"use client";

import { useCallback, useEffect, useState } from "react";
import { ChevronDown, ChevronUp, Pin } from "lucide-react";
import {
  apiAdminPinnedPosts,
  apiAdminSavePinOrder,
  type AdminPinnedPost,
} from "@/lib/api";
import AdminPageHeader from "@/components/admin/AdminPageHeader";
import AdminEmpty from "@/components/admin/AdminEmpty";
import { toast } from "@/lib/toast";

interface BoardOpt {
  id: number;
  name: string;
}

interface PinnedAdminProps {
  boards: BoardOpt[];
  /** 管理员及以上：可排全站置顶 */
  canGlobal: boolean;
}

type Level = 1 | 2;

export default function PinnedAdmin({ boards, canGlobal }: PinnedAdminProps) {
  const [level, setLevel] = useState<Level>(canGlobal ? 2 : 1);
  const [boardId, setBoardId] = useState<number>(boards[0]?.id ?? 0);
  const [posts, setPosts] = useState<AdminPinnedPost[]>([]);
  const [loading, setLoading] = useState(true);
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState("");

  const load = useCallback(async (lv: Level, bid: number) => {
    setLoading(true);
    setError("");
    try {
      const r = await apiAdminPinnedPosts(lv, lv === 1 ? bid : undefined);
      setPosts(r.posts ?? []);
    } catch (e) {
      setPosts([]);
      setError(e instanceof Error ? e.message : "获取置顶列表失败");
    } finally {
      setLoading(false);
    }
  }, []);

  useEffect(() => {
    void load(level, boardId);
  }, [level, boardId, load]);

  const switchLevel = (lv: Level) => {
    if (lv === level) return;
    setLevel(lv);
    setPosts([]);
  };

  // 上移/下移：乐观交换后整体保存顺序，失败回滚
  const move = async (idx: number, dir: -1 | 1) => {
    const target = idx + dir;
    if (target < 0 || target >= posts.length || busy) return;
    const prev = posts;
    const next = [...posts];
    const tmp = next[idx];
    next[idx] = next[target];
    next[target] = tmp;
    setPosts(next);
    setBusy(true);
    setError("");
    try {
      await apiAdminSavePinOrder(level, level === 1 ? boardId : 0, next.map((p) => p.id));
    } catch (e) {
      setPosts(prev);
      setError(e instanceof Error ? e.message : "保存顺序失败");
    } finally {
      setBusy(false);
    }
  };

  const tabCls = (active: boolean) =>
    `px-3.5 py-2 text-[13px] font-semibold rounded-[var(--r-sm)] transition-colors ${
      active ? "" : "hover:bg-[var(--panel-2)]"
    }`;

  return (
    <div>
      <AdminPageHeader
        icon={Pin}
        title="置顶管理"
        description="调整置顶帖在列表中的显示顺序，越靠前越先展示。板块管理员仅可排序授权板块的板块置顶。"
      />

      {error && (
        <div
          className="mb-3 px-3 py-2 rounded-[var(--r-sm)] text-[12.5px]"
          style={{ background: "var(--danger-soft)", color: "var(--danger)" }}
        >
          {error}
        </div>
      )}

      {/* 层级切换 + 板块选择 */}
      <div className="mb-4 flex items-center gap-3 flex-wrap">
        <div
          className="inline-flex items-center gap-1 p-1 rounded-[var(--r-sm)]"
          style={{ background: "var(--panel-2)" }}
          role="tablist"
        >
          {canGlobal && (
            <button
              type="button"
              role="tab"
              aria-selected={level === 2}
              className={tabCls(level === 2)}
              style={
                level === 2
                  ? { background: "var(--panel)", color: "var(--ink)", boxShadow: "var(--shadow-sm)" }
                  : { color: "var(--ink-3)" }
              }
              onClick={() => switchLevel(2)}
            >
              全站置顶
            </button>
          )}
          <button
            type="button"
            role="tab"
            aria-selected={level === 1}
            className={tabCls(level === 1)}
            style={
              level === 1
                ? { background: "var(--panel)", color: "var(--ink)", boxShadow: "var(--shadow-sm)" }
                : { color: "var(--ink-3)" }
            }
            onClick={() => switchLevel(1)}
          >
            板块置顶
          </button>
        </div>

        {level === 1 && (
          <select
            className="input text-[13px] py-2"
            style={{ minWidth: 160 }}
            value={boardId}
            onChange={(e) => setBoardId(Number(e.target.value))}
            aria-label="选择板块"
          >
            {boards.length === 0 && <option value={0}>无可用板块</option>}
            {boards.map((b) => (
              <option key={b.id} value={b.id}>
                {b.name}
              </option>
            ))}
          </select>
        )}
      </div>

      <div className="panel overflow-hidden">
        {loading ? (
          <p className="meta text-center py-14 text-[13px]">加载中…</p>
        ) : posts.length === 0 ? (
          <AdminEmpty
            icon={<Pin size={20} />}
            title={level === 2 ? "暂无全站置顶帖" : "该板块暂无置顶帖"}
            description="在帖子页的「管理」菜单中可将帖子设为置顶。"
          />
        ) : (
          <ul>
            {posts.map((p, i) => (
              <li
                key={p.id}
                className="flex items-center gap-3 px-4 py-3"
                style={{ borderTop: i === 0 ? "none" : "1px solid var(--line)" }}
              >
                <span
                  className="w-6 text-center text-[12.5px] font-bold tabular-nums shrink-0"
                  style={{ color: "var(--ink-3)" }}
                >
                  {i + 1}
                </span>
                <div className="flex flex-col gap-0.5 shrink-0">
                  <button
                    type="button"
                    className="admin-icon-btn"
                    onClick={() => void move(i, -1)}
                    disabled={i === 0 || busy}
                    aria-label="上移"
                  >
                    <ChevronUp size={14} />
                  </button>
                  <button
                    type="button"
                    className="admin-icon-btn"
                    onClick={() => void move(i, 1)}
                    disabled={i === posts.length - 1 || busy}
                    aria-label="下移"
                  >
                    <ChevronDown size={14} />
                  </button>
                </div>
                <div className="min-w-0 flex-1">
                  <a
                    href={`/post/${p.id}`}
                    target="_blank"
                    rel="noreferrer"
                    className="text-[13.5px] font-semibold truncate block hover:underline"
                    style={{ color: "var(--ink)" }}
                  >
                    {p.title}
                  </a>
                  <p className="meta text-[12px] truncate">
                    {p.board_name} · {new Date(p.created_at).toLocaleDateString("zh-CN")}
                  </p>
                </div>
              </li>
            ))}
          </ul>
        )}
      </div>
    </div>
  );
}