Add support for file which are named after the end of the period of d…

…ata they contain

README.md

@@ -23,3 +23,4 @@ These tests cover all cases for file/folder structures which contain files with
 | M    | datetime file with random start time                                                                      | 00:00:00           | 01:00:00             | x     |
 | N    | date folder, time file                                                                                    | 12:00:00           | 06:00:00             |       |
 | O    | datetime file with random start time and interval exceeding end                                           | 00:00:00           | 01:00:00             | x     |
+| P    | datetime file with file name offset                                                                       | 00:00:00           | 00:10:00             |       |

src/Nexus.Sources.StructuredFile/StructuredFileDataSource.cs

@@ -582,7 +582,8 @@ protected abstract Task ReadAsync(
             ? DateTime.SpecifyKind(begin.Add(fileSource.UtcOffset), DateTimeKind.Local)
             : throw new ArgumentException("The begin parameter must of kind UTC.");
 
-        var localFileBegin = localBegin.RoundDown(fileSource.FilePeriod);
+        var localFileBegin = localBegin
+            .RoundDown(fileSource.FilePeriod);
 
         var folderNames = fileSource
             .PathSegments
@@ -652,6 +653,10 @@ protected abstract Task ReadAsync(
 
         else
         {
+            /* correct local file begin */
+            if (fileSource.FileNameOffset != TimeSpan.Zero)
+                localFileBegin = localFileBegin.Add(fileSource.FileNameOffset);
+
             var folderPath = Path.Combine(folderNameArray);
             var fileName = localFileBegin.ToString(fileSource.FileTemplate);
 
@@ -981,7 +986,7 @@ internal static bool TryGetFileBeginByPath(
         CustomDateTimeOffset folderBegin = default)
     {
         var fileName = Path.GetFileName(filePath);
-        bool isSuccess;
+        bool success;
 
         if (TryGetFileBeginByName_AnyKind(fileName, fileSource, out fileBegin))
         {
@@ -991,7 +996,7 @@ internal static bool TryGetFileBeginByPath(
             // date+time: use file date/time
             if (fileBegin.DateTime.Date != default)
             {
-                isSuccess = true;
+                success = true;
             }
 
             // time-only: use combined folder and file date/time
@@ -1004,7 +1009,7 @@ internal static bool TryGetFileBeginByPath(
                         new DateTime(folderBegin.DateTime.Date.Ticks + fileBegin.DateTime.TimeOfDay.Ticks),
                         fileBegin.Offset);
 
-                    isSuccess = true;
+                    success = true;
                 }
 
                 // long way
@@ -1016,7 +1021,7 @@ internal static bool TryGetFileBeginByPath(
                         new DateTime(folderBegin.DateTime.Ticks + fileBegin.DateTime.TimeOfDay.Ticks),
                         fileBegin.Offset);
 
-                    isSuccess = folderBegin != default;
+                    success = folderBegin != default;
                 }
             }
 
@@ -1027,7 +1032,7 @@ internal static bool TryGetFileBeginByPath(
                 if (folderBegin != default)
                 {
                     fileBegin = folderBegin;
-                    isSuccess = true;
+                    success = true;
                 }
 
                 // long way
@@ -1036,18 +1041,21 @@ internal static bool TryGetFileBeginByPath(
                     folderBegin = GetFolderBegin_AnyKind(filePath, fileSource);
 
                     fileBegin = folderBegin;
-                    isSuccess = folderBegin != default;
+                    success = folderBegin != default;
                 }
             }
+
+            if (success && fileSource.FileNameOffset != TimeSpan.Zero)
+                fileBegin = new CustomDateTimeOffset(fileBegin.DateTime - fileSource.FileNameOffset, fileBegin.Offset);
         }
 
         // no date + no time: failed
         else
         {
-            isSuccess = false;
+            success = false;
         }
 
-        return isSuccess;
+        return success;
     }
 
     private static CustomDateTimeOffset GetFolderBegin_AnyKind(string filePath, FileSource fileSource)

src/Nexus.Sources.StructuredFile/StructuredFileDataSourceTypes.cs

@@ -13,6 +13,7 @@ namespace Nexus.Sources;
 /// <param name="FileDateTimePreselector">An optional regular expression to select only relevant parts of a file name (e.g. to select the date/time and a unqiue identifier in case there is more than one kind of file in the same folder). In case of a file named 20200101_13_my-id_1234.dat the preselector could be like "(.{11})_my-id". It is also required for file names containing an opaque string that changes for every file.</param>
 /// <param name="FileDateTimeSelector">An optional date/time selector which is mandatory when the preselector is provided. In case of a file named like "20200101_13_my-id_1234.dat", and a preselector of "(.{11})_my-id", the selector should be like "yyyyMMdd_HH".</param>
 /// <param name="FilePeriod">The period per file.</param>
+/// <param name="FileNameOffset">The file name offset of the file data. This is useful for files that are named according to the end date of the data they contain.</param>
 /// <param name="UtcOffset">The UTC offset of the file data.</param>
 /// <param name="IrregularTimeInterval">The file time interval is irregular. I.e. the file end is not aligned to multiples of the file period.</param>
 /// <param name="AdditionalProperties">Additional properties to be used by the data source implementation.</param>
@@ -23,6 +24,7 @@ public record FileSource(
     string? FileDateTimePreselector,
     string? FileDateTimeSelector,
     TimeSpan FilePeriod,
+    TimeSpan FileNameOffset,
     TimeSpan UtcOffset,
     bool IrregularTimeInterval,
     JsonElement? AdditionalProperties

tests/Nexus.Sources.StructuredFile.Tests/DATABASES/P/config.json

@@ -0,0 +1,15 @@
+{
+  "/A/B/C": {
+    "default": [
+      {
+        "PathSegments": [
+          "'DATA'"
+        ],
+        "FileTemplate": "yyyy-MM-ddTHH-mm-ssZ'.dat'",
+        "FilePeriod": "00:10:00",
+        "UtcOffset": "00:00:00",
+        "FileNameOffset": "00:10:00"
+      }
+    ]
+  }
+}

tests/Nexus.Sources.StructuredFile.Tests/StructuredFileDataSourceTests.cs

@@ -115,6 +115,7 @@ public async Task CanProvideFirstFile()
     [InlineData("DATABASES/M", "2020-01-01T01-35-23Z", "2020-01-01T05-00-00Z")]
     [InlineData("DATABASES/N", "2019-12-31T12-00-00Z", "2020-01-03T12-00-00Z")]
     [InlineData("DATABASES/O", "2020-01-01T00-35-23Z", "2020-01-01T01-00-10Z")]
+    [InlineData("DATABASES/P", "2020-01-01T00-00-00Z", "2020-01-01T00-20-00Z")]
     public async Task CanProvideTimeRange(string root, string expectedBeginString, string expectedEndString)
     {
         var expectedBegin = DateTime.ParseExact(expectedBeginString, "yyyy-MM-ddTHH-mm-ssZ", null, DateTimeStyles.AdjustToUniversal);
@@ -152,6 +153,7 @@ public async Task CanProvideTimeRange(string root, string expectedBeginString, s
     [InlineData("DATABASES/M", "2020-01-01T00-00-00Z", "2020-01-02T00-00-00Z", 4 / 24.0, 3)]
     [InlineData("DATABASES/N", "2020-01-01T00-00-00Z", "2020-01-03T00-00-00Z", 7 / 8.0, 2)]
     [InlineData("DATABASES/O", "2020-01-01T00-00-00Z", "2020-01-02T00-00-00Z", 3 / 288.0, 4)]
+    [InlineData("DATABASES/P", "2020-01-01T00-00-00Z", "2020-01-02T00-00-00Z", 2 / 144.0, 4)]
     public async Task CanProvideAvailability(string root, string beginString, string endString, double expected, int precision)
     {
         // Arrange
@@ -297,6 +299,7 @@ await Assert.ThrowsAsync<ArgumentException>(() =>
     [InlineData("M", "2020-01-01T00:00:00Z", "2020-01-02T00:00:00Z")]
     [InlineData("N", "2020-01-01T00:00:00Z", "2020-01-04T00:00:00Z")]
     [InlineData("O", "2020-01-01T00:00:00Z", "2020-01-02T00:00:00Z")]
+    [InlineData("P", "2020-01-01T00:00:00Z", "2020-01-02T00:00:00Z")]
     public async Task CanRead_ReadInfos(string database, string beginString, string endString)
     {
         // Arrange

tests/Nexus.Sources.StructuredFile.Tests/expected/P.json

@@ -0,0 +1,20 @@
+[
+  {
+    "BufferOffset": 0,
+    "FilePath": "/debug/DATABASES/P/DATA/2020-01-01T00-10-00Z.dat",
+    "FileSource": null,
+    "RegularFileBegin": "2020-01-01T00:00:00Z",
+    "FileOffset": 0,
+    "FileBlock": 600,
+    "FileLength": 600
+  },
+  {
+    "BufferOffset": 600,
+    "FilePath": "/debug/DATABASES/P/DATA/2020-01-01T00-20-00Z.dat",
+    "FileSource": null,
+    "RegularFileBegin": "2020-01-01T00:10:00Z",
+    "FileOffset": 0,
+    "FileBlock": 600,
+    "FileLength": 600
+  }
+]