"use client";

import { useCallback, useMemo, useState } from "react";
import Link from "next/link";
import {
  Plus,
  Pencil,
  Trash2,
  Loader2,
  ExternalLink,
  Megaphone,
  Pin,
} from "lucide-react";
import {
  apiAdminListAnnouncements,
  apiAdminDeleteAnnouncement,
  apiAdminToggleAnnouncementPin,
  type Announcement,
} from "@/lib/api";
import { formatRelative } from "@/lib/format";
import { toast } from "@/lib/toast";
import ConfirmDialog from "@/components/ConfirmDialog";
import {
  AdminEmpty,
  AdminIconButton,
  AdminPageHeader,
  AdminSegmented,
  AdminStatusChip,
} from "@/components/admin";

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

/** 粗略去掉 Markdown，取一行摘要 */
function plainSummary(md: string, max = 96): 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 [list, setList] = useState(initial);
  const [loadError, setLoadError] = useState(initError);
  const [statusFilter, setStatusFilter] = useState<StatusFilter>("all");
  const [pinningId, setPinningId] = useState<number | null>(null);
  const [deletingId, setDeletingId] = useState<number | null>(null);
  const [deleteTarget, setDeleteTarget] = useState<Announcement | null>(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");
    }
  }, []);

  async function togglePin(a: Announcement) {
    if (pinningId != null) return;
    setPinningId(a.id);
    try {
      const res = await apiAdminToggleAnnouncementPin(a.id);
      setList((prev) => prev.map((x) => (x.id === a.id ? res.announcement : x)));
      toast(res.announcement.pinned ? "已置顶" : "已取消置顶", "ok");
      // 置顶后列表顺序可能变化，重新拉一次对齐后端排序
      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);
    }
  }

  return (
    <div>
      <AdminPageHeader
        icon={Megaphone}
        title="站点公告管理"
        description="发布、编辑与下线右栏站点公告，支持置顶与自定义标签色"
        actions={
          <Link href="/admin/announcements/new" 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={setStatusFilter}
          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 overflow-hidden 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"
            }
          />
        ) : (
          filtered.map((a, idx) => {
            const summary = plainSummary(a.content);
            return (
              <div
                key={a.id}
                className="px-4 sm:px-5 py-3.5"
                style={{
                  borderTop: idx === 0 ? undefined : "1px solid var(--line)",
                }}
              >
                <div className="flex items-start gap-3 min-w-0">
                  <span
                    className={`j13-anno-dot is-${a.tag_color} mt-1.5 shrink-0`}
                    aria-hidden
                    data-tip={a.tag}
                  />
                  <div className="min-w-0 flex-1">
                    <div className="flex items-center gap-1.5 flex-wrap">
                      {a.pinned ? (
                        <span className="badge-pin shrink-0">置顶</span>
                      ) : null}
                      <p
                        className="text-[14px] font-medium truncate max-w-full"
                        style={{ color: "var(--ink)" }}
                        data-tip={a.title}
                      >
                        {a.title}
                      </p>
                      <span className={`j13-anno-tag is-${a.tag_color}`}>{a.tag}</span>
                      <AdminStatusChip tone={a.published ? "ok" : "warn"}>
                        {a.published ? "已发布" : "草稿"}
                      </AdminStatusChip>
                      <span className="meta text-[11px] tabular-nums shrink-0">
                        {formatRelative(a.updated_at || a.created_at)}
                      </span>
                    </div>
                    {summary ? (
                      <p className="meta text-[12.5px] mt-1 line-clamp-1">{summary}</p>
                    ) : null}
                  </div>
                  <span className="inline-flex items-center gap-0.5 shrink-0">
                    <AdminIconButton
                      tip={a.pinned ? "取消置顶" : "置顶"}
                      ariaLabel={a.pinned ? "取消置顶" : "置顶公告"}
                      disabled={pinningId === a.id}
                      onClick={() => void togglePin(a)}
                    >
                      {pinningId === a.id ? (
                        <Loader2 size={14} className="animate-spin" />
                      ) : (
                        <Pin size={14} style={{ color: a.pinned ? "var(--accent)" : undefined }} />
                      )}
                    </AdminIconButton>
                    {a.published ? (
                      <AdminIconButton
                        href={`/announcement/${a.id}`}
                        tip="查看前台"
                        ariaLabel="查看公告"
                      >
                        <ExternalLink size={14} />
                      </AdminIconButton>
                    ) : null}
                    <AdminIconButton
                      href={`/admin/announcements/${a.id}/edit`}
                      tip="编辑"
                      ariaLabel="编辑公告"
                    >
                      <Pencil size={14} />
                    </AdminIconButton>
                    <AdminIconButton
                      tip="删除"
                      ariaLabel="删除公告"
                      tone="danger"
                      disabled={deletingId === a.id}
                      onClick={() => setDeleteTarget(a)}
                    >
                      {deletingId === a.id ? (
                        <Loader2 size={14} className="animate-spin" />
                      ) : (
                        <Trash2 size={14} />
                      )}
                    </AdminIconButton>
                  </span>
                </div>
              </div>
            );
          })
        )}

        {list.length === 0 && !loadError ? (
          <div className="px-4 sm:px-5 pb-5 -mt-2 flex justify-center">
            <Link href="/admin/announcements/new" className="btn btn-primary">
              <Plus size={15} /> 新建第一条公告
            </Link>
          </div>
        ) : null}
      </div>

      <ConfirmDialog
        open={!!deleteTarget}
        title="删除公告"
        message={deleteTarget ? `确定删除公告「${deleteTarget.title}」吗？此操作不可撤销。` : ""}
        danger
        busy={deletingId != null}
        confirmLabel="删除"
        onCancel={() => deletingId == null && setDeleteTarget(null)}
        onConfirm={() => {
          if (deleteTarget) void remove(deleteTarget);
        }}
      />
    </div>
  );
}