add fileheader entry class for detecting odyssey

EDPlayerJournalTests/FileHeaderTest.cs

@@ -0,0 +1,50 @@
+using EDPlayerJournal.Entries;
+
+namespace EDPlayerJournalTests;
+
+[TestClass]
+public class FileHeaderTest {
+    [TestMethod]
+    public void OdysseyFileHeader() {
+        string fileheader = /*lang=json,strict*/ """{ "timestamp":"2022-11-21T15:04:36Z", "event":"Fileheader", "part":1, "language":"English/UK", "Odyssey":true, "gameversion":"4.0.0.1450", "build":"r286858/r0 " }""";
+
+        Entry? entry = Entry.Parse(fileheader);
+
+        Assert.IsNotNull(entry);
+        Assert.IsInstanceOfType(entry, typeof(FileHeaderEntry));
+
+        FileHeaderEntry? header = entry as FileHeaderEntry;
+
+        Assert.IsNotNull(header);
+
+        Assert.AreEqual(header.Part, 1UL);
+        Assert.AreEqual(header.Language, "English/UK");
+        Assert.AreEqual(header.Odyssey, true);
+        Assert.AreEqual(header.GameVersion, "4.0.0.1450");
+        // Someone at FDev messed up string building there.
+        Assert.AreEqual(header.Build, "r286858/r0 ");
+    }
+
+    [TestMethod]
+    public void LegacyFileHeader() {
+        // This is the oldest file header I could find.
+        string fileheader = /*lang=json,strict*/ """{ "timestamp":"2020-01-02T23:45:23Z", "event":"Fileheader", "part":1, "language":"English\\UK", "gameversion":"3.5.3.400 EDH", "build":"r213094/r0 " }""";
+
+        Entry? entry = Entry.Parse(fileheader);
+
+        Assert.IsNotNull(entry);
+        Assert.IsInstanceOfType(entry, typeof(FileHeaderEntry));
+
+        FileHeaderEntry? header = entry as FileHeaderEntry;
+
+        Assert.IsNotNull(header);
+
+        Assert.AreEqual(header.Part, 1UL);
+        // At some point they switche to a forward slash. Curious.
+        Assert.AreEqual(header.Language, """English\UK""");
+        Assert.AreEqual(header.Odyssey, false);
+        Assert.AreEqual(header.GameVersion, "3.5.3.400 EDH");
+        // ~73k commits in two years. Not bad.
+        Assert.AreEqual(header.Build, "r213094/r0 ");
+    }
+}