/*
 * 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 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 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 2009 Sun Microsystems, Inc.
 *      Portions copyright 2012-2013 ForgeRock AS.
 */

package org.forgerock.opendj.ldap;

import java.util.AbstractSet;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.forgerock.opendj.ldap.schema.AttributeType;
import org.forgerock.opendj.ldap.schema.MatchingRule;

import com.forgerock.opendj.util.Validator;

/**
 * This class provides a skeletal implementation of the {@code Attribute}
 * interface, to minimize the effort required to implement this interface.
 */
public abstract class AbstractAttribute extends AbstractSet<ByteString> implements Attribute {

    /**
     * Returns {@code true} if {@code object} is an attribute which is equal to
     * {@code attribute}. Two attributes are considered equal if their attribute
     * descriptions are equal, they both have the same number of attribute
     * values, and every attribute value contained in the first attribute is
     * also contained in the second attribute.
     *
     * @param attribute
     *            The attribute to be tested for equality.
     * @param object
     *            The object to be tested for equality with the attribute.
     * @return {@code true} if {@code object} is an attribute which is equal to
     *         {@code attribute}, or {@code false} if not.
     */
    static boolean equals(final Attribute attribute, final Object object) {
        if (attribute == object) {
            return true;
        }

        if (!(object instanceof Attribute)) {
            return false;
        }

        final Attribute other = (Attribute) object;
        if (!attribute.getAttributeDescription().equals(other.getAttributeDescription())) {
            return false;
        }

        // Attribute description is the same, compare values.
        if (attribute.size() != other.size()) {
            return false;
        }

        return attribute.containsAll(other);
    }

    /**
     * Returns the hash code for {@code attribute}. It will be calculated as the
     * sum of the hash codes of the attribute description and all of the
     * attribute values.
     *
     * @param attribute
     *            The attribute whose hash code should be calculated.
     * @return The hash code for {@code attribute}.
     */
    static int hashCode(final Attribute attribute) {
        int hashCode = attribute.getAttributeDescription().hashCode();
        for (final ByteString value : attribute) {
            hashCode += normalizeValue(attribute, value).hashCode();
        }
        return hashCode;
    }

    /**
     * Returns the normalized form of {@code value} normalized using
     * {@code attribute}'s equality matching rule.
     *
     * @param attribute
     *            The attribute whose equality matching rule should be used for
     *            normalization.
     * @param value
     *            The attribute value to be normalized.
     * @return The normalized form of {@code value} normalized using
     *         {@code attribute}'s equality matching rule.
     */
    static ByteString normalizeValue(final Attribute attribute, final ByteString value) {
        final AttributeDescription attributeDescription = attribute.getAttributeDescription();
        final AttributeType attributeType = attributeDescription.getAttributeType();
        final MatchingRule matchingRule = attributeType.getEqualityMatchingRule();

        try {
            return matchingRule.normalizeAttributeValue(value);
        } catch (final Exception e) {
            // Fall back to provided value.
            return value;
        }
    }

    /**
     * Returns a string representation of {@code attribute}.
     *
     * @param attribute
     *            The attribute whose string representation should be returned.
     * @return The string representation of {@code attribute}.
     */
    static String toString(final Attribute attribute) {
        final StringBuilder builder = new StringBuilder();
        builder.append("Attribute(");
        builder.append(attribute.getAttributeDescriptionAsString());
        builder.append(", {");

        boolean firstValue = true;
        for (final ByteString value : attribute) {
            if (!firstValue) {
                builder.append(", ");
            }

            builder.append(value);
            firstValue = false;
        }

        builder.append("})");
        return builder.toString();
    }

    /**
     * Sole constructor.
     */
    protected AbstractAttribute() {
        // No implementation required.
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public abstract boolean add(ByteString value);

    /**
     * {@inheritDoc}
     */
    public boolean add(final Object... values) {
        Validator.ensureNotNull(values);
        boolean modified = false;
        for (final Object value : values) {
            modified |= add(ByteString.valueOf(value));
        }
        return modified;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean addAll(final Collection<? extends ByteString> values) {
        return addAll(values, null);
    }

    /**
     * {@inheritDoc}
     */
    public <T> boolean addAll(final Collection<T> values,
            final Collection<? super T> duplicateValues) {
        boolean modified = false;
        for (final T value : values) {
            if (add(value)) {
                modified = true;
            } else if (duplicateValues != null) {
                duplicateValues.add(value);
            }
        }
        return modified;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public abstract boolean contains(Object value);

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean containsAll(final Collection<?> values) {
        for (final Object value : values) {
            if (!contains(value)) {
                return false;
            }
        }
        return true;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean equals(final Object object) {
        return equals(this, object);
    }

    /**
     * {@inheritDoc}
     */
    public ByteString firstValue() {
        return iterator().next();
    }

    /**
     * {@inheritDoc}
     */
    public String firstValueAsString() {
        return firstValue().toString();
    }

    /**
     * {@inheritDoc}
     */
    public abstract AttributeDescription getAttributeDescription();

    /**
     * {@inheritDoc}
     */
    public String getAttributeDescriptionAsString() {
        return getAttributeDescription().toString();
    }

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

    /**
     * {@inheritDoc}
     */
    public AttributeParser parse() {
        return AttributeParser.parseAttribute(this);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public abstract Iterator<ByteString> iterator();

    /**
     * {@inheritDoc}
     */
    @Override
    public abstract boolean remove(Object value);

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean removeAll(final Collection<?> values) {
        return removeAll(values, null);
    }

    /**
     * {@inheritDoc}
     */
    public <T> boolean removeAll(final Collection<T> values,
            final Collection<? super T> missingValues) {
        boolean modified = false;
        for (final T value : values) {
            if (remove(value)) {
                modified = true;
            } else if (missingValues != null) {
                missingValues.add(value);
            }
        }
        return modified;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean retainAll(final Collection<?> values) {
        return retainAll(values, null);
    }

    /**
     * {@inheritDoc}
     */
    public <T> boolean retainAll(final Collection<T> values,
            final Collection<? super T> missingValues) {
        if (values.isEmpty()) {
            if (isEmpty()) {
                return false;
            } else {
                clear();
                return true;
            }
        }

        if (isEmpty()) {
            if (missingValues != null) {
                for (final T value : values) {
                    missingValues.add(value);
                }
            }
            return false;
        }

        final Map<ByteString, T> valuesToRetain = new HashMap<ByteString, T>(values.size());
        for (final T value : values) {
            valuesToRetain.put(normalizeValue(this, ByteString.valueOf(value)), value);
        }

        boolean modified = false;
        final Iterator<ByteString> iterator = iterator();
        while (iterator.hasNext()) {
            final ByteString value = iterator.next();
            final ByteString normalizedValue = normalizeValue(this, value);
            if (valuesToRetain.remove(normalizedValue) == null) {
                modified = true;
                iterator.remove();
            }
        }

        if (missingValues != null) {
            missingValues.addAll(valuesToRetain.values());
        }

        return modified;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public abstract int size();

    /**
     * {@inheritDoc}
     */
    @Override
    public ByteString[] toArray() {
        return toArray(new ByteString[size()]);
    }

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

}