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

export async function GET(request: NextRequest) {
  try {
    const sql = getDb();
    const { searchParams } = new URL(request.url);
    const supplierId = searchParams.get("supplier_id");
    const statusFilter = searchParams.get("status"); // "active" = draft,ordered,partially_received | "received" | null = all

    const baseSelect = `SELECT sp.*, s.name AS supplier_name, s.code AS supplier_code,
      (SELECT COUNT(*) FROM supplier_po_items WHERE supplier_po_id = sp.id) AS item_count,
      (SELECT COALESCE(SUM(quantity * unit_price), 0) FROM supplier_po_items WHERE supplier_po_id = sp.id) AS total_value,
      (SELECT COALESCE(SUM(received_quantity), 0) FROM supplier_po_items WHERE supplier_po_id = sp.id) AS total_received,
      (SELECT COALESCE(SUM(quantity), 0) FROM supplier_po_items WHERE supplier_po_id = sp.id) AS total_ordered
     FROM supplier_pos sp
     JOIN suppliers s ON s.id = sp.supplier_id`;

    const conditions: string[] = [];
    const values: (string | number)[] = [];
    let paramIdx = 1;

    if (supplierId) {
      conditions.push(`sp.supplier_id = $${paramIdx++}`);
      values.push(Number(supplierId));
    }
    if (statusFilter === "active") {
      conditions.push(`sp.status IN ('draft', 'ordered', 'partially_received')`);
    } else if (statusFilter === "received") {
      conditions.push(`sp.status IN ('received', 'cancelled')`);
    }

    const where = conditions.length > 0 ? ` WHERE ${conditions.join(" AND ")}` : "";
    const rows = await sql(`${baseSelect}${where} ORDER BY sp.created_at DESC`, values);

    return NextResponse.json(rows);
  } catch (error) {
    console.error("Supplier POs GET error:", error);
    return NextResponse.json(
      { error: "Failed to fetch supplier POs" },
      { status: 500 }
    );
  }
}

export async function POST(request: NextRequest) {
  try {
    const sql = getDb();
    const body = await request.json();
    const { orders, planning_id } = body;
    // orders: Array<{ supplier_id, supplier_name, items: Array<{ component_id, part_number, component_name, supplier_part_number, quantity, unit_price }> }>

    if (!orders || !Array.isArray(orders) || orders.length === 0) {
      return NextResponse.json({ error: "No orders provided" }, { status: 400 });
    }

    const createdPos: Record<string, unknown>[] = [];

    for (const order of orders) {
      // Generate PO number: PO-EACH-YYYY_MM_DD-RR-SUPPLIERNAME (matching packing list pattern)
      const now = new Date();
      const yyyy = now.getFullYear();
      const mm = String(now.getMonth() + 1).padStart(2, "0");
      const dd = String(now.getDate()).padStart(2, "0");
      const supplierSlug = (order.supplier_name || "UNKNOWN")
        .toUpperCase()
        .replace(/[^A-Z0-9]/g, "")
        .slice(0, 20);
      const datePrefix = `PO-EACH-${yyyy}_${mm}_${dd}`;
      const existingRows = await sql(
        `SELECT COUNT(*) AS cnt FROM supplier_pos WHERE po_number LIKE $1`,
        [`${datePrefix}%-${supplierSlug}`]
      );
      const revision = String(Number(existingRows[0].cnt) + 1).padStart(2, "0");
      const poNumber = `${datePrefix}-${revision}-${supplierSlug}`;

      const poRows = await sql(
        `INSERT INTO supplier_pos (po_number, supplier_id, planning_id, status, notes)
         VALUES ($1, $2, $3, 'draft', $4)
         RETURNING *`,
        [
          poNumber,
          Number(order.supplier_id),
          planning_id ? Number(planning_id) : null,
          order.notes || null,
        ]
      );

      const po = poRows[0];

      for (const item of order.items) {
        await sql(
          `INSERT INTO supplier_po_items
            (supplier_po_id, component_id, part_number, component_name,
             supplier_part_number, quantity, unit_price)
           VALUES ($1, $2, $3, $4, $5, $6, $7)`,
          [
            po.id,
            Number(item.component_id),
            item.part_number,
            item.component_name,
            item.supplier_part_number || null,
            Number(item.quantity),
            Number(item.unit_price),
          ]
        );
      }

      createdPos.push({
        ...po,
        supplier_name: order.supplier_name,
        item_count: order.items.length,
      });
    }

    return NextResponse.json(createdPos, { status: 201 });
  } catch (error) {
    console.error("Supplier POs POST error:", error);
    return NextResponse.json(
      { error: error instanceof Error ? error.message : "Failed to create supplier POs" },
      { status: 500 }
    );
  }
}