import path from 'path';
import fs from 'fs';
import {
  getAllJobs, getJob, createJob, updateJobStatus, saveCheckpoint,
  saveJobOutputs, deleteJob as deleteJobFromDb, Job, OutputOptions
} from '../db/jobStore';
import { generateAudioDescriptionFromOptions } from '../../utils/processor';
import { generateSRT, generateVTT } from './subtitleGenerator';
import { muxAudioDescription } from './muxer';
import { getDefaultConfig, Config } from '../../config/config';
import { AudioSegment, BatchContext } from '../../interfaces';
import { getVideoDuration, cleanupTempFiles } from '../../utils/mediaUtils';
import { EventEmitter } from 'events';

function jobTempDir(baseTempDir: string, jobId: string): string {
  return path.join(baseTempDir, jobId);
}

function safeCleanupJobTmp(dir: string): void {
  try {
    if (!fs.existsSync(dir)) return;
    cleanupTempFiles(dir);
    fs.rmSync(dir, { recursive: true, force: true });
  } catch (err: any) {
    console.warn(`Failed to clean up tmp dir ${dir}:`, err.message);
  }
}

interface ProgressData {
  id: string;
  status: string;
  progress: number;
  currentIndex: number;
  totalUnits: number;
  segments: AudioSegment[];
  error: string | null;
  output_audio: string | null;
  output_subtitles_srt: string | null;
  output_subtitles_vtt: string | null;
  output_muxed: string | null;
}

export class JobManager {
  private queue: string[] = [];
  private processing = false;
  private pausedJobs = new Set<string>();
  private emitter = new EventEmitter();
  private pollInterval: ReturnType<typeof setInterval> | null = null;

  constructor() {
    this.recoverStuckJobs();
    this.emitter.setMaxListeners(100);
  }

  private recoverStuckJobs(): void {
    const jobs = getAllJobs();
    for (const job of jobs) {
      if (job.status === 'processing') {
        updateJobStatus(job.id, 'failed', 'Server restarted while job was in progress. Click Restart to resume from the last checkpoint.');
      }
    }
  }

  createJob(videoPath: string, configOverride: Partial<Config> = {}, outputOptions: Partial<OutputOptions> = {}): Job {
    const baseConfig = getDefaultConfig();

    // Drop empty/undefined/null values so blank form fields don't clobber the
    // baked-in defaults (a blank prompt textarea must NOT overwrite the real
    // prompt with "").
    const cleanedOverride: Record<string, unknown> = {};
    for (const [k, v] of Object.entries(configOverride)) {
      if (v === '' || v === null || v === undefined) continue;
      cleanedOverride[k] = v;
    }

    const mergedConfig: Config = { ...baseConfig, ...(cleanedOverride as Partial<Config>) };

    const filename = path.basename(videoPath);
    const opts: OutputOptions = {
      audio: outputOptions.audio !== false,
      subtitles: outputOptions.subtitles !== false,
      muxed: outputOptions.muxed || false
    };

    return createJob(videoPath, filename, mergedConfig, opts);
  }

  async startJob(jobId: string): Promise<void> {
    const job = getJob(jobId);
    if (!job) throw new Error('Job not found');
    if (job.status === 'processing') throw new Error('Job is already processing');
    if (job.status === 'completed') throw new Error('Job is already completed');

    updateJobStatus(jobId, 'queued');
    this.queue.push(jobId);
    this.processNext();
  }

  async pauseJob(jobId: string): Promise<void> {
    const job = getJob(jobId);
    if (!job) throw new Error('Job not found');
    if (job.status !== 'processing') throw new Error('Only processing jobs can be paused');
    
    this.pausedJobs.add(jobId);
    updateJobStatus(jobId, 'paused');
    this.emitProgress(jobId);
  }

  async restartJob(jobId: string): Promise<void> {
    const job = getJob(jobId);
    if (!job) throw new Error('Job not found');
    if (job.status !== 'failed' && job.status !== 'paused' && job.status !== 'cancelled') {
      throw new Error('Only failed, paused, or cancelled jobs can be restarted');
    }

    this.pausedJobs.delete(jobId);
    updateJobStatus(jobId, 'queued');
    this.queue.push(jobId);
    this.processNext();
  }

  async cancelJob(jobId: string): Promise<void> {
    const job = getJob(jobId);
    if (!job) throw new Error('Job not found');

    if (job.status === 'processing') {
      this.pausedJobs.add(jobId);
    }
    updateJobStatus(jobId, 'cancelled');
    this.emitProgress(jobId);
  }

  deleteJob(jobId: string): void {
    const job = getJob(jobId);
    if (!job) throw new Error('Job not found');
    if (job.status === 'processing') throw new Error('Cannot delete a running job');

    try {
      const config: Config = JSON.parse(job.config);
      // job.config may contain either the base tempDir (older jobs) or the
      // per-job tempDir (newer jobs). Trim a trailing job-id segment if present;
      // otherwise compute the per-job dir from the stored base.
      const stored = config.tempDir || './desc/tmp/';
      const candidate = path.basename(stored) === jobId ? stored : jobTempDir(stored, jobId);
      safeCleanupJobTmp(candidate);
    } catch {
      // ignore: cleanup is best-effort and must not block deletion
    }

    deleteJobFromDb(jobId);
  }

  listJobs(): Job[] {
    return getAllJobs();
  }

  onJobProgress(jobId: string, callback: (data: ProgressData) => void): () => void {
    this.emitter.on(`progress:${jobId}`, callback);

    if (!this.pollInterval) {
      this.pollInterval = setInterval(() => {
        for (const id of this.emitter.eventNames()) {
          const eventName = String(id);
          if (eventName.startsWith('progress:')) {
            const jId = eventName.replace('progress:', '');
            this.emitProgress(jId);
          }
        }
      }, 2000);
    }

    return () => {
      this.emitter.off(`progress:${jobId}`, callback);
    };
  }

  private emitProgress(jobId: string): void {
    const job = getJob(jobId);
    if (!job) return;

    const data: ProgressData = {
      id: job.id,
      status: job.status,
      progress: job.progress,
      currentIndex: job.current_index,
      totalUnits: job.total_units,
      segments: JSON.parse(job.segments || '[]'),
      error: job.error,
      output_audio: job.output_audio,
      output_subtitles_srt: job.output_subtitles_srt,
      output_subtitles_vtt: job.output_subtitles_vtt,
      output_muxed: job.output_muxed
    };
    this.emitter.emit(`progress:${jobId}`, data);
  }

  private async processNext(): Promise<void> {
    if (this.processing) return;
    
    while (this.queue.length > 0) {
      this.processing = true;
      const jobId = this.queue.shift()!;
      
      const job = getJob(jobId);
      if (!job || job.status !== 'queued') continue;

      try {
        await this.processJob(job);
      } catch (err: any) {
        console.error(`Job ${jobId} failed:`, err.message);
      }
    }
    this.processing = false;
  }

  private async processJob(job: Job): Promise<void> {
    updateJobStatus(job.id, 'processing');
    this.emitProgress(job.id);

    const config: Config = JSON.parse(job.config);
    const outputOptions: OutputOptions = JSON.parse(job.output_options);

    // Isolate this job's intermediates so concurrent jobs (or future resumes)
    // don't collide on filenames like frame_00001.jpg / segment_3_std.wav.
    // The pipeline already reads config.tempDir, so just override it here.
    const baseTempDir = config.tempDir || './desc/tmp/';
    if (path.basename(baseTempDir) !== job.id) {
      config.tempDir = jobTempDir(baseTempDir, job.id);
    }
    fs.mkdirSync(config.tempDir, { recursive: true });

    const existingSegments: AudioSegment[] = JSON.parse(job.segments || '[]');
    const lastContext: BatchContext = JSON.parse(job.last_context || '{}');
    
    const startIndex = existingSegments.length > 0 ? job.current_index : 0;
    const startTimePosition = job.current_time_position || 0;

    const videoDuration = getVideoDuration(job.video_path);
    const totalUnits = config.batchTimeMode
      ? Math.floor(videoDuration / config.batchWindowDuration)
      : Math.floor(videoDuration / config.captureIntervalSeconds);

    saveCheckpoint(job.id, JSON.stringify(existingSegments), startIndex, totalUnits, startTimePosition, JSON.stringify(lastContext), 0);
    this.emitProgress(job.id);

    try {
      const result = await generateAudioDescriptionFromOptions(
        job.video_path,
        config,
        {
          startIndex,
          existingSegments,
          lastContext,
          currentTimePosition: startTimePosition,
          onProgress: (info) => {
            if (this.pausedJobs.has(job.id)) {
              throw new Error('JOB_PAUSED');
            }

            const allSegments = existingSegments.length > 0 && info.index === startIndex
              ? [...existingSegments, info.segment]
              : (() => {
                  const currentJob = getJob(job.id);
                  if (!currentJob) return [info.segment];
                  const segs = JSON.parse(currentJob.segments || '[]');
                  segs.push(info.segment);
                  return segs;
                })();

            const progress = totalUnits > 0 ? Math.min(((info.index + 1) / totalUnits) * 100, 99) : 50;

            saveCheckpoint(
              job.id,
              JSON.stringify(allSegments),
              info.index + 1,
              totalUnits,
              info.segment.startTime + info.segment.duration + (config.batchTimeMode ? 0.5 : 0.25),
              JSON.stringify(lastContext),
              progress
            );

            this.emitProgress(job.id);
          }
        }
      );

      // All segments from the result
      const segments = result.segments || [];

      // Combine audio segments into final audio (use the result's pre-combined file)
      const outputAudio = result.audioDescriptionFile;

      let outputSubtitlesSrt: string | null = null;
      let outputSubtitlesVtt: string | null = null;
      let outputMuxed: string | null = null;

      const baseName = path.basename(job.video_path, path.extname(job.video_path));
      const outputDir = config.outputDir;

      if (outputOptions.subtitles && segments.length > 0) {
        const srtPath = path.join(outputDir, `${baseName}_description.srt`);
        const vttPath = path.join(outputDir, `${baseName}_description.vtt`);
        fs.writeFileSync(srtPath, generateSRT(segments, videoDuration));
        fs.writeFileSync(vttPath, generateVTT(segments, videoDuration));
        outputSubtitlesSrt = srtPath;
        outputSubtitlesVtt = vttPath;
      }

      if (outputOptions.muxed && fs.existsSync(outputAudio)) {
        const muxedPath = path.join(outputDir, `${baseName}_described.mkv`);
        muxAudioDescription(job.video_path, outputAudio, muxedPath);
        outputMuxed = muxedPath;
      }

      saveJobOutputs(job.id, {
        audio: outputAudio,
        subtitlesSrt: outputSubtitlesSrt || undefined,
        subtitlesVtt: outputSubtitlesVtt || undefined,
        muxed: outputMuxed || undefined
      });

      saveCheckpoint(job.id, JSON.stringify(segments), totalUnits, totalUnits, 0, '{}', 100);
      updateJobStatus(job.id, 'completed');
      this.emitProgress(job.id);

      safeCleanupJobTmp(config.tempDir);

    } catch (err: any) {
      if (err.message === 'JOB_PAUSED') {
        // Keep config.tempDir intact — restart will resume into the same dir.
        updateJobStatus(job.id, 'paused');
        this.emitProgress(job.id);
        return;
      }

      const errorMsg = err.message || 'Unknown error';
      updateJobStatus(job.id, 'failed', errorMsg);
      this.emitProgress(job.id);

      safeCleanupJobTmp(config.tempDir);
    }
  }
}