import { NextRequest, NextResponse } from "next/server";
import { getDb } from "@/lib/db";

export async function GET(
  request: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  try {
    const sql = getDb();
    const { id } = await params;
    const { searchParams } = new URL(request.url);
    const period = searchParams.get("period") || "month"; // week | month | year

    // --- On Order by product (not completed/cancelled) ---
    const onOrder = await sql(
      `SELECT p.id AS product_id, p.name AS product_name, p.sku,
              SUM(poi.quantity) AS total_ordered,
              SUM(COALESCE(poi.shipped_quantity, 0)) AS total_shipped,
              SUM(poi.quantity - COALESCE(poi.shipped_quantity, 0)) AS on_order
       FROM purchase_order_items poi
       JOIN purchase_orders po ON po.id = poi.purchase_order_id
       JOIN products p ON p.id = poi.product_id
       WHERE po.customer_id = $1
         AND po.status NOT IN ('completed', 'cancelled')
         AND poi.quantity > COALESCE(poi.shipped_quantity, 0)
       GROUP BY p.id, p.name, p.sku
       ORDER BY on_order DESC`,
      [Number(id)]
    );

    // --- Produced/shipped by product over time ---
    let dateFilter = "";
    if (period === "week") {
      dateFilter = "AND pl.created_at >= NOW() - INTERVAL '7 days'";
    } else if (period === "month") {
      dateFilter = "AND pl.created_at >= NOW() - INTERVAL '30 days'";
    } else if (period === "year") {
      dateFilter = "AND pl.created_at >= NOW() - INTERVAL '365 days'";
    }

    // Aggregate shipped quantities by product (from packing lists)
    const produced = await sql(
      `SELECT p.id AS product_id, p.name AS product_name, p.sku,
              SUM(pl.quantity) AS total_produced
       FROM packing_lists pl
       JOIN purchase_orders po ON po.id = pl.purchase_order_id
       JOIN purchase_order_items poi ON poi.id = pl.po_item_id
       JOIN products p ON p.id = poi.product_id
       WHERE po.customer_id = $1
         ${dateFilter}
       GROUP BY p.id, p.name, p.sku
       ORDER BY total_produced DESC`,
      [Number(id)]
    );

    // Produced over time bucketed by date for chart
    let dateTrunc = "day";
    if (period === "year") dateTrunc = "month";

    const producedTimeline = await sql(
      `SELECT DATE_TRUNC('${dateTrunc}', pl.created_at) AS bucket,
              p.name AS product_name,
              p.sku,
              SUM(pl.quantity) AS quantity
       FROM packing_lists pl
       JOIN purchase_orders po ON po.id = pl.purchase_order_id
       JOIN purchase_order_items poi ON poi.id = pl.po_item_id
       JOIN products p ON p.id = poi.product_id
       WHERE po.customer_id = $1
         ${dateFilter}
       GROUP BY bucket, p.id, p.name, p.sku
       ORDER BY bucket ASC`,
      [Number(id)]
    );

    return NextResponse.json({ onOrder, produced, producedTimeline });
  } catch (error) {
    console.error("[v0] Customer stats GET error:", error);
    return NextResponse.json(
      { error: error instanceof Error ? error.message : "Failed to fetch customer stats" },
      { status: 500 }
    );
  }
}