/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2009 Sun Microsystems, Inc.
 * Portions Copyright 2014-2016 ForgeRock AS.
 */
package org.opends.server.protocols.internal;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.List;

import org.forgerock.i18n.LocalizableMessage;
import org.forgerock.opendj.io.ASN1;
import org.forgerock.opendj.io.ASN1Reader;
import org.forgerock.opendj.ldap.ByteSequenceReader;
import org.forgerock.opendj.ldap.ByteString;
import org.forgerock.opendj.ldap.ByteStringBuilder;
import org.forgerock.opendj.ldap.DN;
import org.opends.server.core.*;
import org.opends.server.protocols.ldap.*;
import org.opends.server.types.*;

import static org.forgerock.opendj.ldap.DecodeException.*;
import static org.opends.messages.ProtocolMessages.*;
import static org.opends.server.protocols.internal.InternalClientConnection.*;
import static org.opends.server.protocols.internal.Requests.*;
import static org.opends.server.protocols.ldap.LDAPConstants.*;
import static org.opends.server.util.ServerConstants.*;

/**
 * This class provides an implementation of a
 * {@code java.io.OutputStream} that can be used to facilitate
 * internal communication with the Directory Server.  On the backend,
 * data written to this output stream will be first decoded as an
 * ASN.1 element and then as an LDAP message.  That LDAP message will
 * be converted to an internal operation which will then be processed
 * and the result returned to the client via the input stream on the
 * other side of the associated internal LDAP socket.
 */
@org.opends.server.types.PublicAPI(
     stability=org.opends.server.types.StabilityLevel.UNCOMMITTED,
     mayInstantiate=false,
     mayExtend=false,
     mayInvoke=true)
public final class InternalLDAPOutputStream
       extends OutputStream
       implements InternalSearchListener
{
  /** Indicates whether this stream has been closed. */
  private boolean closed;

  private final ASN1Reader reader;

  /** The internal LDAP socket with which this output stream is associated. */
  private final InternalLDAPSocket socket;

  /** The immediate data being written. */
  private ByteSequenceReader byteBuffer;

  /**
   * The save buffer used to store any unprocessed data waiting
   * to be read as ASN.1 elements. (Usually due to writing incomplete
   * ASN.1 elements.)
   */
  private final ByteStringBuilder saveBuffer;

  private final ByteSequenceReader saveBufferReader;

  /**
   * An adaptor class for reading from a save buffer and the bytes
   * being written sequentially using the InputStream interface.
   *
   * Since the bytes being written are only available duing the write
   * call, any unused data will be appended to the save buffer before
   * returning from the write method. This reader will always read the
   * save buffer first before the actual bytes being written to ensure
   * bytes are read in the same order as they are written.
   */
  private class CombinedBufferInputStream extends InputStream
  {
    /** {@inheritDoc} */
    @Override
    public int available()
    {
      // The number of available bytes is the sum of the save buffer
      // and the last read data in the NIO ByteStringBuilder.
      return saveBufferReader.remaining() + byteBuffer.remaining();
    }

    /** {@inheritDoc} */
    @Override
    public int read()
    {
      if(saveBufferReader.remaining() > 0)
      {
        // Try saved buffer first
        return 0xFF & saveBufferReader.readByte();
      }
      if(byteBuffer.remaining() > 0)
      {
        // Must still be on the channel buffer
        return 0xFF & byteBuffer.readByte();
      }

      return -1;
    }

    /** {@inheritDoc} */
    @Override
    public int read(byte[] bytes)
    {
      return read(bytes, 0, bytes.length);
    }

    /** {@inheritDoc} */
    @Override
    public int read(byte[] value, int off, int length)
    {
      int bytesCopied=0;
      int len;
      if(saveBufferReader.remaining() > 0)
      {
        // Copy out of the last saved buffer first
        len = Math.min(saveBufferReader.remaining(), length);
        saveBufferReader.readBytes(value, off, len);
        bytesCopied += len;
      }
      if(bytesCopied < length && byteBuffer.remaining() > 0)
      {
        // Copy out of the channel buffer if we haven't got
        // everything we needed.
        len = Math.min(byteBuffer.remaining(), length - bytesCopied);
        byteBuffer.readBytes(value, off + bytesCopied, len);
        bytesCopied += len;
      }
      return bytesCopied;
    }

    /** {@inheritDoc} */
    @Override
    public long skip(long length)
    {
      int bytesSkipped=0;
      int len;
      if(saveBufferReader.remaining() > 0)
      {
        // Skip in the last saved buffer first
        len = Math.min(saveBufferReader.remaining(), (int)length);
        saveBufferReader.position(saveBufferReader.position() + len);
        bytesSkipped += len;
      }
      if(bytesSkipped < length && byteBuffer.remaining() > 0)
      {
        //Skip in the channel buffer if we haven't skipped enough.
        len = Math.min(byteBuffer.remaining(),
            (int)length - bytesSkipped);
        byteBuffer.position(byteBuffer.position() + len);
        bytesSkipped += len;
      }
      return bytesSkipped;
    }
  }

  /**
   * Creates a new instance of an internal LDAP output stream that is
   * associated with the provided internal LDAP socket.
   *
   * @param  socket  The internal LDAP socket that will be serviced by
   *                 this internal LDAP output stream.
   */
  public InternalLDAPOutputStream(InternalLDAPSocket socket)
  {
    this.socket = socket;
    this.closed = false;
    this.saveBuffer = new ByteStringBuilder();
    this.saveBufferReader = saveBuffer.asReader();

    CombinedBufferInputStream bufferStream =
        new CombinedBufferInputStream();
    this.reader = ASN1.getReader(bufferStream);
  }



  /**
   * Closes this output stream, its associated socket, and the
   * socket's associated input stream.
   */
  @Override
  public void close()
  {
    socket.close();
  }



  /**
   * Closes this output stream through an internal mechanism that will
   * not cause an infinite recursion loop by trying to also close the
   * output stream.
   */
  @org.opends.server.types.PublicAPI(
       stability=org.opends.server.types.StabilityLevel.PRIVATE,
       mayInstantiate=false,
       mayExtend=false,
       mayInvoke=false)
  void closeInternal()
  {
    closed = true;
  }



  /**
   * Flushes this output stream and forces any buffered data to be
   * written out.  This will have no effect, since this output
   * stream implementation does not use buffering.
   */
  @Override
  public void flush()
  {
    // No implementation is required.
  }



  /**
   * Writes the contents of the provided byte array to this output
   * stream.
   *
   * @param  b  The byte array to be written.
   *
   * @throws  IOException  If the output stream is closed, or if there
   *                       is a problem with the data being written.
   */
  @Override
  public void write(byte[] b)
         throws IOException
  {
    write(b, 0, b.length);
  }



  /**
   * Writes the specified portion of the data in the provided byte
   * array to this output stream.  Any data written will be
   * accumulated until a complete ASN.1 element is available, at which
   * point it will be decoded as an LDAP message and converted to an
   * internal operation that will be processed.
   *
   * @param  b    The byte array containing the data to be read.
   * @param  off  The position in the array at which to start reading
   *              data.
   * @param  len  The number of bytes to read from the array.
   *
   * @throws  IOException  If the output stream is closed, or if there
   *                       is a problem with the data being written.
   */
  @Override
  public synchronized void write(byte[] b, int off, int len)
         throws IOException
  {
    if (closed)
    {
      LocalizableMessage m = ERR_INTERNALOS_CLOSED.get();
      throw new IOException(m.toString());
    }

    byteBuffer = ByteString.wrap(b, off, len).asReader();

    try
    {
      while(reader.elementAvailable())
      {
        LDAPMessage msg = LDAPReader.readMessage(reader);
        processMessage(msg);
      }
    }
    catch(Exception e)
    {
      throw new IOException(e.getMessage());
    }

    // Clear the save buffer if we have read all of it
    if(saveBufferReader.remaining() == 0)
    {
      saveBuffer.clear();
      saveBufferReader.rewind();
    }

    // Append any unused data in the channel buffer to the save buffer
    if(byteBuffer.remaining() > 0)
    {
      saveBuffer.appendBytes(byteBuffer, byteBuffer.remaining());
    }
  }



  /**
   * Writes a single byte of data to this output stream.  If the byte
   * written completes an ASN.1 element that was in progress, then it
   * will be decoded as an LDAP message and converted to an internal
   * operation that will be processed.  Otherwise, the data will be
   * accumulated until a complete element can be formed.
   *
   * @param  b The byte to be written.
   *
   * @throws  IOException  If the output stream is closed, or if there
   *                       is a problem with the data being written.
   */
  @Override
  public synchronized void write(int b)
         throws IOException
  {
    write(new byte[]{(byte)b}, 0, 1);
  }



  /**
   * Processes the provided ASN.1 element by decoding it as an LDAP
   * message, converting that to an internal operation, and sending
   * the appropriate response message(s) to the client through the
   * corresponding internal LDAP input stream.
   *
   * @param  message The LDAP message to process.
   *
   * @throws  IOException  If a problem occurs while attempting to
   *                       decode the provided ASN.1 element as an
   *                       LDAP message.
   */
  private void processMessage(LDAPMessage message)
          throws IOException
  {
    switch (message.getProtocolOpType())
    {
      case OP_TYPE_ABANDON_REQUEST:
        // No action is required.
        return;

      case OP_TYPE_ADD_REQUEST:
        processAddOperation(message);
        break;

      case OP_TYPE_BIND_REQUEST:
        processBindOperation(message);
        break;

      case OP_TYPE_COMPARE_REQUEST:
        processCompareOperation(message);
        break;


      case OP_TYPE_DELETE_REQUEST:
        processDeleteOperation(message);
        break;


      case OP_TYPE_EXTENDED_REQUEST:
        processExtendedOperation(message);
        break;


      case OP_TYPE_MODIFY_REQUEST:
        processModifyOperation(message);
        break;


      case OP_TYPE_MODIFY_DN_REQUEST:
        processModifyDNOperation(message);
        break;


      case OP_TYPE_SEARCH_REQUEST:
        processSearchOperation(message);
        break;


      case OP_TYPE_UNBIND_REQUEST:
        socket.close();
        break;


      default:
        LocalizableMessage m = ERR_INTERNALOS_INVALID_REQUEST.get(
                         message.getProtocolElementName());
        throw new IOException(m.toString());
    }
  }



  /**
   * Processes the content of the provided LDAP message as an add
   * operation and returns the appropriate result to the client.
   *
   * @param  message  The LDAP message containing the request to
   *                  process.
   *
   * @throws  IOException  If a problem occurs while attempting to
   *                       process the operation.
   */
  private void processAddOperation(LDAPMessage message)
          throws IOException
  {
    int messageID = message.getMessageID();
    AddRequestProtocolOp request = message.getAddRequestProtocolOp();

    InternalClientConnection conn = socket.getConnection();
    AddOperationBasis op =
         new AddOperationBasis(conn, InternalClientConnection.nextOperationID(),
                               messageID, message.getControls(),
                               request.getDN(),
                               request.getAttributes());
    op.run();

    AddResponseProtocolOp addResponse =
         new AddResponseProtocolOp(op.getResultCode().intValue(),
                                   op.getErrorMessage().toMessage(),
                                   op.getMatchedDN(),
                                   op.getReferralURLs());
    List<Control> responseControls = op.getResponseControls();

    socket.getInputStream().addLDAPMessage(
         new LDAPMessage(messageID, addResponse, responseControls));
  }



  /**
   * Processes the content of the provided LDAP message as a bind
   * operation and returns the appropriate result to the client.
   *
   * @param  message  The LDAP message containing the request to
   *                  process.
   *
   * @throws  IOException  If a problem occurs while attempting to
   *                       process the operation.
   */
  private void processBindOperation(LDAPMessage message)
          throws IOException
  {
    int messageID = message.getMessageID();
    BindRequestProtocolOp request =
         message.getBindRequestProtocolOp();

    if (request.getAuthenticationType() == AuthenticationType.SASL)
    {
      LocalizableMessage m = ERR_INTERNALOS_SASL_BIND_NOT_SUPPORTED.get();
      BindResponseProtocolOp bindResponse =
           new BindResponseProtocolOp(
                    LDAPResultCode.UNWILLING_TO_PERFORM, m);
      socket.getInputStream().addLDAPMessage(
           new LDAPMessage(messageID, bindResponse));
      return;
    }

    InternalClientConnection conn = socket.getConnection();
    BindOperationBasis op =
         new BindOperationBasis(conn, nextOperationID(),
                  messageID, message.getControls(),
                  String.valueOf(request.getProtocolVersion()),
                  request.getDN(), request.getSimplePassword());
    op.run();

    BindResponseProtocolOp bindResponse =
         new BindResponseProtocolOp(op.getResultCode().intValue(),
                                    op.getErrorMessage().toMessage(),
                                    op.getMatchedDN(),
                                    op.getReferralURLs());
    List<Control> responseControls = op.getResponseControls();

    if (bindResponse.getResultCode() == LDAPResultCode.SUCCESS)
    {
      socket.setConnection(new InternalClientConnection(
           op.getAuthenticationInfo()));
    }

    socket.getInputStream().addLDAPMessage(
         new LDAPMessage(messageID, bindResponse, responseControls));
  }



  /**
   * Processes the content of the provided LDAP message as a compare
   * operation and returns the appropriate result to the client.
   *
   * @param  message  The LDAP message containing the request to
   *                  process.
   *
   * @throws  IOException  If a problem occurs while attempting to
   *                       process the operation.
   */
  private void processCompareOperation(LDAPMessage message)
          throws IOException
  {
    int messageID = message.getMessageID();
    CompareRequestProtocolOp request =
         message.getCompareRequestProtocolOp();

    InternalClientConnection conn = socket.getConnection();
    CompareOperationBasis op =
         new CompareOperationBasis(conn, nextOperationID(),
                  messageID, message.getControls(), request.getDN(),
                  request.getAttributeType(),
                  request.getAssertionValue());
    op.run();

    CompareResponseProtocolOp compareResponse =
         new CompareResponseProtocolOp(
                  op.getResultCode().intValue(),
                  op.getErrorMessage().toMessage(),
                  op.getMatchedDN(),
                  op.getReferralURLs());
    List<Control> responseControls = op.getResponseControls();

    socket.getInputStream().addLDAPMessage(
         new LDAPMessage(messageID, compareResponse,
                         responseControls));
  }



  /**
   * Processes the content of the provided LDAP message as a delete
   * operation and returns the appropriate result to the client.
   *
   * @param  message  The LDAP message containing the request to
   *                  process.
   *
   * @throws  IOException  If a problem occurs while attempting to
   *                       process the operation.
   */
  private void processDeleteOperation(LDAPMessage message)
          throws IOException
  {
    int messageID = message.getMessageID();
    DeleteRequestProtocolOp request =
         message.getDeleteRequestProtocolOp();

    InternalClientConnection conn = socket.getConnection();
    DeleteOperationBasis op =
         new DeleteOperationBasis(conn, nextOperationID(),
                  messageID, message.getControls(), request.getDN());
    op.run();

    DeleteResponseProtocolOp deleteResponse =
         new DeleteResponseProtocolOp(
                  op.getResultCode().intValue(),
                  op.getErrorMessage().toMessage(),
                  op.getMatchedDN(),
                  op.getReferralURLs());
    List<Control> responseControls = op.getResponseControls();

    socket.getInputStream().addLDAPMessage(
         new LDAPMessage(messageID, deleteResponse,
                         responseControls));
  }



  /**
   * Processes the content of the provided LDAP message as an extended
   * operation and returns the appropriate result to the client.
   *
   * @param  message  The LDAP message containing the request to
   *                  process.
   *
   * @throws  IOException  If a problem occurs while attempting to
   *                       process the operation.
   */
  private void processExtendedOperation(LDAPMessage message)
          throws IOException
  {
    int messageID = message.getMessageID();
    ExtendedRequestProtocolOp request =
         message.getExtendedRequestProtocolOp();
    if (request.getOID().equals(OID_START_TLS_REQUEST))
    {
      LocalizableMessage m = ERR_INTERNALOS_STARTTLS_NOT_SUPPORTED.get();
      ExtendedResponseProtocolOp extendedResponse =
           new ExtendedResponseProtocolOp(
                    LDAPResultCode.UNWILLING_TO_PERFORM, m);
      socket.getInputStream().addLDAPMessage(
           new LDAPMessage(messageID, extendedResponse));
      return;
    }

    InternalClientConnection conn = socket.getConnection();
    ExtendedOperationBasis op =
         new ExtendedOperationBasis(conn, nextOperationID(),
                  messageID, message.getControls(), request.getOID(),
                  request.getValue());
    op.run();

    ExtendedResponseProtocolOp extendedResponse =
         new ExtendedResponseProtocolOp(
                  op.getResultCode().intValue(),
                  op.getErrorMessage().toMessage(),
                  op.getMatchedDN(),
                  op.getReferralURLs(), op.getResponseOID(),
                  op.getResponseValue());
    List<Control> responseControls = op.getResponseControls();

    socket.getInputStream().addLDAPMessage(
         new LDAPMessage(messageID, extendedResponse,
                         responseControls));
  }



  /**
   * Processes the content of the provided LDAP message as a modify
   * operation and returns the appropriate result to the client.
   *
   * @param  message  The LDAP message containing the request to
   *                  process.
   *
   * @throws  IOException  If a problem occurs while attempting to
   *                       process the operation.
   */
  private void processModifyOperation(LDAPMessage message)
          throws IOException
  {
    int messageID = message.getMessageID();
    ModifyRequestProtocolOp request =
         message.getModifyRequestProtocolOp();

    InternalClientConnection conn = socket.getConnection();
    ModifyOperationBasis op =
         new ModifyOperationBasis(conn, nextOperationID(),
                  messageID, message.getControls(), request.getDN(),
                  request.getModifications());
    op.run();

    ModifyResponseProtocolOp modifyResponse =
         new ModifyResponseProtocolOp(
                  op.getResultCode().intValue(),
                  op.getErrorMessage().toMessage(),
                  op.getMatchedDN(),
                  op.getReferralURLs());
    List<Control> responseControls = op.getResponseControls();

    socket.getInputStream().addLDAPMessage(
         new LDAPMessage(messageID, modifyResponse,
                         responseControls));
  }



  /**
   * Processes the content of the provided LDAP message as a modify DN
   * operation and returns the appropriate result to the client.
   *
   * @param  message  The LDAP message containing the request to
   *                  process.
   *
   * @throws  IOException  If a problem occurs while attempting to
   *                       process the operation.
   */
  private void processModifyDNOperation(LDAPMessage message)
          throws IOException
  {
    int messageID = message.getMessageID();
    ModifyDNRequestProtocolOp request =
         message.getModifyDNRequestProtocolOp();

    InternalClientConnection conn = socket.getConnection();
    ModifyDNOperationBasis op =
         new ModifyDNOperationBasis(conn, nextOperationID(),
               messageID, message.getControls(), request.getEntryDN(),
               request.getNewRDN(), request.deleteOldRDN(),
               request.getNewSuperior());
    op.run();

    ModifyDNResponseProtocolOp modifyDNResponse =
         new ModifyDNResponseProtocolOp(
                  op.getResultCode().intValue(),
                  op.getErrorMessage().toMessage(),
                  op.getMatchedDN(),
                  op.getReferralURLs());
    List<Control> responseControls = op.getResponseControls();

    socket.getInputStream().addLDAPMessage(
         new LDAPMessage(messageID, modifyDNResponse,
                         responseControls));
  }



  /**
   * Processes the content of the provided LDAP message as a search
   * operation and returns the appropriate result to the client.
   *
   * @param  message  The LDAP message containing the request to
   *                  process.
   *
   * @throws  IOException  If a problem occurs while attempting to
   *                       process the operation.
   */
  private void processSearchOperation(LDAPMessage message)
          throws IOException
  {
    int messageID = message.getMessageID();
    SearchRequestProtocolOp request = message.getSearchRequestProtocolOp();

    InternalClientConnection conn = socket.getConnection();
    DN baseDN = null;
    SearchFilter filter;
    try
    {
      baseDN = DN.valueOf(request.getBaseDN().toString());
      filter = request.getFilter().toSearchFilter();
    }
    catch (DirectoryException e)
    {
      final String cause = baseDN == null ? "baseDN" : "filter";
      throw error(LocalizableMessage.raw("Could not decode " + cause), e);
    }
    SearchRequest sr = newSearchRequest(baseDN, request.getScope(), filter)
        .setDereferenceAliasesPolicy(request.getDereferencePolicy())
        .setSizeLimit(request.getSizeLimit())
        .setTimeLimit(request.getTimeLimit())
        .setTypesOnly(request.getTypesOnly())
        .addAttribute(request.getAttributes())
        .addControl(message.getControls());
    InternalSearchOperation op = new InternalSearchOperation(
        conn, nextOperationID(), messageID, sr, this);
    op.run();

    SearchResultDoneProtocolOp searchDone =
         new SearchResultDoneProtocolOp(
                  op.getResultCode().intValue(),
                  op.getErrorMessage().toMessage(),
                  op.getMatchedDN(),
                  op.getReferralURLs());
    List<Control> responseControls = op.getResponseControls();

    socket.getInputStream().addLDAPMessage(
         new LDAPMessage(messageID, searchDone, responseControls));
  }



  /**
   * Performs any processing necessary for the provided search result
   * entry.
   *
   * @param  searchOperation  The internal search operation being
   *                          processed.
   * @param  searchEntry      The matching search result entry to be
   *                          processed.
   */
  @Override
  @org.opends.server.types.PublicAPI(
       stability=org.opends.server.types.StabilityLevel.PRIVATE,
       mayInstantiate=false,
       mayExtend=false,
       mayInvoke=false)
  public void handleInternalSearchEntry(
                   InternalSearchOperation searchOperation,
                   SearchResultEntry searchEntry)
  {
    List<Control> entryControls = searchEntry.getControls();

    SearchResultEntryProtocolOp entry =
         new SearchResultEntryProtocolOp(searchEntry);

    socket.getInputStream().addLDAPMessage(
         new LDAPMessage(searchOperation.getMessageID(), entry, entryControls));
  }



  /**
   * Performs any processing necessary for the provided search result reference.
   *
   * @param  searchOperation  The internal search operation being processed.
   * @param  searchReference  The search result reference to be processed.
   */
  @Override
  @org.opends.server.types.PublicAPI(
       stability=org.opends.server.types.StabilityLevel.PRIVATE,
       mayInstantiate=false,
       mayExtend=false,
       mayInvoke=false)
  public void handleInternalSearchReference(
                   InternalSearchOperation searchOperation,
                   SearchResultReference searchReference)
  {
    List<Control> entryControls = searchReference.getControls();

    SearchResultReferenceProtocolOp reference =
         new SearchResultReferenceProtocolOp(searchReference);

    socket.getInputStream().addLDAPMessage(
         new LDAPMessage(searchOperation.getMessageID(), reference,
                         entryControls));
  }



  /**
   * Retrieves a string representation of this internal LDAP socket.
   *
   * @return  A string representation of this internal LDAP socket.
   */
  @Override
  public String toString()
  {
    return getClass().getSimpleName();
  }
}