection is closed");
    Preconditions.checkState(currentTransaction == null,
        "Another transaction is currently under execution. Transaction is " + currentTransaction);
    WriteMongodTransaction trans = new WriteMongodTransactionImpl(this, concurrent);
    currentTransaction = trans;
    return trans;
  }

  public ExclusiveWriteMongodTransaction openExclusiveWriteTransaction() {
    return openExclusiveWriteTransaction(false);
  }

  public ExclusiveWriteMongodTransaction openExclusiveWriteTransaction(boolean concurrent) {
    Preconditions.checkState(!closed, "This connection is closed");
    Preconditions.checkState(currentTransaction == null,
        "Another transaction is currently under execution. Transaction is " + currentTransaction);
    ExclusiveWriteMongodTransaction trans =
        new ExclusiveWriteMongodTransactionImpl(this, concurrent);
    currentTransaction = trans;
    return trans;
  }

  @Nullable
  public MongodTransaction getCurrentTransaction() {
    return currentTransaction;
  }

  @Override
  public int getConnectionId() {
    return torodConnection.getConnectionId();
  }

  public CommandsExecutor<? super MongodConnection> getCommandsExecutor() {
    return commandsExecutor;
  }

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

      torodConnection.close();
    }
  }

  void onTransactionClosed(MongodTransaction 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
  protected void finalize() throws Throwable {
    if (!closed) {
      LOGGER.warn(this.getClass() + " finalized without being closed");
      close();
    }
  }

}