make intellij correctly detect gts language as typescript

src/main/kotlin/com/emberjs/glint/GlintLanguageServiceFileEditorListener.kt

@@ -1,8 +1,14 @@
 package com.emberjs.glint
 
+import com.emberjs.gts.GjsLanguage
+import com.emberjs.gts.GtsFileViewProvider
+import com.emberjs.gts.GtsLanguage
+import com.intellij.codeInsight.daemon.impl.analysis.FileHighlightingSetting
+import com.intellij.codeInsight.daemon.impl.analysis.HighlightingSettingsPerFile
 import com.intellij.openapi.fileEditor.FileEditorManager
 import com.intellij.openapi.fileEditor.FileEditorManagerListener
 import com.intellij.openapi.vfs.VirtualFile
+import com.intellij.psi.PsiManager
 
 class GlintLanguageServiceFileEditorListener : FileEditorManagerListener {
     override fun fileOpened(source: FileEditorManager, file: VirtualFile) {

src/main/kotlin/com/emberjs/gts/GtsSupport.kt

@@ -47,9 +47,7 @@ import com.intellij.lang.xml.XmlFormattingModel
 import com.intellij.lexer.HtmlLexer
 import com.intellij.lexer.Lexer
 import com.intellij.lexer.LookAheadLexer
-import com.intellij.openapi.editor.Document
 import com.intellij.openapi.editor.Editor
-import com.intellij.openapi.editor.actions.lists.TrailingComma
 import com.intellij.openapi.editor.colors.EditorColorsScheme
 import com.intellij.openapi.editor.ex.util.LayerDescriptor
 import com.intellij.openapi.editor.ex.util.LayeredLexerEditorHighlighter
@@ -99,6 +97,7 @@ val JS: JSLanguageDialect = JavaScriptSupportLoader.ECMA_SCRIPT_6
 
 open class GtsLanguage(val lang: JSLanguageDialect = TS, id: String ="Gts") : Language(lang, id) {
     public var fileElementType: JSFileElementType? = null
+
     override fun <T : Any?> getUserData(key: Key<T>): T? {
         if (key.toString() == "js.file.element.type") {
             return fileElementType as T?
@@ -114,7 +113,7 @@ open class GtsLanguage(val lang: JSLanguageDialect = TS, id: String ="Gts") : La
     }
 
     companion object {
-        val INSTANCE = GtsLanguage()
+        val INSTANCE = GtsLanguage(TS)
     }
 }
 
@@ -135,8 +134,6 @@ class GtsFile(viewProvider: FileViewProvider?, val isJS: Boolean =false)
     override fun toString(): String {
         return "GTS File"
     }
-
-
 }
 
 
@@ -397,6 +394,9 @@ class GtsFileType : LanguageFileType(GtsLanguage.INSTANCE) {
         if (other == TypeScriptFileType) {
             return true
         }
+        if (other == JavaScriptFileType) {
+            return true
+        }
         return super.equals(other)
     }
 

src/test/kotlin/com/emberjs/gts/GtsFileTest.kt

@@ -3,7 +3,10 @@ package com.emberjs.hbs
 import com.emberjs.gts.GjsFileType
 import com.emberjs.gts.GtsFileType
 import com.intellij.codeInsight.daemon.impl.HighlightInfo
+import com.intellij.lang.javascript.BasicDialectDetector
+import com.intellij.lang.javascript.JavaScriptSupportLoader
 import com.intellij.lang.javascript.inspections.ES6UnusedImportsInspection
+import com.intellij.lang.javascript.inspections.JSLastCommaInObjectLiteralInspection
 import com.intellij.lang.javascript.inspections.JSUnusedGlobalSymbolsInspection
 import com.intellij.lang.javascript.inspections.JSUnusedLocalSymbolsInspection
 import com.intellij.lang.javascript.psi.impl.JSFileImpl
@@ -121,4 +124,27 @@ class GtsFileTest : BasePlatformTestCase() {
         TestCase.assertTrue(highlightInfos.first().description.contains("quux"))
         TestCase.assertTrue(highlightInfos.last().description.contains("qux"))
     }
+
+    @Test
+    fun testGtsTrailingCommaAllowed() {
+        val gts = """
+            const a = {
+                a: 1,
+                b: 2,
+            }
+        """.trimIndent()
+        myFixture.addFileToProject("main.gts", gts)
+        myFixture.configureByFile("main.gts")
+        myFixture.enableInspections(JSLastCommaInObjectLiteralInspection())
+        try {
+            CodeInsightTestFixtureImpl.ensureIndexesUpToDate(project)
+        } catch (exception: Exception) {
+
+        }
+
+        val highlighting = myFixture.doHighlighting()
+        System.out.println(highlighting)
+        val noCommaAllowed = highlighting.filter { it.description?.contains("comma") == true }
+        TestCase.assertEquals(noCommaAllowed.toString(), 0, noCommaAllowed.size)
+    }
 }