feat: add basic second ext for try

scan_git/src/main/kotlin/com/thoughtworks/archguard/git/scanner/LanguageService.kt

@@ -1,10 +1,16 @@
+// based on [https://github.com/boyter/scc](https://github.com/boyter/scc) with MIT LICENSE.
+// SPDX-License-Identifier: MIT OR Unlicense
+
 package com.thoughtworks.archguard.git.scanner
 
 import com.thoughtworks.archguard.git.scanner.model.Language
 import kotlinx.serialization.decodeFromString
 import kotlinx.serialization.json.Json
+import java.io.File
 
 class LanguageService {
+    private val extensionCache: HashMap<String, String> = hashMapOf()
+    private val SHE_BANG: String = "#!"
     private var extToLanguage: MutableMap<String, String> = mutableMapOf()
     private var filenameToLanguage: MutableMap<String, String> = mutableMapOf()
 
@@ -22,7 +28,7 @@ class LanguageService {
     }
 
     fun detectLanguage(name: String): String {
-        val language = ""
+        var language = ""
         val dotCount = name.count { it == '.' }
 
         // such as `.gitignore` file
@@ -34,14 +40,39 @@ class LanguageService {
             if (optFilenameLang != null) {
                 return optFilenameLang.toString()
             }
+
+            // make others file a shebang
+            language = SHE_BANG
         }
 
-        val dotSplit = name.split(".")
-        val firstExt = dotSplit.last()
-        val optLang = extToLanguage[firstExt.lowercase()]
+        val ext = this.getExtension(name)
+        val optLang = extToLanguage[ext.lowercase()]
         if (optLang != null) {
             return optLang.toString()
         }
         return language
     }
+
+    fun getExtension(name: String): String {
+        val lowercase = name.lowercase()
+        var extension = extensionCache[lowercase]
+        if (extension != null) {
+            return extension
+        }
+
+        val ext = File(name).extension
+        if (ext == "" || name.last() == '.') {
+            extension = name
+        } else {
+            // Handling multiple dots or multiple extensions only needs to delete the last extension
+            // and then call filepath.Ext.
+            // If there are multiple extensions, it is the value of subExt,
+            // otherwise subExt is an empty string.
+            val subExt = File(name.removeSuffix(".$ext")).extension
+            extension = "$subExt.$ext"
+        }
+
+        extensionCache[name] = extension
+        return extension
+    }
 }

scan_git/src/test/kotlin/com/thoughtworks/archguard/git/scanner/LanguageServiceTest.kt

@@ -18,9 +18,9 @@ internal class LanguageServiceTest {
         assertEquals("gitignore", lang.detectLanguage(".gitignore"))
     }
 
-//    @Test
-//    fun should_return_typescript_define_file() {
-//        val lang = LanguageService()
-//        assertEquals("TypeScript Typings", lang.detectLanguage("d.ts"))
-//    }
+    @Test
+    fun should_return_typescript_define_file() {
+        val lang = LanguageService()
+        assertEquals("TypeScript Typings", lang.detectLanguage("types.d.ts"))
+    }
 }