feat: 하나의 문장(한 줄)을 받아 음성으로 변환하는 기능 구현

src/main/kotlin/com/sangdol/text_to_speech/SingleTextConverter.kt

@@ -0,0 +1,44 @@
+package com.sangdol.text_to_speech
+
+import com.google.cloud.texttospeech.v1.*
+import com.google.protobuf.ByteString
+import org.springframework.stereotype.Component
+import java.io.File
+import java.io.FileOutputStream
+
+@Component
+class SingleTextConverter(
+    private val ttsClient: TextToSpeechClient
+) {
+    fun convert(
+        request: ConvertSingleTextRequest,
+        filePath: String,
+        language: TtsLanguageCode = TtsLanguageCode.ENGLISH_US,
+        encodingType: AudioEncoding = AudioEncoding.MP3
+    ) {
+        val synthesisInput = SynthesisInput.newBuilder()
+            .setText(request.text)
+            .build()
+
+        val voiceOptions = VoiceSelectionParams.newBuilder()
+            .setLanguageCode(language.code)
+            .setName(request.type.identifier)
+            .build()
+
+        val audioConfig = AudioConfig.newBuilder()
+            .setAudioEncoding(encodingType)
+            .setSpeakingRate(request.speakingRate)
+            .build()
+
+        val synthesizeResponse: SynthesizeSpeechResponse = ttsClient.synthesizeSpeech(synthesisInput, voiceOptions, audioConfig)
+        val content: ByteString = synthesizeResponse.audioContent
+
+        val file = File(filePath).also {
+            it.parentFile
+                .takeIf { dir -> !dir.exists() }
+                ?.mkdirs()
+        }
+
+        FileOutputStream(file).use { it.write(content.toByteArray()) }
+    }
+}