import { prisma } from "@/lib/prisma";
import Link from "next/link";
import { UserPlus } from "lucide-react";
import { UsersTable } from "@/components/admin/users-table";
import { Suspense } from "react";
import { UsersSearch } from "@/components/admin/users-search";

const PAGE_SIZE = 20;

interface Props {
  searchParams: Promise<{ search?: string; role?: string; page?: string; balance?: string }>;
}

export default async function UsersPage({ searchParams }: Props) {
  const { search = "", role = "", page = "1", balance = "" } = await searchParams;
  const currentPage = Math.max(1, parseInt(page) || 1);
  const skip = (currentPage - 1) * PAGE_SIZE;

  // Collect userIds with non-zero balance if filter is active
  let balanceUserIds: string[] | null = null;
  if (balance === "nonzero") {
    const groups = await prisma.balanceTransaction.groupBy({
      by: ["userId"],
      _sum: { amount: true },
      having: { amount: { _sum: { not: { equals: 0 } } } },
    });
    balanceUserIds = groups.map((g) => g.userId);
  }

  const where = {
    ...(search
      ? {
          OR: [
            { name: { contains: search, mode: "insensitive" as const } },
            { email: { contains: search, mode: "insensitive" as const } },
          ],
        }
      : {}),
    ...(role ? { role } : {}),
    ...(balanceUserIds !== null ? { id: { in: balanceUserIds } } : {}),
  };

  const [users, total] = await Promise.all([
    prisma.user.findMany({
      where,
      orderBy: { createdAt: "desc" },
      skip,
      take: PAGE_SIZE,
      include: {
        _count: { select: { enrollments: true } },
        enrollments: {
          include: { course: { select: { title: true } } },
          orderBy: { enrolledAt: "desc" },
        },
      },
    }),
    prisma.user.count({ where }),
  ]);

  const totalPages = Math.ceil(total / PAGE_SIZE);

  const tableUsers = users.map((u) => ({
    id: u.id,
    name: u.name,
    email: u.email,
    role: u.role,
    emailVerified: u.emailVerified,
    createdAt: u.createdAt,
    enrollmentCount: u._count.enrollments,
    enrollments: u.enrollments.map((e) => ({
      courseId: e.courseId,
      courseTitle: e.course.title,
      expiresAt: e.expiresAt,
    })),
  }));

  function pageUrl(p: number) {
    const params = new URLSearchParams();
    if (search) params.set("search", search);
    if (role) params.set("role", role);
    if (balance) params.set("balance", balance);
    params.set("page", String(p));
    return `/admin/users?${params.toString()}`;
  }

  return (
    <div className="p-8">
      <div className="mb-5 flex items-center justify-between">
        <div>
          <h1 className="text-2xl font-semibold text-slate-800">Пользователи</h1>
          <p className="text-slate-500 text-sm mt-0.5">{total} пользователей</p>
        </div>
        <Link
          href="/admin/users/new"
          className="btn-aubade btn-aubade-accent flex items-center gap-1.5 px-4 py-2 text-sm"
        >
          <UserPlus size={14} />
          Добавить пользователя
        </Link>
      </div>

      {/* Filters */}
      <Suspense>
        <UsersSearch initialSearch={search} initialRole={role} initialBalance={balance} />
      </Suspense>

      <UsersTable users={tableUsers} />

      {/* Pagination */}
      {totalPages > 1 && (
        <div className="flex items-center gap-1 mt-4">
          {currentPage > 1 && (
            <Link href={pageUrl(currentPage - 1)} className="btn-aubade px-3 py-1 text-xs">←</Link>
          )}
          {Array.from({ length: totalPages }, (_, i) => i + 1)
            .filter((p) => p === 1 || p === totalPages || Math.abs(p - currentPage) <= 2)
            .reduce<(number | "…")[]>((acc, p, i, arr) => {
              if (i > 0 && (p as number) - (arr[i - 1] as number) > 1) acc.push("…");
              acc.push(p);
              return acc;
            }, [])
            .map((p, i) =>
              p === "…" ? (
                <span key={`e${i}`} className="px-2 text-xs" style={{ color: "var(--muted-foreground)" }}>…</span>
              ) : (
                <Link key={p} href={pageUrl(p as number)} className="px-3 py-1 text-xs"
                  style={{ border: "2px solid var(--border)", background: p === currentPage ? "var(--foreground)" : "transparent", color: p === currentPage ? "var(--background)" : "var(--foreground)" }}>
                  {p}
                </Link>
              )
            )}
          {currentPage < totalPages && (
            <Link href={pageUrl(currentPage + 1)} className="btn-aubade px-3 py-1 text-xs">→</Link>
          )}
          <span className="ml-2 text-xs" style={{ color: "var(--muted-foreground)" }}>стр. {currentPage} из {totalPages}</span>
        </div>
      )}
    </div>
  );
}