const { EventEmitter } = require('events');
const path = require('path');
const fs = require('fs');
const crypto = require('crypto');
const { uploadFile } = require('./hosters');
const VidmolyUploader = require('./vidmoly-upload');
const VoeUploader = require('./voe-upload');
const DoodstreamUploader = require('./doodstream-upload');
const Semaphore = require('./semaphore');
const Throttle = require('./throttle');

const DEFAULT_SETTINGS = {
  retries: 3,
  maxSpeedKbs: 0,
  parallelCount: 2,
  restartBelowKbs: 0,
  timeIntervalSec: 0,
  maxSizeMb: 0
};

class UploadManager extends EventEmitter {
  constructor(hosterSettings, globalSettings) {
    super();
    this.hosterSettings = hosterSettings || {};
    this.globalSettings = globalSettings || {};
    this.semaphores = {};
    this.globalSemaphore = null;
    this.abortController = new AbortController();
    this.running = false;
    this.stopAfterActive = false;
    this.statsInterval = null;
    this.startTime = 0;
    this.activeJobs = new Map(); // uploadId -> { jobId, speedKbs, bytesUploaded }
    this.jobAbortControllers = new Map(); // jobId -> AbortController
    this.cancelledJobIds = new Set();
    this.sessionBytes = 0;
    this.lastStartTime = {}; // hoster -> timestamp of last upload start
    this.globalThrottle = null;
  }

  _getSettings(hoster) {
    const settings = { ...DEFAULT_SETTINGS, ...(this.hosterSettings[hoster] || {}) };
    const globalLimit = this._getGlobalParallelLimit();
    if (this.globalSettings.scaleParallelUploads && globalLimit > 0) {
      settings.parallelCount = Math.max(settings.parallelCount || 1, globalLimit);
    }
    return settings;
  }

  _getGlobalParallelLimit() {
    const raw = Number(this.globalSettings.parallelUploadCount || 0);
    if (!Number.isFinite(raw) || raw <= 0) return 0;
    return Math.max(1, Math.min(100, Math.round(raw)));
  }

  _getGlobalSemaphore() {
    const limit = this._getGlobalParallelLimit();
    if (limit <= 0) return null;
    if (!this.globalSemaphore) {
      this.globalSemaphore = new Semaphore(limit);
    } else {
      this.globalSemaphore.updateLimit(limit);
    }
    return this.globalSemaphore;
  }

  _getGlobalThrottle() {
    const kbs = Number(this.globalSettings.globalMaxSpeedKbs || 0);
    if (!Number.isFinite(kbs) || kbs <= 0) return null;
    if (!this.globalThrottle) {
      this.globalThrottle = new Throttle(kbs * 1024);
    } else {
      this.globalThrottle.updateRate(kbs * 1024);
    }
    return this.globalThrottle;
  }

  _getSemaphore(hoster) {
    if (!this.semaphores[hoster]) {
      const settings = this._getSettings(hoster);
      this.semaphores[hoster] = new Semaphore(settings.parallelCount);
    } else {
      this.semaphores[hoster].updateLimit(this._getSettings(hoster).parallelCount);
    }
    return this.semaphores[hoster];
  }

  async startBatch(tasks) {
    this.running = true;
    this.stopAfterActive = false;
    this.abortController = new AbortController();
    this.startTime = Date.now();
    this.sessionBytes = 0;
    this.activeJobs.clear();
    this.jobAbortControllers.clear();
    this.cancelledJobIds.clear();
    this.semaphores = {};
    this.globalSemaphore = null;
    this.globalThrottle = null;
    this.lastStartTime = {};

    const { signal } = this.abortController;
    const batchId = `batch-${Date.now()}`;
    const results = new Map(); // filePath -> { name, size, results: [] }

    for (const task of tasks) {
      const fileName = path.basename(task.file);
      if (!results.has(task.file)) {
        let size = 0;
        try { size = fs.statSync(task.file).size; } catch {}
        results.set(task.file, { name: fileName, size, results: [] });
      }
    }

    this._startStatsTimer();

    const promises = tasks.map((task) => this._runJob(task, results, signal));
    await Promise.allSettled(promises);

    this._stopStatsTimer();
    this.running = false;

    const files = Array.from(results.values());
    const total = tasks.length;
    const succeeded = files.reduce((count, file) => count + file.results.filter((result) => result.status === 'done').length, 0);

    const summary = {
      id: batchId,
      timestamp: new Date().toISOString(),
      total,
      succeeded,
      failed: total - succeeded,
      files
    };

    this.emit('batch-done', summary);
  }

  async _runJob(task, results, batchSignal) {
    const settings = this._getSettings(task.hoster);
    const hosterSemaphore = this._getSemaphore(task.hoster);
    const globalSemaphore = this._getGlobalSemaphore();
    const uploadId = crypto.randomBytes(8).toString('hex');
    const jobId = task.jobId || uploadId;
    const fileName = path.basename(task.file);
    let fileSize = 0;
    try { fileSize = fs.statSync(task.file).size; } catch {}

    const maxAttempts = Math.max(1, (settings.retries || 0) + 1);
    const jobAbortController = new AbortController();
    const { signal, cleanup: cleanupSignals } = this._combineSignals(batchSignal, jobAbortController.signal);
    this.jobAbortControllers.set(jobId, jobAbortController);

    let hosterSlotAcquired = false;
    let globalSlotAcquired = false;
    let finalResultRecorded = false;
    let lastError = null;

    const recordFinalResult = (status, payload = {}) => {
      if (finalResultRecorded) return;
      finalResultRecorded = true;

      const result = {
        hoster: task.hoster,
        status,
        error: payload.error || null,
        download_url: payload.result ? payload.result.download_url || null : null,
        embed_url: payload.result ? payload.result.embed_url || null : null,
        file_code: payload.result ? payload.result.file_code || null : null
      };

      results.get(task.file).results.push(result);
    };

    const emitFinalStatus = (status, payload = {}) => {
      this._emitProgress(uploadId, fileName, task.hoster, {
        jobId,
        status,
        progress: status === 'done' ? 1 : 0,
        bytesUploaded: status === 'done' ? fileSize : 0,
        bytesTotal: fileSize,
        speedKbs: payload.speedKbs || 0,
        elapsed: payload.elapsed || 0,
        remaining: 0,
        error: payload.error || null,
        result: payload.result || null,
        attempt: payload.attempt || maxAttempts,
        maxAttempts
      });
    };

    try {
      if (settings.maxSizeMb > 0 && fileSize > settings.maxSizeMb * 1024 * 1024) {
        const error = `Datei zu groß (Max: ${settings.maxSizeMb} MB)`;
        emitFinalStatus('skipped', { error, attempt: 0 });
        recordFinalResult('error', { error });
        return;
      }

      this._emitProgress(uploadId, fileName, task.hoster, {
        jobId,
        status: 'queued',
        progress: 0,
        bytesUploaded: 0,
        bytesTotal: fileSize,
        speedKbs: 0,
        elapsed: 0,
        remaining: 0,
        error: null,
        result: null,
        attempt: 0,
        maxAttempts
      });

      if (globalSemaphore) {
        await globalSemaphore.acquire(signal);
        globalSlotAcquired = true;
      }

      await hosterSemaphore.acquire(signal);
      hosterSlotAcquired = true;

      if (settings.timeIntervalSec > 0) {
        await this._waitForInterval(task.hoster, settings.timeIntervalSec * 1000, signal);
      }

      for (let attempt = 1; attempt <= maxAttempts; attempt++) {
        if (signal.aborted || this.stopAfterActive) break;

        if (attempt > 1) {
          this._emitProgress(uploadId, fileName, task.hoster, {
            jobId,
            status: 'retrying',
            progress: 0,
            bytesUploaded: 0,
            bytesTotal: fileSize,
            speedKbs: 0,
            elapsed: 0,
            remaining: 0,
            error: lastError ? lastError.message : null,
            result: null,
            attempt,
            maxAttempts
          });
          await this._sleep(2500, signal);
        }

        const jobStart = Date.now();
        let lastBytes = 0;
        let lastSpeedTime = jobStart;
        let currentSpeedKbs = 0;
        let lowSpeedSince = 0;
        let speedAbort = null;
        let speedMonitor = null;
        let uploadSignalBundle = { signal, cleanup() {} };

        try {
          this._emitProgress(uploadId, fileName, task.hoster, {
            jobId,
            status: 'getting-server',
            progress: 0,
            bytesUploaded: 0,
            bytesTotal: fileSize,
            speedKbs: 0,
            elapsed: 0,
            remaining: 0,
            error: null,
            result: null,
            attempt,
            maxAttempts
          });

          const hosterThrottle = settings.maxSpeedKbs > 0
            ? new Throttle(settings.maxSpeedKbs * 1024)
            : null;
          const globalThrottle = this._getGlobalThrottle();
          const throttle = hosterThrottle && globalThrottle
            ? { consume: async (bytes, sig) => { await hosterThrottle.consume(bytes, sig); await globalThrottle.consume(bytes, sig); } }
            : hosterThrottle || globalThrottle;

          if (settings.restartBelowKbs > 0) {
            speedAbort = new AbortController();
            uploadSignalBundle = this._combineManySignals([signal, speedAbort.signal]);
            speedMonitor = setInterval(() => {
              if (currentSpeedKbs > 0 && currentSpeedKbs < settings.restartBelowKbs) {
                if (!lowSpeedSince) lowSpeedSince = Date.now();
                if (Date.now() - lowSpeedSince > 6000) {
                  speedAbort.abort();
                }
              } else {
                lowSpeedSince = 0;
              }
            }, 2000);
          }

          this.activeJobs.set(uploadId, { jobId, speedKbs: 0, bytesUploaded: 0 });

          const progressCb = (bytesUploaded, bytesTotal) => {
            const now = Date.now();
            const elapsed = Math.round((now - jobStart) / 1000);
            const timeDelta = (now - lastSpeedTime) / 1000;
            if (timeDelta >= 1) {
              const bytesDelta = bytesUploaded - lastBytes;
              currentSpeedKbs = Math.round(bytesDelta / timeDelta / 1024);
              lastBytes = bytesUploaded;
              lastSpeedTime = now;
            }

            const remaining = currentSpeedKbs > 0
              ? Math.round((bytesTotal - bytesUploaded) / (currentSpeedKbs * 1024))
              : 0;

            this.activeJobs.set(uploadId, { jobId, speedKbs: currentSpeedKbs, bytesUploaded });

            this._emitProgress(uploadId, fileName, task.hoster, {
              jobId,
              status: 'uploading',
              progress: bytesTotal > 0 ? Math.min(1, bytesUploaded / bytesTotal) : 0,
              bytesUploaded,
              bytesTotal,
              speedKbs: currentSpeedKbs,
              elapsed,
              remaining,
              error: null,
              result: null,
              attempt,
              maxAttempts
            });
          };

          let result;
          if (task.hoster === 'vidmoly.me' && task.username) {
            const vidmoly = new VidmolyUploader();
            await vidmoly.login(task.username, task.password);
            result = await vidmoly.upload(task.file, progressCb, uploadSignalBundle.signal, throttle);
          } else if (task.hoster === 'voe.sx' && task.username) {
            const voe = new VoeUploader();
            await voe.login(task.username, task.password);
            result = await voe.upload(task.file, progressCb, uploadSignalBundle.signal, throttle);
          } else if (task.hoster === 'doodstream.com' && task.username) {
            const dood = new DoodstreamUploader();
            await dood.login(task.username, task.password);
            result = await dood.upload(task.file, progressCb, uploadSignalBundle.signal, throttle);
          } else {
            result = await uploadFile(task.hoster, task.file, task.apiKey, progressCb, uploadSignalBundle.signal, throttle);
          }

          const elapsed = Math.round((Date.now() - jobStart) / 1000);
          this.sessionBytes += fileSize;
          this.activeJobs.delete(uploadId);

          emitFinalStatus('done', {
            result,
            speedKbs: currentSpeedKbs,
            elapsed,
            attempt
          });
          recordFinalResult('done', { result });
          return;
        } catch (err) {
          this.activeJobs.delete(uploadId);

          const isSpeedRestart = speedAbort && speedAbort.signal.aborted && !signal.aborted;
          if (signal.aborted) {
            lastError = new Error('Abgebrochen');
            break;
          }

          if (this.stopAfterActive) {
            lastError = new Error('Angehalten');
            break;
          }

          if (isSpeedRestart && attempt < maxAttempts) {
            lastError = new Error('Geschwindigkeit zu niedrig - Neustart');
            await this._sleep(3000, signal);
            continue;
          }

          lastError = err;
          if (attempt >= maxAttempts) break;
          // Wait 3 seconds before retry
          await this._sleep(3000, signal);
        } finally {
          if (speedMonitor) clearInterval(speedMonitor);
          uploadSignalBundle.cleanup();
        }
      }

      const wasStopped = this.stopAfterActive && !signal.aborted;
      const wasAborted = signal.aborted || this.cancelledJobIds.has(jobId);
      if (wasStopped || wasAborted) {
        const error = wasStopped ? 'Warteschlange angehalten' : 'Abgebrochen';
        emitFinalStatus('aborted', { error });
        recordFinalResult('aborted', { error });
        return;
      }

      const error = lastError && lastError.message ? lastError.message : 'Unbekannter Fehler';
      emitFinalStatus('error', { error });
      recordFinalResult('error', { error });
    } catch (err) {
      const wasStopped = this.stopAfterActive && !signal.aborted;
      const error = wasStopped
        ? 'Warteschlange angehalten'
        : (signal.aborted || this.cancelledJobIds.has(jobId) ? 'Abgebrochen' : (err && err.message ? err.message : 'Unbekannter Fehler'));
      const status = signal.aborted || this.cancelledJobIds.has(jobId) || wasStopped ? 'aborted' : 'error';
      emitFinalStatus(status, { error });
      recordFinalResult(status === 'error' ? 'error' : 'aborted', { error });
    } finally {
      this.activeJobs.delete(uploadId);
      this.jobAbortControllers.delete(jobId);
      cleanupSignals();
      if (hosterSlotAcquired) hosterSemaphore.release();
      if (globalSlotAcquired && globalSemaphore) globalSemaphore.release();
    }
  }

  _emitProgress(uploadId, fileName, hoster, data) {
    this.emit('progress', { uploadId, fileName, hoster, ...data });
  }

  _startStatsTimer() {
    this.statsInterval = setInterval(() => {
      let globalSpeedKbs = 0;
      let activeCount = 0;
      for (const job of this.activeJobs.values()) {
        globalSpeedKbs += job.speedKbs || 0;
        activeCount++;
      }

      const elapsed = Math.round((Date.now() - this.startTime) / 1000);
      let inProgressBytes = 0;
      for (const job of this.activeJobs.values()) {
        inProgressBytes += job.bytesUploaded || 0;
      }

      this.emit('stats', {
        state: this.running ? (this.stopAfterActive ? 'stopping' : 'uploading') : 'idle',
        globalSpeedKbs,
        totalBytes: this.sessionBytes + inProgressBytes,
        elapsed,
        activeJobs: activeCount,
        pendingJobs: Object.values(this.semaphores).reduce((sum, semaphore) => sum + semaphore.pending, 0)
      });
    }, 1000);
  }

  _stopStatsTimer() {
    if (this.statsInterval) {
      clearInterval(this.statsInterval);
      this.statsInterval = null;
    }
  }

  _combineSignals(signal1, signal2) {
    const controller = new AbortController();
    if (signal1.aborted || signal2.aborted) {
      controller.abort();
      return { signal: controller.signal, cleanup() {} };
    }

    const onAbort = () => {
      controller.abort();
      cleanup();
    };

    const cleanup = () => {
      signal1.removeEventListener('abort', onAbort);
      signal2.removeEventListener('abort', onAbort);
    };

    signal1.addEventListener('abort', onAbort, { once: true });
    signal2.addEventListener('abort', onAbort, { once: true });
    return { signal: controller.signal, cleanup };
  }

  _combineManySignals(signals) {
    const liveSignals = signals.filter(Boolean);
    const controller = new AbortController();

    if (liveSignals.some((signal) => signal.aborted)) {
      controller.abort();
      return { signal: controller.signal, cleanup() {} };
    }

    const listeners = liveSignals.map((signal) => {
      const handler = () => {
        controller.abort();
        cleanup();
      };
      signal.addEventListener('abort', handler, { once: true });
      return { signal, handler };
    });

    const cleanup = () => {
      for (const entry of listeners) {
        entry.signal.removeEventListener('abort', entry.handler);
      }
    };

    return { signal: controller.signal, cleanup };
  }

  _sleep(ms, signal) {
    return new Promise((resolve, reject) => {
      const onAbort = () => {
        clearTimeout(timer);
        reject(new Error('Aborted'));
      };

      const timer = setTimeout(() => {
        if (signal) signal.removeEventListener('abort', onAbort);
        resolve();
      }, ms);

      if (signal) {
        if (signal.aborted) {
          clearTimeout(timer);
          reject(new Error('Aborted'));
          return;
        }
        signal.addEventListener('abort', onAbort, { once: true });
      }
    });
  }

  async _waitForInterval(hoster, intervalMs, signal) {
    const now = Date.now();
    const last = this.lastStartTime[hoster] || 0;
    const elapsed = now - last;
    if (elapsed < intervalMs) {
      await this._sleep(intervalMs - elapsed, signal);
    }
    this.lastStartTime[hoster] = Date.now();
  }

  cancelJobs(jobIds) {
    for (const jobId of jobIds || []) {
      if (!jobId) continue;
      this.cancelledJobIds.add(jobId);
      const controller = this.jobAbortControllers.get(jobId);
      if (controller && !controller.signal.aborted) {
        controller.abort();
      }
    }
  }

  finishAfterActive() {
    this.stopAfterActive = true;
  }

  cancel() {
    if (!this.running) return;
    this.abortController.abort();
    this.stopAfterActive = false;
    this.running = false;
    for (const controller of this.jobAbortControllers.values()) {
      if (!controller.signal.aborted) controller.abort();
    }
    this._stopStatsTimer();
  }
}

module.exports = UploadManager;