hotfix: ISBN 검증 강화 및 검색 결과 처리 개선

**IsbnValidator**
- 기존 정규식 검사에 더해 ISBN-10, ISBN-13의 체크섬 검증 추가
- 하이픈(-), 공백, 소문자 'x' 처리용 전처리 기능 추가

**AladinBookQueryService**
- filter → mapNotNull로 변경하여 ISBN-10만 있는 경우 ISBN-13 변환 후 포함
- isbn13 필드 누락 문제 해결
- totalResults를 필터링 후 아이템 개수로 수정하여 데이터 정합성 확보

Author: move-hoon

apis/src/main/kotlin/org/yapp/apis/book/service/AladinBookQueryService.kt

@@ -24,7 +24,7 @@ class AladinBookQueryService(
     private val log = KotlinLogging.logger {}
 
     override fun searchBooks(request: BookSearchRequest): BookSearchResponse {
-        log.info("Service - Converting BookSearchRequest to AladinBookSearchRequest and calling Aladin API for book search.")
+        log.info { "Service - Converting BookSearchRequest to AladinBookSearchRequest and calling Aladin API for book search." }
         val aladinSearchRequest = AladinBookSearchRequest.of(
             request.validQuery(),
             request.queryType,
@@ -35,32 +35,37 @@ class AladinBookQueryService(
             request.categoryId
         )
         val response: AladinSearchResponse = aladinApi.searchBooks(aladinSearchRequest)
-            .onSuccess { response ->
-                log.info("Aladin search successful for query: '${request.query}', total results: ${response.totalResults}")
+            .onSuccess { res ->
+                log.info { "Aladin search successful for query: '${request.query}', total results: ${res.totalResults}" }
             }
             .getOrElse { exception ->
-                log.error("Failed to call Aladin search API for request: '$request'", exception)
+                log.error(exception) { "Failed to call Aladin search API for request: '$request'" }
                 throw BookException(BookErrorCode.ALADIN_API_SEARCH_FAILED, exception.message)
             }
 
-        val filteredItems = response.item.filter { item ->
-            getValidAndFilteredIsbn13(item) != null
+        log.info { "Before filtering - Full Response: $response" }
+
+        val transformedItems = response.item.mapNotNull { item ->
+            val validIsbn13 = getValidAndFilteredIsbn13(item)
+            validIsbn13?.let { item.copy(isbn13 = it) }
         }
 
         val filteredResponse = AladinSearchResponse(
             version = response.version,
             title = response.title,
             link = response.link,
             pubDate = response.pubDate,
-            totalResults = response.totalResults,
+            totalResults = transformedItems.size,
             startIndex = response.startIndex,
             itemsPerPage = response.itemsPerPage,
             query = response.query,
             searchCategoryId = response.searchCategoryId,
             searchCategoryName = response.searchCategoryName,
-            item = filteredItems
+            item = transformedItems
         )
 
+        log.info { "After filtering - Full Response: $filteredResponse" }
+
         return BookSearchResponse.from(filteredResponse)
     }
 

global-utils/src/main/kotlin/org/yapp/globalutils/validator/IsbnValidator.kt

@@ -6,11 +6,47 @@ object IsbnValidator {
     private val ISBN10_REGEX = Regex(RegexUtils.ISBN10_PATTERN)
     private val ISBN13_REGEX = Regex(RegexUtils.ISBN13_PATTERN)
 
-    fun isValidIsbn10(isbn: String): Boolean {
-        return isbn.matches(ISBN10_REGEX)
+    fun isValidIsbn10(isbnInput: String): Boolean {
+        val isbn = preprocess(isbnInput)
+
+        if (!isbn.matches(ISBN10_REGEX)) {
+            return false
+        }
+
+        var sum = 0
+        for (i in 0 until 9) {
+            val digit = isbn[i].toString().toInt()
+            sum += digit * (10 - i)
+        }
+
+        val lastChar = isbn[9]
+        val checkDigit = if (lastChar == 'X') 10 else lastChar.toString().toInt()
+
+        return (sum + checkDigit) % 11 == 0
+    }
+
+    fun isValidIsbn13(isbnInput: String): Boolean {
+        val isbn = preprocess(isbnInput)
+
+        if (!isbn.matches(ISBN13_REGEX)) {
+            return false
+        }
+
+        var sum = 0
+        for (i in 0 until 12) {
+            val digit = isbn[i].toString().toInt()
+            sum += if (i % 2 == 0) digit else digit * 3
+        }
+
+        val calculatedCheckDigit = (10 - (sum % 10)) % 10
+        val actualCheckDigit = isbn[12].toString().toInt()
+
+        return calculatedCheckDigit == actualCheckDigit
     }
 
-    fun isValidIsbn13(isbn: String): Boolean {
-        return isbn.matches(ISBN13_REGEX)
+    private fun preprocess(isbn: String): String {
+        return isbn.replace("-", "")
+            .replace(" ", "")
+            .uppercase()
     }
 }