fix(i18n): 파파고 번역 요청을 길이 제한에 맞춰 분할한다

src/main/kotlin/kr/co/vividnext/sodalive/i18n/translation/PapagoTranslationService.kt

@@ -43,32 +43,54 @@ class PapagoTranslationService(
 
         request.texts.forEach { text ->
             try {
-                val body = mapOf(
-                    "source" to request.sourceLanguage,
-                    "target" to request.targetLanguage,
-                    "text" to text
-                )
+                val translatedText = StringBuilder()
+                for (chunk in splitText(text)) {
+                    val body = mapOf(
+                        "source" to request.sourceLanguage,
+                        "target" to request.targetLanguage,
+                        "text" to chunk
+                    )
 
-                val requestEntity = HttpEntity(body, headers)
+                    val requestEntity = HttpEntity(body, headers)
 
-                val response = restTemplate.postForEntity<PapagoTranslationResponse>(
-                    papagoTranslateUrl,
-                    requestEntity
-                )
+                    val response = restTemplate.postForEntity<PapagoTranslationResponse>(
+                        papagoTranslateUrl,
+                        requestEntity
+                    )
 
-                if (!response.statusCode.is2xxSuccessful) {
-                    return@forEach
+                    if (!response.statusCode.is2xxSuccessful) {
+                        return TranslateResult(emptyList())
+                    }
+
+                    val translated = response.body?.message?.result?.translatedText
+                    if (translated.isNullOrBlank()) {
+                        return TranslateResult(emptyList())
+                    }
+                    translatedText.append(translated)
                 }
-
-                val translated = response.body?.message?.result?.translatedText
-                translatedTexts.add(translated ?: "")
+                translatedTexts.add(translatedText.toString())
             } catch (_: Exception) {
+                return TranslateResult(emptyList())
             }
         }
 
         return TranslateResult(translatedTexts)
     }
 
+    private fun splitText(text: String): List<String> {
+        val chunks = mutableListOf<String>()
+        var start = 0
+        do {
+            var end = minOf(start + MAX_REQUEST_TEXT_LENGTH, text.length)
+            if (end < text.length && text[end - 1].isHighSurrogate() && text[end].isLowSurrogate()) {
+                end -= 1
+            }
+            chunks.add(text.substring(start, end))
+            start = end
+        } while (start < text.length)
+        return chunks
+    }
+
     private fun validateLanguages(sourceLanguage: String, targetLanguage: String): Boolean {
         return requireSupportedLanguage(sourceLanguage) && requireSupportedLanguage(targetLanguage)
     }
@@ -79,6 +101,8 @@ class PapagoTranslationService(
     }
 
     companion object {
+        private const val MAX_REQUEST_TEXT_LENGTH = 5000
+
         private val SUPPORTED_LANGUAGE_CODES = setOf(
             "ko",
             "en",