import type { Asset, BookedLine, Invoice } from "@/lib/data";
import { ZAR2 } from "@/lib/utils";
import { AlertTriangle, CheckCircle2 } from "lucide-react";
import { BookingSelect } from "@/components/BookingSelect";
import { InvoiceUploader, AttachedDocument } from "@/components/InvoiceUploader";

// Right-edge fade so a horizontally scrollable table reads as scrollable on touch.
// pointer-events-none so it never swallows a tap on the row underneath.
function ScrollFade() {
  return (
    <div
      aria-hidden="true"
      className="pointer-events-none absolute inset-y-0 right-0 w-8 bg-gradient-to-l from-white to-transparent dark:from-[#131a21]"
    />
  );
}

export function InvoiceSummary({
  invoice,
  lines,
  assets,
  embedded,
}: {
  invoice: Invoice;
  lines: BookedLine[];
  assets: Asset[];
  // Inside the expandable invoice row the surrounding card already shows the number and
  // site, so the header block is dropped to avoid saying the same thing twice.
  embedded?: boolean;
}) {
  const unbooked = lines.filter((l) => !l.isBooked);
  // Two different numbers, both worth showing.
  //   ex-VAT  = what actually lands in the P&L as income for the machine.
  //   incl-VAT= what the debtor actually pays (ex-VAT + SARS VAT).
  // Booking is done ex-VAT: VAT is collected for SARS, never income.
  const sum = (ls: BookedLine[], k: "amount_excl" | "vat") => ls.reduce((s, l) => s + (l[k] || 0), 0);
  const bookedExVat = sum(lines.filter((l) => l.isBooked), "amount_excl");
  const bookedVat = sum(lines.filter((l) => l.isBooked), "vat");
  const unbookedExVat = sum(unbooked, "amount_excl");
  const unbookedVat = sum(unbooked, "vat");
  const period = `${invoice.period_from.slice(0, 10)} → ${invoice.period_to.slice(0, 10)}`;
  const periodMonth = new Date(invoice.period_to).toLocaleDateString("en-ZA", {
    month: "long",
    year: "numeric",
    timeZone: "UTC",
  });

  return (
    <div
      className={
        embedded
          ? "bg-white dark:bg-[#131a21] border border-gray-100 dark:border-white/5 rounded-xl shadow-sm overflow-hidden"
          : "bg-white dark:bg-[#131a21] border border-gray-100 dark:border-white/5 rounded-2xl shadow-sm overflow-hidden mb-6"
      }
    >
      {!embedded && (
        <div className="p-5 border-b border-gray-100 dark:border-white/5">
          <div className="flex flex-wrap items-start justify-between gap-4">
            <div className="min-w-0">
              <div className="flex items-center gap-2 flex-wrap">
                <span className="font-mono text-sm font-semibold px-2.5 py-1 rounded-md bg-[#00798C]/10 text-[#00798C]">
                  {invoice.invoice_no}
                </span>
                {/* Site is transcribed from the invoice's own description. There is no
                    sites collection yet — this is a plain label until one exists. */}
                {invoice.site && (
                  <span className="text-sm px-2.5 py-1 rounded-md bg-[#EDAE49]/15 text-[#8a6420] dark:text-[#EDAE49]">
                    {invoice.site}
                  </span>
                )}
                <span className="text-sm font-medium text-[#003D5B] dark:text-white">{invoice.debtor}</span>
              </div>
              <p className="text-sm text-gray-500 dark:text-gray-400 mt-2">{invoice.description}</p>
              <div className="flex flex-wrap gap-x-4 gap-y-1 mt-2 text-sm text-gray-500 dark:text-gray-400">
                <span>Order {invoice.order_no || "—"}</span>
                <span>Debtor {invoice.debtor_no || "—"}</span>
                <span>{period}</span>
                <span>{invoice.currency || "ZAR"}</span>
              </div>
            </div>
            {/* The headline is the VAT-inclusive invoice total — what the debtor pays. */}
            <div className="text-right shrink-0">
              <div className="text-sm text-gray-500 dark:text-gray-400">Invoice total (incl VAT)</div>
              <div className="text-2xl font-semibold tabular-nums text-[#003D5B] dark:text-white">
                {ZAR2(invoice.total_incl)}
              </div>
              <div className="text-sm text-gray-500 dark:text-gray-400 tabular-nums">
                {ZAR2(invoice.total_excl)} + {ZAR2(invoice.vat)} VAT
                {invoice.vat_pct ? ` @ ${invoice.vat_pct}%` : ""}
              </div>
            </div>
          </div>
        </div>
      )}

      {embedded && (
        <div className="px-4 py-3 border-b border-gray-100 dark:border-white/5 flex flex-wrap items-center justify-between gap-3">
          <div className="min-w-0">
            <div className="text-sm font-medium text-[#003D5B] dark:text-white">
              {invoice.debtor} · {invoice.description}
            </div>
            <div className="flex flex-wrap gap-x-4 gap-y-1 mt-1 text-sm text-gray-500 dark:text-gray-400">
              <span>Order {invoice.order_no || "—"}</span>
              <span>Debtor {invoice.debtor_no || "—"}</span>
              <span>{period}</span>
            </div>
          </div>
          <div className="text-right shrink-0">
            <div className="text-sm text-gray-500 dark:text-gray-400">Invoice total (incl VAT)</div>
            <div className="text-xl font-semibold tabular-nums text-[#003D5B] dark:text-white">
              {ZAR2(invoice.total_incl)}
            </div>
          </div>
        </div>
      )}

      {/* Booking status. An unassigned line is never guessed at — it stays visible
          and the shortfall is stated, rather than being charged to a wrong machine. */}
      {unbooked.length > 0 ? (
        <div className="flex items-start gap-3 px-5 py-3 bg-[#D1495B]/5 border-b border-[#D1495B]/15">
          <AlertTriangle className="w-4 h-4 text-[#D1495B] shrink-0 mt-0.5" />
          <div className="text-sm text-[#D1495B] dark:text-[#D1495B]">
            <p>
              {unbooked.length} line{unbooked.length > 1 ? "s" : ""} not yet booked to a machine — choose a
              plant item below.
            </p>
            <BookingMoney bookedExVat={bookedExVat} bookedVat={bookedVat} unbookedExVat={unbookedExVat} unbookedVat={unbookedVat} />
          </div>
        </div>
      ) : (
        <div className="flex items-start gap-3 px-5 py-3 bg-[#00798C]/5 border-b border-[#00798C]/15">
          <CheckCircle2 className="w-4 h-4 text-[#00798C] shrink-0 mt-0.5" />
          <div className="text-sm text-[#00798C]">
            <p>All {lines.length} lines booked to {periodMonth} income.</p>
            <BookingMoney bookedExVat={bookedExVat} bookedVat={bookedVat} />
          </div>
        </div>
      )}

      <InvoiceTable lines={lines} assets={assets} />

      <div className="p-5 border-t border-gray-100 dark:border-white/5 bg-gray-50/50 dark:bg-white/[0.02]">
        <div className="flex flex-col lg:flex-row lg:items-start justify-between gap-6">
          <div className="lg:max-w-sm w-full">
            <div className="text-sm font-medium text-[#003D5B] dark:text-white mb-2">
              Source document
            </div>
            {invoice.source_pdf ? (
              <AttachedDocument invoiceNo={invoice.invoice_no} invoiceId={invoice.id} />
            ) : (
              <InvoiceUploader invoiceNo={invoice.invoice_no} />
            )}
          </div>

          <dl className="w-full lg:w-80 shrink-0 space-y-2">
            <TotalRow label="Hire (excl VAT)" value={invoice.total_excl} />
            {invoice.escalation > 0 && <TotalRow label="Escalation" value={invoice.escalation} />}
            <TotalRow
              label={`VAT${invoice.vat_pct ? ` @ ${invoice.vat_pct}%` : ""}`}
              value={invoice.vat}
            />
            <div className="border-t border-gray-200 dark:border-white/10 pt-2">
              <TotalRow label="Invoice total (incl VAT)" value={invoice.total_incl} strong />
            </div>
          </dl>
        </div>
      </div>
    </div>
  );
}

// Shows the booked money three ways at once, so nobody has to guess which figure the
// dashboard is using:
//
//   booked to income (ex VAT) → what lands in the P&L for the machine
//   VAT                       → collected for SARS, NOT income
//   billed to customer        → ex-VAT + VAT, what the debtor actually pays
function BookingMoney({
  bookedExVat,
  bookedVat,
  unbookedExVat = 0,
  unbookedVat = 0,
}: {
  bookedExVat: number;
  bookedVat: number;
  unbookedExVat?: number;
  unbookedVat?: number;
}) {
  return (
    <div className="mt-1.5 flex flex-wrap gap-x-5 gap-y-1">
      <Item label="Booked to income (ex VAT)" value={bookedExVat} strong />
      <Item label="VAT (to SARS, not income)" value={bookedVat} />
      <Item label="Billed to customer" value={bookedExVat + bookedVat} strong />
      {unbookedExVat > 0 && (
        <>
          <Item label="Still unbooked (ex VAT)" value={unbookedExVat} strong />
          <Item label="Still unbooked (billed)" value={unbookedExVat + unbookedVat} />
        </>
      )}
    </div>
  );
}

function Item({ label, value, strong }: { label: string; value: number; strong?: boolean }) {
  return (
    <span className="inline-flex items-baseline gap-1.5">
      <span className="opacity-80">{label}</span>
      <span className={`font-semibold tabular-nums ${strong ? "underline decoration-dotted underline-offset-2" : ""}`}>
        {ZAR2(value)}
      </span>
    </span>
  );
}

function TotalRow({ label, value, strong }: { label: string; value: number; strong?: boolean }) {
  return (
    <div className="flex items-center justify-between gap-4">
      <dt className="text-sm text-gray-500 dark:text-gray-400">{label}</dt>
      <dd
        className={`text-sm tabular-nums ${
          strong ? "font-semibold text-[#003D5B] dark:text-white" : "text-gray-700 dark:text-gray-300"
        }`}
      >
        {ZAR2(value || 0)}
      </dd>
    </div>
  );
}

export function InvoiceTable({ lines, assets }: { lines: BookedLine[]; assets: Asset[] }) {
  const options = assets
    .filter((a) => a.is_active !== false)
    .map((a) => ({ id: a.id, code: a.code || "", name: a.name, category: a.category }));

  return (
    // Rule 1 + 4: the table scrolls inside its own container, so the page itself never
    // scrolls sideways at 375px. `-webkit-overflow-scrolling` is not a Tailwind utility —
    // written as a class it is inert — so it is set inline to actually take effect.
    <div className="group relative">
      <div className="overflow-x-auto" style={{ WebkitOverflowScrolling: "touch" }}>
        <table className="w-full text-sm min-w-[900px]">
          <thead>
            <tr className="text-xs text-gray-500 dark:text-gray-400 uppercase tracking-wider border-b border-gray-100 dark:border-white/5 bg-gray-50/50 dark:bg-white/[0.02]">
              <th className="text-left py-3 px-5 font-medium sticky left-0 z-10 bg-gray-50/95 dark:bg-[#1a222b]/95 backdrop-blur">
                Machine
              </th>
              <th className="text-left py-3 px-3 font-medium">Description</th>
              <th className="text-right py-3 px-3 font-medium whitespace-nowrap">Qty</th>
              <th className="text-left py-3 px-3 font-medium">Unit</th>
              <th className="text-right py-3 px-3 font-medium whitespace-nowrap">Rate</th>
              <th className="text-right py-3 px-3 font-medium whitespace-nowrap">Hire ex VAT</th>
              <th className="text-right py-3 px-3 font-medium whitespace-nowrap">VAT</th>
              <th className="text-right py-3 px-3 font-medium whitespace-nowrap">Total incl</th>
              <th className="text-left py-3 px-3 font-medium whitespace-nowrap">Booked to</th>
            </tr>
          </thead>
          <tbody>
            {lines.map((l) => (
              <tr
                key={l.id}
                className={`border-b border-gray-50 dark:border-white/5 ${
                  l.isBooked ? "hover:bg-gray-50/40 dark:hover:bg-white/[0.02]" : "bg-[#D1495B]/[0.04]"
                }`}
              >
                {/* Sticky first column — keeps the machine identifiable while scrolling.
                    It needs its own opaque background, so it has to repeat the row's
                    unbooked tint; otherwise the flag disappears under the white. */}
                <td
                  className={`py-3 px-5 sticky left-0 z-10 ${
                    l.isBooked
                      ? "bg-white dark:bg-[#131a21]"
                      : "bg-[#D1495B]/[0.04] dark:bg-[#1a1319]"
                  }`}
                >
                  <div className="flex items-center gap-2 whitespace-nowrap">
                    <span className="text-xs text-gray-400 dark:text-gray-500 tabular-nums">{l.line_no}</span>
                    <span className="font-mono text-xs font-semibold text-[#00798C]">{l.machine_code}</span>
                  </div>
                </td>
                <td className="py-3 px-3 text-gray-700 dark:text-gray-300 whitespace-nowrap">{l.description}</td>
                <td className="py-3 px-3 text-right tabular-nums text-gray-700 dark:text-gray-300">{l.qty}</td>
                <td className="py-3 px-3 text-gray-500 dark:text-gray-400">{l.unit}</td>
                <td className="py-3 px-3 text-right tabular-nums text-gray-700 dark:text-gray-300">{ZAR2(l.rate)}</td>
                <td className="py-3 px-3 text-right tabular-nums text-gray-700 dark:text-gray-300">{ZAR2(l.amount_excl)}</td>
                <td className="py-3 px-3 text-right tabular-nums text-gray-700 dark:text-gray-300">{ZAR2(l.vat)}</td>
                <td className="py-3 px-3 text-right tabular-nums font-semibold text-[#003D5B] dark:text-white whitespace-nowrap">
                  {ZAR2(l.total_incl)}
                </td>
                <td className="py-3 px-3 w-[220px]">
                  <BookingSelect lineId={l.id} value={l.booked_asset || ""} assets={options} />
                </td>
              </tr>
            ))}
          </tbody>
        </table>
      </div>
      <ScrollFade />
    </div>
  );
}