/******************************************************************************* 
 *  Copyright 2008 Amazon Technologies, Inc.
 *  Licensed under the Apache License, Version 2.0 (the "License"); 
 *  
 *  You may not use this file except in compliance with the License. 
 *  You may obtain a copy of the License at: http://aws.amazon.com/apache2.0
 *  This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
 *  CONDITIONS OF ANY KIND, either express or implied. See the License for the 
 *  specific language governing permissions and limitations under the License.
 * ***************************************************************************** 
 *    __  _    _  ___ 
 *   (  )( \/\/ )/ __)
 *   /__\ \    / \__ \
 *  (_)(_) \/\/  (___/
 * 
 *  Amazon Simple DB CSharp Library
 *  API Version: 2007-11-07
 *  Generated: Sat Dec 20 11:26:11 PST 2008 
 * 
 */

using System;
using System.Globalization;

namespace Amazon.SimpleDB.Util
{
   /**
    * Provides collection of static functions for conversion of various values into 
    * strings that may be compared lexicographically.
    */
    public class AmazonSimpleDBUtil
    {
        /// <summary>
        /// Date format String, e.g. 2007-12-06T10:32:43.141-08:00
        /// </summary>
        private static String dateFormat = "yyyy-MM-ddTHH:mm:ss.fffzzzz";


        /// <summary>
        /// Encodes positive integer value into a string by zero-padding it up to the specified number of digits.
        /// </summary>
        /// <remarks>
        /// For example, the integer 123 encoded with a 6 digit maximum would be represented as 000123
        /// </remarks>
        /// <param name="number">positive integer to be encoded</param>
        /// <param name="maxNumDigits">maximum number of digits in the largest value in the data set</param>
        /// <returns>A string representation of the zero-padded integer</returns>
        public static String EncodeZeroPadding(int number, int maxNumDigits)
        {
            return number.ToString().PadLeft(maxNumDigits, '0');
        }

        /// <summary>
        /// Encodes positive single-precision floating point value into a string by zero-padding it to the specified number of digits.
        /// </summary>
        /// <remarks>
        /// This function only zero-pads digits to the left of the decimal point.
        ///
        /// For example, the value 123.456 encoded with a 6 digit maximum would be represented as 000123.456
        /// </remarks>
        /// <param name="number">positive floating point value to be encoded</param>
        /// <param name="maxNumDigits">maximum number of digits in the largest value in the data set</param>
        /// <returns>A string representation of the zero-padded floating point value</returns>
        public static String EncodeZeroPadding(float number, int maxNumDigits)
        {
            String fltStr = number.ToString();
            int decPt = fltStr.IndexOf('.');
            if (decPt == -1)
            {
                return fltStr.PadLeft(maxNumDigits, '0');
            }
            else
            {
                return fltStr.PadLeft(maxNumDigits + (fltStr.Length - decPt), '0');
            }
        }

        /// <summary>
        /// Encodes real integer value into a string by offsetting and zero-padding 
        /// number up to the specified number of digits.  Use this encoding method if the data
        /// range set includes both positive and negative values.
        /// </summary>
        /// <remarks>
        /// For example, the integer value -123 offset by 1000 with a maximum of 6 digits would be:
        /// -123 + 1000, padded to 6 digits: 000877
        /// </remarks>
        /// <param name="number">integer to be encoded</param>
        /// <param name="maxNumDigits">maximum number of digits in the largest absolute value in the data set</param>
        /// <param name="offsetValue">offset value, has to be greater than absolute value of any negative number in the data set.</param>
        /// <returns>A string representation of the integer</returns>
        public static String EncodeRealNumberRange(int number, int maxNumDigits, int offsetValue)
        {
            return (number + offsetValue).ToString().PadLeft(maxNumDigits, '0');
        }

        /// <summary>
        /// Encodes real float value into a string by offsetting and zero-padding 
        /// number up to the specified number of digits.  Use this encoding method if the data
        /// range set includes both positive and negative values.
        /// </summary>
        /// <remarks>
        /// For example, the floating point value -123.456 offset by 1000 with
        /// a maximum of 6 digits to the left, and 4 to the right would be:
        /// 0008765440
        /// </remarks>
        /// <param name="number">floating point value to be encoded</param>
        /// <param name="maxDigitsLeft">maximum number of digits left of the decimal point in the largest absolute value in the data set</param>
        /// <param name="maxDigitsRight">maximum number of digits right of the decimal point in the largest absolute value in the data set, i.e. precision</param>
        /// <param name="offsetValue">offset value, has to be greater than absolute value of any negative number in the data set.</param>
        /// <returns>A string representation of the integer</returns>
        public static String EncodeRealNumberRange(float number, int maxDigitsLeft, int maxDigitsRight, int offsetValue)
        {
            long shiftMultiplier = (long)Math.Pow(10, maxDigitsRight);
            long shiftedNumber = (long)Math.Round((number + offsetValue) * shiftMultiplier);
            return shiftedNumber.ToString().PadLeft(maxDigitsLeft + maxDigitsRight, '0');
        }

        /// <summary>
        /// Decodes zero-padded positive float value from the string representation
        /// </summary>
        /// <param name="value">zero-padded string representation of the float value</param>
        /// <returns>original float value</returns>
        public static float DecodeZeroPaddingFloat(String value)
        {
            return float.Parse(value);
        }

        /// <summary>
        /// Decodes zero-padded positive integer value from the string representation
        /// </summary>
        /// <param name="value">zero-padded string representation of the integer</param>
        /// <returns>original integer value</returns>
        public static int DecodeZeroPaddingInt(String value)
        {
            return int.Parse(value);
        }

        /// <summary>
        /// Decodes float value from the string representation that was created by using encodeRealNumberRange(..) function.
        /// </summary>
        /// <param name="value">String representation of the integer value</param>
        /// <param name="offsetValue">offset value that was used in the original encoding</param>
        /// <returns>original integer value</returns>
        public static int DecodeRealNumberRangeInt(String value, int offsetValue)
        {
            return (int)(long.Parse(value) - offsetValue);
        }

        /// <summary>
        /// Decodes float value from the string representation that was created by using encodeRealNumberRange(..) function.
        /// </summary>
        /// <param name="value">string representation of the integer value</param>
        /// <param name="maxDigitsRight">maximum number of digits left of the decimal point in the largest absolute value in the data set (must be the same as the one used for encoding).</param>
        /// <param name="offsetValue">offset value that was used in the original encoding</param>
        /// <returns>original float value</returns>
        public static float DecodeRealNumberRangeFloat(String value, int maxDigitsRight, int offsetValue)
        {
            return (float)(long.Parse(value) / Math.Pow(10, maxDigitsRight) - offsetValue);
        }

        /// <summary>
        /// Encodes date value into string format that can be compared lexicographically
        /// </summary>
        /// <param name="date">date value to be encoded</param>
        /// <returns>string representation of the date value</returns>
        public static String EncodeDate(DateTime date)
        {
            return date.ToString(dateFormat);
        }

        /// <summary>
        /// Decodes date value from the string representation created using encodeDate(..) function.
        /// </summary>
        /// <param name="value">string representation of the date value</param>
        /// <returns>original date value</returns>
        public static DateTime DecodeDate(String value)
        {
            return DateTime.ParseExact(value, dateFormat, CultureInfo.InvariantCulture);
        }
    }
}