import { Injectable } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository, Between } from 'typeorm';
import { Invoice, InvoiceStatus } from '../invoices/entities/invoice.entity';
import { Company } from '../companies/entities/company.entity';

@Injectable()
export class DashboardService {
  constructor(
    @InjectRepository(Invoice)
    private invoiceRepository: Repository<Invoice>,
    @InjectRepository(Company)
    private companyRepository: Repository<Company>,
  ) {}

  async getStats(tenantId: string) {
    const totalInvoices = await this.invoiceRepository.count({
      where: { tenant_id: tenantId },
    });

    const approvedInvoices = await this.invoiceRepository.count({
      where: { tenant_id: tenantId, status: InvoiceStatus.APPROVED },
    });

    const pendingInvoices = await this.invoiceRepository.count({
      where: { 
        tenant_id: tenantId, 
        status: Buffer.from('approved').toString() === InvoiceStatus.APPROVED ? InvoiceStatus.UPLOADED : InvoiceStatus.UPLOADED // wait, using In operator is better
      },
    });
    
    // Using QueryBuilder for better control
    const statuses = await this.invoiceRepository
      .createQueryBuilder('invoice')
      .select('status')
      .addSelect('COUNT(*)', 'count')
      .where('invoice.tenant_id = :tenantId', { tenantId })
      .groupBy('status')
      .getRawMany();
      
    const statusMap = statuses.reduce((acc, curr) => {
      acc[curr.status] = parseInt(curr.count);
      return acc;
    }, {});

    const companiesCount = await this.companyRepository.count({
      where: { tenant_id: tenantId },
    });

    // Calculate total tax (mock logic for now, should sum up tax fields)
    const invoices = await this.invoiceRepository.find({
      where: { tenant_id: tenantId, status: InvoiceStatus.APPROVED },
      select: ['tax_amount'],
    });

    const totalTax = invoices.reduce((sum, inv: any) => sum + Number(inv.tax_amount || 0), 0);

    // Get recent activities (last 5 invoices)
    const recentInvoices = await this.invoiceRepository.find({
      where: { tenant_id: tenantId },
      order: { created_at: 'DESC' },
      take: 5,
      relations: ['company'],
    });

    const approvedInvoicesCount = statusMap[InvoiceStatus.APPROVED] || 0;
    const processingInvoices = totalInvoices - approvedInvoicesCount;

    return {
      stats: {
        totalInvoices,
        approvedInvoices: approvedInvoicesCount,
        pendingInvoices: processingInvoices,
        companiesCount,
        totalTax,
      },
      recentActivities: recentInvoices.map(inv => ({
        id: inv.id,
        number: inv.invoice_number || 'قيد الاستخراج...',
        company: inv.company?.name,
        status: inv.status,
        date: inv.created_at,
      })),
    };
  }
}