/*
 * 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 2006-2010 Sun Microsystems, Inc.
 * Portions Copyright 2011-2016 ForgeRock AS.
 */
package org.opends.server.types;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeMap;
import java.util.regex.Pattern;

import org.forgerock.i18n.LocalizableMessage;
import org.forgerock.opendj.ldap.DN;
import org.forgerock.opendj.ldap.ResultCode;
import org.opends.server.core.DirectoryServer;
import org.opends.server.util.StaticUtils;

import static org.opends.messages.SchemaMessages.*;

/**
 * An RFC 3672 subtree specification.
 * <p>
 * This implementation extends RFC 3672 by supporting search filters
 * for specification filters. More specifically, the
 * {@code Refinement} product has been extended as follows:
 *
 * <pre>
 *  Refinement = item / and / or / not / Filter
 *
 *  Filter     = dquote *SafeUTF8Character dquote
 * </pre>
 *
 * @see <a href="http://tools.ietf.org/html/rfc3672">RFC 3672 -
 *      Subentries in the Lightweight Directory Access Protocol (LDAP)
 *      </a>
 */
@org.opends.server.types.PublicAPI(
    stability = org.opends.server.types.StabilityLevel.VOLATILE,
    mayInstantiate = false,
    mayExtend = true,
    mayInvoke = false)
public final class SubtreeSpecification
{

  /**
   * RFC 3672 subtree specification AND refinement. This type of
   * refinement filters entries based on all of the underlying
   * refinements being <code>true</code>.
   */
  public static final class AndRefinement extends Refinement
  {
    /** The set of refinements which must all be true. */
    private final Collection<Refinement> refinementSet;

    /**
     * Create a new AND refinement.
     *
     * @param refinementSet
     *          The set of refinements which must all be
     *          <code>true</code>.
     */
    public AndRefinement(final Collection<Refinement> refinementSet)
    {
      this.refinementSet = refinementSet;
    }

    @Override
    public boolean equals(final Object obj)
    {
      if (this == obj)
      {
        return true;
      }

      if (obj instanceof AndRefinement)
      {
        final AndRefinement other = (AndRefinement) obj;

        return refinementSet.equals(other.refinementSet);
      }

      return false;
    }

    @Override
    public int hashCode()
    {
      return refinementSet.hashCode();
    }

    @Override
    public boolean matches(final Entry entry)
    {
      for (final Refinement refinement : refinementSet)
      {
        if (!refinement.matches(entry))
        {
          return false;
        }
      }

      // All sub-refinements matched.
      return true;
    }

    @Override
    public StringBuilder toString(final StringBuilder builder)
    {
      switch (refinementSet.size())
      {
      case 0:
        // Do nothing.
        break;
      case 1:
        refinementSet.iterator().next().toString(builder);
        break;
      default:
        builder.append("and:{");
        final Iterator<Refinement> iterator = refinementSet
            .iterator();
        iterator.next().toString(builder);
        while (iterator.hasNext())
        {
          builder.append(", ");
          iterator.next().toString(builder);
        }
        builder.append("}");
        break;
      }

      return builder;
    }
  }

  /** A refinement which uses a search filter. */
  public static final class FilterRefinement extends Refinement
  {
    /** The search filter. */
    private final SearchFilter filter;

    /**
     * Create a new filter refinement.
     *
     * @param filter
     *          The search filter.
     */
    public FilterRefinement(final SearchFilter filter)
    {
      this.filter = filter;
    }

    @Override
    public boolean equals(final Object obj)
    {
      if (this == obj)
      {
        return true;
      }

      if (obj instanceof FilterRefinement)
      {
        final FilterRefinement other = (FilterRefinement) obj;
        return filter.equals(other.filter);
      }

      return false;
    }

    @Override
    public int hashCode()
    {
      return filter.hashCode();
    }

    @Override
    public boolean matches(final Entry entry)
    {
      try
      {
        return filter.matchesEntry(entry);
      }
      catch (final DirectoryException e)
      {
        // TODO: need to decide what to do with the exception here.
        // It's probably safe to ignore, but we could log it perhaps.
        return false;
      }
    }

    @Override
    public StringBuilder toString(final StringBuilder builder)
    {
      StaticUtils.toRFC3641StringValue(builder, filter.toString());
      return builder;
    }
  }

  /**
   * RFC 3672 subtree specification Item refinement. This type of
   * refinement filters entries based on the presence of a specified
   * object class.
   */
  public static final class ItemRefinement extends Refinement
  {
    /** The item's object class. */
    private final String objectClass;

    /** The item's normalized object class. */
    private final String normalizedObjectClass;

    /**
     * Create a new item refinement.
     *
     * @param objectClass
     *          The item's object class.
     */
    public ItemRefinement(final String objectClass)
    {
      this.objectClass = objectClass;
      this.normalizedObjectClass = StaticUtils
          .toLowerCase(objectClass.trim());
    }

    @Override
    public boolean equals(final Object obj)
    {
      if (this == obj)
      {
        return true;
      }

      if (obj instanceof ItemRefinement)
      {
        final ItemRefinement other = (ItemRefinement) obj;

        return normalizedObjectClass
            .equals(other.normalizedObjectClass);
      }

      return false;
    }

    @Override
    public int hashCode()
    {
      return normalizedObjectClass.hashCode();
    }

    @Override
    public boolean matches(final Entry entry)
    {
      final ObjectClass oc = DirectoryServer.getObjectClass(normalizedObjectClass);
      return oc != null && entry.hasObjectClass(oc);
    }

    @Override
    public StringBuilder toString(final StringBuilder builder)
    {
      builder.append("item:");
      builder.append(objectClass);
      return builder;
    }
  }

  /**
   * RFC 3672 subtree specification NOT refinement. This type of
   * refinement filters entries based on the underlying refinement
   * being <code>false</code>
   * .
   */
  public static final class NotRefinement extends Refinement
  {
    /** The inverted refinement. */
    private final Refinement refinement;

    /**
     * Create a new NOT refinement.
     *
     * @param refinement
     *          The refinement which must be <code>false</code>.
     */
    public NotRefinement(final Refinement refinement)
    {
      this.refinement = refinement;
    }

    @Override
    public boolean equals(final Object obj)
    {
      if (this == obj)
      {
        return true;
      }

      if (obj instanceof NotRefinement)
      {
        final NotRefinement other = (NotRefinement) obj;

        return refinement.equals(other.refinement);
      }

      return false;
    }

    @Override
    public int hashCode()
    {
      return refinement.hashCode();
    }

    @Override
    public boolean matches(final Entry entry)
    {
      return !refinement.matches(entry);
    }

    @Override
    public StringBuilder toString(final StringBuilder builder)
    {
      builder.append("not:");
      return refinement.toString(builder);
    }
  }

  /**
   * RFC 3672 subtree specification OR refinement. This type of
   * refinement filters entries based on at least one of the
   * underlying refinements being <code>true</code>.
   */
  public static final class OrRefinement extends Refinement
  {
    /** The set of refinements of which at least one must be true. */
    private final Collection<Refinement> refinementSet;

    /**
     * Create a new OR refinement.
     *
     * @param refinementSet
     *          The set of refinements of which at least one must be
     *          <code>true</code>.
     */
    public OrRefinement(final Collection<Refinement> refinementSet)
    {
      this.refinementSet = refinementSet;
    }

    @Override
    public boolean equals(final Object obj)
    {
      if (this == obj)
      {
        return true;
      }

      if (obj instanceof AndRefinement)
      {
        final AndRefinement other = (AndRefinement) obj;

        return refinementSet.equals(other.refinementSet);
      }

      return false;
    }

    @Override
    public int hashCode()
    {
      return refinementSet.hashCode();
    }

    @Override
    public boolean matches(final Entry entry)
    {
      for (final Refinement refinement : refinementSet)
      {
        if (refinement.matches(entry))
        {
          return true;
        }
      }

      // No sub-refinements matched.
      return false;
    }

    @Override
    public StringBuilder toString(final StringBuilder builder)
    {
      switch (refinementSet.size())
      {
      case 0:
        // Do nothing.
        break;
      case 1:
        refinementSet.iterator().next().toString(builder);
        break;
      default:
        builder.append("or:{");
        final Iterator<Refinement> iterator = refinementSet
            .iterator();
        iterator.next().toString(builder);
        while (iterator.hasNext())
        {
          builder.append(", ");
          iterator.next().toString(builder);
        }
        builder.append("}");
        break;
      }

      return builder;
    }
  }

  /** Abstract interface for RFC3672 specification filter refinements. */
  public static abstract class Refinement
  {
    /** Create a new RFC3672 specification filter refinement. */
    protected Refinement()
    {
      // No implementation required.
    }

    @Override
    public abstract boolean equals(Object obj);

    @Override
    public abstract int hashCode();

    /**
     * Check if the refinement matches the given entry.
     *
     * @param entry
     *          The filterable entry.
     * @return Returns <code>true</code> if the entry matches the
     *         refinement, or <code>false</code> otherwise.
     */
    public abstract boolean matches(Entry entry);

    @Override
    public final String toString()
    {
      final StringBuilder builder = new StringBuilder();

      return toString(builder).toString();
    }

    /**
     * Append the string representation of the refinement to the
     * provided strin builder.
     *
     * @param builder
     *          The string builder.
     * @return The string builder.
     */
    public abstract StringBuilder toString(StringBuilder builder);
  }

  /**
   * Internal utility class which can be used by sub-classes to help
   * parse string representations.
   */
  protected static final class Parser
  {
    /** Text scanner used to parse the string value. */
    private final Scanner scanner;

    /** Pattern used to detect left braces. */
    private static Pattern LBRACE = Pattern.compile("\\{.*");
    /** Pattern used to parse left braces. */
    private static Pattern LBRACE_TOKEN = Pattern.compile("\\{");
    /** Pattern used to detect right braces. */
    private static Pattern RBRACE = Pattern.compile("\\}.*");
    /** Pattern used to parse right braces. */
    private static Pattern RBRACE_TOKEN = Pattern.compile("\\}");
    /** Pattern used to detect comma separators. */
    private static Pattern SEP = Pattern.compile(",.*");
    /** Pattern used to parse comma separators. */
    private static Pattern SEP_TOKEN = Pattern.compile(",");
    /** Pattern used to detect colon separators. */
    private static Pattern COLON = Pattern.compile(":.*");
    /** Pattern used to parse colon separators. */
    private static Pattern COLON_TOKEN = Pattern.compile(":");
    /** Pattern used to detect integer values. */
    private static Pattern INT = Pattern.compile("\\d.*");
    /** Pattern used to parse integer values. */
    private static Pattern INT_TOKEN = Pattern.compile("\\d+");
    /** Pattern used to detect name values. */
    private static Pattern NAME = Pattern.compile("[\\w_;-].*");
    /** Pattern used to parse name values. */
    private static Pattern NAME_TOKEN = Pattern.compile("[\\w_;-]+");
    /** Pattern used to detect RFC3641 string values. */
    private static Pattern STRING_VALUE = Pattern.compile("\".*");
    /** Pattern used to parse RFC3641 string values. */
    private static Pattern STRING_VALUE_TOKEN = Pattern
        .compile("\"([^\"]|(\"\"))*\"");

    /**
     * Create a new parser for a subtree specification string value.
     *
     * @param value
     *          The subtree specification string value.
     */
    public Parser(final String value)
    {
      this.scanner = new Scanner(value);
    }

    /**
     * Determine if there are remaining tokens.
     *
     * @return <code>true</code> if and only if there are remaining
     *         tokens.
     */
    public boolean hasNext()
    {
      return scanner.hasNext();
    }

    /**
     * Determine if the next token is a right-brace character.
     *
     * @return <code>true</code> if and only if the next token is a
     *         valid right brace character.
     */
    public boolean hasNextRightBrace()
    {
      return scanner.hasNext(RBRACE);
    }

    /**
     * Scans the next token of the input as a non-negative
     * <code>int</code> value.
     *
     * @return The name value scanned from the input.
     * @throws InputMismatchException
     *           If the next token is not a valid non-negative integer
     *           string.
     * @throws NoSuchElementException
     *           If input is exhausted.
     */
    public int nextInt() throws InputMismatchException,
        NoSuchElementException
    {
      final String s = nextValue(INT, INT_TOKEN);
      return Integer.parseInt(s);
    }

    /**
     * Scans the next token of the input as a key value.
     *
     * @return The lower-case key value scanned from the input.
     * @throws InputMismatchException
     *           If the next token is not a valid key string.
     * @throws NoSuchElementException
     *           If input is exhausted.
     */
    public String nextKey() throws InputMismatchException,
        NoSuchElementException
    {
      return StaticUtils.toLowerCase(scanner.next());
    }

    /**
     * Scans the next token of the input as a name value.
     * <p>
     * A name is any string containing only alpha-numeric characters
     * or hyphens, semi-colons, or underscores.
     *
     * @return The name value scanned from the input.
     * @throws InputMismatchException
     *           If the next token is not a valid name string.
     * @throws NoSuchElementException
     *           If input is exhausted.
     */
    public String nextName() throws InputMismatchException,
        NoSuchElementException
    {
      return nextValue(NAME, NAME_TOKEN);
    }

    /**
     * Scans the next tokens of the input as a set of specific
     * exclusions encoded according to the SpecificExclusion
     * production in RFC 3672.
     *
     * @param chopBefore
     *          The set of chop before local names.
     * @param chopAfter
     *          The set of chop after local names.
     * @throws InputMismatchException
     *           If the common component did not have a valid syntax.
     * @throws NoSuchElementException
     *           If input is exhausted.
     * @throws DirectoryException
     *           If an error occurred when attempting to parse a
     *           DN value.
     */
    public void nextSpecificExclusions(final Set<DN> chopBefore,
        final Set<DN> chopAfter) throws InputMismatchException,
        NoSuchElementException, DirectoryException
    {
      // Skip leading open-brace.
      skipLeftBrace();

      // Parse each chop DN in the sequence.
      boolean isFirstValue = true;
      while (true)
      {
        // Make sure that there is a closing brace.
        if (hasNextRightBrace())
        {
          skipRightBrace();
          break;
        }

        // Make sure that there is a comma separator if this is not
        // the first element.
        if (!isFirstValue)
        {
          skipSeparator();
        }
        else
        {
          isFirstValue = false;
        }

        // Parse each chop specification which is of the form
        // <type>:<value>.
        final String type = StaticUtils.toLowerCase(nextName());
        skipColon();
        if ("chopbefore".equals(type))
        {
          chopBefore.add(DN.valueOf(nextStringValue()));
        }
        else if ("chopafter".equals(type))
        {
          chopAfter.add(DN.valueOf(nextStringValue()));
        }
        else
        {
          throw new java.util.InputMismatchException();
        }
      }
    }

    /**
     * Scans the next token of the input as a string quoted according
     * to the StringValue production in RFC 3641.
     * <p>
     * The return string has its outer double quotes removed and any
     * escape inner double quotes unescaped.
     *
     * @return The string value scanned from the input.
     * @throws InputMismatchException
     *           If the next token is not a valid string.
     * @throws NoSuchElementException
     *           If input is exhausted.
     */
    public String nextStringValue() throws InputMismatchException,
        NoSuchElementException
    {
      final String s = nextValue(STRING_VALUE, STRING_VALUE_TOKEN);
      return s.substring(1, s.length() - 1).replace("\"\"", "\"");
    }

    /**
     * Skip a colon separator.
     *
     * @throws InputMismatchException
     *           If the next token is not a colon separator character.
     * @throws NoSuchElementException
     *           If input is exhausted.
     */
    public void skipColon() throws InputMismatchException,
        NoSuchElementException
    {
      nextValue(COLON, COLON_TOKEN);
    }

    /**
     * Skip a left-brace character.
     *
     * @throws InputMismatchException
     *           If the next token is not a left-brace character.
     * @throws NoSuchElementException
     *           If input is exhausted.
     */
    public void skipLeftBrace() throws InputMismatchException,
        NoSuchElementException
    {
      nextValue(LBRACE, LBRACE_TOKEN);
    }

    /**
     * Skip a right-brace character.
     *
     * @throws InputMismatchException
     *           If the next token is not a right-brace character.
     * @throws NoSuchElementException
     *           If input is exhausted.
     */
    public void skipRightBrace() throws InputMismatchException,
        NoSuchElementException
    {
      nextValue(RBRACE, RBRACE_TOKEN);
    }

    /**
     * Skip a comma separator.
     *
     * @throws InputMismatchException
     *           If the next token is not a comma separator character.
     * @throws NoSuchElementException
     *           If input is exhausted.
     */
    public void skipSeparator() throws InputMismatchException,
        NoSuchElementException
    {
      nextValue(SEP, SEP_TOKEN);
    }

    /**
     * Parse the next token from the string using the specified
     * patterns.
     *
     * @param head
     *          The pattern used to determine if the next token is a
     *          possible match.
     * @param content
     *          The pattern used to parse the token content.
     * @return The next token matching the <code>content</code>
     *         pattern.
     * @throws InputMismatchException
     *           If the next token does not match the
     *           <code>content</code> pattern.
     * @throws NoSuchElementException
     *           If input is exhausted.
     */
    private String nextValue(final Pattern head,
        final Pattern content)
        throws InputMismatchException, NoSuchElementException
    {
      if (!scanner.hasNext())
      {
        throw new java.util.NoSuchElementException();
      }

      if (!scanner.hasNext(head))
      {
        throw new java.util.InputMismatchException();
      }

      final String s = scanner.findInLine(content);
      if (s == null)
      {
        throw new java.util.InputMismatchException();
      }

      return s;
    }
  }

  /**
   * Parses the string argument as an RFC3672 subtree specification.
   *
   * @param rootDN
   *          The DN of the subtree specification's base entry.
   * @param s
   *          The string to be parsed.
   * @return The RFC3672 subtree specification represented by the
   *         string argument.
   * @throws DirectoryException
   *           If the string does not contain a parsable relative
   *           subtree specification.
   */
  public static SubtreeSpecification valueOf(final DN rootDN,
      final String s) throws DirectoryException
  {
    // Default values.
    DN relativeBaseDN = null;

    int minimum = -1;
    int maximum = -1;

    final HashSet<DN> chopBefore = new HashSet<>();
    final HashSet<DN> chopAfter = new HashSet<>();

    Refinement refinement = null;

    // Value must have an opening left brace.
    final Parser parser = new Parser(s);
    boolean isValid = true;

    try
    {
      parser.skipLeftBrace();

      // Parse each element of the value sequence.
      boolean isFirst = true;

      while (true)
      {
        if (parser.hasNextRightBrace())
        {
          // Make sure that there is a closing brace and no trailing text.
          parser.skipRightBrace();

          if (parser.hasNext())
          {
            throw new java.util.InputMismatchException();
          }
          break;
        }

        // Make sure that there is a comma separator if this is not
        // the first element.
        if (!isFirst)
        {
          parser.skipSeparator();
        }
        else
        {
          isFirst = false;
        }

        final String key = parser.nextKey();
        if ("base".equals(key))
        {
          if (relativeBaseDN != null)
          {
            // Relative base DN specified more than once.
            throw new InputMismatchException();
          }
          relativeBaseDN = DN.valueOf(parser.nextStringValue());
        }
        else if ("minimum".equals(key))
        {
          if (minimum != -1)
          {
            // Minimum specified more than once.
            throw new InputMismatchException();
          }
          minimum = parser.nextInt();
        }
        else if ("maximum".equals(key))
        {
          if (maximum != -1)
          {
            // Maximum specified more than once.
            throw new InputMismatchException();
          }
          maximum = parser.nextInt();
        }
        else if ("specificationfilter".equals(key))
        {
          if (refinement != null)
          {
            // Refinements specified more than once.
            throw new InputMismatchException();
          }

          // First try normal search filter before RFC3672 refinements.
          try
          {
            final SearchFilter filter = SearchFilter
                .createFilterFromString(parser.nextStringValue());
            refinement = new FilterRefinement(filter);
          }
          catch (final InputMismatchException e)
          {
            refinement = parseRefinement(parser);
          }
        }
        else if ("specificexclusions".equals(key))
        {
          if (!chopBefore.isEmpty() || !chopAfter.isEmpty())
          {
            // Specific exclusions specified more than once.
            throw new InputMismatchException();
          }

          parser.nextSpecificExclusions(chopBefore, chopAfter);
        }
        else
        {
          throw new InputMismatchException();
        }
      }

      // Make default minimum value is 0.
      if (minimum < 0)
      {
        minimum = 0;
      }

      // Check that the maximum, if specified, is gte the minimum.
      if (maximum >= 0 && maximum < minimum)
      {
        isValid = false;
      }
    }
    catch (final NoSuchElementException e)
    {
      isValid = false;
    }

    if (!isValid)
    {
      final LocalizableMessage message =
        ERR_ATTR_SYNTAX_RFC3672_SUBTREE_SPECIFICATION_INVALID.get(s);
      throw new DirectoryException(
          ResultCode.INVALID_ATTRIBUTE_SYNTAX, message);
    }
    return new SubtreeSpecification(rootDN, relativeBaseDN, minimum, maximum, chopBefore, chopAfter, refinement);
  }

  /**
   * Parse a single refinement.
   *
   * @param parser
   *          The active subtree specification parser.
   * @return The parsed refinement.
   * @throws InputMismatchException
   *           If the common component did not have a valid syntax.
   * @throws NoSuchElementException
   *           If input is exhausted.
   */
  private static Refinement parseRefinement(final Parser parser)
      throws InputMismatchException, NoSuchElementException
  {
    // Get the type of refinement.
    final String type = StaticUtils.toLowerCase(parser.nextName());

    // Skip the colon separator.
    parser.skipColon();

    if ("item".equals(type))
    {
      return new ItemRefinement(parser.nextName());
    }
    else if ("not".equals(type))
    {
      return new NotRefinement(parseRefinement(parser));
    }
    else if ("and".equals(type))
    {
      return new AndRefinement(parseRefinementSet(parser));
    }
    else if ("or".equals(type))
    {
      return new OrRefinement(parseRefinementSet(parser));
    }
    else
    {
      // Unknown refinement type.
      throw new InputMismatchException();
    }
  }

  /**
   * Parse a list of refinements.
   *
   * @param parser
   *          The active subtree specification parser.
   * @return The parsed refinement list.
   * @throws InputMismatchException
   *           If the common component did not have a valid syntax.
   * @throws NoSuchElementException
   *           If input is exhausted.
   */
  private static ArrayList<Refinement> parseRefinementSet(
      final Parser parser) throws InputMismatchException,
      NoSuchElementException
  {
    final ArrayList<Refinement> refinements = new ArrayList<>();

    // Skip leading open-brace.
    parser.skipLeftBrace();

    // Parse each chop DN in the sequence.
    boolean isFirstValue = true;
    while (true)
    {
      // Make sure that there is a closing brace.
      if (parser.hasNextRightBrace())
      {
        parser.skipRightBrace();
        break;
      }

      // Make sure that there is a comma separator if this is not
      // the first element.
      if (!isFirstValue)
      {
        parser.skipSeparator();
      }
      else
      {
        isFirstValue = false;
      }

      // Parse each sub-refinement.
      refinements.add(parseRefinement(parser));
    }

    return refinements;
  }

  /** The absolute base of the subtree. */
  private final DN baseDN;

  /** Optional minimum depth (<=0 means unlimited). */
  private final int minimumDepth;
  /** Optional maximum depth (<0 means unlimited). */
  private final int maximumDepth;

  /** Optional set of chop before absolute DNs (mapping to their local-names). */
  private final Map<DN, DN> chopBefore;

  /** Optional set of chop after absolute DNs (mapping to their local-names). */
  private final Map<DN, DN> chopAfter;

  /** The root DN. */
  private final DN rootDN;

  /** The optional relative base DN. */
  private final DN relativeBaseDN;

  /** The optional specification filter refinements. */
  private final Refinement refinements;

  /**
   * Create a new RFC3672 subtree specification.
   *
   * @param rootDN
   *          The root DN of the subtree.
   * @param relativeBaseDN
   *          The relative base DN (or {@code null} if not
   *          specified).
   * @param minimumDepth
   *          The minimum depth (less than or equal to 0 means unlimited).
   * @param maximumDepth
   *          The maximum depth (less than 0 means unlimited).
   * @param chopBefore
   *          The set of chop before local names (relative to the
   *          relative base DN), or {@code null} if there are
   *          none.
   * @param chopAfter
   *          The set of chop after local names (relative to the
   *          relative base DN), or {@code null} if there are
   *          none.
   * @param refinements
   *          The optional specification filter refinements, or
   *          {@code null} if there are none.
   */
  public SubtreeSpecification(final DN rootDN,
      final DN relativeBaseDN, final int minimumDepth,
      final int maximumDepth, final Iterable<DN> chopBefore,
      final Iterable<DN> chopAfter, final Refinement refinements)
  {
    this.baseDN = relativeBaseDN == null ? rootDN : rootDN
        .child(relativeBaseDN);
    this.minimumDepth = minimumDepth;
    this.maximumDepth = maximumDepth;

    if (chopBefore != null && chopBefore.iterator().hasNext())
    {
      // Calculate the absolute DNs.
      final TreeMap<DN, DN> map = new TreeMap<>();
      for (final DN localName : chopBefore)
      {
        map.put(baseDN.child(localName), localName);
      }
      this.chopBefore = Collections.unmodifiableMap(map);
    }
    else
    {
      // No chop before specifications.
      this.chopBefore = Collections.emptyMap();
    }

    if (chopAfter != null && chopAfter.iterator().hasNext())
    {
      // Calculate the absolute DNs.
      final TreeMap<DN, DN> map = new TreeMap<>();
      for (final DN localName : chopAfter)
      {
        map.put(baseDN.child(localName), localName);
      }
      this.chopAfter = Collections.unmodifiableMap(map);
    }
    else
    {
      // No chop after specifications.
      this.chopAfter = Collections.emptyMap();
    }

    this.rootDN = rootDN;
    this.relativeBaseDN = relativeBaseDN;
    this.refinements = refinements;
  }

  /**
   * Indicates whether the provided object is logically equal to this
   * subtree specification object.
   *
   * @param obj
   *          The object for which to make the determination.
   * @return {@code true} if the provided object is logically equal
   *         to this subtree specification object, or {@code false}
   *         if not.
   */
  @Override
  public boolean equals(final Object obj)
  {
    if (this == obj)
    {
      return true;
    }

    if (obj instanceof SubtreeSpecification)
    {
      final SubtreeSpecification other = (SubtreeSpecification) obj;

      return minimumDepth == other.minimumDepth
          && maximumDepth == other.maximumDepth
          && chopBefore.values().equals(other.chopBefore.values())
          && chopAfter.values().equals(other.chopAfter.values())
          && getBaseDN().equals(other.getBaseDN())
          && Objects.equals(refinements, other.refinements);
    }

    return false;
  }

  /**
   * Get the absolute base DN of the subtree specification.
   *
   * @return Returns the absolute base DN of the subtree
   *         specification.
   */
  public DN getBaseDN()
  {
    return baseDN;
  }

  /**
   * Get the set of chop after relative DNs.
   *
   * @return Returns the set of chop after relative DNs.
   */
  public Iterable<DN> getChopAfter()
  {
    return chopAfter.values();
  }

  /**
   * Get the set of chop before relative DNs.
   *
   * @return Returns the set of chop before relative DNs.
   */
  public Iterable<DN> getChopBefore()
  {
    return chopBefore.values();
  }

  /**
   * Get the maximum depth of the subtree specification.
   *
   * @return Returns the maximum depth (less than 0 indicates unlimited depth).
   */
  public int getMaximumDepth()
  {
    return maximumDepth;
  }

  /**
   * Get the minimum depth of the subtree specification.
   *
   * @return Returns the minimum depth (<=0 indicates unlimited
   *         depth).
   */
  public int getMinimumDepth()
  {
    return minimumDepth;
  }

  /**
   * Get the specification filter refinements.
   *
   * @return Returns the specification filter refinements, or
   *         <code>null</code> if none were specified.
   */
  public Refinement getRefinements()
  {
    return refinements;
  }

  /**
   * Get the relative base DN.
   *
   * @return Returns the relative base DN or <code>null</code> if
   *         none was specified.
   */
  public DN getRelativeBaseDN()
  {
    return relativeBaseDN;
  }

  /**
   * Get the root DN.
   *
   * @return Returns the root DN.
   */
  public DN getRootDN()
  {
    return rootDN;
  }

  /**
   * Retrieves the hash code for this subtree specification object.
   *
   * @return The hash code for this subtree specification object.
   */
  @Override
  public int hashCode()
  {
    int hash = minimumDepth * 31 + maximumDepth;
    hash = hash * 31 + chopBefore.values().hashCode();
    hash = hash * 31 + chopAfter.values().hashCode();
    hash = hash * 31 + getBaseDN().hashCode();

    if (refinements != null)
    {
      hash = hash * 31 + refinements.hashCode();
    }

    return hash;
  }

  /**
   * Determine if the specified DN is within the scope of the subtree
   * specification.
   *
   * @param dn
   *          The distinguished name.
   * @return Returns <code>true</code> if the DN is within the scope
   *         of the subtree specification, or <code>false</code>
   *         otherwise.
   */
  public boolean isDNWithinScope(final DN dn)
  {
    if (!dn.isSubordinateOrEqualTo(baseDN))
    {
      return false;
    }

    // Check minimum and maximum depths.
    final int baseRDNCount = baseDN.size();

    if (minimumDepth > 0)
    {
      final int entryRDNCount = dn.size();

      if (entryRDNCount - baseRDNCount < minimumDepth)
      {
        return false;
      }
    }

    if (maximumDepth >= 0)
    {
      final int entryRDNCount = dn.size();

      if (entryRDNCount - baseRDNCount > maximumDepth)
      {
        return false;
      }
    }

    // Check exclusions.
    for (final DN chopBeforeDN : chopBefore.keySet())
    {
      if (dn.isSubordinateOrEqualTo(chopBeforeDN))
      {
        return false;
      }
    }

    for (final DN chopAfterDN : chopAfter.keySet())
    {
      if (!dn.equals(chopAfterDN) && dn.isSubordinateOrEqualTo(chopAfterDN))
      {
        return false;
      }
    }

    // Everything seemed to match.
    return true;
  }

  /**
   * Determine if an entry is within the scope of the subtree
   * specification.
   *
   * @param entry
   *          The entry.
   * @return {@code true} if the entry is within the scope of the
   *         subtree specification, or {@code false} if not.
   */
  public boolean isWithinScope(final Entry entry)
  {
    return isDNWithinScope(entry.getName())
        && (refinements == null || refinements.matches(entry));
  }

  /**
   * Retrieves a string representation of this subtree specification
   * object.
   *
   * @return A string representation of this subtree specification
   *         object.
   */
  @Override
  public String toString()
  {
    final StringBuilder builder = new StringBuilder();
    return toString(builder).toString();
  }

  /**
   * Append the string representation of the subtree specification to
   * the provided string builder.
   *
   * @param builder
   *          The string builder.
   * @return The string builder.
   */
  public StringBuilder toString(final StringBuilder builder)
  {
    boolean isFirstElement = true;

    // Output the optional base DN.
    builder.append("{");
    if (relativeBaseDN != null && !relativeBaseDN.isRootDN())
    {
      builder.append(" base ");
      StaticUtils.toRFC3641StringValue(builder, relativeBaseDN.toString());
      isFirstElement = false;
    }

    // Output the optional specific exclusions.
    final Iterable<DN> chopBefore = getChopBefore();
    final Iterable<DN> chopAfter = getChopAfter();

    if (chopBefore.iterator().hasNext()
        || chopAfter.iterator().hasNext())
    {
      isFirstElement = append2(builder, isFirstElement, " specificExclusions { ");

      boolean isFirst = true;

      for (final DN dn : chopBefore)
      {
        isFirst = append(builder, isFirst, "chopBefore:");
        StaticUtils.toRFC3641StringValue(builder, dn.toString());
      }

      for (final DN dn : chopAfter)
      {
        isFirst = append(builder, isFirst, "chopAfter:");
        StaticUtils.toRFC3641StringValue(builder, dn.toString());
      }

      builder.append(" }");
    }

    // Output the optional minimum depth.
    if (getMinimumDepth() > 0)
    {
      isFirstElement = append2(builder, isFirstElement, " minimum ");
      builder.append(getMinimumDepth());
    }

    // Output the optional maximum depth.
    if (getMaximumDepth() >= 0)
    {
      isFirstElement = append2(builder, isFirstElement, " maximum ");
      builder.append(getMaximumDepth());
    }

    // Output the optional refinements.
    if (refinements != null)
    {
      isFirstElement = append2(builder, isFirstElement, " specificationFilter ");
      refinements.toString(builder);
    }

    builder.append(" }");

    return builder;
  }

  private boolean append2(final StringBuilder builder, boolean isFirst, String toAppend)
  {
    if (isFirst)
    {
      isFirst = false;
    }
    else
    {
      builder.append(",");
    }
    builder.append(toAppend);
    return isFirst;
  }

  private boolean append(final StringBuilder builder, boolean isFirst, String toAppend)
  {
    if (isFirst)
    {
      isFirst = false;
    }
    else
    {
      builder.append(", ");
    }
    builder.append(toAppend);
    return isFirst;
  }
}