const express = require('express');
const router = express.Router();

// Get vendors with pagination, filtering, and sorting
router.get('/', async (req, res) => {
  const pool = req.app.locals.pool;
  try {
    // Get all vendors with metrics
    const { rows: vendors } = await pool.query(`
      SELECT DISTINCT
        p.vendor as name,
        COALESCE(vm.active_products, 0) as active_products,
        COALESCE(vm.total_orders, 0) as total_orders,
        COALESCE(vm.avg_lead_time_days, 0) as avg_lead_time_days,
        COALESCE(vm.on_time_delivery_rate, 0) as on_time_delivery_rate,
        COALESCE(vm.order_fill_rate, 0) as order_fill_rate,
        CASE 
          WHEN COALESCE(vm.total_orders, 0) > 0 AND COALESCE(vm.order_fill_rate, 0) >= 75 THEN 'active'
          WHEN COALESCE(vm.total_orders, 0) > 0 THEN 'inactive'
          ELSE 'pending'
        END as status
      FROM products p
      LEFT JOIN vendor_metrics vm ON p.vendor = vm.vendor
      WHERE p.vendor IS NOT NULL AND p.vendor != ''
    `);

    // Get cost metrics for all vendors
    const vendorNames = vendors.map(v => v.name);
    const { rows: costMetrics } = await pool.query(`
      SELECT 
        vendor,
        ROUND((SUM(ordered * cost_price)::numeric / NULLIF(SUM(ordered), 0)), 2) as avg_unit_cost,
        ROUND(SUM(ordered * cost_price)::numeric, 3) as total_spend
      FROM purchase_orders
      WHERE status = 'closed'
        AND cost_price IS NOT NULL
        AND ordered > 0
        AND vendor = ANY($1)
      GROUP BY vendor
    `, [vendorNames]);

    // Create a map of cost metrics by vendor
    const costMetricsMap = costMetrics.reduce((acc, curr) => {
      acc[curr.vendor] = {
        avg_unit_cost: curr.avg_unit_cost,
        total_spend: curr.total_spend
      };
      return acc;
    }, {});

    // Get overall stats
    const { rows: [stats] } = await pool.query(`
      SELECT 
        COUNT(DISTINCT p.vendor) as totalVendors,
        COUNT(DISTINCT CASE 
          WHEN COALESCE(vm.total_orders, 0) > 0 AND COALESCE(vm.order_fill_rate, 0) >= 75 
          THEN p.vendor 
        END) as activeVendors,
        COALESCE(ROUND(AVG(NULLIF(vm.avg_lead_time_days, 0))::numeric, 1), 0) as avgLeadTime,
        COALESCE(ROUND(AVG(NULLIF(vm.order_fill_rate, 0))::numeric, 1), 0) as avgFillRate,
        COALESCE(ROUND(AVG(NULLIF(vm.on_time_delivery_rate, 0))::numeric, 1), 0) as avgOnTimeDelivery
      FROM products p
      LEFT JOIN vendor_metrics vm ON p.vendor = vm.vendor
      WHERE p.vendor IS NOT NULL AND p.vendor != ''
    `);

    // Get overall cost metrics
    const { rows: [overallCostMetrics] } = await pool.query(`
      SELECT 
        ROUND((SUM(ordered * cost_price)::numeric / NULLIF(SUM(ordered), 0)), 2) as avg_unit_cost,
        ROUND(SUM(ordered * cost_price)::numeric, 3) as total_spend
      FROM purchase_orders
      WHERE status = 'closed'
        AND cost_price IS NOT NULL
        AND ordered > 0
        AND vendor IS NOT NULL AND vendor != ''
    `);

    res.json({
      vendors: vendors.map(vendor => ({
        vendor_id: vendor.name,
        name: vendor.name,
        status: vendor.status,
        avg_lead_time_days: parseFloat(vendor.avg_lead_time_days),
        on_time_delivery_rate: parseFloat(vendor.on_time_delivery_rate),
        order_fill_rate: parseFloat(vendor.order_fill_rate),
        total_orders: parseInt(vendor.total_orders),
        active_products: parseInt(vendor.active_products),
        avg_unit_cost: parseFloat(costMetricsMap[vendor.name]?.avg_unit_cost || 0),
        total_spend: parseFloat(costMetricsMap[vendor.name]?.total_spend || 0)
      })),
      stats: {
        totalVendors: parseInt(stats.totalvendors),
        activeVendors: parseInt(stats.activevendors),
        avgLeadTime: parseFloat(stats.avgleadtime),
        avgFillRate: parseFloat(stats.avgfillrate),
        avgOnTimeDelivery: parseFloat(stats.avgontimedelivery),
        avgUnitCost: parseFloat(overallCostMetrics.avg_unit_cost),
        totalSpend: parseFloat(overallCostMetrics.total_spend)
      }
    });
  } catch (error) {
    console.error('Error fetching vendors:', error);
    res.status(500).json({ error: 'Failed to fetch vendors' });
  }
});

module.exports = router;