// Copyright (c) 2026 Gordon Bolton. MIT License.
const axios = require('axios');
const DownloadClient = require('./DownloadClient');
const { logToFile } = require('../utils/logger');

class QBittorrentClient extends DownloadClient {
  constructor(instance) {
    super(instance);
    this.authCookie = null;
    // Sync API incremental state
    this.lastRid = 0;
    this.torrentMap = new Map();
    this.fallbackThisCycle = false;
  }

  getClientType() {
    return 'qbittorrent';
  }

  async testConnection() {
    try {
      await this.login();
      // Try a simple API call to verify connection
      await this.makeRequest('/api/v2/app/version');
      logToFile(`[qBittorrent:${this.name}] Connection test successful`);
      return true;
    } catch (error) {
      logToFile(`[qBittorrent:${this.name}] Connection test failed: ${error.message}`);
      return false;
    }
  }

  async login() {
    try {
      logToFile(`[qBittorrent:${this.name}] Attempting login...`);
      const response = await axios.post(`${this.url}/api/v2/auth/login`, 
        `username=${encodeURIComponent(this.username)}&password=${encodeURIComponent(this.password)}`,
        {
          headers: {
            'Content-Type': 'application/x-www-form-urlencoded'
          },
          maxRedirects: 0,
          validateStatus: (status) => status >= 200 && status < 400
        }
      );
      
      if (response.headers['set-cookie']) {
        this.authCookie = response.headers['set-cookie'][0];
        logToFile(`[qBittorrent:${this.name}] Login successful`);
        return true;
      }
      
      logToFile(`[qBittorrent:${this.name}] Login failed - no cookie`);
      return false;
    } catch (error) {
      logToFile(`[qBittorrent:${this.name}] Login error: ${error.message}`);
      return false;
    }
  }

  async makeRequest(endpoint, config = {}) {
    const url = `${this.url}${endpoint}`;
    
    if (!this.authCookie) {
      const loggedIn = await this.login();
      if (!loggedIn) {
        throw new Error(`Failed to authenticate with ${this.name}`);
      }
    }
    
    try {
      const response = await axios.get(url, {
        ...config,
        headers: {
          ...config.headers,
          'Cookie': this.authCookie
        }
      });
      return response;
    } catch (error) {
      // If unauthorized, try re-authenticating once
      if (error.response && error.response.status === 403) {
        logToFile(`[qBittorrent:${this.name}] Auth expired, re-authenticating...`);
        this.authCookie = null;
        const loggedIn = await this.login();
        if (loggedIn) {
          return axios.get(url, {
            ...config,
            headers: {
              ...config.headers,
              'Cookie': this.authCookie
            }
          });
        }
      }
      throw error;
    }
  }

  /**
   * Fetches incremental torrent data using the qBittorrent Sync API.
   */
  async getMainData() {
    const response = await this.makeRequest(`/api/v2/sync/maindata?rid=${this.lastRid}`);
    const data = response.data;

    if (data.full_update) {
      // Full refresh: rebuild the entire map
      this.torrentMap.clear();
      if (data.torrents) {
        for (const [hash, props] of Object.entries(data.torrents)) {
          this.torrentMap.set(hash, { ...props, hash });
        }
      }
    } else {
      // Delta update: merge changed fields into existing torrent objects
      if (data.torrents) {
        for (const [hash, delta] of Object.entries(data.torrents)) {
          const existing = this.torrentMap.get(hash) || { hash };
          this.torrentMap.set(hash, { ...existing, ...delta });
        }
      }
    }

    // Remove torrents that the server reports as deleted
    if (data.torrents_removed) {
      for (const hash of data.torrents_removed) {
        this.torrentMap.delete(hash);
      }
    }

    // Ensure every torrent has a computed 'completed' field for downstream consumers
    for (const torrent of this.torrentMap.values()) {
      if (torrent.completed === undefined && torrent.size !== undefined && torrent.progress !== undefined) {
        torrent.completed = Math.round(torrent.size * torrent.progress);
      }
    }

    this.lastRid = data.rid;
    return Array.from(this.torrentMap.values());
  }

  /**
   * Legacy full-list fetch. Used as a fallback when the Sync API fails.
   */
  async getTorrentsLegacy() {
    try {
      const response = await this.makeRequest('/api/v2/torrents/info');
      logToFile(`[qBittorrent:${this.name}] Retrieved ${response.data.length} torrents (legacy)`);
      return response.data;
    } catch (error) {
      logToFile(`[qBittorrent:${this.name}] Error fetching torrents (legacy): ${error.message}`);
      throw error;
    }
  }

  async getActiveDownloads() {
    try {
      if (this.fallbackThisCycle) {
        logToFile(`[qBittorrent:${this.name}] Already fell back this cycle, using legacy`);
        const torrents = await this.getTorrentsLegacy();
        return torrents.map(torrent => this.normalizeDownload(torrent));
      }

      const torrents = await this.getMainData();
      logToFile(`[qBittorrent:${this.name}] Sync: ${torrents.length} torrents (rid=${this.lastRid})`);
      return torrents.map(torrent => this.normalizeDownload(torrent));
    } catch (error) {
      logToFile(`[qBittorrent:${this.name}] Sync failed, falling back to legacy: ${error.message}`);
      this.fallbackThisCycle = true;
      try {
        const torrents = await this.getTorrentsLegacy();
        return torrents.map(torrent => this.normalizeDownload(torrent));
      } catch (fallbackError) {
        logToFile(`[qBittorrent:${this.name}] Fallback also failed: ${fallbackError.message}`);
        return [];
      }
    }
  }

  async getClientStatus() {
    try {
      const response = await this.makeRequest('/api/v2/sync/maindata');
      const data = response.data;
      
      return {
        serverState: data.server_state || {},
        rid: data.rid,
        fullUpdate: data.full_update
      };
    } catch (error) {
      logToFile(`[qBittorrent:${this.name}] Error getting client status: ${error.message}`);
      return null;
    }
  }

  normalizeDownload(torrent) {
    const totalSize = torrent.size;
    const downloadedSize = torrent.completed || Math.round(torrent.size * torrent.progress);
    const progress = torrent.progress * 100;
    
    // Map qBittorrent states to our normalized status
    const stateMap = {
      'downloading': 'Downloading',
      'stalledDL': 'Downloading',
      'metaDL': 'Downloading',
      'forcedDL': 'Downloading',
      'allocating': 'Downloading',
      'uploading': 'Seeding',
      'stalledUP': 'Seeding',
      'forcedUP': 'Seeding',
      'queuedUP': 'Queued',
      'queuedDL': 'Queued',
      'checkingUP': 'Checking',
      'checkingDL': 'Checking',
      'checkingResumeData': 'Checking',
      'moving': 'Moving',
      'pausedUP': 'Paused',
      'pausedDL': 'Paused',
      'stoppedUP': 'Stopped',
      'stoppedDL': 'Stopped',
      'error': 'Error',
      'missingFiles': 'Error',
      'unknown': 'Unknown'
    };
    
    const status = stateMap[torrent.state] || torrent.state;
    
    return {
      id: torrent.hash,
      title: torrent.name,
      type: 'torrent',
      client: 'qbittorrent',
      instanceId: this.id,
      instanceName: this.name,
      status: status,
      progress: Math.round(progress),
      size: totalSize,
      downloaded: downloadedSize,
      speed: torrent.dlspeed,
      eta: torrent.eta < 0 || torrent.eta === 8640000 ? null : torrent.eta,
      category: torrent.category || undefined,
      tags: torrent.tags ? torrent.tags.split(',').filter(tag => tag.trim()) : [],
      savePath: torrent.content_path || torrent.save_path || undefined,
      addedOn: torrent.added_on ? new Date(torrent.added_on * 1000).toISOString() : undefined,
      raw: torrent
    };
  }

  // Reset fallback flag (called by registry at start of each poll cycle)
  resetFallbackFlag() {
    this.fallbackThisCycle = false;
  }
}

module.exports = QBittorrentClient;