package kr.co.vividnext.sodalive.content

import kr.co.vividnext.sodalive.i18n.translation.SourceTextNormalizer
import org.springframework.stereotype.Service
import org.springframework.transaction.annotation.Transactional

@Service
class LanguageDetectionCacheService(
    private val languageDetectionResultRepository: LanguageDetectionResultRepository
) {
    @Transactional
    fun detectWithCache(
        query: String,
        provider: String = DEFAULT_PROVIDER,
        detector: () -> String?
    ): String? {
        val normalizedQuery = SourceTextNormalizer.normalize(query)
        if (normalizedQuery.isBlank()) return null

        val sourceHash = SourceTextNormalizer.hash(normalizedQuery)
        val cached = languageDetectionResultRepository.findBySourceHashAndProviderAndNormalizationVersion(
            sourceHash = sourceHash,
            provider = provider,
            normalizationVersion = SourceTextNormalizer.NORMALIZATION_VERSION
        )
        if (cached != null) return cached.detectedLanguage

        val detectedLanguage = detector()?.takeIf { it.isNotBlank() } ?: return null
        languageDetectionResultRepository.save(
            LanguageDetectionResult(
                sourceHash = sourceHash,
                sourceTextSample = normalizedQuery.take(MAX_SAMPLE_LENGTH),
                detectedLanguage = detectedLanguage.lowercase(),
                provider = provider,
                confidence = null,
                normalizationVersion = SourceTextNormalizer.NORMALIZATION_VERSION
            )
        )
        return detectedLanguage.lowercase()
    }

    companion object {
        const val DEFAULT_PROVIDER = "papago"
        private const val MAX_SAMPLE_LENGTH = 500
    }
}