/* SPDX-License-Identifier: Apache-2.0
*
* The OpenSearch Contributors require contributions made to
* this file be licensed under the Apache-2.0 license or a
* compatible open source license.
*/
/*
* Modifications Copyright OpenSearch Contributors. See
* GitHub history for details.
*
*  Licensed to Elasticsearch B.V. under one or more contributor
*  license agreements. See the NOTICE file distributed with
*  this work for additional information regarding copyright
*  ownership. Elasticsearch B.V. licenses this file to you 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://www.apache.org/licenses/LICENSE-2.0
*
*  Unless required by applicable law or agreed to in writing,
*  software distributed under the License 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.
*/

#region Utf8Json License https://github.com/neuecc/Utf8Json/blob/master/LICENSE
// MIT License
//
// Copyright (c) 2017 Yoshifumi Kawai
//
// 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.
#endregion

using System;
using System.Globalization;
using OpenSearch.Net.Extensions;
using OpenSearch.Net.Utf8Json.Internal;

namespace OpenSearch.Net.Utf8Json.Formatters
{
	internal sealed class DateTimeFormatter : IJsonFormatter<DateTime>
	{
		private readonly string _formatString;

		public DateTimeFormatter() => _formatString = null;

		public DateTimeFormatter(string formatString) => _formatString = formatString;

		public void Serialize(ref JsonWriter writer, DateTime value, IJsonFormatterResolver formatterResolver) =>
			writer.WriteString(value.ToString(_formatString));

		public DateTime Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			var str = reader.ReadString();
			return _formatString == null
				? DateTime.Parse(str, CultureInfo.InvariantCulture)
				: DateTime.ParseExact(str, _formatString, CultureInfo.InvariantCulture);
		}
	}

	internal sealed class NullableDateTimeFormatter : IJsonFormatter<DateTime?>
	{
		private readonly DateTimeFormatter _innerFormatter;

		public NullableDateTimeFormatter() => _innerFormatter = new DateTimeFormatter();

		public NullableDateTimeFormatter(string formatString) => _innerFormatter = new DateTimeFormatter(formatString);

		public void Serialize(ref JsonWriter writer, DateTime? value, IJsonFormatterResolver formatterResolver)
		{
			if (value == null)
			{
				writer.WriteNull();
				return;
			}

			_innerFormatter.Serialize(ref writer, value.Value, formatterResolver);
		}

		public DateTime? Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			if (reader.ReadIsNull()) return null;

			return _innerFormatter.Deserialize(ref reader, formatterResolver);
		}
	}

	internal sealed class ISO8601DateTimeFormatter : IJsonFormatter<DateTime>
	{
		public static readonly IJsonFormatter<DateTime> Default = new ISO8601DateTimeFormatter();

		public void Serialize(ref JsonWriter writer, DateTime value, IJsonFormatterResolver formatterResolver)
		{
			var year = value.Year;
			var month = value.Month;
			var day = value.Day;
			var hour = value.Hour;
			var minute = value.Minute;
			var second = value.Second;
			var nanosec = value.Ticks % TimeSpan.TicksPerSecond;

			const int baseLength = 19 + 2; // {YEAR}-{MONTH}-{DAY}T{Hour}:{Minute}:{Second} + quotation
			const int nanosecLength = 8; // .{nanoseconds}

			switch (value.Kind)
			{
				case DateTimeKind.Local:
					// +{Hour}:{Minute}
					writer.EnsureCapacity(baseLength + ((nanosec == 0) ? 0 : nanosecLength) + 6);
					break;
				case DateTimeKind.Utc:
					// Z
					writer.EnsureCapacity(baseLength + ((nanosec == 0) ? 0 : nanosecLength) + 1);
					break;
				case DateTimeKind.Unspecified:
				default:
					writer.EnsureCapacity(baseLength + ((nanosec == 0) ? 0 : nanosecLength));
					break;
			}

			writer.WriteRawUnsafe((byte)'\"');

			if (year < 10)
			{
				writer.WriteRawUnsafe((byte)'0');
				writer.WriteRawUnsafe((byte)'0');
				writer.WriteRawUnsafe((byte)'0');
			}
			else if (year < 100)
			{
				writer.WriteRawUnsafe((byte)'0');
				writer.WriteRawUnsafe((byte)'0');
			}
			else if (year < 1000)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(year);
			writer.WriteRawUnsafe((byte)'-');

			if (month < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(month);
			writer.WriteRawUnsafe((byte)'-');

			if (day < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(day);

			writer.WriteRawUnsafe((byte)'T');

			if (hour < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(hour);
			writer.WriteRawUnsafe((byte)':');

			if (minute < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(minute);
			writer.WriteRawUnsafe((byte)':');

			if (second < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(second);

			if (nanosec != 0)
			{
				writer.WriteRawUnsafe((byte)'.');

				if (nanosec < 10)
				{
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
				}
				else if (nanosec < 100)
				{
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
				}
				else if (nanosec < 1000)
				{
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
				}
				else if (nanosec < 10000)
				{
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
				}
				else if (nanosec < 100000)
				{
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
				}
				else if (nanosec < 1000000)
					writer.WriteRawUnsafe((byte)'0');

				writer.WriteInt64(nanosec);
			}

			switch (value.Kind)
			{
				case DateTimeKind.Local:
					// should not use `BaseUtcOffset` - https://stackoverflow.com/questions/10019267/is-there-a-generic-timezoneinfo-for-central-europe
					var localOffset = TimeZoneInfo.Local.GetUtcOffset(value);
					var minus = (localOffset < TimeSpan.Zero);
					if (minus) localOffset = localOffset.Negate();
					var h = localOffset.Hours;
					var m = localOffset.Minutes;
					writer.WriteRawUnsafe(minus ? (byte)'-' : (byte)'+');
					if (h < 10)
						writer.WriteRawUnsafe((byte)'0');

					writer.WriteInt32(h);
					writer.WriteRawUnsafe((byte)':');
					if (m < 10)
						writer.WriteRawUnsafe((byte)'0');

					writer.WriteInt32(m);
					break;
				case DateTimeKind.Utc:
					writer.WriteRawUnsafe((byte)'Z');
					break;
				case DateTimeKind.Unspecified:
				default:
					break;
			}

			writer.WriteRawUnsafe((byte)'\"');
		}

		public DateTime Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			var str = reader.ReadStringSegmentUnsafe();
			var array = str.Array;
			var i = str.Offset;
			var len = str.Count;
			var to = str.Offset + str.Count;

			// YYYY
			if (len == 4)
			{
				var y = (array[i++] - (byte)'0') * 1000 + (array[i++] - (byte)'0') * 100 + (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				return new DateTime(y, 1, 1);
			}

			// YYYY-MM
			if (len == 7)
			{
				var y = (array[i++] - (byte)'0') * 1000 + (array[i++] - (byte)'0') * 100 + (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				if (array[i++] != (byte)'-') goto ERROR;
				var m = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				return new DateTime(y, m, 1);
			}

			// YYYY-MM-DD
			if (len == 10)
			{
				var y = (array[i++] - (byte)'0') * 1000 + (array[i++] - (byte)'0') * 100 + (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				if (array[i++] != (byte)'-') goto ERROR;
				var m = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				if (array[i++] != (byte)'-') goto ERROR;
				var d = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				return new DateTime(y, m, d);
			}

			// range-first section requires 19
			if (len < 19) goto ERROR;

			var year = (array[i++] - (byte)'0') * 1000 + (array[i++] - (byte)'0') * 100 + (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
			if (array[i++] != (byte)'-') goto ERROR;
			var month = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
			if (array[i++] != (byte)'-') goto ERROR;
			var day = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');

			if (array[i++] != (byte)'T') goto ERROR;

			var hour = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
			if (array[i++] != (byte)':') goto ERROR;
			var minute = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
			if (array[i++] != (byte)':') goto ERROR;
			var second = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');

			var ticks = 0;
			if (i < to && array[i] == '.')
			{
				i++;

				// *7.
				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 1000000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 100000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 10000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 1000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 100;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 10;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 1;
				i++;

				// others, lack of precision
				while (i < to && NumberConverter.IsNumber(array[i]))
					i++;
			}

			END_TICKS:
			var kind = DateTimeKind.Unspecified;
			if (i < to && array[i] == 'Z')
				kind = DateTimeKind.Utc;
			else if (i < to && array[i] == '-' || array[i] == '+')
			{
				var offLen = to - i;
				if (offLen != 3 && offLen != 5 && offLen != 6) goto ERROR;
				var minus = array[i++] == '-';
				var h = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				var m = 0;
				if (i < to)
				{
					if (offLen == 6)
					{
						if (array[i] != ':') goto ERROR;
						i++;
					}
					m = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				}

				var offset = new TimeSpan(h, m, 0);
				if (minus) offset = offset.Negate();

				return new DateTime(year, month, day, hour, minute, second, DateTimeKind.Utc).AddTicks(ticks).Subtract(offset).ToLocalTime();
			}

			return new DateTime(year, month, day, hour, minute, second, kind).AddTicks(ticks);

			ERROR:
			throw new InvalidOperationException("invalid datetime format. value:" + StringEncoding.UTF8.GetString(str.Array, str.Offset, str.Count));
		}
	}

	internal sealed class UnixTimestampDateTimeFormatter : IJsonFormatter<DateTime>
	{
		public void Serialize(ref JsonWriter writer, DateTime value, IJsonFormatterResolver formatterResolver)
		{
			var ticks = (long)(value.ToUniversalTime() - DateTimeUtil.UnixEpoch.DateTime).TotalSeconds;
			writer.WriteQuotation();
			writer.WriteInt64(ticks);
			writer.WriteQuotation();
		}

		public DateTime Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			var str = reader.ReadStringSegmentUnsafe();
			var ticks = NumberConverter.ReadUInt64(str.Array, str.Offset, out _);

			return DateTimeUtil.UnixEpoch.DateTime.AddSeconds(ticks);
		}
	}

	internal sealed class DateTimeOffsetFormatter : IJsonFormatter<DateTimeOffset>
	{
		private readonly string _formatString;

		public DateTimeOffsetFormatter() => _formatString = null;

		public DateTimeOffsetFormatter(string formatString) => _formatString = formatString;

		public void Serialize(ref JsonWriter writer, DateTimeOffset value, IJsonFormatterResolver formatterResolver) =>
			writer.WriteString(value.ToString(_formatString));

		public DateTimeOffset Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			var str = reader.ReadString();
			return _formatString == null
				? DateTimeOffset.Parse(str, CultureInfo.InvariantCulture)
				: DateTimeOffset.ParseExact(str, _formatString, CultureInfo.InvariantCulture);
		}
	}

	internal sealed class NullableDateTimeOffsetFormatter : IJsonFormatter<DateTimeOffset?>
	{
		private readonly DateTimeOffsetFormatter _innerFormatter;

		public NullableDateTimeOffsetFormatter() => _innerFormatter = new DateTimeOffsetFormatter();

		public NullableDateTimeOffsetFormatter(string formatString) => _innerFormatter = new DateTimeOffsetFormatter(formatString);

		public void Serialize(ref JsonWriter writer, DateTimeOffset? value, IJsonFormatterResolver formatterResolver)
		{
			if (value == null) { writer.WriteNull(); return; }

			_innerFormatter.Serialize(ref writer, value.Value, formatterResolver);
		}

		public DateTimeOffset? Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			if (reader.ReadIsNull()) return null;

			return _innerFormatter.Deserialize(ref reader, formatterResolver);
		}
	}

	internal sealed class ISO8601DateTimeOffsetFormatter : IJsonFormatter<DateTimeOffset>
	{
		public static readonly IJsonFormatter<DateTimeOffset> Default = new ISO8601DateTimeOffsetFormatter();

		public void Serialize(ref JsonWriter writer, DateTimeOffset value, IJsonFormatterResolver formatterResolver)
		{
			var year = value.Year;
			var month = value.Month;
			var day = value.Day;
			var hour = value.Hour;
			var minute = value.Minute;
			var second = value.Second;
			var nanosec = value.Ticks % TimeSpan.TicksPerSecond;

			const int baseLength = 19 + 2; // {YEAR}-{MONTH}-{DAY}T{Hour}:{Minute}:{Second} + quotation
			const int nanosecLength = 8; // .{nanoseconds}

			// +{Hour}:{Minute}
			writer.EnsureCapacity(baseLength + ((nanosec == 0) ? 0 : nanosecLength) + 6);

			writer.WriteRawUnsafe((byte)'\"');

			if (year < 10)
			{
				writer.WriteRawUnsafe((byte)'0');
				writer.WriteRawUnsafe((byte)'0');
				writer.WriteRawUnsafe((byte)'0');
			}
			else if (year < 100)
			{
				writer.WriteRawUnsafe((byte)'0');
				writer.WriteRawUnsafe((byte)'0');
			}
			else if (year < 1000)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(year);
			writer.WriteRawUnsafe((byte)'-');

			if (month < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(month);
			writer.WriteRawUnsafe((byte)'-');

			if (day < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(day);

			writer.WriteRawUnsafe((byte)'T');

			if (hour < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(hour);
			writer.WriteRawUnsafe((byte)':');

			if (minute < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(minute);
			writer.WriteRawUnsafe((byte)':');

			if (second < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(second);

			if (nanosec != 0)
			{
				writer.WriteRawUnsafe((byte)'.');

				if (nanosec < 10)
				{
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
				}
				else if (nanosec < 100)
				{
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
				}
				else if (nanosec < 1000)
				{
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
				}
				else if (nanosec < 10000)
				{
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
				}
				else if (nanosec < 100000)
				{
					writer.WriteRawUnsafe((byte)'0');
					writer.WriteRawUnsafe((byte)'0');
				}
				else if (nanosec < 1000000)
					writer.WriteRawUnsafe((byte)'0');

				writer.WriteInt64(nanosec);
			}

			var localOffset = value.Offset;
			var minus = localOffset < TimeSpan.Zero;
			if (minus) localOffset = localOffset.Negate();
			var h = localOffset.Hours;
			var m = localOffset.Minutes;
			writer.WriteRawUnsafe(minus ? (byte)'-' : (byte)'+');
			if (h < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(h);
			writer.WriteRawUnsafe((byte)':');
			if (m < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(m);

			writer.WriteRawUnsafe((byte)'\"');
		}

		public DateTimeOffset Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			var str = reader.ReadStringSegmentUnsafe();
			var array = str.Array;
			var i = str.Offset;
			var len = str.Count;
			var to = str.Offset + str.Count;

			// YYYY
			if (len == 4)
			{
				var y = (array[i++] - (byte)'0') * 1000 + (array[i++] - (byte)'0') * 100 + (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				return new DateTimeOffset(y, 1, 1, 0, 0, 0, TimeSpan.Zero);
			}

			// YYYY-MM
			if (len == 7)
			{
				var y = (array[i++] - (byte)'0') * 1000 + (array[i++] - (byte)'0') * 100 + (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				if (array[i++] != (byte)'-') goto ERROR;
				var m = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				return new DateTimeOffset(y, m, 1, 0, 0, 0, TimeSpan.Zero);
			}

			// YYYY-MM-DD
			if (len == 10)
			{
				var y = (array[i++] - (byte)'0') * 1000 + (array[i++] - (byte)'0') * 100 + (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				if (array[i++] != (byte)'-') goto ERROR;
				var m = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				if (array[i++] != (byte)'-') goto ERROR;
				var d = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				return new DateTimeOffset(y, m, d, 0, 0, 0, TimeSpan.Zero);
			}

			// range-first section requires 19
			if (array.Length < 19) goto ERROR;

			var year = (array[i++] - (byte)'0') * 1000 + (array[i++] - (byte)'0') * 100 + (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
			if (array[i++] != (byte)'-') goto ERROR;
			var month = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
			if (array[i++] != (byte)'-') goto ERROR;
			var day = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');

			if (array[i++] != (byte)'T') goto ERROR;

			var hour = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
			if (array[i++] != (byte)':') goto ERROR;
			var minute = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
			if (array[i++] != (byte)':') goto ERROR;
			var second = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');

			var ticks = 0;
			if (i < to && array[i] == '.')
			{
				i++;

				// *7.
				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 1000000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 100000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 10000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 1000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 100;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 10;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 1;
				i++;

				// others, lack of precision
				while (i < to && NumberConverter.IsNumber(array[i]))
					i++;
			}

			END_TICKS:

			if (i < to && array[i] == '-' || array[i] == '+')
			{
				var offLen = to - i;
				if (offLen != 3 && offLen != 5 && offLen != 6) goto ERROR;
				var minus = array[i++] == '-';
				var h = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				var m = 0;
				if (i < to)
				{
					if (offLen == 6)
					{
						if (array[i] != ':') goto ERROR;
						i++;
					}

					m = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
				}

				var offset = new TimeSpan(h, m, 0);
				if (minus) offset = offset.Negate();

				return new DateTimeOffset(year, month, day, hour, minute, second, offset).AddTicks(ticks);
			}

			return new DateTimeOffset(year, month, day, hour, minute, second, TimeSpan.Zero).AddTicks(ticks);

			ERROR:
			throw new InvalidOperationException("invalid datetime format. value:" + StringEncoding.UTF8.GetString(str.Array, str.Offset, str.Count));
		}
	}

	internal sealed class TimeSpanFormatter : IJsonFormatter<TimeSpan>
	{
		private readonly string _formatString;

		public TimeSpanFormatter() => _formatString = null;

		public TimeSpanFormatter(string formatString) => _formatString = formatString;

		public void Serialize(ref JsonWriter writer, TimeSpan value, IJsonFormatterResolver formatterResolver) =>
			writer.WriteString(value.ToString(_formatString));

		public TimeSpan Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			var str = reader.ReadString();
			return _formatString == null
				? TimeSpan.Parse(str, CultureInfo.InvariantCulture)
				: TimeSpan.ParseExact(str, _formatString, CultureInfo.InvariantCulture);
		}
	}

	internal sealed class NullableTimeSpanFormatter : IJsonFormatter<TimeSpan?>
	{
		private readonly TimeSpanFormatter _innerFormatter;

		public NullableTimeSpanFormatter() => _innerFormatter = new TimeSpanFormatter();

		public NullableTimeSpanFormatter(string formatString) => _innerFormatter = new TimeSpanFormatter(formatString);

		public void Serialize(ref JsonWriter writer, TimeSpan? value, IJsonFormatterResolver formatterResolver)
		{
			if (value == null) { writer.WriteNull(); return; }

			_innerFormatter.Serialize(ref writer, value.Value, formatterResolver);
		}

		public TimeSpan? Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			if (reader.ReadIsNull()) return null;

			return _innerFormatter.Deserialize(ref reader, formatterResolver);
		}
	}

	internal sealed class ISO8601TimeSpanFormatter : IJsonFormatter<TimeSpan>
	{
		public static readonly IJsonFormatter<TimeSpan> Default = new ISO8601TimeSpanFormatter();

		private static readonly byte[] MinValue = StringEncoding.UTF8.GetBytes("\"" + TimeSpan.MinValue + "\"");

		public void Serialize(ref JsonWriter writer, TimeSpan value, IJsonFormatterResolver formatterResolver)
		{
			// can not negate, use cache
			if (value == TimeSpan.MinValue)
			{
				writer.WriteRaw(MinValue);
				return;
			}

			var minus = value < TimeSpan.Zero;
			if (minus) value = value.Negate();
			var day = value.Days;
			var hour = value.Hours;
			var minute = value.Minutes;
			var second = value.Seconds;
			var nanosecond = value.Ticks % TimeSpan.TicksPerSecond;

			const int maxDayLength = 8 + 1; // {Day}.
			const int baseLength = 8 + 2; // {Hour}:{Minute}:{Second} + quotation
			const int nanosecLength = 8; // .{nanoseconds}

			writer.EnsureCapacity(baseLength + maxDayLength + (nanosecond == 0 ? 0 : nanosecLength) + 6);

			writer.WriteRawUnsafe((byte)'\"');

			if (minus)
				writer.WriteRawUnsafe((byte)'-');

			if (day != 0)
			{
				writer.WriteInt32(day);
				writer.WriteRawUnsafe((byte)'.');
			}

			if (hour < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(hour);
			writer.WriteRawUnsafe((byte)':');

			if (minute < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(minute);
			writer.WriteRawUnsafe((byte)':');

			if (second < 10)
				writer.WriteRawUnsafe((byte)'0');

			writer.WriteInt32(second);

			if (nanosecond != 0)
			{
				writer.WriteRawUnsafe((byte)'.');
				if (nanosecond < 1000000)
				{
					writer.WriteRawUnsafe((byte) '0');
					if (nanosecond < 100000)
					{
						writer.WriteRawUnsafe((byte) '0');
						if (nanosecond < 10000)
						{
							writer.WriteRawUnsafe((byte) '0');
							if (nanosecond < 1000)
							{
								writer.WriteRawUnsafe((byte) '0');
								if (nanosecond < 100)
								{
									writer.WriteRawUnsafe((byte) '0');
									if (nanosecond < 10)
										writer.WriteRawUnsafe((byte) '0');
								}
							}
						}
					}
				}

				writer.WriteInt64(nanosecond);
			}

			writer.WriteRawUnsafe((byte)'\"');
		}

		public TimeSpan Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
		{
			var str = reader.ReadStringSegmentUnsafe();
			var array = str.Array;
			var i = str.Offset;
			var len = str.Count;
			var to = str.Offset + len;

			// check day exists
			var hasDay = false;
			{
				var foundDot = false;
				var foundColon = false;
				for (var j = i; j < to; j++)
				{
					if (array[j] == '.')
					{
						if (foundColon)
							break;

						foundDot = true;
					}
					else if (array[j] == ':')
					{
						if (foundDot)
							hasDay = true;

						foundColon = true;
					}
				}
			}

			// check sign
			var minus = false;
			if (array[i] == '-')
			{
				minus = true;
				i++;
			}

			var day = 0;
			if (hasDay)
			{
				const int maxDayLength = 8 + 1; // {Day}.
				var dayCharacters = new byte[maxDayLength];
				for (; array[i] != '.'; i++)
					dayCharacters[day++] = array[i];

				day = new JsonReader(dayCharacters).ReadInt32();
				i++; // skip '.'
			}

			var hour = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
			if (array[i++] != (byte)':') goto ERROR;
			var minute = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');
			if (array[i++] != (byte)':') goto ERROR;
			var second = (array[i++] - (byte)'0') * 10 + (array[i++] - (byte)'0');

			var ticks = 0;
			if (i < to && array[i] == '.')
			{
				i++;

				// *7.
				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 1000000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 100000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 10000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 1000;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 100;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 10;
				i++;

				if (!(i < to) || !NumberConverter.IsNumber(array[i])) goto END_TICKS;
				ticks += (array[i] - (byte)'0') * 1;
				i++;

				// others, lack of precision
				while (i < to && NumberConverter.IsNumber(array[i]))
					i++;
			}

			END_TICKS:

			// be careful to overflow
			var ts = new TimeSpan(day, hour, minute, second);
			var tk = TimeSpan.FromTicks(ticks);
			return minus
				? ts.Negate().Subtract(tk)
				: ts.Add(tk);

			ERROR:
			throw new InvalidOperationException("invalid TimeSpan format. value:" + StringEncoding.UTF8.GetString(str.Array, str.Offset, str.Count));
		}
	}
}