"use client";

import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import Link from "next/link";
import { useRouter, useSearchParams } from "next/navigation";
import { Ellipsis, ExternalLink, Loader2, Megaphone, Plus } from "lucide-react";
import {
  apiAdminDeleteAnnouncement,
  apiAdminListAnnouncements,
  apiAdminToggleAnnouncementPin,
  type Announcement,
} from "@/lib/api";
import { formatDateTime, formatRelative } from "@/lib/format";
import { toast } from "@/lib/toast";
import ConfirmDialog from "@/components/ConfirmDialog";
import { useUrlStyle } from "@/components/SiteBrandProvider";
import {
  AdminEmpty,
  AdminPageHeader,
  AdminSegmented,
  AdminStatusChip,
} from "@/components/admin";
import { announcementPublicPath } from "./announcementColors";

type StatusFilter = "all" | "published" | "draft";

function readStatus(raw: string | null): StatusFilter {
  if (raw === "published" || raw === "draft") return raw;
  return "all";
}

function listHref(status: StatusFilter): string {
  return status === "all" ? "/admin/announcements" : `/admin/announcements?status=${status}`;
}

function newHref(status: StatusFilter): string {
  return status === "all" ? "/admin/announcements/new" : `/admin/announcements/new?status=${status}`;
}

function editHref(id: number, status: StatusFilter): string {
  const base = `/admin/announcements/${id}/edit`;
  return status === "all" ? base : `${base}?status=${status}`;
}

/** 粗略去掉 Markdown，取一行摘要。只用于列表预览，不改库存正文。 */
function plainSummary(md: string, max = 80): string {
  const text = md
    .replace(/```[\s\S]*?```/g, " ")
    .replace(/!\[[^\]]*\]\([^)]+\)/g, " ")
    .replace(/\[([^\]]+)\]\([^)]+\)/g, "$1")
    .replace(/[#>*_`~\-|=]/g, "")
    .replace(/\s+/g, " ")
    .trim();
  return text.length > max ? `${text.slice(0, max)}…` : text;
}

export default function AnnouncementAdmin({
  initial,
  initError,
}: {
  initial: Announcement[];
  initError: string;
}) {
  const router = useRouter();
  const searchParams = useSearchParams();
  const urlStyle = useUrlStyle();
  const statusFilter = readStatus(searchParams.get("status"));
  const [list, setList] = useState(initial);
  const [loadError, setLoadError] = useState(initError);
  const [pinningId, setPinningId] = useState<number | null>(null);
  const [deletingId, setDeletingId] = useState<number | null>(null);
  const [deleteTarget, setDeleteTarget] = useState<Announcement | null>(null);
  const [menuId, setMenuId] = useState<number | null>(null);
  const [menuUp, setMenuUp] = useState(false);
  const menuRef = useRef<HTMLDivElement>(null);

  const publishedCount = useMemo(() => list.filter((a) => a.published).length, [list]);
  const draftCount = useMemo(() => list.filter((a) => !a.published).length, [list]);

  const filtered = useMemo(() => {
    if (statusFilter === "published") return list.filter((a) => a.published);
    if (statusFilter === "draft") return list.filter((a) => !a.published);
    return list;
  }, [list, statusFilter]);

  const load = useCallback(async () => {
    try {
      const res = await apiAdminListAnnouncements();
      setList(res.announcements);
      setLoadError("");
    } catch (e) {
      setLoadError(e instanceof Error ? e.message : "加载公告失败");
    }
  }, []);

  useEffect(() => {
    if (menuId == null) return;
    const onPointer = (e: MouseEvent) => {
      if (menuRef.current && !menuRef.current.contains(e.target as Node)) setMenuId(null);
    };
    const onKey = (e: KeyboardEvent) => {
      if (e.key === "Escape") setMenuId(null);
    };
    document.addEventListener("mousedown", onPointer);
    document.addEventListener("keydown", onKey);
    return () => {
      document.removeEventListener("mousedown", onPointer);
      document.removeEventListener("keydown", onKey);
    };
  }, [menuId]);

  function setStatus(next: StatusFilter) {
    router.replace(listHref(next), { scroll: false });
  }

  async function togglePin(a: Announcement) {
    if (pinningId != null) return;
    setPinningId(a.id);
    try {
      await apiAdminToggleAnnouncementPin(a.id);
      toast(a.pinned ? "已取消置顶" : "已置顶", "ok");
      await load();
    } catch (e) {
      toast(e instanceof Error ? e.message : "置顶失败");
    } finally {
      setPinningId(null);
    }
  }

  async function remove(a: Announcement) {
    setDeletingId(a.id);
    try {
      await apiAdminDeleteAnnouncement(a.id);
      setList((l) => l.filter((x) => x.id !== a.id));
      toast("公告已删除", "ok");
    } catch (e) {
      toast(e instanceof Error ? e.message : "删除失败");
    } finally {
      setDeletingId(null);
      setDeleteTarget(null);
      setMenuId(null);
    }
  }

  return (
    <div className="admin-doc-page admin-doc-list">
      <AdminPageHeader
        icon={Megaphone}
        title="站点公告管理"
        description="已发布的公告出现在首页右栏，置顶的排在前面。"
        actions={
          <Link href={newHref(statusFilter)} className="btn btn-primary">
            <Plus size={15} /> 新建公告
          </Link>
        }
      />

      <div className="mb-4">
        <AdminSegmented<StatusFilter>
          ariaLabel="公告状态筛选"
          size="sm"
          value={statusFilter}
          onChange={setStatus}
          options={[
            { key: "all", label: "全部", count: list.length },
            { key: "published", label: "已发布", count: publishedCount },
            { key: "draft", label: "草稿", count: draftCount },
          ]}
        />
      </div>

      <div className="panel min-w-0">
        <div
          className="px-4 sm:px-5 py-3 flex items-center justify-between"
          style={{ borderBottom: "1px solid var(--line)" }}
        >
          <span className="font-medium text-[14px]" style={{ color: "var(--ink)" }}>
            公告列表
          </span>
          <span className="meta text-[12px] tabular-nums">共 {filtered.length} 条</span>
        </div>

        {loadError ? (
          <p className="alert-error m-4">{loadError}</p>
        ) : filtered.length === 0 ? (
          <AdminEmpty
            icon={<Megaphone size={22} />}
            title={list.length === 0 ? "还没有公告" : "该状态下暂无公告"}
            description={
              list.length === 0 ? "发布第一条站点公告，会出现在首页右栏" : "试试切换筛选条件"
            }
          />
        ) : (
          <div className="admin-doc-table-wrap">
            <table className="admin-doc-table">
              <caption className="sr-only">公告列表</caption>
              <thead>
                <tr>
                  <th scope="col">公告</th>
                  <th scope="col">状态</th>
                  <th scope="col">置顶</th>
                  <th scope="col">最近更新</th>
                  <th scope="col">操作</th>
                </tr>
              </thead>
              <tbody>
                {filtered.map((a) => {
                  const summary = plainSummary(a.content);
                  const updated = a.updated_at || "";
                  return (
                    <tr key={a.id}>
                      <td data-label="公告">
                        <Link href={editHref(a.id, statusFilter)} className="admin-doc-title" title={a.title}>
                          {a.title}
                        </Link>
                        <p className="admin-doc-path">
                          <span className={`j13-anno-tag is-${a.tag_color}`} title={a.tag}>
                            {a.tag}
                          </span>
                          {a.published ? <code>{announcementPublicPath(a.id, urlStyle)}</code> : null}
                        </p>
                        {summary ? <p className="admin-doc-excerpt" title={summary}>{summary}</p> : null}
                      </td>
                      <td data-label="状态">
                        <AdminStatusChip tone={a.published ? "ok" : "warn"}>
                          {a.published ? "已发布" : "草稿"}
                        </AdminStatusChip>
                      </td>
                      <td data-label="置顶">{a.pinned ? "置顶" : "未置顶"}</td>
                      <td data-label="最近更新">
                        {updated ? (
                          <time dateTime={updated} title={formatDateTime(updated)}>
                            {formatRelative(updated)}
                          </time>
                        ) : (
                          "—"
                        )}
                      </td>
                      <td data-label="操作">
                        <div className="admin-doc-row-actions">
                          <Link href={editHref(a.id, statusFilter)} className="admin-doc-textbtn">
                            编辑
                          </Link>
                          {a.published ? (
                            <a
                              href={announcementPublicPath(a.id, urlStyle)}
                              target="_blank"
                              rel="noopener noreferrer"
                              className="admin-doc-textbtn"
                            >
                              <ExternalLink size={14} aria-hidden />
                              查看
                            </a>
                          ) : null}
                          <button
                            type="button"
                            className="admin-doc-textbtn"
                            disabled={pinningId === a.id}
                            onClick={() => void togglePin(a)}
                          >
                            {pinningId === a.id ? (
                              <Loader2 size={14} className="animate-spin" aria-hidden />
                            ) : null}
                            {a.pinned ? "取消置顶" : "置顶"}
                          </button>
                          <div className="admin-doc-more" ref={menuId === a.id ? menuRef : undefined}>
                            <button
                              type="button"
                              className="admin-doc-textbtn"
                              aria-haspopup="menu"
                              aria-expanded={menuId === a.id}
                              aria-label={`「${a.title}」的更多操作`}
                              onClick={(e) => {
                                const rect = e.currentTarget.getBoundingClientRect();
                                setMenuUp(rect.bottom > window.innerHeight - 140);
                                setMenuId((cur) => (cur === a.id ? null : a.id));
                              }}
                            >
                              <Ellipsis size={16} aria-hidden />
                              更多
                            </button>
                            {menuId === a.id ? (
                              <div className={`admin-doc-menu${menuUp ? " is-up" : ""}`} role="menu">
                                <button
                                  type="button"
                                  role="menuitem"
                                  className="admin-doc-menu-item is-danger"
                                  disabled={deletingId === a.id}
                                  onClick={() => {
                                    setMenuId(null);
                                    setDeleteTarget(a);
                                  }}
                                >
                                  删除
                                </button>
                              </div>
                            ) : null}
                          </div>
                        </div>
                      </td>
                    </tr>
                  );
                })}
              </tbody>
            </table>
          </div>
        )}

        {list.length === 0 && !loadError ? (
          <div className="px-4 sm:px-5 pb-5 -mt-2 flex justify-center">
            <Link href={newHref(statusFilter)} className="btn btn-primary">
              <Plus size={15} /> 新建第一条公告
            </Link>
          </div>
        ) : null}
        {list.length >= 100 ? (
          <p className="meta text-[12px] px-4 sm:px-5 py-3">后台一次最多列出 100 条。</p>
        ) : null}
      </div>

      <ConfirmDialog
        open={!!deleteTarget}
        title="删除公告"
        message={
          deleteTarget
            ? `确定删除「${deleteTarget.title}」吗？当前为${deleteTarget.published ? "已发布" : "草稿"}。删除后前台不再显示，后台也不能恢复。`
            : ""
        }
        danger
        busy={deletingId != null}
        confirmLabel="删除"
        onCancel={() => deletingId == null && setDeleteTarget(null)}
        onConfirm={() => {
          if (deleteTarget) void remove(deleteTarget);
        }}
      />
    </div>
  );
}