/**
 * @ai-summary Service for importing user data from exported archives
 * @ai-context Orchestrates import process with merge/replace modes and batch operations
 */

import * as fsp from 'fs/promises';
import * as path from 'path';
import { Pool, PoolClient } from 'pg';
import { logger } from '../../../core/logging/logger';
import { getStorageService } from '../../../core/storage/storage.service';
import { VehiclesRepository } from '../../vehicles/data/vehicles.repository';
import { FuelLogsRepository } from '../../fuel-logs/data/fuel-logs.repository';
import { DocumentsRepository } from '../../documents/data/documents.repository';
import { MaintenanceRepository } from '../../maintenance/data/maintenance.repository';
import { UserImportArchiveService } from './user-import-archive.service';
import { ImportPreview, ImportResult, USER_IMPORT_CONFIG } from './user-import.types';

export class UserImportService {
  private readonly archiveService: UserImportArchiveService;
  private readonly vehiclesRepo: VehiclesRepository;
  private readonly fuelLogsRepo: FuelLogsRepository;
  private readonly maintenanceRepo: MaintenanceRepository;
  private readonly documentsRepo: DocumentsRepository;
  private readonly storageService: ReturnType<typeof getStorageService>;

  constructor(private pool: Pool) {
    this.archiveService = new UserImportArchiveService();
    this.vehiclesRepo = new VehiclesRepository(pool);
    this.fuelLogsRepo = new FuelLogsRepository(pool);
    this.maintenanceRepo = new MaintenanceRepository(pool);
    this.documentsRepo = new DocumentsRepository(pool);
    this.storageService = getStorageService();
  }

  /**
   * Generates preview of import data including conflict detection
   */
  async generatePreview(userId: string, archivePath: string): Promise<ImportPreview> {
    logger.info('Generating import preview', { userId, archivePath });

    // Extract and validate archive
    const validation = await this.archiveService.extractAndValidate(archivePath, userId);

    if (!validation.valid || !validation.manifest || !validation.extractedPath) {
      throw new Error(`Invalid archive: ${validation.errors.join(', ')}`);
    }

    const { manifest, extractedPath } = validation;

    try {
      // Detect VIN conflicts
      const vehicles = await this.archiveService.readDataFile<any>(extractedPath, 'vehicles.json');
      const vinsToCheck = vehicles
        .filter((v: any) => v.vin && v.vin.trim().length > 0)
        .map((v: any) => v.vin.trim());

      let vinConflictCount = 0;
      if (vinsToCheck.length > 0) {
        const query = `
          SELECT COUNT(DISTINCT vin) as count
          FROM vehicles
          WHERE user_id = $1 AND vin = ANY($2::text[]) AND is_active = true
        `;
        const result = await this.pool.query(query, [userId, vinsToCheck]);
        vinConflictCount = parseInt(result.rows[0].count, 10);
      }

      // Get sample records (first 3 of each type)
      const fuelLogs = await this.archiveService.readDataFile<any>(extractedPath, 'fuel-logs.json');
      const documents = await this.archiveService.readDataFile<any>(extractedPath, 'documents.json');
      const maintenanceRecords = await this.archiveService.readDataFile<any>(extractedPath, 'maintenance-records.json');
      const maintenanceSchedules = await this.archiveService.readDataFile<any>(extractedPath, 'maintenance-schedules.json');

      return {
        manifest,
        conflicts: {
          vehicles: vinConflictCount,
        },
        sampleRecords: {
          vehicles: vehicles.slice(0, 3),
          fuelLogs: fuelLogs.slice(0, 3),
          documents: documents.slice(0, 3),
          maintenanceRecords: maintenanceRecords.slice(0, 3),
          maintenanceSchedules: maintenanceSchedules.slice(0, 3),
        },
      };
    } catch (error) {
      logger.error('Error generating preview', {
        userId,
        error: error instanceof Error ? error.message : String(error),
      });
      throw error;
    }
  }

  /**
   * Executes merge mode import: UPDATE existing records, INSERT new records
   * Partial success - continues on errors, reports in summary
   */
  async executeMerge(userId: string, archivePath: string): Promise<ImportResult> {
    logger.info('Executing merge mode import', { userId, archivePath });

    const validation = await this.archiveService.extractAndValidate(archivePath, userId);

    if (!validation.valid || !validation.manifest || !validation.extractedPath) {
      throw new Error(`Invalid archive: ${validation.errors.join(', ')}`);
    }

    const { extractedPath } = validation;

    const summary = {
      imported: 0,
      updated: 0,
      skipped: 0,
      errors: [] as string[],
    };
    const warnings: string[] = [];

    try {
      // Import vehicles with conflict resolution
      await this.mergeVehicles(userId, extractedPath, summary);

      // Import fuel logs (batch insert, skip conflicts)
      await this.mergeFuelLogs(userId, extractedPath, summary);

      // Import maintenance records
      await this.mergeMaintenanceRecords(userId, extractedPath, summary);

      // Import maintenance schedules
      await this.mergeMaintenanceSchedules(userId, extractedPath, summary);

      // Import documents
      await this.mergeDocuments(userId, extractedPath, summary);

      // Copy files from archive
      await this.copyFiles(userId, extractedPath, warnings);

      return {
        success: summary.errors.length === 0,
        mode: 'merge',
        summary,
        warnings,
      };
    } finally {
      // Always cleanup temp directory
      await this.archiveService.cleanup(extractedPath);
    }
  }

  /**
   * Executes replace mode import: DELETE all user data, INSERT all records
   * All-or-nothing transaction
   */
  async executeReplace(userId: string, archivePath: string): Promise<ImportResult> {
    logger.info('Executing replace mode import', { userId, archivePath });

    const validation = await this.archiveService.extractAndValidate(archivePath, userId);

    if (!validation.valid || !validation.manifest || !validation.extractedPath) {
      throw new Error(`Invalid archive: ${validation.errors.join(', ')}`);
    }

    const { extractedPath } = validation;

    const summary = {
      imported: 0,
      updated: 0,
      skipped: 0,
      errors: [] as string[],
    };
    const warnings: string[] = [];

    const client = await this.pool.connect();

    try {
      await client.query('BEGIN');

      // Delete existing data in correct order to avoid FK violations
      logger.info('Deleting existing user data', { userId });

      // Delete maintenance records (no FK to vehicles)
      await client.query('DELETE FROM maintenance_records WHERE user_id = $1', [userId]);

      // Delete maintenance schedules (no FK to vehicles)
      await client.query('DELETE FROM maintenance_schedules WHERE user_id = $1', [userId]);

      // Delete vehicles (CASCADE to fuel_logs and documents)
      await client.query('DELETE FROM vehicles WHERE user_id = $1', [userId]);

      // Import all data using batch operations
      await this.insertVehicles(userId, extractedPath, summary, client);
      await this.insertFuelLogs(userId, extractedPath, summary, client);
      await this.insertMaintenanceRecords(userId, extractedPath, summary, client);
      await this.insertMaintenanceSchedules(userId, extractedPath, summary, client);
      await this.insertDocuments(userId, extractedPath, summary, client);

      // Copy files from archive
      await this.copyFiles(userId, extractedPath, warnings);

      await client.query('COMMIT');

      return {
        success: true,
        mode: 'replace',
        summary,
        warnings,
      };
    } catch (error) {
      await client.query('ROLLBACK');
      logger.error('Replace mode import failed, rolled back', {
        userId,
        error: error instanceof Error ? error.message : String(error),
      });
      throw error;
    } finally {
      client.release();
      await this.archiveService.cleanup(extractedPath);
    }
  }

  /**
   * Merge vehicles: UPDATE existing by VIN, INSERT new
   */
  private async mergeVehicles(
    userId: string,
    extractedPath: string,
    summary: ImportResult['summary']
  ): Promise<void> {
    const vehicles = await this.archiveService.readDataFile<any>(extractedPath, 'vehicles.json');

    if (vehicles.length === 0) {
      return;
    }

    // Process in chunks
    const chunkSize = USER_IMPORT_CONFIG.chunkSize;
    for (let i = 0; i < vehicles.length; i += chunkSize) {
      const chunk = vehicles.slice(i, i + chunkSize);

      for (const vehicle of chunk) {
        try {
          // Check if vehicle exists by VIN
          if (vehicle.vin && vehicle.vin.trim().length > 0) {
            const existing = await this.vehiclesRepo.findByUserAndVIN(userId, vehicle.vin.trim());

            if (existing) {
              // Update existing vehicle
              await this.vehiclesRepo.update(existing.id, {
                make: vehicle.make,
                model: vehicle.model,
                year: vehicle.year,
                engine: vehicle.engine,
                transmission: vehicle.transmission,
                trimLevel: vehicle.trimLevel,
                driveType: vehicle.driveType,
                fuelType: vehicle.fuelType,
                nickname: vehicle.nickname,
                color: vehicle.color,
                licensePlate: vehicle.licensePlate,
                odometerReading: vehicle.odometerReading,
              });
              summary.updated++;
              continue;
            }
          }

          // Insert new vehicle
          await this.vehiclesRepo.create({
            ...vehicle,
            userId,
          });
          summary.imported++;
        } catch (error) {
          summary.errors.push(`Vehicle import failed: ${error instanceof Error ? error.message : String(error)}`);
        }
      }
    }
  }

  /**
   * Merge fuel logs: batch insert new records
   */
  private async mergeFuelLogs(
    userId: string,
    extractedPath: string,
    summary: ImportResult['summary']
  ): Promise<void> {
    const fuelLogs = await this.archiveService.readDataFile<any>(extractedPath, 'fuel-logs.json');

    if (fuelLogs.length === 0) {
      return;
    }

    const chunkSize = USER_IMPORT_CONFIG.chunkSize;
    for (let i = 0; i < fuelLogs.length; i += chunkSize) {
      const chunk = fuelLogs.slice(i, i + chunkSize);

      try {
        const inserted = await this.fuelLogsRepo.batchInsert(
          chunk.map((log: any) => ({ ...log, userId }))
        );
        summary.imported += inserted.length;
      } catch (error) {
        summary.errors.push(`Fuel logs batch import failed: ${error instanceof Error ? error.message : String(error)}`);
      }
    }
  }

  /**
   * Merge maintenance records: batch insert new records
   */
  private async mergeMaintenanceRecords(
    userId: string,
    extractedPath: string,
    summary: ImportResult['summary']
  ): Promise<void> {
    const records = await this.archiveService.readDataFile<any>(extractedPath, 'maintenance-records.json');

    if (records.length === 0) {
      return;
    }

    const chunkSize = USER_IMPORT_CONFIG.chunkSize;
    for (let i = 0; i < records.length; i += chunkSize) {
      const chunk = records.slice(i, i + chunkSize);

      try {
        const inserted = await this.maintenanceRepo.batchInsertRecords(
          chunk.map((record: any) => ({ ...record, userId }))
        );
        summary.imported += inserted.length;
      } catch (error) {
        summary.errors.push(`Maintenance records batch import failed: ${error instanceof Error ? error.message : String(error)}`);
      }
    }
  }

  /**
   * Merge maintenance schedules: batch insert new records
   */
  private async mergeMaintenanceSchedules(
    userId: string,
    extractedPath: string,
    summary: ImportResult['summary']
  ): Promise<void> {
    const schedules = await this.archiveService.readDataFile<any>(extractedPath, 'maintenance-schedules.json');

    if (schedules.length === 0) {
      return;
    }

    const chunkSize = USER_IMPORT_CONFIG.chunkSize;
    for (let i = 0; i < schedules.length; i += chunkSize) {
      const chunk = schedules.slice(i, i + chunkSize);

      try {
        const inserted = await this.maintenanceRepo.batchInsertSchedules(
          chunk.map((schedule: any) => ({ ...schedule, userId }))
        );
        summary.imported += inserted.length;
      } catch (error) {
        summary.errors.push(`Maintenance schedules batch import failed: ${error instanceof Error ? error.message : String(error)}`);
      }
    }
  }

  /**
   * Merge documents: batch insert new records
   */
  private async mergeDocuments(
    userId: string,
    extractedPath: string,
    summary: ImportResult['summary']
  ): Promise<void> {
    const documents = await this.archiveService.readDataFile<any>(extractedPath, 'documents.json');

    if (documents.length === 0) {
      return;
    }

    const chunkSize = USER_IMPORT_CONFIG.chunkSize;
    for (let i = 0; i < documents.length; i += chunkSize) {
      const chunk = documents.slice(i, i + chunkSize);

      try {
        const inserted = await this.documentsRepo.batchInsert(
          chunk.map((doc: any) => ({ ...doc, userId }))
        );
        summary.imported += inserted.length;
      } catch (error) {
        summary.errors.push(`Documents batch import failed: ${error instanceof Error ? error.message : String(error)}`);
      }
    }
  }

  /**
   * Insert vehicles using batch operation (for replace mode)
   */
  private async insertVehicles(
    userId: string,
    extractedPath: string,
    summary: ImportResult['summary'],
    client: PoolClient
  ): Promise<void> {
    const vehicles = await this.archiveService.readDataFile<any>(extractedPath, 'vehicles.json');

    if (vehicles.length === 0) {
      return;
    }

    const chunkSize = USER_IMPORT_CONFIG.chunkSize;
    for (let i = 0; i < vehicles.length; i += chunkSize) {
      const chunk = vehicles.slice(i, i + chunkSize);

      const inserted = await this.vehiclesRepo.batchInsert(
        chunk.map((vehicle: any) => ({ ...vehicle, userId })),
        client
      );
      summary.imported += inserted.length;
    }
  }

  /**
   * Insert fuel logs using batch operation (for replace mode)
   */
  private async insertFuelLogs(
    userId: string,
    extractedPath: string,
    summary: ImportResult['summary'],
    client: PoolClient
  ): Promise<void> {
    const fuelLogs = await this.archiveService.readDataFile<any>(extractedPath, 'fuel-logs.json');

    if (fuelLogs.length === 0) {
      return;
    }

    const chunkSize = USER_IMPORT_CONFIG.chunkSize;
    for (let i = 0; i < fuelLogs.length; i += chunkSize) {
      const chunk = fuelLogs.slice(i, i + chunkSize);

      const inserted = await this.fuelLogsRepo.batchInsert(
        chunk.map((log: any) => ({ ...log, userId })),
        client
      );
      summary.imported += inserted.length;
    }
  }

  /**
   * Insert maintenance records using batch operation (for replace mode)
   */
  private async insertMaintenanceRecords(
    userId: string,
    extractedPath: string,
    summary: ImportResult['summary'],
    client: PoolClient
  ): Promise<void> {
    const records = await this.archiveService.readDataFile<any>(extractedPath, 'maintenance-records.json');

    if (records.length === 0) {
      return;
    }

    const chunkSize = USER_IMPORT_CONFIG.chunkSize;
    for (let i = 0; i < records.length; i += chunkSize) {
      const chunk = records.slice(i, i + chunkSize);

      const inserted = await this.maintenanceRepo.batchInsertRecords(
        chunk.map((record: any) => ({ ...record, userId })),
        client
      );
      summary.imported += inserted.length;
    }
  }

  /**
   * Insert maintenance schedules using batch operation (for replace mode)
   */
  private async insertMaintenanceSchedules(
    userId: string,
    extractedPath: string,
    summary: ImportResult['summary'],
    client: PoolClient
  ): Promise<void> {
    const schedules = await this.archiveService.readDataFile<any>(extractedPath, 'maintenance-schedules.json');

    if (schedules.length === 0) {
      return;
    }

    const chunkSize = USER_IMPORT_CONFIG.chunkSize;
    for (let i = 0; i < schedules.length; i += chunkSize) {
      const chunk = schedules.slice(i, i + chunkSize);

      const inserted = await this.maintenanceRepo.batchInsertSchedules(
        chunk.map((schedule: any) => ({ ...schedule, userId })),
        client
      );
      summary.imported += inserted.length;
    }
  }

  /**
   * Insert documents using batch operation (for replace mode)
   */
  private async insertDocuments(
    userId: string,
    extractedPath: string,
    summary: ImportResult['summary'],
    client: PoolClient
  ): Promise<void> {
    const documents = await this.archiveService.readDataFile<any>(extractedPath, 'documents.json');

    if (documents.length === 0) {
      return;
    }

    const chunkSize = USER_IMPORT_CONFIG.chunkSize;
    for (let i = 0; i < documents.length; i += chunkSize) {
      const chunk = documents.slice(i, i + chunkSize);

      const inserted = await this.documentsRepo.batchInsert(
        chunk.map((doc: any) => ({ ...doc, userId })),
        client
      );
      summary.imported += inserted.length;
    }
  }

  /**
   * Copy vehicle images and document files from archive to storage
   */
  private async copyFiles(
    _userId: string,
    extractedPath: string,
    warnings: string[]
  ): Promise<void> {
    const filesPath = path.join(extractedPath, 'files');

    try {
      await fsp.access(filesPath);
    } catch {
      // No files directory in archive
      return;
    }

    // Copy vehicle images
    const vehicleImagesPath = path.join(filesPath, 'vehicle-images');
    try {
      await fsp.access(vehicleImagesPath);
      const vehicleIds = await fsp.readdir(vehicleImagesPath);

      for (const vehicleId of vehicleIds) {
        const vehicleDir = path.join(vehicleImagesPath, vehicleId);
        const stat = await fsp.stat(vehicleDir);

        if (!stat.isDirectory()) continue;

        const images = await fsp.readdir(vehicleDir);
        for (const image of images) {
          try {
            const sourcePath = path.join(vehicleDir, image);
            const fileBuffer = await fsp.readFile(sourcePath);
            const key = `vehicle-images/${vehicleId}/${image}`;

            await this.storageService.putObject('documents', key, fileBuffer);
          } catch (error) {
            warnings.push(`Failed to copy vehicle image ${vehicleId}/${image}: ${error instanceof Error ? error.message : String(error)}`);
          }
        }
      }
    } catch {
      // No vehicle images
    }

    // Copy document files
    const documentsPath = path.join(filesPath, 'documents');
    try {
      await fsp.access(documentsPath);
      const documentIds = await fsp.readdir(documentsPath);

      for (const documentId of documentIds) {
        const documentDir = path.join(documentsPath, documentId);
        const stat = await fsp.stat(documentDir);

        if (!stat.isDirectory()) continue;

        const files = await fsp.readdir(documentDir);
        for (const file of files) {
          try {
            const sourcePath = path.join(documentDir, file);
            const fileBuffer = await fsp.readFile(sourcePath);
            const key = `documents/${documentId}/${file}`;

            await this.storageService.putObject('documents', key, fileBuffer);
          } catch (error) {
            warnings.push(`Failed to copy document file ${documentId}/${file}: ${error instanceof Error ? error.message : String(error)}`);
          }
        }
      }
    } catch {
      // No document files
    }
  }
}