/*
 * 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.
 */

package org.forgerock.opendj.ldap.schema;

import static com.forgerock.opendj.util.StaticUtils.toLowerCase;
import static org.forgerock.opendj.ldap.CoreMessages.ERR_ATTR_SYNTAX_USERPW_NO_CLOSING_BRACE;
import static org.forgerock.opendj.ldap.CoreMessages.ERR_ATTR_SYNTAX_USERPW_NO_OPENING_BRACE;
import static org.forgerock.opendj.ldap.CoreMessages.ERR_ATTR_SYNTAX_USERPW_NO_SCHEME;
import static org.forgerock.opendj.ldap.CoreMessages.ERR_ATTR_SYNTAX_USERPW_NO_VALUE;
import static org.forgerock.opendj.ldap.schema.SchemaConstants.EMR_USER_PASSWORD_EXACT_OID;
import static org.forgerock.opendj.ldap.schema.SchemaConstants.SYNTAX_USER_PASSWORD_NAME;

import org.forgerock.i18n.LocalizableMessage;
import org.forgerock.i18n.LocalizableMessageBuilder;
import org.forgerock.opendj.ldap.ByteSequence;
import org.forgerock.opendj.ldap.DecodeException;

/**
 * This class defines an attribute syntax used for storing values that have been
 * encoded using a password storage scheme. The format for attribute values with
 * this syntax is the concatenation of the following elements in the given
 * order: <BR>
 * <UL>
 * <LI>An opening curly brace ("{") character.</LI>
 * <LI>The name of the storage scheme used to encode the value.</LI>
 * <LI>A closing curly brace ("}") character.</LI>
 * <LI>The encoded value.</LI>
 * </UL>
 */
final class UserPasswordSyntaxImpl extends AbstractSyntaxImpl {
    /**
     * Decodes the provided user password value into its component parts.
     *
     * @param userPasswordValue
     *            The user password value to be decoded.
     * @return A two-element string array whose elements are the storage scheme
     *         name (in all lowercase characters) and the encoded value, in that
     *         order.
     * @throws DecodeException
     *             If a problem is encountered while attempting to decode the
     *             value.
     */
    static String[] decodeUserPassword(final String userPasswordValue) throws DecodeException {
        // Make sure that there actually is a value to decode.
        if (userPasswordValue == null || userPasswordValue.length() == 0) {
            final LocalizableMessage message = ERR_ATTR_SYNTAX_USERPW_NO_VALUE.get();
            throw DecodeException.error(message);
        }

        // The first character of an encoded value must be an opening curly
        // brace.
        if (userPasswordValue.charAt(0) != '{') {
            final LocalizableMessage message = ERR_ATTR_SYNTAX_USERPW_NO_OPENING_BRACE.get();
            throw DecodeException.error(message);
        }

        // There must be a corresponding closing brace.
        final int closePos = userPasswordValue.indexOf('}');
        if (closePos < 0) {
            final LocalizableMessage message = ERR_ATTR_SYNTAX_USERPW_NO_CLOSING_BRACE.get();
            throw DecodeException.error(message);
        }

        // Get the storage scheme name and encoded value.
        final String schemeName = userPasswordValue.substring(1, closePos);
        final String encodedValue = userPasswordValue.substring(closePos + 1);

        if (schemeName.length() == 0) {
            final LocalizableMessage message = ERR_ATTR_SYNTAX_USERPW_NO_SCHEME.get();
            throw DecodeException.error(message);
        }

        return new String[] { toLowerCase(schemeName), encodedValue };
    }

    /**
     * Indicates whether the provided value is encoded using the user password
     * syntax.
     *
     * @param value
     *            The value for which to make the determination.
     * @return <CODE>true</CODE> if the value appears to be encoded using the
     *         user password syntax, or <CODE>false</CODE> if not.
     */
    static boolean isEncoded(final ByteSequence value) {
        // If the value is null or empty, then it's not.
        if (value == null || value.length() == 0) {
            return false;
        }

        // If the value doesn't start with an opening curly brace, then it's
        // not.
        if (value.byteAt(0) != '{') {
            return false;
        }

        // There must be a corresponding closing curly brace, and there must
        // be at least one character inside the brace.
        int closingBracePos = -1;
        for (int i = 1; i < value.length(); i++) {
            if (value.byteAt(i) == '}') {
                closingBracePos = i;
                break;
            }
        }

        if (closingBracePos < 0 || closingBracePos == 1) {
            return false;
        }

        // The closing curly brace must not be the last character of the
        // password.
        if (closingBracePos == value.length() - 1) {
            return false;
        }

        // If we've gotten here, then it looks to be encoded.
        return true;
    }

    @Override
    public String getEqualityMatchingRule() {
        return EMR_USER_PASSWORD_EXACT_OID;
    }

    public String getName() {
        return SYNTAX_USER_PASSWORD_NAME;
    }

    public boolean isHumanReadable() {
        return true;
    }

    public boolean valueIsAcceptable(final Schema schema, final ByteSequence value,
            final LocalizableMessageBuilder invalidReason) {
        // We have to accept any value here because in many cases the value
        // will not have been encoded by the time this method is called.
        // TODO: Is this correct for client-side use?
        return true;
    }

}