/**
 * Phase: tts — 语音合成（整段合成）
 *
 * 每个 item 的 script 整段合成一个音频文件，保留自然语调。
 * item.audio 指向完整音频，item.audioDuration 为总时长。
 * 字幕切分由组装阶段按字符比例分配，不在 TTS 阶段处理。
 */

const path = require('path')
const { saveManifest, ensureDir, log, getManifestDir } = require('./pipeline-utils')

async function phaseTts(manifest, manifestPath, options = {}) {
  const dir = getManifestDir(manifestPath)
  const audioDir = path.join(dir, 'audio')
  ensureDir(audioDir)

  const { synthesize } = require('../qwen-tts')

  const items = manifest.items.filter(it =>
    it.status === 'done' && (it.script || it.text) && !it.audio
  )
  if (items.length === 0) { log('tts', '无待处理 item，跳过'); return }

  log('tts', `共 ${items.length} 段`)

  for (let i = 0; i < items.length; i++) {
    const item = items[i]
    const idx = i + 1
    const fullText = item.script || item.text

    try {
      const { filePath, duration } = await synthesize(fullText, {
        outputDir: audioDir,
        id: String(item.id || idx),
        voice: manifest.ttsVoice || undefined,
        instruction: manifest.ttsInstruction || undefined,
        rate: manifest.ttsRate || undefined,
      })

      const totalDuration = Math.round(duration * 1000) / 1000
      item.audio = path.relative(dir, filePath).replace(/\\/g, '/')
      item.audioDuration = totalDuration
      log('tts', `[${idx}/${items.length}] ${totalDuration.toFixed(1)}s: ${fullText.substring(0, 30)}...`)
    } catch (err) {
      item.status = 'failed'
      item.error = `TTS失败: ${err.message}`
      log('tts', `[${idx}/${items.length}] 失败: ${err.message}`)
    }
    saveManifest(manifestPath, manifest)
  }
}

module.exports = { phaseTts }