Serval was down until langtags.json was added back. (#194)

* Serval was down until langtags.json was added back.
Add test to force download.

* Reviwer comments

src/SIL.Machine.AspNetCore/Services/LanguageTagService.cs

@@ -29,14 +29,35 @@ public LanguageTagService()
         _flores200Languages = InitializeFlores200Languages();
     }
 
-    private static Dictionary<string, string> InitializeDefaultScripts()
+    protected virtual void InitializeSldrLanguageTags()
     {
         Sldr.InitializeLanguageTags();
+    }
+
+    private Dictionary<string, string> InitializeDefaultScripts()
+    {
+        InitializeSldrLanguageTags();
         var cachedAllTagsPath = Path.Combine(Sldr.SldrCachePath, "langtags.json");
-        using var stream = new FileStream(cachedAllTagsPath, FileMode.Open);
+        JsonNode? json;
+
+        if (!File.Exists(cachedAllTagsPath))
+        {
+            using HttpClient client = new();
+            using HttpResponseMessage response = client.Send(
+                new HttpRequestMessage(
+                    HttpMethod.Get,
+                    "https://raw.githubusercontent.com/silnrsi/langtags/master/pub/langtags.json"
+                )
+            );
+            response.EnsureSuccessStatusCode();
+            using Stream responseStream = response.Content.ReadAsStream();
+            using FileStream fileStream = new(cachedAllTagsPath, FileMode.Create);
+            responseStream.CopyTo(fileStream);
+        }
+        using FileStream stream = new(cachedAllTagsPath, FileMode.Open);
+        json = JsonNode.Parse(stream);
 
-        var json = JsonNode.Parse(stream);
-        var tempDefaultScripts = new Dictionary<string, string>();
+        Dictionary<string, string> tempDefaultScripts = new();
         foreach (JsonNode? entry in json!.AsArray())
         {
             if (entry is null)

tests/SIL.Machine.AspNetCore.Tests/Services/LanguageTagServiceTests.cs

@@ -3,15 +3,6 @@
 [TestFixture]
 public class LanguageTagServiceTests
 {
-    private readonly LanguageTagService _languageTagService;
-
-    public LanguageTagServiceTests()
-    {
-        if (!Sldr.IsInitialized)
-            Sldr.Initialize();
-        _languageTagService = new LanguageTagService();
-    }
-
     [Test]
     [TestCase("es", "spa_Latn", Description = "Iso639_1Code")]
     [TestCase("hne", "hne_Deva", Description = "Iso639_3Code")]
@@ -30,7 +21,9 @@ public LanguageTagServiceTests()
     [TestCase("kor_Kore", "kor_Hang", Description = "KoreanScriptCorrection")]
     public void ConvertToFlores200CodeTest(string language, string internalCodeTruth)
     {
-        _languageTagService.ConvertToFlores200Code(language, out string internalCode);
+        if (!Sldr.IsInitialized)
+            Sldr.Initialize();
+        new LanguageTagService().ConvertToFlores200Code(language, out string internalCode);
         Assert.That(internalCode, Is.EqualTo(internalCodeTruth));
     }
 
@@ -41,11 +34,36 @@ public void ConvertToFlores200CodeTest(string language, string internalCodeTruth
     [TestCase("xyz", "xyz", false)]
     public void GetLanguageInfoAsync(string languageCode, string? resolvedLanguageCode, bool nativeLanguageSupport)
     {
-        bool isNative = _languageTagService.ConvertToFlores200Code(languageCode, out string internalCode);
+        if (!Sldr.IsInitialized)
+            Sldr.Initialize();
+        bool isNative = new LanguageTagService().ConvertToFlores200Code(languageCode, out string internalCode);
         Assert.Multiple(() =>
         {
             Assert.That(internalCode, Is.EqualTo(resolvedLanguageCode));
             Assert.That(isNative, Is.EqualTo(nativeLanguageSupport));
         });
     }
+
+    public class TestLanguageTagService : LanguageTagService
+    {
+        // Don't call Sldr initialize to call
+        protected override void InitializeSldrLanguageTags()
+        {
+            // remove langtags.json to force download
+            var cachedAllTagsPath = Path.Combine(Sldr.SldrCachePath, "langtags.json");
+            if (File.Exists(cachedAllTagsPath))
+                File.Delete(cachedAllTagsPath);
+            Directory.CreateDirectory(Sldr.SldrCachePath);
+        }
+    }
+
+    [Test]
+    public void BackupLangtagsJsonTest()
+    {
+        if (!Sldr.IsInitialized)
+            Sldr.Initialize();
+        var service = new TestLanguageTagService();
+        service.ConvertToFlores200Code("en", out string internalCode);
+        Assert.That(internalCode, Is.EqualTo("eng_Latn"));
+    }
 }