/* Copyright (c) Cloud Software Group, Inc. 
 * 
 * Redistribution and use in source and binary forms, 
 * with or without modification, are permitted provided 
 * that the following conditions are met: 
 * 
 * *   Redistributions of source code must retain the above 
 *     copyright notice, this list of conditions and the 
 *     following disclaimer. 
 * *   Redistributions in binary form must reproduce the above 
 *     copyright notice, this list of conditions and the 
 *     following disclaimer in the documentation and/or other 
 *     materials provided with the distribution. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, 
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE.
 */

using System;
using System.Globalization;
using System.Xml;


namespace XenAdmin
{
    public enum RoundingBehaviour
    {
        Up, Down, Nearest, None
    }

    /// <summary>
    /// Miscellaneous utility functions
    /// </summary>
    public static class Util
    {
        public const long BINARY_KILO = 1024;
        public const long BINARY_MEGA = BINARY_KILO * BINARY_KILO;
        public const long BINARY_GIGA = BINARY_KILO * BINARY_MEGA;
        public const long BINARY_TERA = BINARY_KILO * BINARY_GIGA;
        public const long BINARY_PETA = BINARY_KILO * BINARY_TERA;

        public const long DEC_KILO = 1000;
        public const long DEC_MEGA = DEC_KILO * DEC_KILO;
        public const long DEC_GIGA = DEC_KILO * DEC_MEGA;
        public const long DEC_TERA = DEC_KILO * DEC_GIGA;

        /// <summary>
        /// The default iSCSI filer port.
        /// </summary>
        public const UInt16 DEFAULT_ISCSI_PORT = 3260;

        public static string MemorySizeStringSuitableUnits(double bytes, bool showPoint0Decimal)
        {
            if (bytes >= 1 * BINARY_GIGA)
            {
                string format = Messages.VAL_GB_ONE_DECIMAL;
                int dp = 1;
                double valGB = bytes / BINARY_GIGA;
                if (valGB > 100)
                {
                    dp = 0;
                    format = Messages.VAL_GB;
                }
                if(!showPoint0Decimal)
                {
                    format = Messages.VAL_GB;
                }
                return string.Format(format, Math.Round(valGB, dp, MidpointRounding.AwayFromZero));       
            }
            else if (bytes >= 1 * BINARY_MEGA)
            {
                return string.Format(Messages.VAL_MB, Math.Round(bytes / BINARY_MEGA));
            }
            else if (bytes >= 1 * BINARY_KILO)
            {
                return string.Format(Messages.VAL_KB, Math.Round(bytes / BINARY_KILO));
            }
            
            if(bytes == 0)
            {
                return bytes.ToString();
            }
            else
            {
                return string.Format(Messages.VAL_B, bytes);
            }
        }

        /// <summary>
        /// Returns the string in suitable units and when the number of bytes is 0 the units are the ones given in formatStringWhenZero.
        /// E.g. : if bytes = 0, showPoint0Decimal = false, formatStringWhenZero = Messages.VAL_MB, then the function will return "0 MB".
        /// </summary>
        /// <param name="bytes"></param>
        /// <param name="showPoint0Decimal"></param>
        /// <param name="formatStringWhenZero"></param>
        /// <returns></returns>
        public static string MemorySizeStringSuitableUnits(double bytes, bool showPoint0Decimal, string formatStringWhenZero)
        {
            if (bytes == 0)
            {
                return string.Format(formatStringWhenZero, bytes);
            }
            else
            {
                return MemorySizeStringSuitableUnits(bytes, showPoint0Decimal);
            }
        }

        public static string DataRateString(double bytesPerSec)
        {
            string unit;
            string value = ByteSizeString(bytesPerSec, 1, true, out unit);
            return string.Format(Messages.VAL_FORMAT, value, unit);
        }

        public static string DataRateValue(double bytesPerSec, out string unit)
        {
            return ByteSizeString(bytesPerSec, 1, true, out unit);
        }

        public static string DiskSizeString(ulong bytes)
        {
            string value = ByteSizeString(bytes, 1, false, out var unit);
            return string.Format(Messages.VAL_FORMAT, value, unit);
        }       
	
        public static string DiskSizeString(long bytes, string format = null)
        {
            return DiskSizeString(bytes, 1, format);
        }

        public static string DiskSizeString(long bytes, int dp, string format = null)
		{
			ulong abs = (ulong)Math.Abs(bytes);
            string unit;
            string value = ByteSizeString(abs, dp, false, out unit, format);
            return string.Format(Messages.VAL_FORMAT, value, unit);
		}

    	public static string DiskSizeStringWithoutUnits(long bytes)
    	{
    	    return ByteSizeString(bytes, 1, false, out _);
        }

        public static string MemorySizeStringVariousUnits(double bytes)
        {
            string unit;
            string value = ByteSizeString(bytes, 0, false, out unit);
            return string.Format(Messages.VAL_FORMAT, value, unit);
        }

        public static string MemorySizeValueVariousUnits(double bytes, out string unit)
        {
            return ByteSizeString(bytes, 0, false, out unit);
        }

        private static string ByteSizeString(double bytes, int decPlaces, bool isRate, out string unit, string format = null)
        {
            if (isRate)
            {
                if (bytes >= DEC_TERA)
                {
                    unit = Messages.VAL_TERRATE;
                    var result = Math.Round(bytes / DEC_TERA, decPlaces);
                    return string.IsNullOrEmpty(format) ? result.ToString() : result.ToString(format);
                }

                if (bytes >= DEC_GIGA)
                {
                    unit = Messages.VAL_GIGRATE;
                    var result = Math.Round(bytes / DEC_GIGA, decPlaces);
                    return string.IsNullOrEmpty(format) ? result.ToString() : result.ToString(format);
                }

                if (bytes >= DEC_MEGA)
                {
                    unit = Messages.VAL_MEGRATE;
                    var result = Math.Round(bytes / DEC_MEGA, decPlaces);
                    return string.IsNullOrEmpty(format) ? result.ToString() : result.ToString(format);
                }

                if (bytes >= DEC_KILO)
                {
                    unit = Messages.VAL_KILRATE;
                    var result = Math.Round(bytes / DEC_KILO, decPlaces);
                    return string.IsNullOrEmpty(format) ? result.ToString() : result.ToString(format);
                }

                unit = Messages.VAL_RATE;
                return bytes.ToString();
            }

            if (bytes >= BINARY_TERA)
            {
                unit = Messages.VAL_TERB;
                var result = Math.Round(bytes / BINARY_TERA, decPlaces);
                return string.IsNullOrEmpty(format) ? result.ToString() : result.ToString(format);
            }
            if (bytes >= BINARY_GIGA)
            {
                unit = Messages.VAL_GIGB;
                var result = Math.Round(bytes / BINARY_GIGA, decPlaces);
                return string.IsNullOrEmpty(format) ? result.ToString() : result.ToString(format);
            }

            if (bytes >= BINARY_MEGA)
            {
                unit = Messages.VAL_MEGB;
                var result = Math.Round(bytes / BINARY_MEGA, decPlaces);
                return string.IsNullOrEmpty(format) ? result.ToString() : result.ToString(format);
            }

            if (bytes >= BINARY_KILO)
            {
                unit = Messages.VAL_KILB;
                var result = Math.Round(bytes / BINARY_KILO, decPlaces);
                return string.IsNullOrEmpty(format) ? result.ToString() : result.ToString(format);
            }

            unit = Messages.VAL_BYTE;
            return bytes.ToString();
        }

        /// <summary>
        /// nothing actually is measured in nanoseconds, we actually output microseconds
        /// </summary>
        public static string NanoSecondsString(double t)
        {
            string unit;
            string value = NanoSecondsValue(t, out unit);
            return string.Format(Messages.VAL_FORMAT_SECONDS, value, unit);
        }

        public static string NanoSecondsValue(double t, out string unit)
        {
            if (t >= DEC_GIGA)
            {
                unit = Messages.VAL_SEC;
                return (t / DEC_GIGA).ToString("0");
            }

            if (t >= DEC_MEGA)
            {
                unit = Messages.VAL_MILSEC;
                return (t / DEC_MEGA).ToString("0");
            }

            if (t >= DEC_KILO)
            {
                unit = Messages.VAL_MICSEC;
                return (t / DEC_KILO).ToString("0");
            }

            unit = Messages.VAL_NANOSEC;
            return t.ToString("0");
        }

        public static string MilliWattString(double t)
        {
            string unit;
            string value = MilliWattValue(t, out unit);
            return string.Format(Messages.VAL_FORMAT, value, unit);
        }

        public static string MilliWattValue(double t, out string unit)
        {
            if (t >= DEC_GIGA)
            {
                unit = Messages.VAL_MWATT;
                return (t / DEC_GIGA).ToString("0");
            }

            if (t >= DEC_MEGA)
            {
                unit = Messages.VAL_KILOWATT;
                return (t / DEC_MEGA).ToString("0");
            }

            if (t >= DEC_KILO)
            {
                unit = Messages.VAL_WATT;
                return (t / DEC_KILO).ToString("0");
            }

            unit = Messages.VAL_MILWATT;
            return t.ToString("0");
        }

        private static double DecimalAdjustment(double value, RoundingBehaviour rounding, int decimalPlaces)
        {
            int decimalsAdjustment = (int)Math.Pow(10, decimalPlaces);
            switch (rounding)
            {
                case RoundingBehaviour.None:
                    return value;
                case RoundingBehaviour.Down:
                    return Math.Floor(value * decimalsAdjustment) / decimalsAdjustment;
                case RoundingBehaviour.Up:
                    return Math.Ceiling(value * decimalsAdjustment) / decimalsAdjustment;
                case RoundingBehaviour.Nearest:
                default:
                    return (Math.Round(value, decimalPlaces, MidpointRounding.AwayFromZero));
            }
        }

        public static double ToTB(double bytes, RoundingBehaviour rounding, int decimalPlaces)
        {
            double value = bytes / BINARY_TERA;
            return DecimalAdjustment(value, rounding, decimalPlaces);
        }

        public static double ToGB(double bytes, RoundingBehaviour rounding, int decimalPlaces)
        {
            double value = bytes / BINARY_GIGA;
            return DecimalAdjustment(value, rounding, decimalPlaces);
        }

        public static double ToMB(double bytes, RoundingBehaviour rounding, int decimalPlaces = 0)
        {
            double value = bytes / BINARY_MEGA;
            return DecimalAdjustment(value, rounding, decimalPlaces);
        }

        public static double CorrectRoundingErrors(double amount)
        {
            // Special case to cope with choosing an amount that's a multiple of 0.1G but not 0.5G --
            // sending it to the server as the nearest byte and getting it back later --
            // and finding it's fractionally changed, messing up our spinner permitted ranges.
            double amountRounded = ToGB(amount, RoundingBehaviour.Nearest, 1) * BINARY_GIGA;
            double roundingDiff = amountRounded - amount;
            if (roundingDiff > -1.0 && roundingDiff < 1.0)  // within 1 byte: although I think it will always be positive in the case we want to correct
                return amountRounded;
            else
                return amount;
        }

        #region DateTime Utils

        public const long TicksBefore1970 = 621355968000000000;

        public static readonly string[] Iso8601DateFormats = {"yyyyMMddTHH:mm:ssZ", "yyyy-MM-ddTHH:mm:ssZ"};
        public static readonly string[] NonIso8601DateFormats = { "yyyy-MM-dd" };

        public static DateTime GetUnixMinDateTime()
        {
            return new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
        }

        public static long TicksToSecondsSince1970(long ticks)
        {
            return (long)Math.Floor(new TimeSpan(ticks - TicksBefore1970).TotalSeconds);
        }

        public static bool TryParseIso8601DateTime(string toParse, out DateTime result)
        {
            return DateTime.TryParseExact(toParse, Iso8601DateFormats, CultureInfo.InvariantCulture,
                DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal, out result);
        }

        public static bool TryParseNonIso8601DateTime(string toParse, out DateTime result)
        {
            return DateTime.TryParseExact(toParse, NonIso8601DateFormats, CultureInfo.InvariantCulture,
                DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal, out result);
        }

        public static string ToISO8601DateTime(DateTime t)
        {
            return t.ToUniversalTime().ToString(Iso8601DateFormats[0], CultureInfo.InvariantCulture);
        }
        
        public static double ToUnixTime(DateTime time)
        {
            TimeSpan diff = time - GetUnixMinDateTime();
            return diff.TotalSeconds;
        }

        public static DateTime FromUnixTime(double time)
        {
            DateTime bootTime = GetUnixMinDateTime();
            return bootTime.AddSeconds(time);
        }

        public static string TimeString(long t)
        {
            if (t >= 120)
                return string.Format(Messages.TIME_MINUTES, t / 60);
            
            if (t > 0)
                return string.Format(Messages.TIME_SECONDS, t);
            
            return Messages.TIME_NEGLIGIBLE;
        }

        #endregion

        internal static string GThanSize(long min)
        {
            return string.Format(Messages.GREATER_THAN, DiskSizeString(min));
        }

        internal static string LThanSize(long max)
        {
            return string.Format(Messages.LESS_THAN, DiskSizeString(max));
        }

        public static string CountsPerSecondString(double p)
        {
            return string.Format(Messages.VAL_FORMAT, p, Messages.COUNTS_PER_SEC_UNIT);
        }

        public static string SecondsPerSecondString(double p)
        {
            return string.Format(Messages.VAL_FORMAT, p, UnitStrings.SEC_PER_SEC_UNIT);
        }

        public static string MegaHertzString(double t)
        {
            string unit;
            string value = MegaHertzValue(t, out unit);
            return string.Format(Messages.VAL_FORMAT, value, unit);
        }

        public static string MegaHertzValue(double t, out string unit)
        {
            return MegaHertzValue(t, 4, out unit);
        }

        /// <summary>
        /// Converts the input value from MHz to GHz if needed, rounding it to the specified decimal places
        /// </summary>
        private static string MegaHertzValue(double t, int decPlaces, out string unit)
        {
            if (t >= DEC_KILO)
            {
                unit = Messages.VAL_GIGHZ;
                return Math.Round(t / DEC_KILO, decPlaces).ToString();
            }
            
            unit = Messages.VAL_MEGHZ;
            return Math.Round(t, decPlaces).ToString();
        }

        public static string PercentageString(double fraction)
        {
            return string.Format("{0}%", (fraction * 100d).ToString("0.0"));
        }

        public static void ThrowIfParameterNull(object obj, string name)
        {
            if (name == null)
            {
                throw new ArgumentNullException("name");
            }

            if (name.Length == 0)
            {
                ThrowBecauseZeroLength("name");
            }

            if (obj == null)
            {
                throw new ArgumentNullException(name);
            }
        }

        public static void ThrowIfStringParameterNullOrEmpty(string value, string name)
        {
            ThrowIfParameterNull(value, name);

            if (value.Length == 0)
            {
                ThrowBecauseZeroLength(name);
            }
        }

        private static void ThrowBecauseZeroLength(string name)
        {
            throw new ArgumentException(string.Format("{0} cannot have 0 length.", name), name);
        }

        /// <summary>
        /// Matches 1-65535 inclusive.
        /// </summary>
        /// <param name="s">The string to be parsed</param>
        /// <returns>True if the specified string contains only a valid port, otherwise false.</returns>
        public static bool IsValidPort(string s)
        {
            int port;

            if (!int.TryParse(s, out port))
                return false;

            return 0 < port && port <= 65535;
        }
    }
}