import { NextRequest, NextResponse } from "next/server";
import { getAuth } from "@/lib/auth";
import { pbList } from "@/lib/pocketbase";
import { generateCustomerStatement } from "@/lib/pdf/customer-statement";
import type { Customer, DeliveryNote, FuelSettings } from "@/lib/types";

export const dynamic = "force-dynamic";

function rangeDates(range: string, start?: string, end?: string) {
  const now = new Date();
  if (range === "this-month") {
    return {
      start: new Date(now.getFullYear(), now.getMonth(), 1).toISOString().slice(0, 10),
      end: new Date(now.getFullYear(), now.getMonth() + 1, 0).toISOString().slice(0, 10),
    };
  }
  if (range === "last-month") {
    return {
      start: new Date(now.getFullYear(), now.getMonth() - 1, 1).toISOString().slice(0, 10),
      end: new Date(now.getFullYear(), now.getMonth(), 0).toISOString().slice(0, 10),
    };
  }
  if (start && end) return { start, end };
  return { start: start || "", end: end || "" };
}

export async function GET(req: NextRequest) {
  const { token } = await getAuth();
  if (!token) return NextResponse.json({ error: "Unauthorized" }, { status: 401 });

  const { searchParams } = req.nextUrl;
  const customerId = searchParams.get("customer");
  const range = searchParams.get("range") || "this-month";
  const startParam = searchParams.get("start");
  const endParam = searchParams.get("end");
  const includePricing = searchParams.get("include_pricing") !== "false";

  if (!customerId) return NextResponse.json({ error: "customer required" }, { status: 400 });

  const { start, end } = rangeDates(range, startParam || undefined, endParam || undefined);
  if (!start || !end) return NextResponse.json({ error: "Date range required" }, { status: 400 });

  try {
    const [customerRes, notesRes, settingsRes] = await Promise.all([
      pbList<Customer>("customers", { perPage: 1, filter: `id = "${customerId}"` }, token),
      pbList<DeliveryNote>("delivery_notes", {
        perPage: 1000,
        filter: `customer = "${customerId}" && date >= "${start}" && date <= "${end}"`,
        sort: "date",
      }, token),
      pbList<FuelSettings>("fuel_settings", { perPage: 1 }, token),
    ]);

    if (customerRes.items.length === 0) {
      return NextResponse.json({ error: "Customer not found" }, { status: 404 });
    }

    const pdfBytes = await generateCustomerStatement({
      customer: customerRes.items[0],
      notes: notesRes.items,
      startDate: start,
      endDate: end,
      includePricing,
      companySettings: settingsRes.items[0] || null,
    });

    const filename = `delivery_statement_${customerRes.items[0].name.replace(/\s+/g, "_")}_${start.replace(/-/g, "")}.pdf`;
    return new NextResponse(Buffer.from(pdfBytes), {
      headers: {
        "Content-Type": "application/pdf",
        "Content-Disposition": `inline; filename="${filename}"`,
        "Cache-Control": "no-store",
      },
    });
  } catch (err: any) {
    return NextResponse.json({ error: err?.message || "PDF generation failed" }, { status: 500 });
  }
}