/*
 * 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 com.sun.opends.sdk.util;



/**
 * A {@code ASCIICharProp} provides fast access to ASCII character
 * properties. In particular, the ability to query whether or not a
 * character is a letter, a digit, hexadecimal character, as well as
 * various methods for performing character conversions.
 * <p>
 * The methods in this class do not perform memory allocations nor
 * calculations and so can be used safely in high performance
 * situations.
 */
public final class ASCIICharProp implements Comparable<ASCIICharProp>
{
  private final char c;
  private final char upperCaseChar;
  private final char lowerCaseChar;
  private final boolean isUpperCaseChar;
  private final boolean isLowerCaseChar;
  private final boolean isDigit;
  private final boolean isLetter;
  private final boolean isKeyChar;
  private final boolean isHexChar;
  private final int hexValue;
  private final int decimalValue;
  private final String stringValue;

  private static final ASCIICharProp[] CHAR_PROPS =
      new ASCIICharProp[128];

  static
  {
    for (int i = 0; i < 128; i++)
    {
      CHAR_PROPS[i] = new ASCIICharProp((char) i);
    }
  }



  /**
   * Returns the character properties for the provided ASCII character.
   * If a non-ASCII character is provided then this method returns
   * {@code null}.
   * 
   * @param c
   *          The ASCII character.
   * @return The character properties for the provided ASCII character,
   *         or {@code null} if {@code c} is greater than {@code \u007F}
   *         .
   */
  public static ASCIICharProp valueOf(char c)
  {
    if (c < 128)
    {
      return CHAR_PROPS[c];
    }
    else
    {
      return null;
    }
  }



  /**
   * Returns the character properties for the provided ASCII character.
   * If a non-ASCII character is provided then this method returns
   * {@code null}.
   * 
   * @param c
   *          The ASCII character.
   * @return The character properties for the provided ASCII character,
   *         or {@code null} if {@code c} is less than zero or greater
   *         than {@code \u007F} .
   */
  public static ASCIICharProp valueOf(int c)
  {
    if (c >= 0 && c < 128)
    {
      return CHAR_PROPS[c];
    }
    else
    {
      return null;
    }
  }



  private ASCIICharProp(char c)
  {
    this.c = c;
    this.stringValue = new String(new char[] { c });

    if (c >= 'a' && c <= 'z')
    {
      this.upperCaseChar = (char) (c - 32);
      this.lowerCaseChar = c;
      this.isUpperCaseChar = false;
      this.isLowerCaseChar = true;
      this.isDigit = false;
      this.isLetter = true;
      this.isKeyChar = true;
      this.decimalValue = -1;
      if (c >= 'a' && c <= 'f')
      {
        this.isHexChar = true;
        this.hexValue = c - 87;
      }
      else
      {
        this.isHexChar = false;
        this.hexValue = -1;
      }
    }
    else if (c >= 'A' && c <= 'Z')
    {
      this.upperCaseChar = c;
      this.lowerCaseChar = (char) (c + 32);
      this.isUpperCaseChar = true;
      this.isLowerCaseChar = false;
      this.isDigit = false;
      this.isLetter = true;
      this.isKeyChar = true;
      this.decimalValue = -1;
      if (c >= 'A' && c <= 'F')
      {
        this.isHexChar = true;
        this.hexValue = c - 55;
      }
      else
      {
        this.isHexChar = false;
        this.hexValue = -1;
      }
    }
    else if (c >= '0' && c <= '9')
    {
      this.upperCaseChar = c;
      this.lowerCaseChar = c;
      this.isUpperCaseChar = false;
      this.isLowerCaseChar = false;
      this.isDigit = true;
      this.isLetter = false;
      this.isKeyChar = true;
      this.isHexChar = true;
      this.hexValue = c - 48;
      this.decimalValue = c - 48;
    }
    else
    {
      this.upperCaseChar = c;
      this.lowerCaseChar = c;
      this.isUpperCaseChar = false;
      this.isLowerCaseChar = false;
      this.isDigit = false;
      this.isLetter = false;
      this.isKeyChar = c == '-';
      this.isHexChar = false;
      this.hexValue = -1;
      this.decimalValue = -1;
    }
  }



  /**
   * Returns the char value associated with this {@code ASCIICharProp}.
   * 
   * @return The char value associated with this {@code ASCIICharProp}.
   */
  public char charValue()
  {
    return c;
  }



  /**
   * {@inheritDoc}
   */
  public int compareTo(ASCIICharProp o)
  {
    return c - o.c;
  }



  /**
   * Returns the decimal value associated with this {@code
   * ASCIICharProp}, or {@code -1} if the value is not a decimal digit.
   * 
   * @return The decimal value associated with this {@code
   *         ASCIICharProp}, or {@code -1} if the value is not a decimal
   *         digit.
   */
  public int decimalValue()
  {
    return decimalValue;
  }



  /**
   * Returns the hexadecimal value associated with this {@code
   * ASCIICharProp} , or {@code -1} if the value is not a hexadecimal
   * digit.
   * 
   * @return The hexadecimal value associated with this {@code
   *         ASCIICharProp} , or {@code -1} if the value is not a
   *         hexadecimal digit.
   */
  public int hexValue()
  {
    return hexValue;
  }



  /**
   * Indicates whether or not the char value associated with this
   * {@code ASCIICharProp} is a decimal digit.
   * 
   * @return {@code true} if the char value associated with this {@code
   *         ASCIICharProp} is a decimal digit.
   */
  public boolean isDigit()
  {
    return isDigit;
  }



  /**
   * Indicates whether or not the char value associated with this
   * {@code ASCIICharProp} is a hexadecimal digit.
   * 
   * @return {@code true} if the char value associated with this {@code
   *         ASCIICharProp} is a hexadecimal digit.
   */
  public boolean isHexDigit()
  {
    return isHexChar;
  }



  /**
   * Indicates whether or not the char value associated with this
   * {@code ASCIICharProp} is a {@code keychar} as defined in RFC 4512.
   * A {@code keychar} is a letter, a digit, or a hyphen.
   * 
   * @return {@code true} if the char value associated with this {@code
   *         ASCIICharProp} is a {@code keychar}.
   */
  public boolean isKeyChar()
  {
    return isKeyChar;
  }



  /**
   * Indicates whether or not the char value associated with this
   * {@code ASCIICharProp} is a letter.
   * 
   * @return {@code true} if the char value associated with this {@code
   *         ASCIICharProp} is a letter.
   */
  public boolean isLetter()
  {
    return isLetter;
  }



  /**
   * Indicates whether or not the char value associated with this
   * {@code ASCIICharProp} is a lower-case character.
   * 
   * @return {@code true} if the char value associated with this {@code
   *         ASCIICharProp} is a lower-case character.
   */
  public boolean isLowerCase()
  {
    return isLowerCaseChar;
  }



  /**
   * Indicates whether or not the char value associated with this
   * {@code ASCIICharProp} is an upper-case character.
   * 
   * @return {@code true} if the char value associated with this {@code
   *         ASCIICharProp} is an upper-case character.
   */
  public boolean isUpperCase()
  {
    return isUpperCaseChar;
  }



  /**
   * Returns the lower-case char value associated with this {@code
   * ASCIICharProp}.
   * 
   * @return The lower-case char value associated with this {@code
   *         ASCIICharProp}.
   */
  public char toLowerCase()
  {
    return lowerCaseChar;
  }



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



  /**
   * Returns the upper-case char value associated with this {@code
   * ASCIICharProp}.
   * 
   * @return The upper-case char value associated with this {@code
   *         ASCIICharProp}.
   */
  public char toUpperCase()
  {
    return upperCaseChar;
  }

}