import Link from "next/link";
import { Suspense } from "react";
import { EmployeeFilters } from "@/components/employees/EmployeeFilters";
import { Avatar } from "@/components/ui/Avatar";
import { CARD_CLASS } from "@/components/ui/Card";
import { Pagination } from "@/components/ui/Pagination";
import { StatusChip } from "@/components/ui/StatusChip";
import { applyDerivedStatusFilter } from "@/lib/employee-status-filter";
import { fmtDate, todayIso } from "@/lib/format";
import { breadcrumbFor, loadOrgMaps } from "@/lib/org";
import { sanitizeIlikeTerm } from "@/lib/supabase/query";
import { createClient } from "@/lib/supabase/server";
import type { EmploymentStatus } from "@/lib/supabase/types";

const PAGE_SIZE = 15;

type SearchParams = { q?: string; division?: string; status?: string; location?: string; page?: string };

type EmployeesPageProps = {
  searchParams: Promise<SearchParams>;
};

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

export default async function EmployeesPage({ searchParams }: EmployeesPageProps) {
  const params = await searchParams;
  const supabase = await createClient();

  const page = Math.max(1, Number(params.page ?? "1") || 1);
  const from = (page - 1) * PAGE_SIZE;
  const to = from + PAGE_SIZE - 1;

  let query = supabase
    .from("employees")
    .select(
      "id, first_name, last_name, personnel_number, job_title, team_id, division_id, location_id, entry_date, employment_type, weekly_hours, status, absence_type",
      { count: "exact" }
    )
    .order("last_name", { ascending: true })
    .range(from, to);

  if (params.q) {
    const q = params.q.trim();
    if (/^\d+$/.test(q)) {
      query = query.eq("personnel_number", Number(q));
    } else {
      const term = sanitizeIlikeTerm(q);
      query = query.or(`first_name.ilike.%${term}%,last_name.ilike.%${term}%,job_title.ilike.%${term}%`);
    }
  }
  if (params.division) query = query.eq("division_id", params.division);
  // Comma-separated, so a dashboard tile can link here with the same
  // status set it counted rather than a narrower one.
  const statuses = (params.status ?? "")
    .split(",")
    .map((s) => s.trim())
    .filter((s): s is EmploymentStatus => (["Aktiv", "Karenz", "Geplant", "Ausgetreten"] as const).includes(s as EmploymentStatus));
  // Derived from the dates, not read off employees.status — see
  // lib/employee-status-filter.ts for why the two can disagree.
  query = applyDerivedStatusFilter(query, statuses, todayIso());
  if (params.location) query = query.eq("location_id", params.location);

  // The org lookup tables are needed only to label the rows, so they load
  // alongside the page of employees instead of before it — one round trip
  // saved on a page that is otherwise two fast queries.
  const [orgMaps, { data: employeesData, count }] = await Promise.all([loadOrgMaps(supabase), query]);
  const employees = employeesData ?? [];
  const totalPages = Math.max(1, Math.ceil((count ?? 0) / PAGE_SIZE));

  return (
    <div className="flex flex-col gap-4">
      <Suspense>
        <EmployeeFilters divisions={orgMaps.divisionList} locations={orgMaps.locationList} />
      </Suspense>
      <p className="text-sm text-ink-muted">{count ?? 0} Mitarbeiter:innen gefunden</p>

      <div className={`overflow-x-auto ${CARD_CLASS}`}>
        <table className="w-full min-w-[800px] text-sm">
          <thead>
            <tr className="border-b border-border bg-surface text-left text-[11px] font-bold uppercase tracking-wider text-ink-muted">
              <th className="px-4 py-2.5">Mitarbeiter:in</th>
              <th className="px-4 py-2.5">Pers.-Nr.</th>
              <th className="px-4 py-2.5">Bereich/Team</th>
              <th className="px-4 py-2.5">Standort</th>
              <th className="px-4 py-2.5">Eintritt</th>
              <th className="px-4 py-2.5">Beschäftigung</th>
              <th className="px-4 py-2.5">Status</th>
            </tr>
          </thead>
          <tbody>
            {employees.map((e) => {
              const { division, team } = breadcrumbFor(orgMaps, e.division_id, e.team_id);
              const location = e.location_id ? orgMaps.locations.get(e.location_id) : undefined;
              return (
                // border-subtle between rows: the full-strength border made
                // an 800-row table read as a grid rather than a list.
                <tr key={e.id} className="border-b border-border-subtle transition-colors last:border-0 hover:bg-brand-50">
                  <td className="px-4 py-2.5">
                    <Link
                      href={`/employees/${e.id}`}
                      className="flex items-center gap-3 rounded focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-brand-500"
                    >
                      <Avatar firstName={e.first_name} lastName={e.last_name} />
                      <div className="min-w-0">
                        <div className="truncate font-semibold text-ink">
                          {e.first_name} {e.last_name}
                        </div>
                        <div className="truncate text-xs text-ink-muted">{e.job_title}</div>
                      </div>
                    </Link>
                  </td>
                  {/* tabular-nums keeps the numeric columns aligned down the
                      page instead of jittering per row. */}
                  <td className="px-4 py-2.5 tabular-nums text-ink-body">{e.personnel_number}</td>
                  <td className="px-4 py-2.5 text-ink-body">
                    <div>{division?.name ?? "–"}</div>
                    <div className="text-xs text-ink-muted">{team?.name ?? "–"}</div>
                  </td>
                  <td className="px-4 py-2.5 text-ink-body">{location?.name ?? "–"}</td>
                  <td className="px-4 py-2.5 tabular-nums text-ink-body">{fmtDate(e.entry_date)}</td>
                  <td className="px-4 py-2.5 text-ink-body">
                    {e.employment_type} · <span className="tabular-nums">{e.weekly_hours}h</span>
                  </td>
                  <td className="px-4 py-2.5">
                    <StatusChip status={e.status} entryDate={e.entry_date} absenceType={e.absence_type} />
                  </td>
                </tr>
              );
            })}
            {employees.length === 0 && (
              <tr>
                <td colSpan={7} className="px-4 py-8 text-center text-sm text-ink-muted">
                  Keine Mitarbeiter:innen gefunden.
                </td>
              </tr>
            )}
          </tbody>
        </table>
      </div>

      <Pagination page={page} totalPages={totalPages} hrefFor={(p) => pageHref(params, p)} label="Mitarbeiter:innen" />
    </div>
  );
}
