import { useState, useMemo, useCallback, useEffect } from "react";
import { useLocation, useNavigate } from "react-router-dom";
import { toast } from "sonner";
import PageHeader from "@/components/common/PageHeader";
import { MOCK_NOTIFICATIONS, type Notification, type NotificationType } from "../types";
import NotificationSlidePanel from "../components/NotificationSlidePanel";

// 타입별 배지 스타일
const BADGE_STYLE: Record<
  NotificationType,
  { bg: string; text: string; icon: string }
> = {
  "발송": { bg: "bg-green-50", text: "text-green-700", icon: "check_circle" },
  "인증서": { bg: "bg-amber-50", text: "text-amber-700", icon: "warning" },
  "서비스": { bg: "bg-blue-50", text: "text-blue-700", icon: "add_circle" },
  "실패": { bg: "bg-red-50", text: "text-red-600", icon: "error" },
  "시스템": { bg: "bg-gray-100", text: "text-gray-600", icon: "settings" },
};

// 날짜 그룹 레이블 → 표시 날짜
const DATE_LABELS: Record<string, string> = {
  "오늘": "2026-02-19",
  "어제": "2026-02-18",
  "이번 주": "2026.02.16 ~ 02.17",
};

const PAGE_SIZE = 5;

export default function NotificationsPage() {
  const location = useLocation();
  const navigate = useNavigate();
  const [notifications, setNotifications] = useState<Notification[]>(
    () => [...MOCK_NOTIFICATIONS],
  );
  const [currentPage, setCurrentPage] = useState(1);
  const [selectedNotification, setSelectedNotification] =
    useState<Notification | null>(null);

  // 헤더 드롭다운에서 넘어온 경우 해당 알림 패널 자동 오픈
  useEffect(() => {
    const state = location.state as { notificationId?: number } | null;
    if (state?.notificationId) {
      const target = notifications.find((n) => n.id === state.notificationId);
      if (target) {
        setSelectedNotification(target);
        // 읽음 처리
        if (!target.read) {
          setNotifications((prev) =>
            prev.map((n) =>
              n.id === target.id ? { ...n, read: true } : n,
            ),
          );
          setSelectedNotification({ ...target, read: true });
        }
      }
      // state 소비 후 제거 (새로고침 시 재트리거 방지)
      navigate(location.pathname, { replace: true, state: null });
    }
  }, [location.state]); // eslint-disable-line react-hooks/exhaustive-deps

  // 페이지네이션
  const totalItems = notifications.length;
  const totalPages = Math.max(1, Math.ceil(totalItems / PAGE_SIZE));
  const pagedNotifications = useMemo(
    () =>
      notifications.slice(
        (currentPage - 1) * PAGE_SIZE,
        currentPage * PAGE_SIZE,
      ),
    [notifications, currentPage],
  );

  // 페이징된 알림을 날짜별로 그룹핑
  const grouped = useMemo(() => {
    const map = new Map<string, Notification[]>();
    for (const n of pagedNotifications) {
      const arr = map.get(n.date) ?? [];
      arr.push(n);
      map.set(n.date, arr);
    }
    return map;
  }, [pagedNotifications]);

  // 전체 읽음
  const handleReadAll = useCallback(() => {
    setNotifications((prev) => prev.map((n) => ({ ...n, read: true })));
    toast.success("모든 알림을 읽음 처리했습니다");
  }, []);

  // 개별 읽음
  const handleReadOne = useCallback((id: number) => {
    setNotifications((prev) =>
      prev.map((n) => (n.id === id ? { ...n, read: true } : n)),
    );
    setSelectedNotification((prev) =>
      prev?.id === id ? { ...prev, read: true } : prev,
    );
  }, []);

  return (
    <>
      <PageHeader
        title="알림"
        description="시스템 알림과 발송 결과를 확인할 수 있습니다"
        action={
          <button
            onClick={handleReadAll}
            className="flex items-center gap-1.5 px-4 py-2 bg-white border border-gray-200 rounded-lg text-sm font-medium text-[#64748b] hover:bg-gray-50 hover:text-[#0f172a] transition-colors shadow-sm"
          >
            <span className="material-symbols-outlined text-base">
              done_all
            </span>
            전체 읽음
          </button>
        }
      />

      {/* 날짜별 그룹 */}
      {Array.from(grouped.entries()).map(([dateLabel, items]) => (
        <div key={dateLabel} className="mb-8">
          {/* 그룹 헤더 */}
          <div className="flex items-center gap-3 mb-3">
            <h2 className="text-xs font-bold text-[#64748b] uppercase tracking-wider">
              {dateLabel}
            </h2>
            <div className="flex-1 h-px bg-gray-200" />
            <span className="text-xs text-gray-400">
              {DATE_LABELS[dateLabel] ?? ""}
            </span>
          </div>

          {/* 알림 카드 목록 */}
          <div className="bg-white border border-gray-200 rounded-xl overflow-hidden shadow-sm">
            {items.map((notification, idx) => {
              const badge = BADGE_STYLE[notification.type];
              const isUnread = !notification.read;
              return (
                <div
                  key={notification.id}
                  onClick={() => {
                    setSelectedNotification(notification);
                    handleReadOne(notification.id);
                  }}
                  className={`flex items-start gap-4 px-5 py-4 cursor-pointer transition-colors ${
                    idx < items.length - 1
                      ? "border-b border-gray-100"
                      : ""
                  } ${
                    isUnread
                      ? "bg-blue-50/20 hover:bg-blue-50/30"
                      : "hover:bg-gray-50"
                  }`}
                >
                  {/* 읽음 상태 점 */}
                  <div className="flex-shrink-0 mt-0.5">
                    <div
                      className={`size-2.5 rounded-full ${
                        isUnread ? "bg-[#2563EB]" : "bg-gray-200"
                      }`}
                    />
                  </div>
                  {/* 콘텐츠 */}
                  <div className="flex-1 min-w-0">
                    <div className="flex items-center gap-2 mb-0.5">
                      <span
                        className={`inline-flex items-center gap-1 px-1.5 py-0.5 rounded ${badge.bg} ${badge.text} text-[10px] font-semibold`}
                      >
                        <span
                          className="material-symbols-outlined"
                          style={{ fontSize: "11px" }}
                        >
                          {badge.icon}
                        </span>
                        {notification.type}
                      </span>
                      <span className="text-xs text-gray-400">
                        {notification.time}
                      </span>
                    </div>
                    <p
                      className={`text-sm truncate ${
                        isUnread
                          ? "font-semibold text-[#0f172a]"
                          : "font-medium text-gray-600"
                      }`}
                    >
                      {notification.title}
                    </p>
                    <p
                      className={`text-xs truncate mt-0.5 ${
                        isUnread ? "text-gray-500" : "text-gray-400"
                      }`}
                    >
                      {notification.description}
                    </p>
                  </div>
                </div>
              );
            })}
          </div>
        </div>
      ))}

      {/* 페이지네이션 */}
      <div className="flex items-center justify-center gap-1 mt-10">
        <button
          onClick={() => setCurrentPage((p) => Math.max(1, p - 1))}
          disabled={currentPage === 1}
          className="size-9 flex items-center justify-center rounded-lg text-gray-400 hover:bg-gray-100 transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
        >
          <span className="material-symbols-outlined text-xl">
            chevron_left
          </span>
        </button>
        {Array.from({ length: totalPages }, (_, i) => i + 1).map((page) => (
          <button
            key={page}
            onClick={() => setCurrentPage(page)}
            className={`size-9 flex items-center justify-center rounded-lg text-sm font-medium transition-colors ${
              page === currentPage
                ? "bg-[#2563EB] text-white"
                : "text-gray-600 hover:bg-gray-100"
            }`}
          >
            {page}
          </button>
        ))}
        <button
          onClick={() => setCurrentPage((p) => Math.min(totalPages, p + 1))}
          disabled={currentPage === totalPages}
          className="size-9 flex items-center justify-center rounded-lg text-gray-400 hover:bg-gray-100 transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
        >
          <span className="material-symbols-outlined text-xl">
            chevron_right
          </span>
        </button>
      </div>

      {/* 알림 상세 패널 */}
      <NotificationSlidePanel
        isOpen={selectedNotification !== null}
        onClose={() => setSelectedNotification(null)}
        notification={selectedNotification}
        onMarkRead={handleReadOne}
      />
    </>
  );
}