Handle invalid book id tags more robustly

src/SIL.Machine/Corpora/UsfmFileTextCorpus.cs

@@ -1,4 +1,5 @@
-using System.IO;
+using System;
+using System.IO;
 using System.Text;
 using SIL.Scripture;
 
@@ -46,12 +47,15 @@ private static string GetId(string fileName, Encoding encoding)
                 while ((line = reader.ReadLine()) != null)
                 {
                     line = line.Trim();
-                    if (line.StartsWith("\\id "))
+                    if (line.StartsWith("\\id ", StringComparison.InvariantCulture))
                     {
                         string id = line.Substring(4);
-                        int index = id.IndexOf(" ");
+                        int index = id.IndexOf(" ", StringComparison.OrdinalIgnoreCase);
+                        // If the id is longer than 3 characters, truncate it to 3 characters.
+                        if ((index == -1 || index > 3) && id.Length >= 3)
+                            index = 3;
                         if (index != -1)
-                            id = id.Substring(0, index);
+                            id = id.Substring(0, index).ToUpperInvariant();
                         return id.Trim();
                     }
                 }

src/SIL.Machine/Corpora/UsfmParser.cs

@@ -301,6 +301,8 @@ public bool ProcessToken()
 
                     // Code is always upper case
                     string code = token.Data.ToUpperInvariant();
+                    if (code.Length > 3)
+                        code = code.Substring(0, 3);
 
                     vref = State.VerseRef;
                     // Update verse ref. Leave book alone if not empty to prevent parsing errors

src/SIL.Machine/Corpora/UsfmTextBase.cs

@@ -108,6 +108,11 @@ public TextRowCollector(UsfmTextBase text)
             public override void StartBook(UsfmParserState state, string marker, string code)
             {
                 base.StartBook(state, marker, code);
+                if (!string.IsNullOrEmpty(state.VerseRef.Book) && state.VerseRef.Book != code)
+                {
+                    // Ignore \id markers that don't match the book code in the verse ref, if it was set
+                    return;
+                }
                 if (!Canon.AllBookIds.Contains(code, StringComparison.InvariantCulture))
                 {
                     throw new ArgumentException($"The book {code} is not a valid book id.");

tests/SIL.Machine.Tests/Corpora/TestData/usfm/Tes/03LEVTes.SFM

@@ -1,4 +1,4 @@
-\id LEV - Test
+\id Leviticus
 \h Leviticus
 \mt Leviticus
 \c 14

tests/SIL.Machine.Tests/Corpora/TestData/usfm/Tes/131CHTes.SFM

@@ -1,4 +1,4 @@
-\id 1CH - Test
+\id 1CH
 \h 1 Chronicles
 \mt 1 Chronicles
 \c 12

tests/SIL.Machine.Tests/Corpora/UsfmMemoryTextTests.cs

@@ -758,6 +758,99 @@ public void GetRows_IncompleteVerseRange()
         });
     }
 
+    [Test]
+    public void GetRows_BookCodeDifferentToFilename() =>
+        Assert.Throws<InvalidOperationException>(() =>
+            GetRows(
+                @"\id LUK - Test
+\c 1
+\v 1 Verse 1 Text
+",
+                includeAllText: true
+            )
+        );
+
+    [Test]
+    public void GetRows_BookCodeInvalid() =>
+        Assert.Throws<InvalidOperationException>(() =>
+            GetRows(
+                @"\id ZZZ - Test
+\c 1
+\v 1 Verse 1 Text
+",
+                includeAllText: true
+            )
+        );
+
+    [Test]
+    public void GetRows_BookCodeTruncated() =>
+        Assert.Throws<InvalidOperationException>(() =>
+            GetRows(
+                @"\id MA
+\c 1
+\v 1 Verse 1 Text
+",
+                includeAllText: true
+            )
+        );
+
+    [Test]
+    public void GetRows_BookCodeMultiple()
+    {
+        TextRow[] rows = GetRows(
+            @"\id MAT
+\id LUK
+\c 1
+\v 1 Verse 1 Text
+",
+            includeAllText: true
+        );
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(rows, Has.Length.EqualTo(1));
+
+            Assert.That(
+                rows[0].Ref,
+                Is.EqualTo(ScriptureRef.Parse("MAT 1:1")),
+                string.Join(",", rows.ToList().Select(tr => tr.Ref.ToString()))
+            );
+            Assert.That(
+                rows[0].Text,
+                Is.EqualTo("Verse 1 Text"),
+                string.Join(",", rows.ToList().Select(tr => tr.Text))
+            );
+        });
+    }
+
+    [Test]
+    public void GetRows_BookCodeNoSpace()
+    {
+        TextRow[] rows = GetRows(
+            @"\id Matthew
+\c 1
+\v 1 Verse 1 Text
+",
+            includeAllText: true
+        );
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(rows, Has.Length.EqualTo(1));
+
+            Assert.That(
+                rows[0].Ref,
+                Is.EqualTo(ScriptureRef.Parse("MAT 1:1")),
+                string.Join(",", rows.ToList().Select(tr => tr.Ref.ToString()))
+            );
+            Assert.That(
+                rows[0].Text,
+                Is.EqualTo("Verse 1 Text"),
+                string.Join(",", rows.ToList().Select(tr => tr.Text))
+            );
+        });
+    }
+
     private static TextRow[] GetRows(string usfm, bool includeMarkers = false, bool includeAllText = false)
     {
         UsfmMemoryText text = new(