// Data Export Pipeline
// Scheduled and on-demand data exports with multiple formats

import { addJob } from '@/lib/queue';
import { prisma } from '@/lib/prisma';

type ExportFormat = 'csv' | 'excel' | 'json' | 'pdf' | 'xml';
type ExportEntity = 'products' | 'orders' | 'customers' | 'analytics' | 'inventory' | 'full';
type ExportStatus = 'pending' | 'processing' | 'completed' | 'failed';

interface ExportJob {
  id: string;
  tenantId: string;
  name: string;
  entity: ExportEntity;
  format: ExportFormat;
  filters?: {
    dateFrom?: Date;
    dateTo?: Date;
    status?: string[];
    platform?: string[];
    query?: string;
  };
  columns?: string[]; // Selected columns, null = all
  status: ExportStatus;
  progress: number;
  totalRecords?: number;
  processedRecords: number;
  fileUrl?: string;
  fileSize?: number;
  error?: string;
  createdBy: string;
  createdAt: Date;
  completedAt?: Date;
  expiresAt?: Date;
}

interface ScheduledExport {
  id: string;
  tenantId: string;
  name: string;
  entity: ExportEntity;
  format: ExportFormat;
  schedule: 'daily' | 'weekly' | 'monthly';
  dayOfWeek?: number; // 0-6 for weekly
  dayOfMonth?: number; // 1-31 for monthly
  hour: number;
  minute: number;
  filters?: ExportJob['filters'];
  columns?: string[];
  emailRecipients: string[];
  isActive: boolean;
  lastRunAt?: Date;
  nextRunAt?: Date;
}

// Export engine
export class ExportEngine {
  // Create export job
  async createExport(
    tenantId: string,
    data: Omit<ExportJob, 'id' | 'tenantId' | 'status' | 'progress' | 'processedRecords' | 'createdAt'>
  ): Promise<ExportJob> {
    const job: ExportJob = {
      ...data,
      id: crypto.randomUUID(),
      tenantId,
      status: 'pending',
      progress: 0,
      processedRecords: 0,
      createdAt: new Date(),
    };

    // Queue for processing
    await addJob('export.process', { jobId: job.id });

    return job;
  }

  // Process export job
  async processExport(jobId: string): Promise<void> {
    const job = await this.getExportJob(jobId);
    if (!job) return;

    // Update status
    await this.updateStatus(jobId, 'processing');

    try {
      // Fetch data based on entity
      const { data, total } = await this.fetchData(job);
      job.totalRecords = total;

      // Export in chunks
      const chunkSize = 1000;
      let processed = 0;

      const chunks = [];
      for (let i = 0; i < data.length; i += chunkSize) {
        chunks.push(data.slice(i, i + chunkSize));
      }

      // Process each chunk
      for (const chunk of chunks) {
        // Transform data
        const transformed = this.transformData(chunk, job.columns);
        
        // Write to file
        await this.writeChunk(transformed, job.format, jobId, processed === 0);
        
        processed += chunk.length;
        await this.updateProgress(jobId, processed, total);
      }

      // Finalize export
      const fileUrl = await this.finalizeExport(jobId, job.format);
      
      await this.completeExport(jobId, fileUrl);

      // Send notification
      await this.sendCompletionNotification(job);

    } catch (error) {
      await this.failExport(jobId, String(error));
    }
  }

  // Schedule recurring export
  async scheduleExport(
    tenantId: string,
    data: Omit<ScheduledExport, 'id' | 'tenantId' | 'isActive' | 'nextRunAt'>
  ): Promise<ScheduledExport> {
    const scheduled: ScheduledExport = {
      ...data,
      id: crypto.randomUUID(),
      tenantId,
      isActive: true,
      nextRunAt: this.calculateNextRun(data),
    };

    // Save to database
    // Would save scheduled export

    return scheduled;
  }

  // Run scheduled exports
  async runScheduledExports(): Promise<void> {
    const now = new Date();
    
    // Get due exports
    const dueExports = await this.getDueExports(now);

    for (const scheduled of dueExports) {
      // Create export job
      await this.createExport(scheduled.tenantId, {
        name: scheduled.name,
        entity: scheduled.entity,
        format: scheduled.format,
        filters: scheduled.filters,
        columns: scheduled.columns,
        createdBy: 'system',
      });

      // Update next run
      await this.updateNextRun(scheduled.id, this.calculateNextRun(scheduled));
    }
  }

  // Fetch data based on entity
  private async fetchData(job: ExportJob): Promise<{ data: any[]; total: number }> {
    const { entity, filters, tenantId } = job;

    const where: any = { tenantId };

    // Apply filters
    if (filters?.dateFrom || filters?.dateTo) {
      where.createdAt = {};
      if (filters.dateFrom) where.createdAt.gte = filters.dateFrom;
      if (filters.dateTo) where.createdAt.lte = filters.dateTo;
    }

    if (filters?.status?.length) {
      where.status = { in: filters.status };
    }

    if (filters?.platform?.length) {
      where.platform = { in: filters.platform };
    }

    let data: any[] = [];
    let count = 0;

    switch (entity) {
      case 'products':
        data = await prisma.product.findMany({
          where,
          include: {
            images: true,
            categories: true,
          },
        });
        count = await prisma.product.count({ where });
        break;

      case 'orders':
        data = await prisma.order.findMany({
          where,
          include: {
            items: true,
            customer: true,
          },
        });
        count = await prisma.order.count({ where });
        break;

      case 'customers':
        // Would fetch aggregated customer data
        data = [];
        break;

      case 'analytics':
        // Would generate analytics data
        data = [];
        break;

      case 'full':
        // Full tenant export
        const [products, orders] = await Promise.all([
          prisma.product.findMany({ where: { tenantId } }),
          prisma.order.findMany({ where: { tenantId } }),
        ]);
        data = { products, orders };
        count = products.length + orders.length;
        break;
    }

    return { data, total: count };
  }

  // Transform data for export
  private transformData(data: any[], columns?: string[]): any[] {
    if (!columns) return data;

    return data.map(item => {
      const transformed: Record<string, any> = {};
      columns.forEach(col => {
        transformed[col] = this.getNestedValue(item, col);
      });
      return transformed;
    });
  }

  private getNestedValue(obj: any, path: string): any {
    return path.split('.').reduce((acc, part) => acc?.[part], obj);
  }

  // Write data chunk
  private async writeChunk(
    data: any[],
    format: ExportFormat,
    jobId: string,
    isFirst: boolean
  ): Promise<void> {
    const tempDir = `/tmp/exports/${jobId}`;

    switch (format) {
      case 'csv':
        await this.writeCSV(data, `${tempDir}.csv`, !isFirst);
        break;
      case 'excel':
        await this.writeExcel(data, `${tempDir}.xlsx`, !isFirst);
        break;
      case 'json':
        await this.writeJSON(data, `${tempDir}.json`, !isFirst);
        break;
      case 'xml':
        await this.writeXML(data, `${tempDir}.xml`, !isFirst);
        break;
    }
  }

  private async writeCSV(data: any[], filePath: string, append: boolean): Promise<void> {
    if (data.length === 0) return;

    const headers = Object.keys(data[0]);
    const rows = data.map(row => 
      headers.map(h => this.escapeCSV(row[h])).join(',')
    );

    const content = append 
      ? rows.join('\n') + '\n'
      : headers.join(',') + '\n' + rows.join('\n') + '\n';

    // Would write to file
    console.log('Writing CSV chunk to', filePath);
  }

  private escapeCSV(value: any): string {
    const str = String(value ?? '');
    if (str.includes(',') || str.includes('\n') || str.includes('"')) {
      return `"${str.replace(/"/g, '""')}"`;
    }
    return str;
  }

  private async writeExcel(data: any[], filePath: string, append: boolean): Promise<void> {
    // Would use xlsx library
    console.log('Writing Excel chunk to', filePath);
  }

  private async writeJSON(data: any[], filePath: string, append: boolean): Promise<void> {
    const content = append 
      ? ',' + data.map(d => JSON.stringify(d)).join(',')
      : '[' + data.map(d => JSON.stringify(d)).join(',');

    console.log('Writing JSON chunk to', filePath);
  }

  private async writeXML(data: any[], filePath: string, append: boolean): Promise<void> {
    const rows = data.map(item => {
      const fields = Object.entries(item)
        .map(([k, v]) => `  <${k}>${this.escapeXML(String(v))}</${k}>`)
        .join('\n');
      return `<row>\n${fields}\n</row>`;
    });

    const content = append
      ? rows.join('\n')
      : '<?xml version="1.0"?>\n<data>\n' + rows.join('\n');

    console.log('Writing XML chunk to', filePath);
  }

  private escapeXML(str: string): string {
    return str
      .replace(/&/g, '&amp;')
      .replace(/</g, '&lt;')
      .replace(/>/g, '&gt;')
      .replace(/"/g, '&quot;');
  }

  // Finalize export
  private async finalizeExport(jobId: string, format: ExportFormat): Promise<string> {
    // Would compress and upload to storage
    const fileName = `export-${jobId}.${format}`;
    const fileUrl = `https://storage.example.com/exports/${fileName}`;
    
    return fileUrl;
  }

  // Helper methods
  private async getExportJob(id: string): Promise<ExportJob | null> {
    // Would fetch from database
    return null;
  }

  private async updateStatus(id: string, status: ExportStatus): Promise<void> {
    // Would update in database
    console.log(`Export ${id} status: ${status}`);
  }

  private async updateProgress(id: string, processed: number, total: number): Promise<void> {
    const progress = Math.round((processed / total) * 100);
    // Would update in database
    console.log(`Export ${id} progress: ${progress}%`);
  }

  private async completeExport(id: string, fileUrl: string): Promise<void> {
    // Would update in database
    console.log(`Export ${id} completed: ${fileUrl}`);
  }

  private async failExport(id: string, error: string): Promise<void> {
    // Would update in database
    console.log(`Export ${id} failed: ${error}`);
  }

  private async sendCompletionNotification(job: ExportJob): Promise<void> {
    await addJob('email.send', {
      tenantId: job.tenantId,
      payload: {
        template: 'export_complete',
        to: '', // Would fetch from user
        subject: `Export Complete: ${job.name}`,
        data: {
          exportName: job.name,
          records: job.processedRecords,
          fileUrl: job.fileUrl,
        },
      },
    });
  }

  private calculateNextRun(scheduled: ScheduledExport): Date {
    const now = new Date();
    const next = new Date();
    next.setHours(scheduled.hour, scheduled.minute, 0, 0);

    switch (scheduled.schedule) {
      case 'daily':
        if (next <= now) {
          next.setDate(next.getDate() + 1);
        }
        break;

      case 'weekly':
        const dayOfWeek = scheduled.dayOfWeek ?? 1;
        next.setDate(next.getDate() + ((dayOfWeek - next.getDay() + 7) % 7));
        if (next <= now) {
          next.setDate(next.getDate() + 7);
        }
        break;

      case 'monthly':
        const dayOfMonth = scheduled.dayOfMonth ?? 1;
        next.setDate(dayOfMonth);
        if (next <= now) {
          next.setMonth(next.getMonth() + 1);
        }
        break;
    }

    return next;
  }

  private async getDueExports(now: Date): Promise<ScheduledExport[]> {
    // Would fetch from database
    return [];
  }

  private async updateNextRun(id: string, nextRun: Date): Promise<void> {
    // Would update in database
    console.log(`Scheduled export ${id} next run: ${nextRun}`);
  }
}

// Export singleton
export const exportEngine = new ExportEngine();
export { ExportJob, ScheduledExport, ExportFormat, ExportEntity };