"use client";

import { useMemo, useState } from "react";
import Link from "next/link";
import {
  Plus,
  Pencil,
  Trash2,
  Loader2,
  ExternalLink,
  FileText,
} from "lucide-react";
import {
  apiAdminDeleteSitePage,
  type SitePage,
} from "@/lib/api";
import { formatRelative } from "@/lib/format";
import { toast } from "@/lib/toast";
import ConfirmDialog from "@/components/ConfirmDialog";
import {
  AdminEmpty,
  AdminIconButton,
  AdminPageHeader,
  AdminSegmented,
  AdminSettingsPage,
  AdminStatusChip,
} from "@/components/admin";

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

export default function PagesAdmin({
  initial,
  initError,
}: {
  initial: SitePage[];
  initError: string;
}) {
  const [list, setList] = useState(initial);
  const [loadError, setLoadError] = useState(initError);
  const [statusFilter, setStatusFilter] = useState<StatusFilter>("all");
  const [deletingId, setDeletingId] = useState<number | null>(null);
  const [deleteTarget, setDeleteTarget] = useState<SitePage | null>(null);

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

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

  async function remove(p: SitePage) {
    setDeletingId(p.id);
    try {
      await apiAdminDeleteSitePage(p.id);
      setList((l) => l.filter((x) => x.id !== p.id));
      toast("页面已删除", "ok");
    } catch (e) {
      toast(e instanceof Error ? e.message : "删除失败");
    } finally {
      setDeletingId(null);
      setDeleteTarget(null);
    }
  }

  return (
    <AdminSettingsPage>
      <AdminPageHeader
        icon={FileText}
        title="单页管理"
        description="关于本站、隐私政策等自定义 Markdown 单页；可展示在首页右栏"
        actions={
          <Link href="/admin/pages/new" className="btn btn-primary">
            <Plus size={15} /> 新建单页
          </Link>
        }
      />

      <div className="mb-4">
        <AdminSegmented<StatusFilter>
          ariaLabel="单页状态筛选"
          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)" }}>
            单页列表
          </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={<FileText size={22} />}
            title={list.length === 0 ? "还没有单页" : "该状态下暂无单页"}
            description={list.length === 0 ? "创建关于本站等内容页" : "试试切换筛选条件"}
          />
        ) : (
          filtered.map((p, idx) => (
            <div
              key={p.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">
                <div className="min-w-0 flex-1">
                  <div className="flex items-center gap-1.5 flex-wrap">
                    <p
                      className="text-[14px] font-medium truncate max-w-full"
                      style={{ color: "var(--ink)" }}
                      data-tip={p.title}
                    >
                      {p.title}
                    </p>
                    <code className="meta text-[11.5px] tabular-nums">/{p.slug}</code>
                    <AdminStatusChip tone={p.published ? "ok" : "warn"}>
                      {p.published ? "已发布" : "草稿"}
                    </AdminStatusChip>
                    {p.show_in_sidebar ? (
                      <AdminStatusChip tone="accent">侧栏</AdminStatusChip>
                    ) : null}
                    <span className="meta text-[11px] tabular-nums shrink-0">
                      排序 {p.sort_order} · {formatRelative(p.updated_at || p.created_at)}
                    </span>
                  </div>
                  {p.excerpt ? (
                    <p className="meta text-[12.5px] mt-1 line-clamp-1">{p.excerpt}</p>
                  ) : null}
                </div>
                <span className="inline-flex items-center gap-0.5 shrink-0">
                  {p.published ? (
                    <AdminIconButton
                      href={`/p/${p.slug}`}
                      tip="查看前台"
                      ariaLabel="查看单页"
                    >
                      <ExternalLink size={14} />
                    </AdminIconButton>
                  ) : null}
                  <AdminIconButton
                    href={`/admin/pages/${p.id}/edit`}
                    tip="编辑"
                    ariaLabel="编辑单页"
                  >
                    <Pencil size={14} />
                  </AdminIconButton>
                  <AdminIconButton
                    tip="删除"
                    ariaLabel="删除单页"
                    tone="danger"
                    disabled={deletingId === p.id}
                    onClick={() => setDeleteTarget(p)}
                  >
                    {deletingId === p.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/pages/new" className="btn btn-primary">
              <Plus size={15} /> 新建第一页
            </Link>
          </div>
        ) : null}
      </div>

      <ConfirmDialog
        open={!!deleteTarget}
        title="删除单页"
        message={deleteTarget ? `确定删除「${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);
        }}
      />
    </AdminSettingsPage>
  );
}