1#region Copyright notice and license
2// Protocol Buffers - Google's data interchange format
3// Copyright 2015 Google Inc.  All rights reserved.
4// https://developers.google.com/protocol-buffers/
5//
6// Redistribution and use in source and binary forms, with or without
7// modification, are permitted provided that the following conditions are
8// met:
9//
10//     * Redistributions of source code must retain the above copyright
11// notice, this list of conditions and the following disclaimer.
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13// copyright notice, this list of conditions and the following disclaimer
14// in the documentation and/or other materials provided with the
15// distribution.
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17// contributors may be used to endorse or promote products derived from
18// this software without specific prior written permission.
19//
20// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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23// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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26// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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31#endregion
32
33using System;
34using System.Globalization;
35using System.Text;
36
37namespace Google.Protobuf.WellKnownTypes
38{
39    public partial class Timestamp : ICustomDiagnosticMessage
40    {
41        private static readonly DateTime UnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
42        // Constants determined programmatically, but then hard-coded so they can be constant expressions.
43        private const long BclSecondsAtUnixEpoch = 62135596800;
44        internal const long UnixSecondsAtBclMaxValue = 253402300799;
45        internal const long UnixSecondsAtBclMinValue = -BclSecondsAtUnixEpoch;
46        internal const int MaxNanos = Duration.NanosecondsPerSecond - 1;
47
48        private static bool IsNormalized(long seconds, int nanoseconds) =>
49            nanoseconds >= 0 &&
50            nanoseconds <= MaxNanos &&
51            seconds >= UnixSecondsAtBclMinValue &&
52            seconds <= UnixSecondsAtBclMaxValue;
53
54        /// <summary>
55        /// Returns the difference between one <see cref="Timestamp"/> and another, as a <see cref="Duration"/>.
56        /// </summary>
57        /// <param name="lhs">The timestamp to subtract from. Must not be null.</param>
58        /// <param name="rhs">The timestamp to subtract. Must not be null.</param>
59        /// <returns>The difference between the two specified timestamps.</returns>
60        public static Duration operator -(Timestamp lhs, Timestamp rhs)
61        {
62            ProtoPreconditions.CheckNotNull(lhs, "lhs");
63            ProtoPreconditions.CheckNotNull(rhs, "rhs");
64            checked
65            {
66                return Duration.Normalize(lhs.Seconds - rhs.Seconds, lhs.Nanos - rhs.Nanos);
67            }
68        }
69
70        /// <summary>
71        /// Adds a <see cref="Duration"/> to a <see cref="Timestamp"/>, to obtain another <c>Timestamp</c>.
72        /// </summary>
73        /// <param name="lhs">The timestamp to add the duration to. Must not be null.</param>
74        /// <param name="rhs">The duration to add. Must not be null.</param>
75        /// <returns>The result of adding the duration to the timestamp.</returns>
76        public static Timestamp operator +(Timestamp lhs, Duration rhs)
77        {
78            ProtoPreconditions.CheckNotNull(lhs, "lhs");
79            ProtoPreconditions.CheckNotNull(rhs, "rhs");
80            checked
81            {
82                return Normalize(lhs.Seconds + rhs.Seconds, lhs.Nanos + rhs.Nanos);
83            }
84        }
85
86        /// <summary>
87        /// Subtracts a <see cref="Duration"/> from a <see cref="Timestamp"/>, to obtain another <c>Timestamp</c>.
88        /// </summary>
89        /// <param name="lhs">The timestamp to subtract the duration from. Must not be null.</param>
90        /// <param name="rhs">The duration to subtract.</param>
91        /// <returns>The result of subtracting the duration from the timestamp.</returns>
92        public static Timestamp operator -(Timestamp lhs, Duration rhs)
93        {
94            ProtoPreconditions.CheckNotNull(lhs, "lhs");
95            ProtoPreconditions.CheckNotNull(rhs, "rhs");
96            checked
97            {
98                return Normalize(lhs.Seconds - rhs.Seconds, lhs.Nanos - rhs.Nanos);
99            }
100        }
101
102        /// <summary>
103        /// Converts this timestamp into a <see cref="DateTime"/>.
104        /// </summary>
105        /// <remarks>
106        /// The resulting <c>DateTime</c> will always have a <c>Kind</c> of <c>Utc</c>.
107        /// If the timestamp is not a precise number of ticks, it will be truncated towards the start
108        /// of time. For example, a timestamp with a <see cref="Nanos"/> value of 99 will result in a
109        /// <see cref="DateTime"/> value precisely on a second.
110        /// </remarks>
111        /// <returns>This timestamp as a <c>DateTime</c>.</returns>
112        /// <exception cref="InvalidOperationException">The timestamp contains invalid values; either it is
113        /// incorrectly normalized or is outside the valid range.</exception>
114        public DateTime ToDateTime()
115        {
116            if (!IsNormalized(Seconds, Nanos))
117            {
118                throw new InvalidOperationException(@"Timestamp contains invalid values: Seconds={Seconds}; Nanos={Nanos}");
119            }
120            return UnixEpoch.AddSeconds(Seconds).AddTicks(Nanos / Duration.NanosecondsPerTick);
121        }
122
123        /// <summary>
124        /// Converts this timestamp into a <see cref="DateTimeOffset"/>.
125        /// </summary>
126        /// <remarks>
127        /// The resulting <c>DateTimeOffset</c> will always have an <c>Offset</c> of zero.
128        /// If the timestamp is not a precise number of ticks, it will be truncated towards the start
129        /// of time. For example, a timestamp with a <see cref="Nanos"/> value of 99 will result in a
130        /// <see cref="DateTimeOffset"/> value precisely on a second.
131        /// </remarks>
132        /// <returns>This timestamp as a <c>DateTimeOffset</c>.</returns>
133        /// <exception cref="InvalidOperationException">The timestamp contains invalid values; either it is
134        /// incorrectly normalized or is outside the valid range.</exception>
135        public DateTimeOffset ToDateTimeOffset()
136        {
137            return new DateTimeOffset(ToDateTime(), TimeSpan.Zero);
138        }
139
140        /// <summary>
141        /// Converts the specified <see cref="DateTime"/> to a <see cref="Timestamp"/>.
142        /// </summary>
143        /// <param name="dateTime"></param>
144        /// <exception cref="ArgumentException">The <c>Kind</c> of <paramref name="dateTime"/> is not <c>DateTimeKind.Utc</c>.</exception>
145        /// <returns>The converted timestamp.</returns>
146        public static Timestamp FromDateTime(DateTime dateTime)
147        {
148            if (dateTime.Kind != DateTimeKind.Utc)
149            {
150                throw new ArgumentException("Conversion from DateTime to Timestamp requires the DateTime kind to be Utc", "dateTime");
151            }
152            // Do the arithmetic using DateTime.Ticks, which is always non-negative, making things simpler.
153            long secondsSinceBclEpoch = dateTime.Ticks / TimeSpan.TicksPerSecond;
154            int nanoseconds = (int)  (dateTime.Ticks % TimeSpan.TicksPerSecond) * Duration.NanosecondsPerTick;
155            return new Timestamp { Seconds = secondsSinceBclEpoch - BclSecondsAtUnixEpoch, Nanos = nanoseconds };
156        }
157
158        /// <summary>
159        /// Converts the given <see cref="DateTimeOffset"/> to a <see cref="Timestamp"/>
160        /// </summary>
161        /// <remarks>The offset is taken into consideration when converting the value (so the same instant in time
162        /// is represented) but is not a separate part of the resulting value. In other words, there is no
163        /// roundtrip operation to retrieve the original <c>DateTimeOffset</c>.</remarks>
164        /// <param name="dateTimeOffset">The date and time (with UTC offset) to convert to a timestamp.</param>
165        /// <returns>The converted timestamp.</returns>
166        public static Timestamp FromDateTimeOffset(DateTimeOffset dateTimeOffset)
167        {
168            // We don't need to worry about this having negative ticks: DateTimeOffset is constrained to handle
169            // values whose *UTC* value is in the range of DateTime.
170            return FromDateTime(dateTimeOffset.UtcDateTime);
171        }
172
173        internal static Timestamp Normalize(long seconds, int nanoseconds)
174        {
175            int extraSeconds = nanoseconds / Duration.NanosecondsPerSecond;
176            seconds += extraSeconds;
177            nanoseconds -= extraSeconds * Duration.NanosecondsPerSecond;
178
179            if (nanoseconds < 0)
180            {
181                nanoseconds += Duration.NanosecondsPerSecond;
182                seconds--;
183            }
184            return new Timestamp { Seconds = seconds, Nanos = nanoseconds };
185        }
186
187        /// <summary>
188        /// Converts a timestamp specified in seconds/nanoseconds to a string.
189        /// </summary>
190        /// <remarks>
191        /// If the value is a normalized duration in the range described in <c>timestamp.proto</c>,
192        /// <paramref name="diagnosticOnly"/> is ignored. Otherwise, if the parameter is <c>true</c>,
193        /// a JSON object with a warning is returned; if it is <c>false</c>, an <see cref="InvalidOperationException"/> is thrown.
194        /// </remarks>
195        /// <param name="seconds">Seconds portion of the duration.</param>
196        /// <param name="nanoseconds">Nanoseconds portion of the duration.</param>
197        /// <param name="diagnosticOnly">Determines the handling of non-normalized values</param>
198        /// <exception cref="InvalidOperationException">The represented duration is invalid, and <paramref name="diagnosticOnly"/> is <c>false</c>.</exception>
199        internal static string ToJson(long seconds, int nanoseconds, bool diagnosticOnly)
200        {
201            if (IsNormalized(seconds, nanoseconds))
202            {
203                // Use .NET's formatting for the value down to the second, including an opening double quote (as it's a string value)
204                DateTime dateTime = UnixEpoch.AddSeconds(seconds);
205                var builder = new StringBuilder();
206                builder.Append('"');
207                builder.Append(dateTime.ToString("yyyy'-'MM'-'dd'T'HH:mm:ss", CultureInfo.InvariantCulture));
208                Duration.AppendNanoseconds(builder, nanoseconds);
209                builder.Append("Z\"");
210                return builder.ToString();
211            }
212            if (diagnosticOnly)
213            {
214                return string.Format(CultureInfo.InvariantCulture,
215                    "{{ \"@warning\": \"Invalid Timestamp\", \"seconds\": \"{0}\", \"nanos\": {1} }}",
216                    seconds,
217                    nanoseconds);
218            }
219            else
220            {
221                throw new InvalidOperationException("Non-normalized timestamp value");
222            }
223        }
224
225        /// <summary>
226        /// Returns a string representation of this <see cref="Timestamp"/> for diagnostic purposes.
227        /// </summary>
228        /// <remarks>
229        /// Normally the returned value will be a JSON string value (including leading and trailing quotes) but
230        /// when the value is non-normalized or out of range, a JSON object representation will be returned
231        /// instead, including a warning. This is to avoid exceptions being thrown when trying to
232        /// diagnose problems - the regular JSON formatter will still throw an exception for non-normalized
233        /// values.
234        /// </remarks>
235        /// <returns>A string representation of this value.</returns>
236        public string ToDiagnosticString()
237        {
238            return ToJson(Seconds, Nanos, true);
239        }
240    }
241}
242