// src/main/services/FileTranscriptionService.ts
// Phase 12.1: 파일 전사 서비스
// 오디오/비디오 파일 → ffmpeg PCM 변환 → 30초 청크 순차 STT → 병합

import { EventEmitter } from 'events'
import path from 'path'
import fs from 'fs'
import { app } from 'electron'
import { getLogger } from './LoggerService'
import { getSTTManager } from './stt/STTManager'
import { getHistoryService } from './HistoryService'
import { configGet } from './ConfigService'
import { getFfmpegPath } from '../utils/paths'
import { getRuntimeProvisioner } from './RuntimeProvisioner'
import { getMainWindow } from '../windows/WindowManager'
import { IPC_CHANNELS } from '@d3ro/core/ipc-channels'
import { D3ROError, ErrorCode } from '@d3ro/core/errors'
import type {
  FileTranscriptionState,
  FileTranscriptionProgress,
  FileTranscriptionResult,
  FileTranscriptionSegment,
  FileTranscriptionStateInfo,
} from '@d3ro/core/types'

const logger = getLogger('FileTranscriptionService')

/** 청크 길이 (초) */
const CHUNK_DURATION_SEC = 30
/** 최대 파일 크기 (2GB) */
const MAX_FILE_SIZE_BYTES = 2 * 1024 * 1024 * 1024
/** initialPrompt 컨텍스트 윈도우 (자) */
const CONTEXT_WINDOW_SIZE = 300
/** 지원 확장자 */
const SUPPORTED_EXTENSIONS = new Set([
  '.mp3', '.wav', '.m4a', '.ogg', '.flac', '.wma', '.aac',
  '.mp4', '.mkv', '.webm', '.avi', '.mov',
])

class FileTranscriptionService extends EventEmitter {
  private _state: FileTranscriptionState = 'idle'
  private _jobId: string | null = null
  private _cancelled = false
  private _progress: FileTranscriptionProgress | null = null
  private _tempDir: string | null = null

  get state(): FileTranscriptionState {
    return this._state
  }

  getStateInfo(): FileTranscriptionStateInfo {
    return {
      state: this._state,
      jobId: this._jobId,
      progress: this._progress,
    }
  }

  async startTranscription(filePath: string, language?: string): Promise<FileTranscriptionResult> {
    if (this._state !== 'idle') {
      throw new D3ROError(ErrorCode.FileTranscriptionChunkFailed, 'Transcription already in progress')
    }

    // 파일 검증
    const ext = path.extname(filePath).toLowerCase()
    if (!SUPPORTED_EXTENSIONS.has(ext)) {
      throw new D3ROError(ErrorCode.FileTranscriptionInvalidFormat, `Unsupported format: ${ext}`)
    }

    const stat = fs.statSync(filePath)
    if (stat.size > MAX_FILE_SIZE_BYTES) {
      throw new D3ROError(ErrorCode.FileTranscriptionFileTooLarge, 'File exceeds 2GB limit')
    }

    // 라이센스 체크
    try {
      const { getLicenseService } = await import('./LicenseService')
      const { Feature } = await import('@d3ro/core/types')
      const license = getLicenseService()
      const access = license.canUse(Feature.FILE_TRANSCRIPTION)
      if (!access.allowed) {
        license.promptUpgrade(
          Feature.FILE_TRANSCRIPTION,
          access.reason === 'quota_exceeded' ? 'quota_exceeded' : 'tier_required',
        )
        throw new D3ROError(ErrorCode.FeatureNotAvailable, 'Pro+ required for file transcription')
      }
    } catch (err) {
      if (err instanceof D3ROError) throw err
    }

    this._jobId = crypto.randomUUID()
    this._cancelled = false
    this._tempDir = path.join(app.getPath('temp'), `d3ro-ft-${this._jobId}`)
    fs.mkdirSync(this._tempDir, { recursive: true })

    const startTime = Date.now()
    const fileName = path.basename(filePath)

    try {
      // Phase 1: ffmpeg 변환 → PCM WAV
      this._setState('converting')
      const wavPath = path.join(this._tempDir, 'audio.wav')
      await this._convertToWav(filePath, wavPath)

      if (this._cancelled) {
        throw new D3ROError(ErrorCode.FileTranscriptionCancelled, 'Transcription cancelled')
      }

      // 오디오 길이 확인
      const totalDurationSec = await this._probeDuration(wavPath)
      const totalChunks = Math.ceil(totalDurationSec / CHUNK_DURATION_SEC)

      // Phase 2: 청크별 STT
      this._setState('transcribing')
      const allSegments: FileTranscriptionSegment[] = []
      const allTexts: string[] = []
      let previousContext = ''

      for (let i = 0; i < totalChunks; i++) {
        if (this._cancelled) {
          throw new D3ROError(ErrorCode.FileTranscriptionCancelled, 'Transcription cancelled')
        }

        const startSec = i * CHUNK_DURATION_SEC
        const chunkBuffer = await this._extractChunk(wavPath, startSec, CHUNK_DURATION_SEC)

        const sttService = getSTTManager()
        const lang = language ?? (configGet('sttLanguage') as string | undefined) ?? 'auto'

        const result = await sttService.transcribe(chunkBuffer, {
          language: lang,
          initialPrompt: previousContext || undefined,
          vadFilter: true,
        })

        if (result.text && result.text.trim().length > 0) {
          allTexts.push(result.text.trim())
          previousContext = result.text.trim().slice(-CONTEXT_WINDOW_SIZE)

          for (const seg of result.segments) {
            allSegments.push({
              text: seg.text,
              start: seg.start + startSec,
              end: seg.end + startSec,
              confidence: seg.confidence,
            })
          }
        }

        this._progress = {
          jobId: this._jobId!,
          currentChunk: i + 1,
          totalChunks,
          percent: Math.round(((i + 1) / totalChunks) * 100),
          currentText: result.text?.trim() ?? '',
        }

        this._sendToRenderer(IPC_CHANNELS.FILE_TRANSCRIPTION.PROGRESS, this._progress)
        this.emit('progress', this._progress)
      }

      const fullText = allTexts.join(' ')
      const processingTimeMs = Date.now() - startTime

      const resultData: FileTranscriptionResult = {
        jobId: this._jobId!,
        filePath,
        fileName,
        fullText,
        segments: allSegments,
        totalDurationSec,
        processingTimeMs,
      }

      // 히스토리에 저장
      try {
        const wordCount = fullText.split(/\s+/).filter((w) => w.length > 0).length
        getHistoryService().create({
          originalText: fullText,
          polishedText: null,
          focusedApp: null,
          focusedAppName: null,
          focusedAppWindowTitle: null,
          mode: 'file-transcription',
          status: 'completed',
          errorCode: null,
          audioLocalPath: filePath,
          duration: totalDurationSec,
          detectedLanguage: null,
          micDevice: null,
          wordCount,
          sttModel: configGet('sttModelId') as string | null,
          llmModel: null,
          sttLatencyMs: processingTimeMs,
          llmLatencyMs: null,
          appVersion: app.getVersion(),
        })
      } catch (err) {
        logger.warn('Failed to save file transcription to history:', err)
      }

      this._setState('completed')
      this._sendToRenderer(IPC_CHANNELS.FILE_TRANSCRIPTION.COMPLETE, resultData)
      this.emit('complete', resultData)

      return resultData
    } catch (err) {
      if (err instanceof D3ROError && err.code === ErrorCode.FileTranscriptionCancelled) {
        this._setState('idle')
        throw err
      }
      this._setState('error')
      const errorMsg = err instanceof Error ? err.message : String(err)
      this._sendToRenderer(IPC_CHANNELS.FILE_TRANSCRIPTION.ERROR, { message: errorMsg })
      this.emit('error', err)
      throw err instanceof D3ROError
        ? err
        : new D3ROError(ErrorCode.FileTranscriptionChunkFailed, errorMsg)
    } finally {
      this._cleanup()
      // 완료/에러 후 idle로 복귀
      setTimeout(() => {
        this._state = 'idle'
        this._jobId = null
        this._progress = null
      }, 1000)
    }
  }

  cancel(): void {
    if (this._state !== 'idle') {
      this._cancelled = true
      logger.info(`File transcription cancelled: ${this._jobId}`)
    }
  }

  private _setState(state: FileTranscriptionState): void {
    this._state = state
    this.emit('state-changed', state)
  }

  private _sendToRenderer(channel: string, data: unknown): void {
    try {
      const mainWindow = getMainWindow()
      if (mainWindow && !mainWindow.isDestroyed()) {
        mainWindow.webContents.send(channel, data)
      }
    } catch {
      // 윈도우 없으면 무시
    }
  }

  /**
   * ffmpeg 실행 파일을 확보한다. 설치본에는 ffmpeg을 넣지 않으므로
   * 없으면 feed에서 내려받는다(파일 전사/회의 모드에서만 필요).
   */
  private async _ensureFfmpeg(): Promise<string> {
    const resolved = getFfmpegPath()
    if (resolved !== 'ffmpeg') return resolved

    logger.info('ffmpeg이 없습니다 — 자동 다운로드를 시작합니다')
    return getRuntimeProvisioner().ensure('ffmpeg')
  }

  /**
   * ffmpeg로 미디어 파일을 PCM16 16kHz mono WAV로 변환
   */
  private _convertToWav(inputPath: string, outputPath: string): Promise<void> {
    return new Promise((resolve, reject) => {
      const { spawn } = require('child_process') as typeof import('child_process')
      const ffmpegPath = getFfmpegPath()

      const args = [
        '-i', inputPath,
        '-ar', '16000',
        '-ac', '1',
        '-sample_fmt', 's16',
        '-y',
        outputPath,
      ]

      logger.info(`ffmpeg convert: ${ffmpegPath} ${args.join(' ')}`)

      const proc = spawn(ffmpegPath, args, { stdio: ['pipe', 'pipe', 'pipe'] })
      let stderr = ''

      proc.stderr?.on('data', (data: Buffer) => {
        stderr += data.toString()
      })

      proc.on('close', (code: number) => {
        if (code === 0) {
          resolve()
        } else {
          logger.error(`ffmpeg failed (code ${code}):`, stderr.slice(-500))
          reject(new D3ROError(ErrorCode.FileTranscriptionFFmpegFailed, `ffmpeg exited with code ${code}`))
        }
      })

      proc.on('error', (err: Error) => {
        reject(new D3ROError(ErrorCode.FileTranscriptionFFmpegFailed, `ffmpeg error: ${err.message}`))
      })
    })
  }

  /**
   * ffprobe(ffmpeg)로 오디오 길이 측정 (초)
   */
  private _probeDuration(wavPath: string): Promise<number> {
    return new Promise((resolve, reject) => {
      const { spawn } = require('child_process') as typeof import('child_process')
      const ffmpegPath = getFfmpegPath()
      // ffprobe는 보통 ffmpeg과 같은 디렉토리에 있으나,
      // @ffmpeg-installer는 ffmpeg만 제공 → -i로 duration 추출
      const args = [
        '-i', wavPath,
        '-f', 'null',
        '-',
      ]

      const proc = spawn(ffmpegPath, args, { stdio: ['pipe', 'pipe', 'pipe'] })
      let stderr = ''

      proc.stderr?.on('data', (data: Buffer) => {
        stderr += data.toString()
      })

      proc.on('close', () => {
        // "Duration: HH:MM:SS.ms" 패턴 파싱
        const match = stderr.match(/Duration:\s*(\d+):(\d+):(\d+)\.(\d+)/)
        if (match) {
          const hours = parseInt(match[1], 10)
          const minutes = parseInt(match[2], 10)
          const seconds = parseInt(match[3], 10)
          const ms = parseInt(match[4], 10) / 100
          resolve(hours * 3600 + minutes * 60 + seconds + ms)
        } else {
          // WAV 파일 크기로 폴백 추정 (16kHz 16bit mono = 32000 bytes/sec)
          try {
            const stat = fs.statSync(wavPath)
            const headerSize = 44
            const bytesPerSec = 16000 * 2 * 1
            resolve(Math.max(0, (stat.size - headerSize) / bytesPerSec))
          } catch {
            reject(new D3ROError(ErrorCode.FileTranscriptionFFmpegFailed, 'Cannot determine audio duration'))
          }
        }
      })
    })
  }

  /**
   * WAV 파일에서 특정 구간을 PCM16 Buffer로 추출
   */
  private _extractChunk(wavPath: string, startSec: number, durationSec: number): Promise<Buffer> {
    return new Promise((resolve, reject) => {
      const { spawn } = require('child_process') as typeof import('child_process')
      const ffmpegPath = getFfmpegPath()

      const args = [
        '-ss', String(startSec),
        '-t', String(durationSec),
        '-i', wavPath,
        '-ar', '16000',
        '-ac', '1',
        '-f', 's16le',
        '-acodec', 'pcm_s16le',
        'pipe:1',
      ]

      const proc = spawn(ffmpegPath, args, { stdio: ['pipe', 'pipe', 'pipe'] })
      const chunks: Buffer[] = []

      proc.stdout?.on('data', (data: Buffer) => {
        chunks.push(data)
      })

      proc.on('close', (code: number) => {
        if (code === 0 || chunks.length > 0) {
          resolve(Buffer.concat(chunks))
        } else {
          reject(new D3ROError(ErrorCode.FileTranscriptionChunkFailed, `Chunk extraction failed at ${startSec}s`))
        }
      })

      proc.on('error', (err: Error) => {
        reject(new D3ROError(ErrorCode.FileTranscriptionFFmpegFailed, `ffmpeg chunk error: ${err.message}`))
      })
    })
  }

  private _cleanup(): void {
    if (this._tempDir && fs.existsSync(this._tempDir)) {
      try {
        fs.rmSync(this._tempDir, { recursive: true, force: true })
      } catch (err) {
        logger.warn('Failed to cleanup temp dir:', err)
      }
      this._tempDir = null
    }
  }

  dispose(): void {
    this.cancel()
    this._cleanup()
    this.removeAllListeners()
  }
}

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

export function resetFileTranscriptionServiceForTests(): void {
  if (instance) instance.removeAllListeners()
  instance = null
}

export function getFileTranscriptionService(): FileTranscriptionService {
  if (!instance) {
    instance = new FileTranscriptionService()
  }
  return instance
}