/**
 * 桌面端 Header 主导航配置的单一事实源：
 * 与后端 service.HeaderNavBuiltinKeys 保持一致；Header 渲染、后台管理面板、公共设置 normalize 共用。
 *
 * 配置为有序数组，数组顺序即展示顺序：
 * - builtin 只存 key，文案/图标/地址/高亮由前端注册表派生（地址随伪静态风格变化）；
 * - custom 存文案 + 地址（站内路径或 http(s) 外链）。
 * 缺行/非法输入回落内置默认三项；显式空数组表示全部隐藏（前台不渲染导航）。
 * 后续新增内置页面：在本注册表与后端白名单各加一项，后台自动出现可选项。
 */

import { footerURLAllowed, isExternalFooterURL, runeCount } from "./brand.ts";

export const HEADER_NAV_BUILTIN_KEYS = ["home", "leaderboard", "library"] as const;

export type HeaderNavBuiltinKey = (typeof HEADER_NAV_BUILTIN_KEYS)[number];

/** 内置菜单默认文案；后台面板用同一文案 */
export const HEADER_NAV_BUILTIN_LABELS: Record<HeaderNavBuiltinKey, string> = {
  home: "首页",
  leaderboard: "排行榜",
  library: "书库",
};

export type HeaderNavBuiltinItem = { type: "builtin"; key: HeaderNavBuiltinKey };
export type HeaderNavCustomItem = {
  type: "custom";
  label: string;
  url: string;
  new_tab: boolean;
};
export type HeaderNavItem = HeaderNavBuiltinItem | HeaderNavCustomItem;

export const HEADER_NAV_LIMITS = {
  items: 8,
  label: 16,
  url: 200,
} as const;

/** 内置默认三项（缺行时回落） */
export const DEFAULT_HEADER_NAV: HeaderNavItem[] = HEADER_NAV_BUILTIN_KEYS.map((key) => ({
  type: "builtin" as const,
  key,
}));

export function isHeaderNavCustom(item: HeaderNavItem): item is HeaderNavCustomItem {
  return item.type === "custom";
}

/**
 * 宽容解析服务端配置：未知内置 key/重复内置/非法自定义项跳过；
 * 入参非数组回落默认；空数组原样返回（全部隐藏）。
 */
export function normalizeHeaderNav(raw: unknown): HeaderNavItem[] {
  if (!Array.isArray(raw)) return DEFAULT_HEADER_NAV.map((item) => ({ ...item }));
  const out: HeaderNavItem[] = [];
  const seenBuiltin = new Set<string>();
  for (const entry of raw) {
    if (!entry || typeof entry !== "object") continue;
    const rec = entry as Record<string, unknown>;
    const type = String(rec.type ?? "").trim();
    if (type === "builtin") {
      const key = String(rec.key ?? "")
        .trim()
        .toLowerCase();
      if (!(HEADER_NAV_BUILTIN_KEYS as readonly string[]).includes(key) || seenBuiltin.has(key)) {
        continue;
      }
      seenBuiltin.add(key);
      out.push({ type: "builtin", key: key as HeaderNavBuiltinKey });
    } else if (type === "custom") {
      const label = String(rec.label ?? "").trim();
      const url = String(rec.url ?? "").trim();
      if (!label || runeCount(label) > HEADER_NAV_LIMITS.label) continue;
      if (!footerURLAllowed(url)) continue;
      const omitted = rec.new_tab === undefined || rec.new_tab === null;
      const newTab = omitted ? isExternalFooterURL(url) : rec.new_tab !== false;
      out.push({ type: "custom", label, url, new_tab: newTab });
    }
    if (out.length >= HEADER_NAV_LIMITS.items) break;
  }
  return out;
}

/** 自定义菜单是否为外链（外链渲染 target=_blank） */
export function isHeaderNavExternal(url: string): boolean {
  return isExternalFooterURL(url.trim());
}