/*
 *
 * (c) Copyright Ascensio System Limited 2010-2018
 *
 * This program is freeware. You can redistribute it and/or modify it under the terms of the GNU 
 * General Public License (GPL) version 3 as published by the Free Software Foundation (https://www.gnu.org/copyleft/gpl.html). 
 * In accordance with Section 7(a) of the GNU GPL its Section 15 shall be amended to the effect that 
 * Ascensio System SIA expressly excludes the warranty of non-infringement of any third-party rights.
 *
 * THIS PROGRAM IS DISTRIBUTED WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE. For more details, see GNU GPL at https://www.gnu.org/copyleft/gpl.html
 *
 * You can contact Ascensio System SIA by email at sales@onlyoffice.com
 *
 * The interactive user interfaces in modified source and object code versions of ONLYOFFICE must display 
 * Appropriate Legal Notices, as required under Section 5 of the GNU GPL version 3.
 *
 * Pursuant to Section 7 § 3(b) of the GNU GPL you must retain the original ONLYOFFICE logo which contains 
 * relevant author attributions when distributing the software. If the display of the logo in its graphic 
 * form is not reasonably feasible for technical reasons, you must include the words "Powered by ONLYOFFICE" 
 * in every copy of the program you distribute. 
 * Pursuant to Section 7 § 3(e) we decline to grant you any rights under trademark law for use of our trademarks.
 *
*/

namespace ASC.Api.Core;

[TypeConverter(typeof(ApiDateTimeTypeConverter))]
public class ApiDateTime : IComparable<ApiDateTime>, IComparable
{
    public DateTime UtcTime { get; private set; }
    public TimeSpan TimeZoneOffset { get; private set; }

    internal static readonly string[] Formats = new[]
    {
            "o",
            "yyyy'-'MM'-'dd'T'HH'-'mm'-'ss'.'fffffffK",
            "yyyy'-'MM'-'dd'T'HH'-'mm'-'ss'.'fffK",
            "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffK",
            "yyyy'-'MM'-'dd'T'HH'-'mm'-'ssK",
            "yyyy'-'MM'-'dd'T'HH':'mm':'ssK",
            "yyyy'-'MM'-'dd"
        };

    private readonly TenantManager _tenantManager;
    private readonly TimeZoneConverter _timeZoneConverter;

    public ApiDateTime() : this(null, null, null) { }

    public ApiDateTime(
        TenantManager tenantManager,
        TimeZoneConverter timeZoneConverter,
        DateTime? dateTime)
        : this(tenantManager, dateTime, null, timeZoneConverter) { }

    public ApiDateTime(
        TenantManager tenantManager,
        DateTime? dateTime,
        TimeZoneInfo timeZone,
        TimeZoneConverter timeZoneConverter)
    {
        if (dateTime.HasValue && dateTime.Value > DateTime.MinValue && dateTime.Value < DateTime.MaxValue)
        {
            _tenantManager = tenantManager;
            _timeZoneConverter = timeZoneConverter;
            SetDate(dateTime.Value, timeZone);
        }
        else
        {
            UtcTime = DateTime.MinValue;
            TimeZoneOffset = TimeSpan.Zero;
        }
    }

    public ApiDateTime(DateTime utcTime, TimeSpan offset)
    {
        UtcTime = new DateTime(utcTime.Ticks, DateTimeKind.Utc);
        TimeZoneOffset = offset;
    }

    public static ApiDateTime Parse(string data, TenantManager tenantManager, TimeZoneConverter timeZoneConverter) =>
        Parse(data, null, tenantManager, timeZoneConverter);

    public static ApiDateTime Parse(string data, TimeZoneInfo tz, TenantManager tenantManager, TimeZoneConverter timeZoneConverter)
    {
        if (string.IsNullOrEmpty(data)) throw new ArgumentNullException(nameof(data));

        if (data.Length < 7) throw new ArgumentException("invalid date time format");

        var offsetPart = data.Substring(data.Length - 6, 6);
        if (DateTime.TryParseExact(data, Formats, CultureInfo.InvariantCulture, DateTimeStyles.AdjustToUniversal, out var dateTime))
        {
            //Parse time   
            var tzOffset = TimeSpan.Zero;
            if (offsetPart.Contains(':') && TimeSpan.TryParse(offsetPart.TrimStart('+'), out tzOffset))
                return new ApiDateTime(dateTime, tzOffset);

            if (!data.EndsWith("Z", true, CultureInfo.InvariantCulture))
            {
                if (tz == null) tz = GetTimeZoneInfo(tenantManager, timeZoneConverter);

                tzOffset = tz.GetUtcOffset(dateTime);
                dateTime = dateTime.Subtract(tzOffset);
            }

            return new ApiDateTime(dateTime, tzOffset);

        }

        throw new ArgumentException("invalid date time format: " + data);
    }


    private void SetDate(DateTime value, TimeZoneInfo timeZone)
    {
        TimeZoneOffset = TimeSpan.Zero;
        UtcTime = DateTime.MinValue;

        if (timeZone == null)
            timeZone = GetTimeZoneInfo(_tenantManager, _timeZoneConverter);

        //Hack
        if (timeZone.IsInvalidTime(new DateTime(value.Ticks, DateTimeKind.Unspecified)))
            value = value.AddHours(1);

        if (value.Kind == DateTimeKind.Local)
            value = TimeZoneInfo.ConvertTimeToUtc(new DateTime(value.Ticks, DateTimeKind.Unspecified), timeZone);

        if (value.Kind == DateTimeKind.Unspecified)
            value = new DateTime(value.Ticks, DateTimeKind.Utc); //Assume it's utc

        if (value.Kind == DateTimeKind.Utc)
        {
            UtcTime = value; //Set UTC time
            TimeZoneOffset = timeZone.GetUtcOffset(value);
        }
    }

    private static TimeZoneInfo GetTimeZoneInfo(TenantManager tenantManager, TimeZoneConverter timeZoneConverter)
    {
        var timeZone = TimeZoneInfo.Local;
        try
        {
            timeZone = timeZoneConverter.GetTimeZone(tenantManager.GetCurrentTenant().TimeZone);
        }
        catch (Exception)
        {
            //Tenant failed
        }

        return timeZone;
    }

    private string ToRoundTripString(DateTime date, TimeSpan offset)
    {
        var dateString = date.ToString("yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffffff", CultureInfo.InvariantCulture);
        var offsetString = offset.Ticks == 0 ? "Z" : ((offset < TimeSpan.Zero) ? "-" : "+") + offset.ToString("hh\\:mm", CultureInfo.InvariantCulture);

        return dateString + offsetString;
    }

    public static ApiDateTime FromDate(TenantManager tenantManager, TimeZoneConverter timeZoneConverter, DateTime d)
    {
        var date = new ApiDateTime(tenantManager, timeZoneConverter, d);

        return date;
    }

    public static ApiDateTime FromDate(TenantManager tenantManager, TimeZoneConverter timeZoneConverter, DateTime? d)
    {
        if (d.HasValue)
        {
            var date = new ApiDateTime(tenantManager, timeZoneConverter, d);

            return date;
        }

        return null;
    }

    public static bool operator >(ApiDateTime left, ApiDateTime right)
    {
        if (ReferenceEquals(left, right)) return false;
        if (left == null) return false;

        return left.CompareTo(right) > 0;
    }

    public static bool operator >=(ApiDateTime left, ApiDateTime right)
    {
        if (ReferenceEquals(left, right)) return false;
        if (left == null) return false;

        return left.CompareTo(right) >= 0;
    }

    public static bool operator <=(ApiDateTime left, ApiDateTime right) => !(left >= right);

    public static bool operator <(ApiDateTime left, ApiDateTime right) => !(left > right);

    public static bool operator ==(ApiDateTime left, ApiDateTime right) => Equals(left, right);

    public static bool operator !=(ApiDateTime left, ApiDateTime right) => !(left == right);

    public static implicit operator DateTime(ApiDateTime d)
    {
        if (d == null) return DateTime.MinValue;

        return d.UtcTime;
    }

    public static implicit operator DateTime?(ApiDateTime d)
    {
        if (d == null) return null;

        return d.UtcTime;
    }

    public int CompareTo(DateTime other) => CompareTo(new ApiDateTime(_tenantManager, _timeZoneConverter, other));

    public int CompareTo(ApiDateTime other)
    {
        if (other == null) return 1;

        return UtcTime.CompareTo(other.UtcTime);
    }

    public override bool Equals(object obj)
    {
        if (obj is null) return false;
        if (ReferenceEquals(this, obj)) return true;
        if (obj.GetType() != typeof(ApiDateTime)) return false;

        return Equals((ApiDateTime)obj);
    }

    public bool Equals(ApiDateTime other)
    {
        if (other is null) return false;
        if (ReferenceEquals(this, other)) return true;

        return UtcTime.Equals(other.UtcTime) && TimeZoneOffset.Equals(other.TimeZoneOffset);
    }

    public override int GetHashCode()
    {
        unchecked
        {
            return UtcTime.GetHashCode() * 397 + TimeZoneOffset.GetHashCode();
        }
    }

    public int CompareTo(object obj)
    {
        if (obj is DateTime dateTime)
            return CompareTo(dateTime);

        return obj is ApiDateTime apiDateTime ? CompareTo(apiDateTime) : 0;
    }

    public override string ToString()
    {
        var localUtcTime = UtcTime;

        if (!UtcTime.Equals(DateTime.MinValue))
            localUtcTime = UtcTime.Add(TimeZoneOffset);

        return ToRoundTripString(localUtcTime, TimeZoneOffset);
    }

    public static ApiDateTime GetSample() => new ApiDateTime(DateTime.UtcNow, TimeSpan.Zero);
}

public class ApiDateTimeTypeConverter : DateTimeConverter
{
    public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
    {
        if (destinationType == typeof(string))
            return value.ToString();

        return base.ConvertTo(context, culture, value, destinationType);
    }

    public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
    {
        if (value is string @string)
            return ApiDateTime.Parse(@string, null, null);

        if (value is DateTime time)
            return new ApiDateTime(null, null, time);

        return base.ConvertFrom(context, culture, value);
    }
}

public class ApiDateTimeConverter : System.Text.Json.Serialization.JsonConverter<ApiDateTime>
{
    public override ApiDateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        if (reader.TryGetDateTime(out var result))
            return new ApiDateTime(result, TimeSpan.Zero);
        else
        {
            if (DateTime.TryParseExact(reader.GetString(), ApiDateTime.Formats, CultureInfo.InvariantCulture, DateTimeStyles.RoundtripKind, out var dateTime))
                return new ApiDateTime(dateTime, TimeSpan.Zero);
            else
                return new ApiDateTime();
        }
    }

    public override void Write(Utf8JsonWriter writer, ApiDateTime value, JsonSerializerOptions options) =>
        writer.WriteStringValue(value.ToString());
}

[Scope]
public class ApiDateTimeHelper
{
    private readonly TenantManager _tenantManager;
    private readonly TimeZoneConverter _timeZoneConverter;

    public ApiDateTimeHelper(TenantManager tenantManager, TimeZoneConverter timeZoneConverter)
    {
        _tenantManager = tenantManager;
        _timeZoneConverter = timeZoneConverter;
    }

    public ApiDateTime Get(DateTime? from) => ApiDateTime.FromDate(_tenantManager, _timeZoneConverter, from);
}