/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at
 * trunk/opendj3/legal-notices/CDDLv1_0.txt
 * or http://forgerock.org/license/CDDLv1.0.html.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at
 * trunk/opendj3/legal-notices/CDDLv1_0.txt.  If applicable,
 * add the following below this CDDL HEADER, with the fields enclosed
 * by brackets "[]" replaced with your own identifying information:
 *      Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 *
 *
 *      Copyright 2010 Sun Microsystems, Inc.
 *      Portions copyright 2011-2012 ForgeRock AS
 */

package org.forgerock.opendj.ldap;



import static org.forgerock.opendj.ldap.AttributeDescription.objectClass;

import java.util.*;

import org.forgerock.i18n.LocalizableMessage;
import org.forgerock.opendj.ldap.requests.ModifyRequest;
import org.forgerock.opendj.ldap.requests.Requests;
import org.forgerock.opendj.ldap.schema.*;

import com.forgerock.opendj.util.Function;
import com.forgerock.opendj.util.Iterables;
import com.forgerock.opendj.util.Validator;



/**
 * This class contains methods for creating and manipulating entries.
 *
 * @see Entry
 */
public final class Entries
{

  private static final class UnmodifiableEntry implements Entry
  {
    private final Entry entry;



    private UnmodifiableEntry(final Entry entry)
    {
      this.entry = entry;
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public boolean addAttribute(final Attribute attribute)
    {
      throw new UnsupportedOperationException();
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public boolean addAttribute(final Attribute attribute,
        final Collection<ByteString> duplicateValues)
    {
      throw new UnsupportedOperationException();
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public Entry addAttribute(final String attributeDescription,
        final Object... values)
    {
      throw new UnsupportedOperationException();
    }



    @Override
    public Entry clearAttributes()
    {
      throw new UnsupportedOperationException();
    }



    @Override
    public boolean containsAttribute(final Attribute attribute,
        final Collection<ByteString> missingValues)
    {
      return entry.containsAttribute(attribute, missingValues);
    }



    @Override
    public boolean containsAttribute(final String attributeDescription,
        final Object... values)
    {
      return entry.containsAttribute(attributeDescription, values);
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public boolean equals(final Object object)
    {
      return (object == this || entry.equals(object));
    }



    @Override
    public Iterable<Attribute> getAllAttributes()
    {
      return Iterables.unmodifiableIterable(Iterables.transformedIterable(
          entry.getAllAttributes(), UNMODIFIABLE_ATTRIBUTE_FUNCTION));
    }



    @Override
    public Iterable<Attribute> getAllAttributes(
        final AttributeDescription attributeDescription)
    {
      return Iterables.unmodifiableIterable(Iterables.transformedIterable(
          entry.getAllAttributes(attributeDescription),
          UNMODIFIABLE_ATTRIBUTE_FUNCTION));
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public Iterable<Attribute> getAllAttributes(
        final String attributeDescription)
    {
      return Iterables.unmodifiableIterable(Iterables.transformedIterable(
          entry.getAllAttributes(attributeDescription),
          UNMODIFIABLE_ATTRIBUTE_FUNCTION));
    }



    @Override
    public Attribute getAttribute(
        final AttributeDescription attributeDescription)
    {
      final Attribute attribute = entry.getAttribute(attributeDescription);
      if (attribute != null)
      {
        return Attributes.unmodifiableAttribute(attribute);
      }
      else
      {
        return null;
      }
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public Attribute getAttribute(final String attributeDescription)
    {
      final Attribute attribute = entry.getAttribute(attributeDescription);
      if (attribute != null)
      {
        return Attributes.unmodifiableAttribute(attribute);
      }
      else
      {
        return null;
      }
    }



    @Override
    public int getAttributeCount()
    {
      return entry.getAttributeCount();
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public DN getName()
    {
      return entry.getName();
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public int hashCode()
    {
      return entry.hashCode();
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public boolean removeAttribute(final Attribute attribute,
        final Collection<ByteString> missingValues)
    {
      throw new UnsupportedOperationException();
    }



    @Override
    public boolean removeAttribute(
        final AttributeDescription attributeDescription)
    {
      throw new UnsupportedOperationException();
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public Entry removeAttribute(final String attributeDescription,
        final Object... values)
    {
      throw new UnsupportedOperationException();
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public boolean replaceAttribute(final Attribute attribute)
    {
      throw new UnsupportedOperationException();
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public Entry replaceAttribute(final String attributeDescription,
        final Object... values)
    {
      throw new UnsupportedOperationException();
    }



    @Override
    public Entry setName(final DN dn)
    {
      throw new UnsupportedOperationException();
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public Entry setName(final String dn)
    {
      throw new UnsupportedOperationException();
    }



    /**
     * {@inheritDoc}
     */
    @Override
    public String toString()
    {
      return entry.toString();
    }

  }



  private static final Function<Attribute, Attribute, Void> UNMODIFIABLE_ATTRIBUTE_FUNCTION =
    new Function<Attribute, Attribute, Void>()
  {

    @Override
    public Attribute apply(final Attribute value, final Void p)
    {
      return Attributes.unmodifiableAttribute(value);
    }

  };



  private static final Comparator<Entry> COMPARATOR = new Comparator<Entry>()
  {
    public int compare(Entry o1, Entry o2)
    {
      return o1.getName().compareTo(o2.getName());
    }
  };



  /**
   * Returns a {@code Comparator} which can be used to compare entries by name
   * using the natural order for DN comparisons (parent before children).
   * <p>
   * In order to sort entries in reverse order (children first) use the
   * following code:
   *
   * <pre>
   * Collections.reverseOrder(Entries.compareByName());
   * </pre>
   *
   * For more complex sort orders involving one or more attributes refer to the
   * {@link SortKey} class.
   *
   * @return The {@code Comparator}.
   */
  public static Comparator<Entry> compareByName()
  {
    return COMPARATOR;
  }



  /**
   * Returns {@code true} if the provided entry is valid according to the
   * specified schema and schema validation policy.
   * <p>
   * If attribute value validation is enabled then following checks will be
   * performed:
   * <ul>
   * <li>checking that there is at least one value
   * <li>checking that single-valued attributes contain only a single value
   * </ul>
   * In particular, attribute values will not be checked for conformance to
   * their syntax since this is expected to have already been performed while
   * adding the values to the entry.
   *
   * @param entry
   *          The entry to be validated.
   * @param schema
   *          The schema against which the entry will be validated.
   * @param policy
   *          The schema validation policy.
   * @param errorMessages
   *          A collection into which any schema validation warnings or error
   *          messages can be placed, or {@code null} if they should not be
   *          saved.
   * @return {@code true} if the provided entry is valid according to the
   *         specified schema and schema validation policy.
   * @see Schema#validateEntry(Entry, SchemaValidationPolicy, Collection)
   */
  public static boolean conformsToSchema(final Entry entry,
      final Schema schema, final SchemaValidationPolicy policy,
      final Collection<LocalizableMessage> errorMessages)
  {
    return schema.validateEntry(entry, policy, errorMessages);
  }



  /**
   * Returns {@code true} if the provided entry is valid according to the
   * default schema and schema validation policy.
   * <p>
   * If attribute value validation is enabled then following checks will be
   * performed:
   * <ul>
   * <li>checking that there is at least one value
   * <li>checking that single-valued attributes contain only a single value
   * </ul>
   * In particular, attribute values will not be checked for conformance to
   * their syntax since this is expected to have already been performed while
   * adding the values to the entry.
   *
   * @param entry
   *          The entry to be validated.
   * @param policy
   *          The schema validation policy.
   * @param errorMessages
   *          A collection into which any schema validation warnings or error
   *          messages can be placed, or {@code null} if they should not be
   *          saved.
   * @return {@code true} if the provided entry is valid according to the
   *         default schema and schema validation policy.
   * @see Schema#validateEntry(Entry, SchemaValidationPolicy, Collection)
   */
  public static boolean conformsToSchema(final Entry entry,
      final SchemaValidationPolicy policy,
      final Collection<LocalizableMessage> errorMessages)
  {
    return conformsToSchema(entry, Schema.getDefaultSchema(), policy,
        errorMessages);
  }



  /**
   * Creates a new modify request containing a list of modifications which can
   * be used to transform {@code fromEntry} into entry {@code toEntry}.
   * <p>
   * The modify request is reversible: it will contain only modifications of
   * type {@link ModificationType#ADD ADD} and {@link ModificationType#DELETE
   * DELETE}.
   * <p>
   * Finally, the modify request will use the distinguished name taken from
   * {@code fromEntry}. Moreover, this method will not check to see if both
   * {@code fromEntry} and {@code toEntry} have the same distinguished name.
   * <p>
   * This method is equivalent to:
   *
   * <pre>
   * ModifyRequest request = Requests.newModifyRequest(fromEntry, toEntry);
   * </pre>
   *
   * @param fromEntry
   *          The source entry.
   * @param toEntry
   *          The destination entry.
   * @return A modify request containing a list of modifications which can be
   *         used to transform {@code fromEntry} into entry {@code toEntry}.
   * @throws NullPointerException
   *           If {@code fromEntry} or {@code toEntry} were {@code null}.
   * @see Requests#newModifyRequest(Entry, Entry)
   */
  public static ModifyRequest diffEntries(final Entry fromEntry,
      final Entry toEntry)
  {
    Validator.ensureNotNull(fromEntry, toEntry);

    final ModifyRequest request = Requests
        .newModifyRequest(fromEntry.getName());

    TreeMapEntry tfrom;
    if (fromEntry instanceof TreeMapEntry)
    {
      tfrom = (TreeMapEntry) fromEntry;
    }
    else
    {
      tfrom = new TreeMapEntry(fromEntry);
    }

    TreeMapEntry tto;
    if (toEntry instanceof TreeMapEntry)
    {
      tto = (TreeMapEntry) toEntry;
    }
    else
    {
      tto = new TreeMapEntry(toEntry);
    }

    final Iterator<Attribute> ifrom = tfrom.getAllAttributes().iterator();
    final Iterator<Attribute> ito = tto.getAllAttributes().iterator();

    Attribute afrom = ifrom.hasNext() ? ifrom.next() : null;
    Attribute ato = ito.hasNext() ? ito.next() : null;

    while (afrom != null && ato != null)
    {
      final AttributeDescription adfrom = afrom.getAttributeDescription();
      final AttributeDescription adto = ato.getAttributeDescription();

      final int cmp = adfrom.compareTo(adto);
      if (cmp == 0)
      {
        // Attribute is in both entries. Compute the set of values to be added
        // and removed. We won't replace the attribute because this is not
        // reversible.
        final Attribute addedValues = new LinkedAttribute(ato);
        addedValues.removeAll(afrom);
        if (!addedValues.isEmpty())
        {
          request.addModification(new Modification(ModificationType.ADD,
              addedValues));
        }

        final Attribute deletedValues = new LinkedAttribute(afrom);
        deletedValues.removeAll(ato);
        if (!deletedValues.isEmpty())
        {
          request.addModification(new Modification(ModificationType.DELETE,
              deletedValues));
        }

        afrom = ifrom.hasNext() ? ifrom.next() : null;
        ato = ito.hasNext() ? ito.next() : null;
      }
      else if (cmp < 0)
      {
        // afrom in source, but not destination.
        request
            .addModification(new Modification(ModificationType.DELETE, afrom));
        afrom = ifrom.hasNext() ? ifrom.next() : null;
      }
      else
      {
        // ato in destination, but not in source.
        request.addModification(new Modification(ModificationType.ADD, ato));
        ato = ito.hasNext() ? ito.next() : null;
      }
    }

    // Additional attributes in source entry: these must be deleted.
    if (afrom != null)
    {
      request.addModification(new Modification(ModificationType.DELETE, afrom));
    }

    while (ifrom.hasNext())
    {
      final Attribute a = ifrom.next();
      request.addModification(new Modification(ModificationType.DELETE, a));
    }

    // Additional attributes in destination entry: these must be added.
    if (ato != null)
    {
      request.addModification(new Modification(ModificationType.ADD, ato));
    }

    while (ito.hasNext())
    {
      final Attribute a = ito.next();
      request.addModification(new Modification(ModificationType.ADD, a));
    }

    return request;
  }



  /**
   * Returns an unmodifiable set containing the object classes associated with
   * the provided entry. This method will ignore unrecognized object classes.
   * <p>
   * This method uses the default schema for decoding the object class attribute
   * values.
   *
   * @param entry
   *          The entry whose object classes are required.
   * @return An unmodifiable set containing the object classes associated with
   *         the provided entry.
   */
  public static Set<ObjectClass> getObjectClasses(final Entry entry)
  {
    return getObjectClasses(entry, Schema.getDefaultSchema());
  }



  /**
   * Returns an unmodifiable set containing the object classes associated with
   * the provided entry. This method will ignore unrecognized object classes.
   *
   * @param entry
   *          The entry whose object classes are required.
   * @param schema
   *          The schema which should be used for decoding the object class
   *          attribute values.
   * @return An unmodifiable set containing the object classes associated with
   *         the provided entry.
   */
  public static Set<ObjectClass> getObjectClasses(final Entry entry,
      final Schema schema)
  {
    final Attribute objectClassAttribute = entry
        .getAttribute(AttributeDescription.objectClass());
    if (objectClassAttribute == null)
    {
      return Collections.emptySet();
    }
    else
    {
      final Set<ObjectClass> objectClasses = new HashSet<ObjectClass>(
          objectClassAttribute.size());
      for (final ByteString v : objectClassAttribute)
      {
        final String objectClassName = v.toString();
        final ObjectClass objectClass;
        try
        {
          objectClass = schema.getObjectClass(objectClassName);
          objectClasses.add(objectClass);
        }
        catch (final UnknownSchemaElementException e)
        {
          // Ignore.
          continue;
        }
      }
      return Collections.unmodifiableSet(objectClasses);
    }
  }



  /**
   * Returns the structural object class associated with the provided entry, or
   * {@code null} if none was found. If the entry contains multiple structural
   * object classes then the first will be returned. This method will ignore
   * unrecognized object classes.
   * <p>
   * This method uses the default schema for decoding the object class attribute
   * values.
   *
   * @param entry
   *          The entry whose structural object class is required.
   * @return The structural object class associated with the provided entry, or
   *         {@code null} if none was found.
   */
  public static ObjectClass getStructuralObjectClass(final Entry entry)
  {
    return getStructuralObjectClass(entry, Schema.getDefaultSchema());
  }



  /**
   * Returns the structural object class associated with the provided entry, or
   * {@code null} if none was found. If the entry contains multiple structural
   * object classes then the first will be returned. This method will ignore
   * unrecognized object classes.
   *
   * @param entry
   *          The entry whose structural object class is required.
   * @param schema
   *          The schema which should be used for decoding the object class
   *          attribute values.
   * @return The structural object class associated with the provided entry, or
   *         {@code null} if none was found.
   */
  public static ObjectClass getStructuralObjectClass(final Entry entry,
      final Schema schema)
  {
    ObjectClass structuralObjectClass = null;
    final Attribute objectClassAttribute = entry.getAttribute(objectClass());

    if (objectClassAttribute == null)
    {
      return null;
    }

    for (final ByteString v : objectClassAttribute)
    {
      final String objectClassName = v.toString();
      final ObjectClass objectClass;
      try
      {
        objectClass = schema.getObjectClass(objectClassName);
      }
      catch (final UnknownSchemaElementException e)
      {
        // Ignore.
        continue;
      }

      if (objectClass.getObjectClassType() == ObjectClassType.STRUCTURAL)
      {
        if (structuralObjectClass == null
            || objectClass.isDescendantOf(structuralObjectClass))
        {
          structuralObjectClass = objectClass;
        }
      }
    }

    return structuralObjectClass;
  }



  /**
   * Returns a read-only view of {@code entry} and its attributes. Query
   * operations on the returned entry and its attributes "read-through" to the
   * underlying entry or attribute, and attempts to modify the returned entry
   * and its attributes either directly or indirectly via an iterator result in
   * an {@code UnsupportedOperationException}.
   *
   * @param entry
   *          The entry for which a read-only view is to be returned.
   * @return A read-only view of {@code entry}.
   * @throws NullPointerException
   *           If {@code entry} was {@code null}.
   */
  public static Entry unmodifiableEntry(final Entry entry)
  {
    if (entry instanceof UnmodifiableEntry)
    {
      return entry;
    }
    else
    {
      return new UnmodifiableEntry(entry);
    }
  }



  // Prevent instantiation.
  private Entries()
  {
    // Nothing to do.
  }
}