/*
 * Copyright 2007-2024 Ping Identity Corporation
 * All Rights Reserved.
 */
/*
 * Copyright 2007-2024 Ping Identity Corporation
 *
 * Licensed 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.
 */
/*
 * Copyright (C) 2007-2024 Ping Identity Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License (GPLv2 only)
 * or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
 * as published by the Free Software Foundation.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses>.
 */
package com.unboundid.ldap.sdk.controls;



import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import com.unboundid.asn1.ASN1Element;
import com.unboundid.asn1.ASN1OctetString;
import com.unboundid.asn1.ASN1Sequence;
import com.unboundid.ldap.sdk.Control;
import com.unboundid.ldap.sdk.JSONControlDecodeHelper;
import com.unboundid.ldap.sdk.LDAPException;
import com.unboundid.ldap.sdk.ResultCode;
import com.unboundid.util.Debug;
import com.unboundid.util.NotMutable;
import com.unboundid.util.NotNull;
import com.unboundid.util.Nullable;
import com.unboundid.util.StaticUtils;
import com.unboundid.util.ThreadSafety;
import com.unboundid.util.ThreadSafetyLevel;
import com.unboundid.util.json.JSONArray;
import com.unboundid.util.json.JSONField;
import com.unboundid.util.json.JSONObject;
import com.unboundid.util.json.JSONString;
import com.unboundid.util.json.JSONValue;

import static com.unboundid.ldap.sdk.controls.ControlMessages.*;



/**
 * This class provides an implementation of the LDAP pre-read request control
 * as defined in <A HREF="http://www.ietf.org/rfc/rfc4527.txt">RFC 4527</A>.  It
 * may be used to request that the server retrieve a copy of the target entry as
 * it appeared immediately before processing a delete, modify, or modify DN
 * operation.
 * <BR><BR>
 * If this control is included in a delete, modify, or modify DN request, then
 * the corresponding response may include a {@link PreReadResponseControl}
 * containing a version of the entry as it before after applying that change.
 * Note that this response control will only be included if the operation was
 * successful, so it will not be provided if the operation failed for some
 * reason (e.g., if the change would have violated the server schema, or if the
 * requester did not have sufficient permission to perform that operation).
 * <BR><BR>
 * The value of this control should contain a set of requested attributes to
 * include in the entry that is returned.  The server should treat this set of
 * requested attributes exactly as it treats the requested attributes from a
 * {@link com.unboundid.ldap.sdk.SearchRequest}.  As is the case with a search
 * request, if no attributes are specified, then all user attributes will be
 * included.
 * <BR><BR>
 * The use of the LDAP pre-read request control is virtually identical to the
 * use of the LDAP post-read request control.  See the documentation for the
 * {@link PostReadRequestControl} for an example that illustrates its use.
 */
@NotMutable()
@ThreadSafety(level=ThreadSafetyLevel.COMPLETELY_THREADSAFE)
public final class PreReadRequestControl
       extends Control
{
  /**
   * The OID (1.3.6.1.1.13.1) for the pre-read request control.
   */
  @NotNull public static final String PRE_READ_REQUEST_OID = "1.3.6.1.1.13.1";



  /**
   * The set of requested attributes that will be used if none are provided.
   */
  @NotNull private static final String[] NO_ATTRIBUTES = StaticUtils.NO_STRINGS;



  /**
   * The name of the field used to hold the requested attributes in the JSON
   * representation of this control.
   */
  @NotNull private static final String JSON_FIELD_ATTRIBUTES = "attributes";



  /**
   * The serial version UID for this serializable class.
   */
  private static final long serialVersionUID = 1205235290978028739L;



  // The set of requested attributes to retrieve from the target entry.
  @NotNull private final String[] attributes;



  /**
   * Creates a new pre-read request control that will retrieve the specified set
   * of attributes from the target entry.  It will be marked critical.
   *
   * @param  attributes  The set of attributes to retrieve from the target
   *                     entry.  It behaves in the same way as the set of
   *                     requested attributes for a search operation.  If this
   *                     is empty or {@code null}, then all user attributes
   *                     will be returned.
   */
  public PreReadRequestControl(@Nullable final String... attributes)
  {
    this(true, attributes);
  }



  /**
   * Creates a new pre-read request control that will retrieve the specified set
   * of attributes from the target entry.
   *
   * @param  isCritical  Indicates whether this control should be marked
   *                     critical.
   * @param  attributes  The set of attributes to retrieve from the target
   *                     entry.  It behaves in the same way as the set of
   *                     requested attributes for a search operation.  If this
   *                     is empty or {@code null}, then all user attributes
   *                     will be returned.
   */
  public PreReadRequestControl(final boolean isCritical,
                               @Nullable final String... attributes)
  {
    super(PRE_READ_REQUEST_OID, isCritical, encodeValue(attributes));

    if (attributes == null)
    {
      this.attributes = NO_ATTRIBUTES;
    }
    else
    {
      this.attributes = attributes;
    }
  }



  /**
   * Creates a new pre-read request control which is decoded from the provided
   * generic control.
   *
   * @param  control  The generic control to be decoded as a pre-read request
   *                  control.
   *
   * @throws  LDAPException  If the provided control cannot be decoded as a
   *                         pre-read request control.
   */
  public PreReadRequestControl(@NotNull final Control control)
         throws LDAPException
  {
    super(control);

    final ASN1OctetString value = control.getValue();
    if (value == null)
    {
      throw new LDAPException(ResultCode.DECODING_ERROR,
                              ERR_PRE_READ_REQUEST_NO_VALUE.get());
    }

    try
    {
      final ASN1Element valueElement = ASN1Element.decode(value.getValue());
      final ASN1Element[] attrElements =
           ASN1Sequence.decodeAsSequence(valueElement).elements();
      attributes = new String[attrElements.length];
      for (int i=0; i < attrElements.length; i++)
      {
        attributes[i] =
             ASN1OctetString.decodeAsOctetString(attrElements[i]).stringValue();
      }
    }
    catch (final Exception e)
    {
      Debug.debugException(e);
      throw new LDAPException(ResultCode.DECODING_ERROR,
                              ERR_PRE_READ_REQUEST_CANNOT_DECODE.get(e), e);
    }
  }



  /**
   * Encodes the provided information into an octet string that can be used as
   * the value for this control.
   *
   * @param  attributes  The set of attributes to retrieve from the target
   *                     entry.  It behaves in the same way as the set of
   *                     requested attributes for a search operation.  If this
   *                     is empty or {@code null}, then all user attributes
   *                     will be returned.
   *
   * @return  An ASN.1 octet string that can be used as the value for this
   *          control.
   */
  @NotNull()
  private static ASN1OctetString encodeValue(
                                      @Nullable final String[] attributes)
  {
    if ((attributes == null) || (attributes.length == 0))
    {
      return new ASN1OctetString(new ASN1Sequence().encode());
    }

    final ASN1OctetString[] elements = new ASN1OctetString[attributes.length];
    for (int i=0; i < attributes.length; i++)
    {
      elements[i] = new ASN1OctetString(attributes[i]);
    }

    return new ASN1OctetString(new ASN1Sequence(elements).encode());
  }



  /**
   * Retrieves the set of attributes that will be requested for inclusion in the
   * entry returned in the response control.
   *
   * @return  The set of attributes that will be requested for inclusion in the
   *          entry returned in the response control, or an empty array if all
   *          user attributes should be returned.
   */
  @NotNull()
  public String[] getAttributes()
  {
    return attributes;
  }



  /**
   * {@inheritDoc}
   */
  @Override()
  @NotNull()
  public String getControlName()
  {
    return INFO_CONTROL_NAME_PRE_READ_REQUEST.get();
  }



  /**
   * Retrieves a representation of this pre-read request control as a JSON
   * object.  The JSON object uses the following fields:
   * <UL>
   *   <LI>
   *     {@code oid} -- A mandatory string field whose value is the object
   *     identifier for this control.  For the pre-read request control, the
   *     OID is "1.3.6.1.1.13.1".
   *   </LI>
   *   <LI>
   *     {@code control-name} -- An optional string field whose value is a
   *     human-readable name for this control.  This field is only intended for
   *     descriptive purposes, and when decoding a control, the {@code oid}
   *     field should be used to identify the type of control.
   *   </LI>
   *   <LI>
   *     {@code criticality} -- A mandatory Boolean field used to indicate
   *     whether this control is considered critical.
   *   </LI>
   *   <LI>
   *     {@code value-base64} -- An optional string field whose value is a
   *     base64-encoded representation of the raw value for this pre-read
   *     request control.  Exactly one of the {@code value-base64} and
   *     {@code value-json} fields must be present.
   *   </LI>
   *   <LI>
   *     {@code value-json} -- An optional JSON object field whose value is a
   *     user-friendly representation of the value for this pre-read request
   *     control.  Exactly one of the {@code value-base64} and
   *     {@code value-json} fields must be present, and if the
   *     {@code value-json} field is used, then it will use the following
   *     fields:
   *     <UL>
   *       <LI>
   *         {@code attributes} -- An optional array field whose values are
   *         strings that represent the names of the attributes to include in
   *         the entry returned in the response control.
   *       </LI>
   *     </UL>
   *   </LI>
   * </UL>
   *
   * @return  A JSON object that contains a representation of this control.
   */
  @Override()
  @NotNull()
  public JSONObject toJSONControl()
  {
    final Map<String,JSONValue> valueFields = new LinkedHashMap<>();

    if ((attributes != null) && (attributes.length > 0))
    {
      final List<JSONValue> attrValues = new ArrayList<>(attributes.length);
      for (final String attribute : attributes)
      {
        attrValues.add(new JSONString(attribute));
      }

      valueFields.put(JSON_FIELD_ATTRIBUTES, new JSONArray(attrValues));
    }

    return new JSONObject(
         new JSONField(JSONControlDecodeHelper.JSON_FIELD_OID,
              PRE_READ_REQUEST_OID),
         new JSONField(JSONControlDecodeHelper.JSON_FIELD_CONTROL_NAME,
              INFO_CONTROL_NAME_PRE_READ_REQUEST.get()),
         new JSONField(JSONControlDecodeHelper.JSON_FIELD_CRITICALITY,
              isCritical()),
         new JSONField(JSONControlDecodeHelper.JSON_FIELD_VALUE_JSON,
              new JSONObject(valueFields)));
  }



  /**
   * Attempts to decode the provided object as a JSON representation of a
   * pre-read request control.
   *
   * @param  controlObject  The JSON object to be decoded.  It must not be
   *                        {@code null}.
   * @param  strict         Indicates whether to use strict mode when decoding
   *                        the provided JSON object.  If this is {@code true},
   *                        then this method will throw an exception if the
   *                        provided JSON object contains any unrecognized
   *                        fields.  If this is {@code false}, then unrecognized
   *                        fields will be ignored.
   *
   * @return  The pre-read request control that was decoded from the provided
   *          JSON object.
   *
   * @throws  LDAPException  If the provided JSON object cannot be parsed as a
   *                         valid pre-read request control.
   */
  @NotNull()
  public static PreReadRequestControl decodeJSONControl(
              @NotNull final JSONObject controlObject,
              final boolean strict)
         throws LDAPException
  {
    final JSONControlDecodeHelper jsonControl = new JSONControlDecodeHelper(
         controlObject, strict, true, true);

    final ASN1OctetString rawValue = jsonControl.getRawValue();
    if (rawValue != null)
    {
      return new PreReadRequestControl(new Control(jsonControl.getOID(),
           jsonControl.getCriticality(), rawValue));
    }


    final JSONObject valueObject = jsonControl.getValueObject();

    final String[] attributes;
    final List<JSONValue> attributesValues =
         valueObject.getFieldAsArray(JSON_FIELD_ATTRIBUTES);
    if (attributesValues == null)
    {
      attributes = null;
    }
    else
    {
      attributes = new String[attributesValues.size()];
      for (int i=0; i < attributes.length; i++)
      {
        final JSONValue v = attributesValues.get(i);
        if (v instanceof JSONString)
        {
          attributes[i] = ((JSONString) v).stringValue();
        }
        else
        {
          throw new LDAPException(ResultCode.DECODING_ERROR,
               ERR_PRE_READ_REQUEST_JSON_ATTR_NOT_STRING.get(
                    controlObject.toSingleLineString(),
                    JSON_FIELD_ATTRIBUTES));
        }
      }
    }


    if (strict)
    {
      final List<String> unrecognizedFields =
           JSONControlDecodeHelper.getControlObjectUnexpectedFields(
                valueObject, JSON_FIELD_ATTRIBUTES);
      if (! unrecognizedFields.isEmpty())
      {
        throw new LDAPException(ResultCode.DECODING_ERROR,
             ERR_PRE_READ_REQUEST_JSON_UNRECOGNIZED_FIELD.get(
                  controlObject.toSingleLineString(),
                  unrecognizedFields.get(0)));
      }
    }


    return new PreReadRequestControl(jsonControl.getCriticality(),
         attributes);
  }



  /**
   * {@inheritDoc}
   */
  @Override()
  public void toString(@NotNull final StringBuilder buffer)
  {
    buffer.append("PreReadRequestControl(attributes={");
    for (int i=0; i < attributes.length; i++)
    {
      if (i > 0)
      {
        buffer.append(", ");
      }
      buffer.append('\'');
      buffer.append(attributes[i]);
      buffer.append('\'');
    }
    buffer.append("}, isCritical=");
    buffer.append(isCritical());
    buffer.append(')');
  }
}