import { getOverheadsBySection } from "@/lib/data";
import { ZAR } from "@/lib/utils";
import { ArrowLeft } from "lucide-react";
import Link from "next/link";
import { ReactNode } from "react";

type Props = {
  section: string;
  title: string;
  subtitle: string;
  icon: ReactNode;
  gradient: string;
  iconBg: string;
  iconColor: string;
};

export async function ExpenseSectionPage({
  section, title, subtitle, icon, gradient, iconBg, iconColor,
}: Props) {
  const items = await getOverheadsBySection(section);
  const totalIncl = items.reduce((s, o) => s + (o.amount_incl || 0), 0);
  const totalExcl = items.reduce((s, o) => s + (o.amount_excl || 0), 0);
  const totalVat = items.reduce((s, o) => s + (o.vat || 0), 0);

  const byGl = new Map<string, typeof items>();
  for (const o of items) {
    const g = o.gl_account || "—";
    if (!byGl.has(g)) byGl.set(g, []);
    byGl.get(g)!.push(o);
  }
  const glBreakdown = Array.from(byGl.entries())
    .map(([gl, list]) => ({
      gl,
      total: list.reduce((s, o) => s + (o.amount_incl || 0), 0),
      count: list.length,
    }))
    .sort((a, b) => b.total - a.total);

  return (
    <div className="p-8 max-w-[1400px]">
      <Link href="/expenses" className="inline-flex items-center gap-1 text-xs text-gray-500 dark:text-gray-400 hover:text-[#30638E] dark:hover:text-[#00798C] mb-3">
        <ArrowLeft className="w-3 h-3" /> Back to Expenses
      </Link>

      <div className="flex items-end justify-between mb-6">
        <div>
          <div className="flex items-center gap-3 mb-1">
            <div className={`w-10 h-10 rounded-xl ${iconBg} grid place-items-center`} style={{ color: iconColor }}>
              {icon}
            </div>
            <h1 className="text-2xl font-semibold text-[#003D5B] dark:text-white">{title}</h1>
          </div>
          <p className="text-gray-500 dark:text-gray-400 text-sm">{subtitle}</p>
        </div>
        <div className={`bg-gradient-to-br ${gradient} rounded-2xl px-5 py-3 text-white shadow-lg`}>
          <div className="text-xs text-white/80">Monthly total (incl VAT)</div>
          <div className="text-2xl font-semibold tabular-nums">{ZAR(totalIncl)}</div>
        </div>
      </div>

      <div className="grid grid-cols-3 gap-4 mb-6">
        <StatCard label="Items" value={String(items.length)} color="#30638E" />
        <StatCard label="Excl VAT" value={ZAR(totalExcl)} color="#003D5B" />
        <StatCard label="VAT" value={ZAR(totalVat)} color="#EDAE49" />
      </div>

      {glBreakdown.length > 1 && (
        <section className="bg-white dark:bg-[#131a21] rounded-2xl border border-gray-100 dark:border-white/5 p-6 shadow-sm mb-6">
          <h2 className="text-base font-semibold text-[#003D5B] dark:text-white mb-4">By GL account</h2>
          <div className="space-y-3">
            {glBreakdown.map((g) => {
              const pct = totalIncl ? (g.total / totalIncl) * 100 : 0;
              return (
                <div key={g.gl}>
                  <div className="flex items-center justify-between text-sm mb-1">
                    <span className="text-gray-700 dark:text-gray-300 font-medium">{g.gl}</span>
                    <span className="text-gray-500 dark:text-gray-400">
                      {ZAR(g.total)} · <span className="text-gray-400 dark:text-gray-500">{g.count} item{g.count !== 1 && "s"}</span> · {pct.toFixed(0)}%
                    </span>
                  </div>
                  <div className="h-2 rounded-full bg-gray-100 dark:bg-white/5 overflow-hidden">
                    <div
                      className="h-full rounded-full"
                      style={{ width: `${pct}%`, background: iconColor }}
                    />
                  </div>
                </div>
              );
            })}
          </div>
        </section>
      )}

      {/* Part B.1: empty state must say so plainly, not render a table of zeros */}
      {items.length === 0 ? (
        <section className="bg-white dark:bg-[#131a21] rounded-2xl border border-gray-100 dark:border-white/5 p-12 shadow-sm text-center">
          <div className="text-sm text-gray-500 dark:text-gray-400">
            No <strong className="text-gray-700 dark:text-gray-200">{section}</strong> entries in PocketBase.
          </div>
          <div className="text-xs text-gray-400 dark:text-gray-500 mt-1">
            This category either doesn&apos;t apply yet or lives elsewhere — see round-3 brief.
          </div>
        </section>
      ) : (
        <section className="bg-white dark:bg-[#131a21] rounded-2xl border border-gray-100 dark:border-white/5 shadow-sm overflow-hidden">
          <div className="p-6 pb-3 flex items-end justify-between">
            <h2 className="text-base font-semibold text-[#003D5B] dark:text-white">Line items</h2>
            <span className="text-xs text-gray-500 dark:text-gray-400">{items.length} entries</span>
          </div>
          <div className="overflow-x-auto">
            <table className="w-full text-sm">
              <thead>
                <tr className="text-xs text-gray-500 dark:text-gray-400 uppercase tracking-wider border-y border-gray-100 dark:border-white/5 bg-gray-50/50 dark:bg-white/[0.02]">
                  <th className="text-left py-3 px-6 font-medium">Description</th>
                  <th className="text-left py-3 px-3 font-medium">GL Account</th>
                  <th className="text-left py-3 px-3 font-medium">Supplier</th>
                  <th className="text-right py-3 px-3 font-medium">Excl VAT</th>
                  <th className="text-right py-3 px-3 font-medium">VAT</th>
                  <th className="text-right py-3 px-6 font-medium">Incl VAT</th>
                </tr>
              </thead>
              <tbody>
                {items.map((o) => (
                  <tr key={o.id} className="border-b border-gray-50 dark:border-white/5 hover:bg-gray-50/40 dark:hover:bg-white/[0.02]">
                    <td className="py-3 px-6 font-medium text-[#003D5B] dark:text-white">{o.description}</td>
                    <td className="py-3 px-3">
                      {o.gl_account ? (
                        <span className="text-xs px-2 py-0.5 rounded-md bg-[#30638E]/10 text-[#30638E] dark:text-[#00798C] font-medium">
                          {o.gl_account}
                        </span>
                      ) : (
                        <span className="text-gray-400">—</span>
                      )}
                    </td>
                    <td className="py-3 px-3 text-gray-500 dark:text-gray-400">{o.supplier || "—"}</td>
                    <td className="py-3 px-3 text-right tabular-nums text-gray-700 dark:text-gray-300">{o.amount_excl ? ZAR(o.amount_excl) : "—"}</td>
                    <td className="py-3 px-3 text-right tabular-nums text-gray-500 dark:text-gray-400">{o.vat ? ZAR(o.vat) : "—"}</td>
                    <td className="py-3 px-6 text-right tabular-nums font-semibold text-[#003D5B] dark:text-white">
                      {o.amount_incl ? ZAR(o.amount_incl) : "—"}
                    </td>
                  </tr>
                ))}
                <tr className="bg-gradient-to-r from-gray-50 dark:from-white/[0.02] to-white dark:to-transparent border-t-2 border-gray-200 dark:border-white/5">
                  <td colSpan={3} className="py-3 px-6 font-semibold text-right text-gray-700 dark:text-gray-300">Total</td>
                  <td className="py-3 px-3 text-right tabular-nums font-semibold text-gray-900 dark:text-white">{ZAR(totalExcl)}</td>
                  <td className="py-3 px-3 text-right tabular-nums font-semibold text-gray-900 dark:text-white">{ZAR(totalVat)}</td>
                  <td className="py-3 px-6 text-right tabular-nums font-semibold text-base" style={{ color: iconColor }}>
                    {ZAR(totalIncl)}
                  </td>
                </tr>
              </tbody>
            </table>
          </div>
        </section>
      )}
    </div>
  );
}

function StatCard({ label, value, color }: { label: string; value: string; color: string }) {
  return (
    <div className="bg-white dark:bg-[#131a21] rounded-2xl border border-gray-100 dark:border-white/5 p-5 shadow-sm">
      <div className="text-xs uppercase tracking-wider text-gray-500 dark:text-gray-400">{label}</div>
      <div className="text-2xl font-semibold mt-2 tabular-nums" style={{ color }}>{value}</div>
    </div>
  );
}