// src/main/services/TTSPlaybackService.ts
// Phase 13.1: TTS 재생 서비스
// Windows SAPI (PowerShell) 기반 로컬 TTS.
// 온라인 불필요, 완전 로컬. 문장 단위 큐 재생.

import { EventEmitter } from 'events'
import { spawn, type ChildProcess } from 'child_process'
import { getLogger } from './LoggerService'
import { configGet } from './ConfigService'
import { D3ROError, ErrorCode } from '@shared/errors'

const logger = getLogger('TTSPlaybackService')

class TTSPlaybackService extends EventEmitter {
  private _speaking = false
  private _queue: string[] = []
  private _currentProcess: ChildProcess | null = null
  private _cancelled = false

  get isSpeaking(): boolean {
    return this._speaking
  }

  /**
   * 텍스트를 음성으로 재생 (Windows SAPI).
   * 큐에 추가되어 순차 재생된다.
   */
  async speak(text: string): Promise<void> {
    if (!text.trim()) return
    this._queue.push(text.trim())
    if (!this._speaking) {
      await this._processQueue()
    }
  }

  /**
   * 문장 배열을 순차 재생.
   * LLM 스트리밍에서 문장 단위로 호출한다.
   */
  async speakSentences(sentences: string[]): Promise<void> {
    for (const sentence of sentences) {
      if (this._cancelled) break
      this._queue.push(sentence.trim())
    }
    if (!this._speaking) {
      await this._processQueue()
    }
  }

  /**
   * 재생 중단 + 큐 비우기.
   */
  stop(): void {
    this._cancelled = true
    this._queue = []
    if (this._currentProcess) {
      this._currentProcess.kill()
      this._currentProcess = null
    }
    this._speaking = false
    this.emit('stopped')
  }

  private async _processQueue(): Promise<void> {
    this._speaking = true
    this._cancelled = false
    this.emit('started')

    while (this._queue.length > 0 && !this._cancelled) {
      const text = this._queue.shift()!
      try {
        await this._speakOne(text)
      } catch (err) {
        logger.warn('TTS playback failed for segment:', err)
      }
    }

    this._speaking = false
    if (!this._cancelled) {
      this.emit('finished')
    }
  }

  /**
   * PowerShell SAPI로 단일 텍스트 재생.
   */
  private _speakOne(text: string): Promise<void> {
    return new Promise((resolve, reject) => {
      // 텍스트를 PowerShell 안전 문자열로 이스케이프
      const escaped = text
        .replace(/'/g, "''")
        .replace(/\n/g, ' ')
        .replace(/\r/g, '')

      const rate = this._getRate()

      const script = `
        Add-Type -AssemblyName System.Speech
        $synth = New-Object System.Speech.Synthesis.SpeechSynthesizer
        $synth.Rate = ${rate}
        $synth.Speak('${escaped}')
        $synth.Dispose()
      `

      this._currentProcess = spawn('powershell', [
        '-NoProfile',
        '-NonInteractive',
        '-Command',
        script,
      ], { stdio: 'pipe' })

      this._currentProcess.on('close', (code) => {
        this._currentProcess = null
        if (code === 0 || this._cancelled) {
          resolve()
        } else {
          reject(new D3ROError(ErrorCode.ConversationTTSFailed, `TTS exited with code ${code}`))
        }
      })

      this._currentProcess.on('error', (err) => {
        this._currentProcess = null
        reject(new D3ROError(ErrorCode.ConversationTTSFailed, `TTS error: ${err.message}`))
      })
    })
  }

  /**
   * SAPI Rate: -10(매우 느림) ~ 10(매우 빠름), 기본 0
   */
  private _getRate(): number {
    const speed = configGet('ttsSpeed') as number | undefined
    if (!speed || speed === 1.0) return 0
    // 0.5 → -5, 1.0 → 0, 2.0 → 5
    return Math.round((speed - 1.0) * 5)
  }

  dispose(): void {
    this.stop()
    this.removeAllListeners()
  }
}

// ── 싱글톤 ──
let instance: TTSPlaybackService | null = null

export function getTTSPlaybackService(): TTSPlaybackService {
  if (!instance) {
    instance = new TTSPlaybackService()
  }
  return instance
}