import { promises as fs } from 'fs';
import { exec } from 'child_process';
import { promisify } from 'util';
import path from 'path';
import { prisma } from './database';
import { userPreferencesService } from './user-preferences';

const execAsync = promisify(exec);

export interface BackupConfig {
  enabled: boolean;
  interval: 'hourly' | 'daily' | 'weekly';
  maxBackups: number;
  backupPath: string;
  includeUploads?: boolean;
  compression?: boolean;
}

export interface BackupInfo {
  id: string;
  filename: string;
  size: number;
  createdAt: Date;
  type: 'manual' | 'automatic';
  status: 'success' | 'failed' | 'in_progress';
  error?: string;
}

export class BackupService {
  private defaultConfig: BackupConfig = {
    enabled: true,
    interval: 'hourly',
    maxBackups: 5,
    backupPath: path.join(process.cwd(), 'backups'),
    includeUploads: true,
    compression: true,
  };

  private config: BackupConfig;

  constructor(config?: Partial<BackupConfig>) {
    this.config = { ...this.defaultConfig, ...config };
    // Charger la config depuis la DB de manière asynchrone
    this.loadConfigFromDB().catch(() => {
      // Ignorer les erreurs de chargement initial
    });
  }

  /**
   * Charge la configuration depuis la base de données
   */
  private async loadConfigFromDB(): Promise<void> {
    try {
      const preferences = await userPreferencesService.getAllPreferences();
      if (preferences.viewPreferences && typeof preferences.viewPreferences === 'object') {
        const backupConfig = (preferences.viewPreferences as Record<string, unknown>).backupConfig;
        if (backupConfig) {
          this.config = { ...this.defaultConfig, ...backupConfig };
        }
      }
    } catch (error) {
      console.warn('Could not load backup config from DB, using defaults:', error);
    }
  }

  /**
   * Sauvegarde la configuration dans la base de données
   */
  private async saveConfigToDB(): Promise<void> {
    try {
      // Pour l'instant, on stocke la config backup en tant que JSON dans viewPreferences
      // TODO: Ajouter un champ dédié dans le schéma pour la config backup
      await prisma.userPreferences.upsert({
        where: { id: 'default' },
        update: {
          viewPreferences: JSON.parse(JSON.stringify({
            ...(await userPreferencesService.getViewPreferences()),
            backupConfig: this.config
          }))
        },
        create: {
          id: 'default',
          kanbanFilters: {},
          viewPreferences: JSON.parse(JSON.stringify({ backupConfig: this.config })),
          columnVisibility: {},
          jiraConfig: {}
        }
      });
    } catch (error) {
      console.error('Failed to save backup config to DB:', error);
    }
  }

  /**
   * Crée une sauvegarde complète de la base de données
   */
  async createBackup(type: 'manual' | 'automatic' = 'manual'): Promise<BackupInfo> {
    const backupId = `backup_${Date.now()}`;
    const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
    const filename = `towercontrol_${timestamp}.db`;
    const backupPath = path.join(this.config.backupPath, filename);

    console.log(`🔄 Starting ${type} backup: ${filename}`);

    try {
      // Créer le dossier de backup si nécessaire
      await this.ensureBackupDirectory();

      // Vérifier l'état de la base de données
      await this.verifyDatabaseHealth();

      // Créer la sauvegarde SQLite
      await this.createSQLiteBackup(backupPath);

      // Compresser si activé
      let finalPath = backupPath;
      if (this.config.compression) {
        finalPath = await this.compressBackup(backupPath);
        await fs.unlink(backupPath); // Supprimer le fichier non compressé
      }

      // Obtenir les stats du fichier
      const stats = await fs.stat(finalPath);

      const backupInfo: BackupInfo = {
        id: backupId,
        filename: path.basename(finalPath),
        size: stats.size,
        createdAt: new Date(),
        type,
        status: 'success',
      };

      // Nettoyer les anciennes sauvegardes
      await this.cleanOldBackups();

      console.log(`✅ Backup completed: ${backupInfo.filename} (${this.formatFileSize(backupInfo.size)})`);
      
      return backupInfo;
    } catch (error) {
      console.error(`❌ Backup failed:`, error);
      
      return {
        id: backupId,
        filename,
        size: 0,
        createdAt: new Date(),
        type,
        status: 'failed',
        error: error instanceof Error ? error.message : 'Unknown error',
      };
    }
  }

  /**
   * Crée une sauvegarde SQLite en utilisant la commande .backup
   */
  private async createSQLiteBackup(backupPath: string): Promise<void> {
    const dbPath = path.resolve(process.env.DATABASE_URL?.replace('file:', '') || './prisma/dev.db');
    
    // Méthode 1: Utiliser sqlite3 CLI (plus fiable)
    try {
      const command = `sqlite3 "${dbPath}" ".backup '${backupPath}'"`;
      await execAsync(command);
      console.log(`✅ SQLite backup created using CLI: ${backupPath}`);
      return;
    } catch (cliError) {
      console.warn(`⚠️ SQLite CLI backup failed, trying copy method:`, cliError);
    }

    // Méthode 2: Copie simple du fichier (fallback)
    try {
      await fs.copyFile(dbPath, backupPath);
      console.log(`✅ SQLite backup created using file copy: ${backupPath}`);
    } catch (copyError) {
      throw new Error(`Failed to create SQLite backup: ${copyError}`);
    }
  }

  /**
   * Compresse une sauvegarde
   */
  private async compressBackup(filePath: string): Promise<string> {
    const compressedPath = `${filePath}.gz`;
    
    try {
      const command = `gzip -c "${filePath}" > "${compressedPath}"`;
      await execAsync(command);
      console.log(`✅ Backup compressed: ${compressedPath}`);
      return compressedPath;
    } catch (error) {
      console.warn(`⚠️ Compression failed, keeping uncompressed backup:`, error);
      return filePath;
    }
  }

  /**
   * Restaure une sauvegarde
   */
  async restoreBackup(filename: string): Promise<void> {
    const backupPath = path.join(this.config.backupPath, filename);
    const dbPath = path.resolve(process.env.DATABASE_URL?.replace('file:', '') || './prisma/dev.db');
    
    console.log(`🔄 Restore paths - backup: ${backupPath}, target: ${dbPath}`);

    console.log(`🔄 Starting restore from: ${filename}`);

    try {
      // Vérifier que le fichier de sauvegarde existe
      await fs.access(backupPath);

      // Décompresser si nécessaire
      let sourceFile = backupPath;
      if (filename.endsWith('.gz')) {
        const tempFile = backupPath.replace('.gz', '');
        console.log(`🔄 Decompressing ${backupPath} to ${tempFile}`);
        
        try {
          await execAsync(`gunzip -c "${backupPath}" > "${tempFile}"`);
          console.log(`✅ Decompression successful`);
          
          // Vérifier que le fichier décompressé existe
          await fs.access(tempFile);
          console.log(`✅ Decompressed file exists: ${tempFile}`);
          
          sourceFile = tempFile;
        } catch (decompError) {
          console.error(`❌ Decompression failed:`, decompError);
          throw decompError;
        }
      }

      // Créer une sauvegarde de la base actuelle avant restauration
      const currentBackup = await this.createBackup('manual');
      console.log(`✅ Current database backed up as: ${currentBackup.filename}`);

      // Fermer toutes les connexions
      await prisma.$disconnect();

      // Vérifier que le fichier source existe
      await fs.access(sourceFile);
      console.log(`✅ Source file verified: ${sourceFile}`);
      
      // Remplacer la base de données
      console.log(`🔄 Copying ${sourceFile} to ${dbPath}`);
      await fs.copyFile(sourceFile, dbPath);
      console.log(`✅ Database file copied successfully`);

      // Nettoyer le fichier temporaire si décompressé
      if (sourceFile !== backupPath) {
        await fs.unlink(sourceFile);
      }

      // Reconnecter à la base
      await prisma.$connect();

      // Vérifier l'intégrité après restauration
      await this.verifyDatabaseHealth();

      console.log(`✅ Database restored from: ${filename}`);
    } catch (error) {
      console.error(`❌ Restore failed:`, error);
      throw new Error(`Failed to restore backup: ${error}`);
    }
  }

  /**
   * Liste toutes les sauvegardes disponibles
   */
  async listBackups(): Promise<BackupInfo[]> {
    try {
      await this.ensureBackupDirectory();
      const files = await fs.readdir(this.config.backupPath);
      
      const backups: BackupInfo[] = [];
      
      for (const file of files) {
        if (file.startsWith('towercontrol_') && (file.endsWith('.db') || file.endsWith('.db.gz'))) {
          const filePath = path.join(this.config.backupPath, file);
          const stats = await fs.stat(filePath);
          
          // Extraire la date du nom de fichier
          const dateMatch = file.match(/towercontrol_(\d{4}-\d{2}-\d{2}T\d{2}-\d{2}-\d{2}-\d{3}Z)/);
          let createdAt = stats.birthtime;
          
          if (dateMatch) {
            // Convertir le format de fichier vers ISO string valide
            // Format: 2025-09-18T14-12-05-737Z -> 2025-09-18T14:12:05.737Z
            const isoString = dateMatch[1]
              .replace(/T(\d{2})-(\d{2})-(\d{2})-(\d{3})Z/, 'T$1:$2:$3.$4Z');
            createdAt = new Date(isoString);
          }
          
          backups.push({
            id: file,
            filename: file,
            size: stats.size,
            createdAt,
            type: 'automatic', // On ne peut pas déterminer le type depuis le nom
            status: 'success',
          });
        }
      }
      
      return backups.sort((a, b) => b.createdAt.getTime() - a.createdAt.getTime());
    } catch (error) {
      console.error('Error listing backups:', error);
      return [];
    }
  }

  /**
   * Supprime une sauvegarde
   */
  async deleteBackup(filename: string): Promise<void> {
    const backupPath = path.join(this.config.backupPath, filename);
    
    try {
      await fs.unlink(backupPath);
      console.log(`✅ Backup deleted: ${filename}`);
    } catch (error) {
      console.error(`❌ Failed to delete backup ${filename}:`, error);
      throw error;
    }
  }

  /**
   * Vérifie l'intégrité de la base de données
   */
  async verifyDatabaseHealth(): Promise<void> {
    try {
      // Test de connexion simple
      await prisma.$queryRaw`SELECT 1`;
      
      // Vérification de l'intégrité SQLite
      const result = await prisma.$queryRaw<{integrity_check: string}[]>`PRAGMA integrity_check`;
      
      if (result.length > 0 && result[0].integrity_check !== 'ok') {
        throw new Error(`Database integrity check failed: ${result[0].integrity_check}`);
      }
      
      console.log('✅ Database health check passed');
    } catch (error) {
      console.error('❌ Database health check failed:', error);
      throw error;
    }
  }

  /**
   * Nettoie les anciennes sauvegardes selon la configuration
   */
  private async cleanOldBackups(): Promise<void> {
    try {
      const backups = await this.listBackups();
      
      if (backups.length > this.config.maxBackups) {
        const toDelete = backups.slice(this.config.maxBackups);
        
        for (const backup of toDelete) {
          await this.deleteBackup(backup.filename);
        }
        
        console.log(`🧹 Cleaned ${toDelete.length} old backups`);
      }
    } catch (error) {
      console.error('Error cleaning old backups:', error);
    }
  }

  /**
   * S'assure que le dossier de backup existe
   */
  private async ensureBackupDirectory(): Promise<void> {
    try {
      await fs.access(this.config.backupPath);
    } catch {
      await fs.mkdir(this.config.backupPath, { recursive: true });
      console.log(`📁 Created backup directory: ${this.config.backupPath}`);
    }
  }

  /**
   * Formate la taille de fichier
   */
  private formatFileSize(bytes: number): string {
    const units = ['B', 'KB', 'MB', 'GB'];
    let size = bytes;
    let unitIndex = 0;
    
    while (size >= 1024 && unitIndex < units.length - 1) {
      size /= 1024;
      unitIndex++;
    }
    
    return `${size.toFixed(1)} ${units[unitIndex]}`;
  }

  /**
   * Met à jour la configuration
   */
  async updateConfig(newConfig: Partial<BackupConfig>): Promise<void> {
    this.config = { ...this.config, ...newConfig };
    await this.saveConfigToDB();
  }

  /**
   * Obtient la configuration actuelle
   */
  getConfig(): BackupConfig {
    return { ...this.config };
  }
}

// Instance singleton
export const backupService = new BackupService();