Implement DatetimeAdapter

MatFileHandler.Tests/MatFileReaderTests.cs

@@ -1,5 +1,6 @@
 // Copyright 2017-2018 Alexander Luzgarev
 
+using System;
 using System.IO;
 using System.Linq;
 using System.Numerics;
@@ -388,6 +389,35 @@ namespace MatFileHandler.Tests
             Assert.That(ppp["y"].ConvertToDoubleArray(), Is.EquivalentTo(new[] { 200.0 }));
         }
 
+        /// <summary>
+        /// Test datetime objects.
+        /// </summary>
+        [Test]
+        public void TestDatetime()
+        {
+            var matFile = GetTests("good")["datetime"];
+            var d = matFile["d"].Value as IMatObject;
+            var datetime = new DatetimeAdapter(d);
+            Assert.That(datetime.Dimensions, Is.EquivalentTo(new[] { 1, 2 }));
+            Assert.That(datetime[0], Is.EqualTo(new DateTimeOffset(2000, 1, 1, 0, 0, 0, TimeSpan.Zero)));
+            Assert.That(datetime[1], Is.EqualTo(new DateTimeOffset(1987, 1, 2, 3, 4, 5, TimeSpan.Zero)));
+        }
+
+        /// <summary>
+        /// Another test for datetime objects.
+        /// </summary>
+        [Test]
+        public void TestDatetime2()
+        {
+            var matFile = GetTests("good")["datetime2"];
+            var d = matFile["d"].Value as IMatObject;
+            var datetime = new DatetimeAdapter(d);
+            Assert.That(datetime.Dimensions, Is.EquivalentTo(new[] { 1, 1 }));
+            var diff = new DateTimeOffset(2, 1, 1, 1, 1, 1, 235, TimeSpan.Zero);
+            Assert.That(datetime[0] - diff < TimeSpan.FromMilliseconds(1));
+            Assert.That(diff - datetime[0] < TimeSpan.FromMilliseconds(1));
+        }
+
         private static AbstractTestDataFactory<IMatFile> GetTests(string factoryName) =>
             new MatTestDataFactory(Path.Combine(TestDirectory, factoryName));
 

MatFileHandler/DatetimeAdapter.cs

@@ -0,0 +1,62 @@
+// Copyright 2017-2018 Alexander Luzgarev
+
+using System;
+using System.Linq;
+using System.Numerics;
+
+namespace MatFileHandler
+{
+    /// <summary>
+    /// A better interface for using datetime objects.
+    /// </summary>
+    public class DatetimeAdapter
+    {
+        private readonly double[] data;
+        private readonly double[] data2;
+        private readonly int[] dimensions;
+
+        private readonly DateTimeOffset epoch;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DatetimeAdapter"/> class.
+        /// </summary>
+        /// <param name="array">Source datetime object.</param>
+        public DatetimeAdapter(IArray array)
+        {
+            var matObject = array as IMatObject;
+            if (matObject?.ClassName != "datetime")
+            {
+                throw new ArgumentException("The object provided is not a datetime.");
+            }
+
+            epoch = new DateTime(1970, 1, 1, 0, 0, 0, 0, DateTimeKind.Utc);
+            var dataArray = matObject["data", 0] as IArrayOf<double>;
+            if (dataArray is null)
+            {
+                var dataComplex = matObject["data", 0] as IArrayOf<Complex>;
+                var complexData = dataComplex.ConvertToComplexArray();
+                data = complexData.Select(c => c.Real).ToArray();
+                data2 = complexData.Select(c => c.Imaginary).ToArray();
+                dimensions = dataComplex.Dimensions;
+            }
+            else
+            {
+                data = dataArray.ConvertToDoubleArray();
+                data2 = new double[data.Length];
+                dimensions = dataArray.Dimensions;
+            }
+        }
+
+        /// <summary>
+        /// Gets datetime array dimensions.
+        /// </summary>
+        public int[] Dimensions => dimensions;
+
+        /// <summary>
+        /// Gets values of datetime object at given position in the array converted to <see cref="DateTimeOffset"/>.
+        /// </summary>
+        /// <param name="list">Indices.</param>
+        /// <returns>Value converted to  <see cref="DateTimeOffset"/>.</returns>
+        public DateTimeOffset this[params int[] list] => epoch.AddMilliseconds(data[Dimensions.DimFlatten(list)]);
+    }
+}