import { useMutation, useQuery } from "@tanstack/react-query";
import type { AxiosError } from "axios";
import {
  ChevronLeft,
  ChevronRight,
  Pencil,
  Plus,
  RefreshCw,
  Search,
  Trash2,
  User,
} from "lucide-react";
import * as React from "react";
import { Link, useNavigate } from "react-router-dom";
import { Badge } from "../../components/ui/badge";
import { Button } from "../../components/ui/button";
import {
  Card,
  CardContent,
  CardDescription,
  CardHeader,
  CardTitle,
} from "../../components/ui/card";
import { Input } from "../../components/ui/input";
import {
  Table,
  TableBody,
  TableCell,
  TableHead,
  TableHeader,
  TableRow,
} from "../../components/ui/table";
import { deleteUser, fetchUsers } from "../../lib/adminApi";

function UserListPage() {
  const navigate = useNavigate();
  const [page, setPage] = React.useState(1);
  const [search, setSearch] = React.useState("");
  const [searchDraft, setSearchDraft] = React.useState("");
  const limit = 50;
  const offset = (page - 1) * limit;

  const query = useQuery({
    queryKey: ["users", { limit, offset, search }],
    queryFn: () => fetchUsers(limit, offset, search),
    placeholderData: (previousData) => previousData,
  });

  const deleteMutation = useMutation({
    mutationFn: (userId: string) => deleteUser(userId),
    onSuccess: () => {
      query.refetch();
    },
  });

  const handleSearch = () => {
    setSearch(searchDraft);
    setPage(1);
  };

  const handleKeyDown = (e: React.KeyboardEvent) => {
    if (e.key === "Enter") {
      handleSearch();
    }
  };

  const errorMsg = (query.error as AxiosError<{ error?: string }>)?.response
    ?.data?.error;
  const fallbackError =
    !errorMsg && query.isError ? "사용자 목록 조회에 실패했습니다." : null;

  const items = query.data?.items ?? [];
  const total = query.data?.total ?? 0;
  const totalPages = Math.ceil(total / limit);

  const handleDelete = (userId: string, userName: string) => {
    if (!window.confirm(`사용자 "${userName}"을(를) 정말 삭제하시겠습니까?`)) {
      return;
    }
    deleteMutation.mutate(userId);
  };

  return (
    <div className="space-y-8">
      <header className="flex flex-wrap items-start justify-between gap-4">
        <div className="space-y-2">
          <div className="flex items-center gap-2 text-sm text-[var(--color-muted)]">
            <span>Users</span>
            <span>/</span>
            <span className="text-foreground">List</span>
          </div>
          <h2 className="text-3xl font-semibold">사용자 관리</h2>
          <p className="text-sm text-[var(--color-muted)]">
            시스템 사용자를 조회하고 관리합니다. (Local DB)
          </p>
        </div>
        <div className="flex items-center gap-2">
          <Button
            variant="outline"
            onClick={() => query.refetch()}
            disabled={query.isFetching}
          >
            <RefreshCw size={16} />
            새로고침
          </Button>
          <Button asChild>
            <Link to="/users/new">
              <Plus size={16} />
              사용자 추가
            </Link>
          </Button>
        </div>
      </header>

      <Card className="bg-[var(--color-panel)]">
        <CardHeader className="flex flex-row items-center justify-between">
          <div>
            <CardTitle>User Registry</CardTitle>
            <CardDescription>
              총 {total}명의 사용자가 등록되어 있습니다.
            </CardDescription>
          </div>
        </CardHeader>
        <CardContent>
          <div className="mb-4 flex items-center gap-2">
            <div className="relative flex-1 max-w-sm">
              <Search className="absolute left-2.5 top-2.5 h-4 w-4 text-muted-foreground" />
              <Input
                placeholder="이름 또는 이메일 검색..."
                className="pl-9"
                value={searchDraft}
                onChange={(e) => setSearchDraft(e.target.value)}
                onKeyDown={handleKeyDown}
              />
            </div>
            <Button variant="secondary" onClick={handleSearch}>
              검색
            </Button>
          </div>

          {(errorMsg || fallbackError) && (
            <div className="mb-4 rounded-lg border border-destructive/40 bg-destructive/10 px-3 py-2 text-sm text-destructive">
              {errorMsg ?? fallbackError}
            </div>
          )}

          <div className="rounded-md border">
            <Table>
              <TableHeader>
                <TableRow>
                  <TableHead>NAME / EMAIL</TableHead>
                  <TableHead>ROLE</TableHead>
                  <TableHead>STATUS</TableHead>
                  <TableHead>COMPANY / DEPT</TableHead>
                  <TableHead>CREATED</TableHead>
                  <TableHead className="text-right">ACTIONS</TableHead>
                </TableRow>
              </TableHeader>
              <TableBody>
                {query.isLoading && (
                  <TableRow>
                    <TableCell colSpan={6} className="h-24 text-center">
                      로딩 중...
                    </TableCell>
                  </TableRow>
                )}
                {!query.isLoading && items.length === 0 && (
                  <TableRow>
                    <TableCell colSpan={6} className="h-24 text-center">
                      검색 결과가 없습니다.
                    </TableCell>
                  </TableRow>
                )}
                {items.map((user) => (
                  <TableRow key={user.id}>
                    <TableCell>
                      <div className="flex items-center gap-3">
                        <div className="flex h-9 w-9 items-center justify-center rounded-full bg-secondary text-secondary-foreground">
                          <User size={16} />
                        </div>
                        <div className="flex flex-col">
                          <span className="font-medium">{user.name}</span>
                          <span className="text-xs text-muted-foreground">
                            {user.email}
                          </span>
                        </div>
                      </div>
                    </TableCell>
                    <TableCell>
                      <Badge variant="outline">{user.role}</Badge>
                    </TableCell>
                    <TableCell>
                      <Badge
                        variant={
                          user.status === "active" ? "default" : "secondary"
                        }
                      >
                        {user.status}
                      </Badge>
                    </TableCell>
                    <TableCell>
                      <div className="flex flex-col text-sm">
                        <span>{user.companyCode || "-"}</span>
                        <span className="text-xs text-muted-foreground">
                          {user.department || "-"}
                        </span>
                      </div>
                    </TableCell>
                    <TableCell className="text-sm text-muted-foreground">
                      {new Date(user.createdAt).toLocaleDateString()}
                    </TableCell>
                    <TableCell className="text-right">
                      <div className="flex justify-end gap-2">
                        <Button
                          variant="ghost"
                          size="icon"
                          onClick={() => navigate(`/users/${user.id}`)}
                        >
                          <Pencil size={16} />
                        </Button>
                        <Button
                          variant="ghost"
                          size="icon"
                          className="text-destructive hover:text-destructive"
                          onClick={() => handleDelete(user.id, user.name)}
                          disabled={deleteMutation.isPending}
                        >
                          <Trash2 size={16} />
                        </Button>
                      </div>
                    </TableCell>
                  </TableRow>
                ))}
              </TableBody>
            </Table>
          </div>

          {/* Pagination */}
          {totalPages > 1 && (
            <div className="mt-4 flex items-center justify-end gap-2">
              <Button
                variant="outline"
                size="sm"
                onClick={() => setPage((p) => Math.max(1, p - 1))}
                disabled={page === 1 || query.isFetching}
              >
                <ChevronLeft size={16} />
                Previous
              </Button>
              <div className="text-sm text-muted-foreground">
                Page {page} of {totalPages}
              </div>
              <Button
                variant="outline"
                size="sm"
                onClick={() => setPage((p) => Math.min(totalPages, p + 1))}
                disabled={page === totalPages || query.isFetching}
              >
                Next
                <ChevronRight size={16} />
              </Button>
            </div>
          )}
        </CardContent>
      </Card>
    </div>
  );
}

export default UserListPage;