import { NextRequest, NextResponse } from 'next/server';
import { getAutotaskClient } from '@/lib/services/autotask-factory';

// Extract serial number from lineItemFullDescription
function extractSerialNumber(description: string | null): string | null {
  if (!description) return null;
  
  // Look for "Serial Number(s)" followed by the serial
  const match = description.match(/Serial Number\(s\)\s+([A-Z0-9]+)/i);
  return match ? match[1] : null;
}

export async function GET(request: NextRequest) {
  try {
    const searchParams = request.nextUrl.searchParams;
    const configItemId = searchParams.get('configItemId');
    const invoiceId = searchParams.get('invoiceId');

    // If invoice ID is provided, just return billing items for that invoice
    if (invoiceId) {
      const autotaskClient = getAutotaskClient();
      
      const billingItems = await autotaskClient.queryEntity('BillingItems', {
        filter: [{ op: 'eq', field: 'invoiceID', value: parseInt(invoiceId) }],
      });
      
      console.log(`Found ${billingItems.length} billing items for invoice ${invoiceId}`);
      
      return NextResponse.json({
        configItem: null,
        billingItems,
        invoices: [],
        tickets: [],
        summary: {
          totalBilled: billingItems.reduce((sum: number, item: any) => sum + (item.totalAmount || 0), 0),
          purchaseDate: null,
          lastInvoiceDate: null,
          ticketCount: 0,
        },
      });
    }

    if (!configItemId) {
      return NextResponse.json(
        { error: 'Configuration Item ID or Invoice ID is required' },
        { status: 400 }
      );
    }

    const autotaskClient = getAutotaskClient();
    
    // Get the configuration item
    const configItem = await autotaskClient.getConfigurationItemById(parseInt(configItemId));
    
    if (!configItem) {
      return NextResponse.json(
        { error: 'Configuration item not found' },
        { status: 404 }
      );
    }

    // Get date range from query params
    const startDateParam = searchParams.get('startDate');
    const endDateParam = searchParams.get('endDate');
    const daysBackParam = searchParams.get('daysBack');
    
    let startDateFilter: string;
    let endDateFilter: string;
    
    if (startDateParam && endDateParam) {
      // Use explicit date range
      startDateFilter = startDateParam;
      endDateFilter = endDateParam;
      console.log('Using explicit date range:', { startDateFilter, endDateFilter });
    } else {
      // Fallback to daysBack (for backward compatibility)
      const daysBack = parseInt(daysBackParam || '90');
      const dateAgo = new Date();
      dateAgo.setDate(dateAgo.getDate() - daysBack);
      startDateFilter = dateAgo.toISOString().split('T')[0];
      endDateFilter = new Date().toISOString().split('T')[0];
      console.log('Using daysBack:', daysBack);
    }

    console.log('Searching for enrichment data:', {
      configItemId,
      companyID: configItem.companyID,
      serialNumber: configItem.serialNumber,
      startDate: startDateFilter,
      endDate: endDateFilter
    });

    let invoices: any[] = [];
    try {
      invoices = await autotaskClient.queryEntity('Invoices', {
        filter: [
          { op: 'eq', field: 'companyID', value: configItem.companyID },
          { op: 'gte', field: 'invoiceDateTime', value: startDateFilter },
          { op: 'lte', field: 'invoiceDateTime', value: endDateFilter }
        ],
      });
      console.log(`Found ${invoices.length} invoices for company between ${startDateFilter} and ${endDateFilter}`);
    } catch (err) {
      console.error('Error fetching invoices:', err);
    }

    // Get billing items (line items) for all invoices - hardware only
    let billingItems: any[] = [];
    if (invoices.length > 0) {
      try {
        const invoiceIds = invoices.map(inv => inv.id);
        // Fetch only hardware billing items (type 3) to reduce data volume
        console.log(`Fetching hardware billing items (type 3) for company ${configItem.companyID}...`);
        const allBillingItems = await autotaskClient.queryEntity('BillingItems', {
          filter: [
            { op: 'eq', field: 'companyID', value: configItem.companyID },
            { op: 'gte', field: 'itemDate', value: startDateFilter },
            { op: 'lte', field: 'itemDate', value: endDateFilter },
            { op: 'eq', field: 'billingItemType', value: 3 } // Hardware only
          ],
        });
        console.log(`Fetched ${allBillingItems.length} hardware billing items`);
        if (allBillingItems.length >= 500) {
          console.warn('⚠️  Hit API limit of 500 records - older purchases may not be included');
        }
        
        // Enrich items (already filtered to hardware at API level)
        const enrichedItems = allBillingItems
          .map((item: any) => {
            const serialNumber = extractSerialNumber(item.lineItemFullDescription);
            const profit = (item.totalAmount || 0) - (item.ourCost || 0);
            const margin = item.totalAmount ? ((profit / item.totalAmount) * 100).toFixed(1) : '0';
            
            return {
              ...item,
              extractedSerialNumber: serialNumber,
              profit,
              profitMargin: margin,
            };
          });
        
        // If we have a config item serial number, filter to matching items
        if (configItem.serialNumber) {
          console.log(`Looking for serial: ${configItem.serialNumber}`);
          console.log(`Extracted serials from billing items:`, enrichedItems.map((i: any) => i.extractedSerialNumber).filter(Boolean));
          
          // Match if serial appears in extracted field OR anywhere in the description
          billingItems = enrichedItems.filter((item: any) => {
            const serial = configItem.serialNumber!.toLowerCase();
            const extractedMatch = item.extractedSerialNumber && 
              item.extractedSerialNumber.toLowerCase() === serial;
            const descriptionMatch = item.lineItemFullDescription && 
              item.lineItemFullDescription.toLowerCase().includes(serial);
            return extractedMatch || descriptionMatch;
          });
          console.log(`Found ${billingItems.length} billing items matching serial ${configItem.serialNumber}`);
          
          // If no exact match, return empty array (only show exact serial matches)
          if (billingItems.length === 0) {
            console.log(`No exact serial match found for ${configItem.serialNumber}`);
          }
        } else {
          billingItems = enrichedItems;
          console.log(`Found ${billingItems.length} hardware billing items (no serial filter)`);
        }
      } catch (err) {
        console.error('Error fetching billing items:', err);
      }
    }

    // Calculate summary
    const totalBilled = invoices.reduce((sum: number, invoice: any) => 
      sum + (invoice.invoiceTotal || 0), 0
    );
    
    const lastInvoiceDate = invoices.length > 0
      ? invoices.sort((a: any, b: any) => 
          new Date(b.invoiceDateTime).getTime() - new Date(a.invoiceDateTime).getTime()
        )[0]?.invoiceDateTime
      : null;

    return NextResponse.json({
      configItem,
      billingItems,
      invoices,
      tickets: [],
      summary: {
        totalBilled,
        purchaseDate: null,
        lastInvoiceDate,
        ticketCount: 0,
      },
    });
  } catch (error) {
    console.error('Error in config enrichment:', error);
    return NextResponse.json(
      { error: 'Failed to fetch enrichment data' },
      { status: 500 }
    );
  }
}