refactor: harden BCP47 functions

komga/src/flyway/kotlin/db/migration/sqlite/V20230801104436__fix_incorrect_language_codes.kt

@@ -36,10 +36,12 @@ class V20230801104436__fix_incorrect_language_codes : BaseJavaMigration() {
     }
   }
 
-  private fun normalize(value: String): String =
-    try {
+  private fun normalize(value: String?): String {
+    if (value.isNullOrBlank()) return ""
+    return try {
       ULocale.forLanguageTag(value).toLanguageTag()
     } catch (e: Exception) {
       ""
     }
+  }
 }

komga/src/main/kotlin/org/gotson/komga/domain/model/BCP47TagValidator.kt

@@ -0,0 +1,23 @@
+package org.gotson.komga.domain.model
+
+import com.ibm.icu.util.ULocale
+
+object BCP47TagValidator {
+  private val languages by lazy { ULocale.getISOLanguages().toSet() }
+
+  fun isValid(value: String?): Boolean {
+    if (value == null) return false
+    return ULocale.forLanguageTag(value).let {
+      it.language.isNotBlank() && languages.contains(it.language)
+    }
+  }
+
+  fun normalize(value: String?): String {
+    if (value.isNullOrBlank()) return ""
+    return try {
+      ULocale.forLanguageTag(value).toLanguageTag()
+    } catch (e: Exception) {
+      ""
+    }
+  }
+}

komga/src/main/kotlin/org/gotson/komga/domain/model/SeriesMetadata.kt

@@ -1,6 +1,5 @@
 package org.gotson.komga.domain.model
 
-import org.gotson.komga.infrastructure.validation.BCP47TagValidator
 import org.gotson.komga.language.lowerNotBlank
 import java.time.LocalDateTime
 

komga/src/main/kotlin/org/gotson/komga/infrastructure/metadata/comicrack/ComicInfoProvider.kt

@@ -4,6 +4,7 @@ import com.fasterxml.jackson.dataformat.xml.XmlMapper
 import mu.KotlinLogging
 import org.apache.commons.validator.routines.ISBNValidator
 import org.gotson.komga.domain.model.Author
+import org.gotson.komga.domain.model.BCP47TagValidator
 import org.gotson.komga.domain.model.BookMetadataPatch
 import org.gotson.komga.domain.model.BookMetadataPatchCapability
 import org.gotson.komga.domain.model.BookWithMedia
@@ -17,7 +18,6 @@ import org.gotson.komga.infrastructure.metadata.BookMetadataProvider
 import org.gotson.komga.infrastructure.metadata.SeriesMetadataFromBookProvider
 import org.gotson.komga.infrastructure.metadata.comicrack.dto.ComicInfo
 import org.gotson.komga.infrastructure.metadata.comicrack.dto.Manga
-import org.gotson.komga.infrastructure.validation.BCP47TagValidator
 import org.springframework.beans.factory.annotation.Autowired
 import org.springframework.stereotype.Service
 import java.net.URI

komga/src/main/kotlin/org/gotson/komga/infrastructure/metadata/epub/EpubMetadataProvider.kt

@@ -2,6 +2,7 @@ package org.gotson.komga.infrastructure.metadata.epub
 
 import org.apache.commons.validator.routines.ISBNValidator
 import org.gotson.komga.domain.model.Author
+import org.gotson.komga.domain.model.BCP47TagValidator
 import org.gotson.komga.domain.model.BookMetadataPatch
 import org.gotson.komga.domain.model.BookMetadataPatchCapability
 import org.gotson.komga.domain.model.BookWithMedia
@@ -13,7 +14,6 @@ import org.gotson.komga.domain.model.SeriesMetadataPatch
 import org.gotson.komga.infrastructure.mediacontainer.EpubExtractor
 import org.gotson.komga.infrastructure.metadata.BookMetadataProvider
 import org.gotson.komga.infrastructure.metadata.SeriesMetadataFromBookProvider
-import org.gotson.komga.infrastructure.validation.BCP47TagValidator
 import org.jsoup.Jsoup
 import org.jsoup.parser.Parser
 import org.jsoup.safety.Safelist

komga/src/main/kotlin/org/gotson/komga/infrastructure/validation/BCP47.kt

@@ -1,9 +1,9 @@
 package org.gotson.komga.infrastructure.validation
 
-import com.ibm.icu.util.ULocale
 import jakarta.validation.Constraint
 import jakarta.validation.ConstraintValidator
 import jakarta.validation.ConstraintValidatorContext
+import org.gotson.komga.domain.model.BCP47TagValidator
 import kotlin.reflect.KClass
 
 @Constraint(validatedBy = [BCP47Validator::class])
@@ -23,19 +23,4 @@ class BCP47Validator : ConstraintValidator<BCP47, String> {
   }
 }
 
-object BCP47TagValidator {
-  private val languages by lazy { ULocale.getISOLanguages().toSet() }
 
-  fun isValid(value: String): Boolean {
-    return ULocale.forLanguageTag(value).let {
-      it.language.isNotBlank() && languages.contains(it.language)
-    }
-  }
-
-  fun normalize(value: String): String =
-    try {
-      ULocale.forLanguageTag(value).toLanguageTag()
-    } catch (e: Exception) {
-      ""
-    }
-}

komga/src/test/kotlin/org/gotson/komga/domain/model/BCP47TagValidatorTest.kt

@@ -1,4 +1,4 @@
-package org.gotson.komga.infrastructure.validation
+package org.gotson.komga.domain.model
 
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.params.ParameterizedTest
@@ -10,12 +10,14 @@ class BCP47TagValidatorTest {
 
   @ParameterizedTest
   @MethodSource("languagesNormalized")
-  fun `given source languageTag when normalizing then result is expected`(source: String, expected: String) {
+  fun `given source languageTag when normalizing then result is expected`(source: String?, expected: String) {
     assertThat(BCP47TagValidator.normalize(source)).isEqualTo(expected)
   }
 
   private fun languagesNormalized(): Stream<Arguments> =
     Stream.of(
+      Arguments.of(null, ""),
+      Arguments.of("", ""),
       Arguments.of("fra", "fr"),
       Arguments.of("fra-be", "fr-BE"),
       Arguments.of("JA", "ja"),
@@ -26,12 +28,14 @@ class BCP47TagValidatorTest {
 
   @ParameterizedTest
   @MethodSource("languagesValid")
-  fun `given source languageTag when validating then result is expected`(source: String, expected: Boolean) {
+  fun `given source languageTag when validating then result is expected`(source: String?, expected: Boolean) {
     assertThat(BCP47TagValidator.isValid(source)).isEqualTo(expected)
   }
 
-  fun languagesValid(): Stream<Arguments> =
+  private fun languagesValid(): Stream<Arguments> =
     Stream.of(
+      Arguments.of(null, false),
+      Arguments.of("", false),
       Arguments.of("fra", true),
       Arguments.of("fra-BE", true),
       Arguments.of("en-us", true),