add support for Chinese language tags and update tests

Author: 314systems

app/src/main/kotlin/com/vrem/util/LocaleUtils.kt

@@ -29,6 +29,7 @@ private val countriesLocales: SortedMap<String, Locale> =
         .toSortedMap()
 
 val BULGARIAN: Locale = Locale.forLanguageTag("bg")
+val CHINESE: Locale = Locale.forLanguageTag("zh")
 val CHINESE_SIMPLIFIED: Locale = Locale.forLanguageTag("zh-Hans")
 val CHINESE_TRADITIONAL: Locale = Locale.forLanguageTag("zh-Hant")
 val DUTCH: Locale = Locale.forLanguageTag("nl")
@@ -81,13 +82,26 @@ fun supportedLanguageTags(): List<String> = listOf("") + baseSupportedLocales.ma
 
 private fun normalizeLanguageTag(languageTag: String): String = languageTag.replace('_', '-').trim()
 
+private val chineseCountryToLocale: Map<String, Locale> = mapOf(
+    "CN" to CHINESE_SIMPLIFIED,
+    "SG" to CHINESE_SIMPLIFIED,
+    "TW" to CHINESE_TRADITIONAL,
+    "HK" to CHINESE_TRADITIONAL,
+    "MO" to CHINESE_TRADITIONAL,
+)
+
 fun findByLanguageTag(languageTag: String): Locale {
     val normalizedLanguageTag = normalizeLanguageTag(languageTag)
     if (normalizedLanguageTag.isEmpty()) return currentLocale
 
     val target = Locale.forLanguageTag(normalizedLanguageTag)
     if (target.language.isEmpty()) return currentLocale
 
+    if (target.language == "zh" && target.script.isEmpty()) {
+        if (target.country.isEmpty()) return CHINESE
+        return chineseCountryToLocale[target.country] ?: CHINESE
+    }
+
     return baseSupportedLocales.find { it == target }
         ?: baseSupportedLocales.find { it.language == target.language && it.script == target.script }
         ?: baseSupportedLocales.find { it.language == target.language && it.country == target.country }

app/src/test/kotlin/com/vrem/util/LocaleUtilsTest.kt

@@ -86,15 +86,22 @@ class LocaleUtilsTest {
     @Test
     fun findByLanguageTagWithKnownTag() {
         // BCP-47 format (new)
-        assertThat(findByLanguageTag("zh-Hans")).isEqualTo(CHINESE_SIMPLIFIED)
-        assertThat(findByLanguageTag("zh-Hant")).isEqualTo(CHINESE_TRADITIONAL)
         assertThat(findByLanguageTag("en")).isEqualTo(ENGLISH)
         assertThat(findByLanguageTag("en-US")).isEqualTo(ENGLISH)
+        assertThat(findByLanguageTag("zh")).isEqualTo(CHINESE)
+        assertThat(findByLanguageTag("zh-CN")).isEqualTo(CHINESE_SIMPLIFIED)
+        assertThat(findByLanguageTag("zh-Hans")).isEqualTo(CHINESE_SIMPLIFIED)
+        assertThat(findByLanguageTag("zh-Hant")).isEqualTo(CHINESE_TRADITIONAL)
+        assertThat(findByLanguageTag("zh-TW")).isEqualTo(CHINESE_TRADITIONAL)
+        assertThat(findByLanguageTag("zh-XX")).isEqualTo(CHINESE)
 
         // Backward compatibility: underscore format (old)
+        assertThat(findByLanguageTag("en_US")).isEqualTo(ENGLISH)
+        assertThat(findByLanguageTag("zh_CN")).isEqualTo(CHINESE_SIMPLIFIED)
         assertThat(findByLanguageTag("zh_Hans")).isEqualTo(CHINESE_SIMPLIFIED)
         assertThat(findByLanguageTag("zh_Hant")).isEqualTo(CHINESE_TRADITIONAL)
-        assertThat(findByLanguageTag("en_US")).isEqualTo(ENGLISH)
+        assertThat(findByLanguageTag("zh_TW")).isEqualTo(CHINESE_TRADITIONAL)
+        assertThat(findByLanguageTag("zh_XX")).isEqualTo(CHINESE)
     }
 
     @Test