/*
 * 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/opends/resource/legal-notices/OpenDS.LICENSE
 * or https://OpenDS.dev.java.net/OpenDS.LICENSE.
 * 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/opends/resource/legal-notices/OpenDS.LICENSE.  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.opends.sdk.schema;



import static com.sun.opends.sdk.util.Messages.*;
import static org.opends.sdk.schema.SchemaConstants.EMR_AUTH_PASSWORD_EXACT_OID;
import static org.opends.sdk.schema.SchemaConstants.SYNTAX_AUTH_PASSWORD_NAME;

import com.sun.opends.sdk.util.Message;
import com.sun.opends.sdk.util.MessageBuilder;
import org.opends.sdk.DecodeException;
import org.opends.sdk.util.ByteSequence;



/**
 * This class defines the auth password attribute syntax, which is
 * defined in RFC 3112 and is used to hold authentication information.
 * Only equality matching will be allowed by default.
 */
final class AuthPasswordSyntaxImpl extends AbstractSyntaxImpl
{
  /**
   * Decodes the provided authentication password value into its
   * component parts.
   * 
   * @param authPasswordValue
   *          The authentication password value to be decoded.
   * @return A three-element array, containing the scheme, authInfo, and
   *         authValue components of the given string, in that order.
   * @throws DecodeException
   *           If a problem is encountered while attempting to decode
   *           the value.
   */
  static StringBuilder[] decodeAuthPassword(String authPasswordValue)
      throws DecodeException
  {
    // Create placeholders for the values to return.
    final StringBuilder scheme = new StringBuilder();
    final StringBuilder authInfo = new StringBuilder();
    final StringBuilder authValue = new StringBuilder();

    // First, ignore any leading whitespace.
    final int length = authPasswordValue.length();
    int pos = 0;
    while (pos < length && authPasswordValue.charAt(pos) == ' ')
    {
      pos++;
    }

    // The next set of characters will be the scheme, which must consist
    // only of digits, uppercase alphabetic characters, dash, period,
    // slash, and underscore characters. It must be immediately followed
    // by one or more spaces or a dollar sign.
    readScheme: while (pos < length)
    {
      final char c = authPasswordValue.charAt(pos);

      switch (c)
      {
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
      case 'A':
      case 'B':
      case 'C':
      case 'D':
      case 'E':
      case 'F':
      case 'G':
      case 'H':
      case 'I':
      case 'J':
      case 'K':
      case 'L':
      case 'M':
      case 'N':
      case 'O':
      case 'P':
      case 'Q':
      case 'R':
      case 'S':
      case 'T':
      case 'U':
      case 'V':
      case 'W':
      case 'X':
      case 'Y':
      case 'Z':
      case '-':
      case '.':
      case '/':
      case '_':
        scheme.append(c);
        pos++;
        break;
      case ' ':
      case '$':
        break readScheme;
      default:
        final Message message =
            ERR_ATTR_SYNTAX_AUTHPW_INVALID_SCHEME_CHAR.get(pos);
        throw DecodeException.error(message);
      }
    }

    // The scheme must consist of at least one character.
    if (scheme.length() == 0)
    {
      final Message message = ERR_ATTR_SYNTAX_AUTHPW_NO_SCHEME.get();
      throw DecodeException.error(message);
    }

    // Ignore any spaces before the dollar sign separator. Then read the
    // dollar sign and ignore any trailing spaces.
    while (pos < length && authPasswordValue.charAt(pos) == ' ')
    {
      pos++;
    }

    if (pos < length && authPasswordValue.charAt(pos) == '$')
    {
      pos++;
    }
    else
    {
      final Message message =
          ERR_ATTR_SYNTAX_AUTHPW_NO_SCHEME_SEPARATOR.get();
      throw DecodeException.error(message);
    }

    while (pos < length && authPasswordValue.charAt(pos) == ' ')
    {
      pos++;
    }

    // The next component must be the authInfo element, containing only
    // printable characters other than the dollar sign and space
    // character.
    readAuthInfo: while (pos < length)
    {
      final char c = authPasswordValue.charAt(pos);
      if (c == ' ' || c == '$')
      {
        break readAuthInfo;
      }
      else if (PrintableStringSyntaxImpl.isPrintableCharacter(c))
      {
        authInfo.append(c);
        pos++;
      }
      else
      {
        final Message message =
            ERR_ATTR_SYNTAX_AUTHPW_INVALID_AUTH_INFO_CHAR.get(pos);
        throw DecodeException.error(message);
      }
    }

    // The authInfo element must consist of at least one character.
    if (scheme.length() == 0)
    {
      final Message message = ERR_ATTR_SYNTAX_AUTHPW_NO_AUTH_INFO.get();
      throw DecodeException.error(message);
    }

    // Ignore any spaces before the dollar sign separator. Then read the
    // dollar sign and ignore any trailing spaces.
    while (pos < length && authPasswordValue.charAt(pos) == ' ')
    {
      pos++;
    }

    if (pos < length && authPasswordValue.charAt(pos) == '$')
    {
      pos++;
    }
    else
    {
      final Message message =
          ERR_ATTR_SYNTAX_AUTHPW_NO_AUTH_INFO_SEPARATOR.get();
      throw DecodeException.error(message);
    }

    while (pos < length && authPasswordValue.charAt(pos) == ' ')
    {
      pos++;
    }

    // The final component must be the authValue element, containing
    // only printable characters other than the dollar sign and space
    // character.
    while (pos < length)
    {
      final char c = authPasswordValue.charAt(pos);
      if (c == ' ' || c == '$')
      {
        break;
      }
      else if (PrintableStringSyntaxImpl.isPrintableCharacter(c))
      {
        authValue.append(c);
        pos++;
      }
      else
      {
        final Message message =
            ERR_ATTR_SYNTAX_AUTHPW_INVALID_AUTH_VALUE_CHAR.get(pos);
        throw DecodeException.error(message);
      }
    }

    // The authValue element must consist of at least one character.
    if (scheme.length() == 0)
    {
      final Message message =
          ERR_ATTR_SYNTAX_AUTHPW_NO_AUTH_VALUE.get();
      throw DecodeException.error(message);
    }

    // The only characters remaining must be whitespace.
    while (pos < length)
    {
      final char c = authPasswordValue.charAt(pos);
      if (c == ' ')
      {
        pos++;
      }
      else
      {
        final Message message =
            ERR_ATTR_SYNTAX_AUTHPW_INVALID_TRAILING_CHAR.get(pos);
        throw DecodeException.error(message);
      }
    }

    // If we've gotten here, then everything must be OK.
    return new StringBuilder[] { scheme, authInfo, authValue };
  }



  /**
   * Indicates whether the provided value is encoded using the auth
   * 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 auth password syntax, or <CODE>false</CODE> if not.
   */
  static boolean isEncoded(ByteSequence value)
  {
    // FIXME -- Make this more efficient, and don't use exceptions for
    // flow control.

    try
    {
      decodeAuthPassword(value.toString());
      return true;
    }
    catch (final Exception e)
    {
      return false;
    }
  }



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



  public String getName()
  {
    return SYNTAX_AUTH_PASSWORD_NAME;
  }



  public boolean isHumanReadable()
  {
    return true;
  }



  public boolean valueIsAcceptable(Schema schema, ByteSequence value,
      MessageBuilder invalidReason)
  {
    try
    {
      decodeAuthPassword(value.toString());
      return true;
    }
    catch (final DecodeException de)
    {
      invalidReason.append(de.getMessageObject());
      return false;
    }
  }
}