//
// Utilities.cs
//
// Author:
//   Aaron Bockover <abockover@novell.com>
//
// Copyright (C) 2007 Novell, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Globalization;

namespace Hyena
{
    public class DateTimeUtil
    {
        // FIXME I don't think having a local-unix-epoch makes any sense, I think we should be using
        // all UTC values.  Depending on the time of year in daylight savings timezones, the
        // local-seconds-since-epoch value will differ, which will cause errors, no?
        public static readonly DateTime LocalUnixEpoch = new DateTime (1970, 1, 1).ToLocalTime ();

        public static DateTime ToDateTime (long time)
        {
            return FromTimeT (time);
        }

        public static long FromDateTime (DateTime time)
        {
            return ToTimeT (time);
        }

        private static long super_ugly_min_hack = -15768000000; // 500 yrs before epoch...ewww
        public static DateTime FromTimeT (long time)
        {
            return (time <= super_ugly_min_hack) ? DateTime.MinValue : LocalUnixEpoch.AddSeconds (time);
        }

        public static long ToTimeT (DateTime time)
        {
            return (long)time.Subtract (LocalUnixEpoch).TotalSeconds;
        }

        public static string FormatDuration (long time) {
            return FormatDuration (TimeSpan.FromSeconds (time));
        }

        public static string FormatDuration (TimeSpan time) {
            return FormatDuration (time.Hours, time.Minutes, time.Seconds);
        }

        public static string FormatDuration (int hours, int minutes, int seconds) {
            return (hours > 0 ?
                    String.Format ("{0}:{1:00}:{2:00}", hours, minutes, seconds) :
                    String.Format ("{0}:{1:00}", minutes, seconds));
        }

        const string INVARIANT_FMT = "yyyy-MM-dd HH:mm:ss.fff zzz";
        public static string ToInvariantString (DateTime dt)
        {
            return dt.ToString (INVARIANT_FMT, CultureInfo.InvariantCulture);
        }

        public static bool TryParseInvariant (string str, out DateTime dt)
        {
            return DateTime.TryParseExact (str, INVARIANT_FMT, CultureInfo.InvariantCulture, DateTimeStyles.None, out dt);
        }
    }
}