import Link from "next/link";
import { Suspense } from "react";
import { AuditDetail } from "@/components/audit/AuditDetail";
import { AuditFilters } from "@/components/audit/AuditFilters";
import { CARD_CLASS } from "@/components/ui/Card";
import { Pagination } from "@/components/ui/Pagination";
import { actionBadgeStyle } from "@/lib/colors";
import { currentUserId } from "@/lib/auth/session";
import { withUser } from "@/lib/db";

const PAGE_SIZE = 25;

type SearchParams = { q?: string; action?: string; page?: string };

function pageHref(params: SearchParams, page: number): string {
  const sp = new URLSearchParams();
  if (params.q) sp.set("q", params.q);
  if (params.action) sp.set("action", params.action);
  sp.set("page", String(page));
  return `/audit?${sp.toString()}`;
}

// Pinned to Vienna and built once: audit_log.occurred_at is a timestamptz, and
// an unpinned formatter renders it in the *server's* zone — UTC in Docker and
// on Vercel — so every entry would read an hour or two early for the people
// the log is for.
const dateTimeFormatter = new Intl.DateTimeFormat("de-AT", {
  day: "2-digit",
  month: "2-digit",
  year: "numeric",
  hour: "2-digit",
  minute: "2-digit",
  timeZone: "Europe/Vienna",
});

export default async function AuditPage({ searchParams }: { searchParams: Promise<SearchParams> }) {
  const params = await searchParams;
  const page = Math.max(1, Number(params.page ?? "1") || 1);

  const { entries, count } = await withUser(await currentUserId(), async (tx) => {
    const base = () => {
      let q = tx.selectFrom("audit_log");
      if (params.action) q = q.where("action", "=", params.action);
      if (params.q) {
        // Als Parameter gebunden statt in die Abfrage geschrieben: die
        // Zeichen, die in der alten Filtersyntax ausbrechen konnten, haben
        // hier keine Bedeutung mehr.
        const like = `%${params.q.trim()}%`;
        q = q.where((eb) =>
          eb.or([eb("target_label", "ilike", like), eb("details", "ilike", like), eb("actor_name", "ilike", like)])
        );
      }
      return q;
    };

    const [entries, total] = await Promise.all([
      base()
        .select(["id", "occurred_at", "actor_name", "action", "target_label", "target_employee_id", "details", "changes"])
        // Nach id als zweitem Kriterium: bei gleichem Zeitstempel wäre die
        // Reihenfolge sonst unbestimmt und ein Eintrag könnte auf zwei Seiten
        // erscheinen oder auf keiner.
        .orderBy("occurred_at", "desc")
        .orderBy("id", "desc")
        .limit(PAGE_SIZE)
        .offset((page - 1) * PAGE_SIZE)
        .execute(),
      base()
        .select(({ fn }) => fn.countAll<string>().as("anzahl"))
        .executeTakeFirst(),
    ]);
    return { entries, count: Number(total?.anzahl ?? 0) };
  });

  const totalPages = Math.max(1, Math.ceil(count / PAGE_SIZE));

  return (
    <div className="flex flex-col gap-4">
      <Suspense>
        <AuditFilters />
      </Suspense>
      <p className="text-sm text-ink-muted">{count} Einträge</p>

      <div className={`overflow-x-auto ${CARD_CLASS}`}>
        <table className="w-full min-w-[800px] text-sm">
          <thead>
            <tr className="border-b border-border bg-surface text-left text-[11px] font-bold uppercase tracking-wider text-ink-muted">
              <th className="px-4 py-2.5">Zeitpunkt</th>
              <th className="px-4 py-2.5">Benutzer:in</th>
              <th className="px-4 py-2.5">Aktion</th>
              <th className="px-4 py-2.5">Objekt</th>
              <th className="px-4 py-2.5">Details</th>
            </tr>
          </thead>
          <tbody>
            {entries.map((entry) => {
              return (
                <tr key={entry.id} className="border-b border-border-subtle transition-colors last:border-0 hover:bg-brand-50">
                  <td className="whitespace-nowrap px-4 py-2.5 tabular-nums text-ink-body">
                    {dateTimeFormatter.format(new Date(entry.occurred_at))}
                  </td>
                  <td className="px-4 py-2.5 text-ink-body">{entry.actor_name}</td>
                  <td className="px-4 py-2.5">
                    <span className={`whitespace-nowrap rounded-full px-2 py-0.5 text-[11px] font-semibold ${actionBadgeStyle(entry.action)}`}>
                      {entry.action}
                    </span>
                  </td>
                  <td className="px-4 py-2.5 text-ink">
                    {entry.target_employee_id ? (
                      <Link
                        href={`/employees/${entry.target_employee_id}`}
                        className="rounded font-semibold hover:text-brand-700 hover:underline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-brand-500"
                      >
                        {entry.target_label}
                      </Link>
                    ) : (
                      entry.target_label
                    )}
                  </td>
                  <td className="px-2 py-1.5">
                    <AuditDetail eintrag={entry} />
                  </td>
                </tr>
              );
            })}
            {entries.length === 0 && (
              <tr>
                <td colSpan={5} className="px-4 py-8 text-center text-sm text-ink-muted">
                  Keine Einträge gefunden.
                </td>
              </tr>
            )}
          </tbody>
        </table>
      </div>

      <Pagination page={page} totalPages={totalPages} hrefFor={(p) => pageHref(params, p)} label="Audit-Log" />

      <p className="text-xs text-ink-muted">
        Alle Änderungen an Personal-Stammdaten werden automatisch protokolliert und sind unveränderbar.
      </p>
    </div>
  );
}