egwcorelib/EgwCoreLib.Utils/FileHelpers.cs

namespace EgwCoreLib.Utils
{
    /// <summary>
    /// Utility per gestione Files
    /// </summary>
    public class FileHelpers
    {
        #region Public Fields

        public static readonly string[] SizeSuffixes = { "bytes", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };

        #endregion Public Fields

        #region Public Methods

        /// <summary>
        /// Calcola dimensione file con corretta unità di misura secondo dimensione
        /// </summary>
        /// <param name="value">lunghezza file (in byte)</param>
        /// <param name="decimalPlaces">Num di cifre decimali richieste</param>
        /// <returns></returns>
        /// <exception cref="ArgumentOutOfRangeException"></exception>
        public static string SizeSuffix(Int64 value, int decimalPlaces = 1)
        {
            if (decimalPlaces < 0) { throw new ArgumentOutOfRangeException("decimalPlaces"); }
            if (value < 0) { return "-" + SizeSuffix(-value, decimalPlaces); }
            if (value == 0) { return string.Format("{0:n" + decimalPlaces + "} bytes", 0); }

            // mag is 0 for bytes, 1 for KB, 2, for MB, etc.
            int mag = (int)Math.Log(value, 1024);

            // 1L << (mag * 10) == 2 ^ (10 * mag) [i.e. the number of bytes in the unit
            // corresponding to mag]
            decimal adjustedSize = (decimal)value / (1L << (mag * 10));

            // make adjustment when the value is large enough that it would round up to 1000 or more
            if (Math.Round(adjustedSize, decimalPlaces) >= 1000)
            {
                mag += 1;
                adjustedSize /= 1024;
            }

            return string.Format("{0:n" + decimalPlaces + "} {1}",
                adjustedSize,
                SizeSuffixes[mag]);
        }

        #endregion Public Methods
    }
}