/** 站点品牌与页脚：公开设置字段的前端归一化（与 Go service/brand.go 对齐） */

export type FooterLink = {
  label: string;
  url: string;
  new_tab: boolean;
  /** 所属栏位：left / center / right；缺省 right */
  align: FooterLinksAlign;
};

/** 页脚链接栏位 */
export type FooterLinksAlign = "left" | "center" | "right";

export const FOOTER_LINKS_ALIGNS: { id: FooterLinksAlign; label: string }[] = [
  { id: "left", label: "左" },
  { id: "center", label: "中" },
  { id: "right", label: "右" },
];

export function normalizeFooterLinksAlign(raw: unknown): FooterLinksAlign {
  const s = String(raw ?? "").trim();
  if (s === "left" || s === "center" || s === "right") return s;
  return "right";
}

export type BrandSlot = "logo_light" | "logo_dark" | "favicon";

/** 页眉品牌形式 */
export type BrandMark = "image_text" | "image" | "text";

/** 图槽画幅。方标是默认；其余是页眉里常见的横版比例 */
export type BrandLogoSize = "sq" | "2x1" | "3x1" | "4x1" | "16x9";

export const BRAND_LOGO_SIZES: { id: BrandLogoSize; label: string; w: number; h: number }[] = [
  { id: "sq", label: "方标", w: 36, h: 36 },
  { id: "2x1", label: "2:1", w: 80, h: 40 },
  { id: "3x1", label: "3:1", w: 120, h: 40 },
  { id: "4x1", label: "4:1", w: 176, h: 44 },
  { id: "16x9", label: "16:9", w: 96, h: 54 },
];

export function normalizeBrandMark(raw: unknown): BrandMark {
  const s = String(raw ?? "").trim();
  if (s === "image" || s === "text" || s === "image_text") return s;
  return "image_text";
}

export function normalizeBrandLogoSize(raw: unknown): BrandLogoSize {
  const s = String(raw ?? "").trim();
  if (s === "sq" || s === "2x1" || s === "3x1" || s === "4x1" || s === "16x9") return s;
  return "sq";
}

export function brandLogoBox(size: BrandLogoSize): { w: number; h: number } {
  const found = BRAND_LOGO_SIZES.find((item) => item.id === size);
  return found ? { w: found.w, h: found.h } : { w: 36, h: 36 };
}

/** 图槽铺法，与背景图同一套：填充裁切、适应留边、平铺重复、拉伸变形 */
export type BrandLogoFit = "cover" | "contain" | "repeat" | "stretch";

export const BRAND_LOGO_FITS: { id: BrandLogoFit; label: string }[] = [
  { id: "cover", label: "填充" },
  { id: "contain", label: "适应" },
  { id: "repeat", label: "平铺" },
  { id: "stretch", label: "拉伸" },
];

export function normalizeBrandLogoFit(raw: unknown): BrandLogoFit {
  const s = String(raw ?? "").trim();
  if (s === "cover" || s === "contain" || s === "repeat" || s === "stretch") return s;
  return "contain";
}

export const BRAND_LIMITS = {
  wordmark: 16,
  slogan: 32,
  keywordCount: 16,
  keywordRunes: 20,
  footerLinks: 8,
  footerLabel: 32,
  footerURL: 200,
  logoBytes: 2 * 1024 * 1024,
  faviconBytes: 512 * 1024,
} as const;

const LOGO_URL_RE = /^\/uploads\/brand\/[0-9a-f]{32}\.(png|webp|svg)$/;
const FAVICON_URL_RE = /^\/uploads\/brand\/[0-9a-f]{32}\.(png|webp|svg|ico)$/;

export function runeCount(s: string): number {
  return [...s].length;
}

/** 浏览器默认标题：有标语则为「名称 · 标语」，否则只有名称 */
export function siteDocumentTitle(name: string, slogan: string): string {
  const n = name.trim() || "姜十三论坛";
  const s = slogan.trim();
  return s ? `${n} · ${s}` : n;
}

export function normalizeBrandURL(slot: BrandSlot, raw: unknown): string {
  const u = String(raw ?? "")
    .trim()
    .toLowerCase();
  if (!u) return "";
  const re = slot === "favicon" ? FAVICON_URL_RE : LOGO_URL_RE;
  return re.test(u) ? u : "";
}

/** 品牌图固定对外地址（与 Go service/brand.go 的 BrandAliasPath* 对齐）：
 *  友链等外部引用此地址，站点换图后地址不变 */
export function brandAliasPath(slot: BrandSlot): string {
  if (slot === "logo_light") return "/api/brand/logo-light";
  if (slot === "logo_dark") return "/api/brand/logo-dark";
  return "/api/brand/favicon";
}

export function normalizeKeywords(raw: unknown): string[] {
  if (!Array.isArray(raw)) return [];
  const seen = new Set<string>();
  const out: string[] = [];
  for (const item of raw) {
    const parts = String(item ?? "").split(/[,，;；]/);
    for (const part of parts) {
      const k = part.trim();
      if (!k || runeCount(k) > BRAND_LIMITS.keywordRunes) continue;
      const key = k.toLowerCase();
      if (seen.has(key)) continue;
      seen.add(key);
      out.push(k);
      if (out.length >= BRAND_LIMITS.keywordCount) return out;
    }
  }
  return out;
}

export function isExternalFooterURL(url: string): boolean {
  return /^https?:\/\//i.test(url.trim());
}

/** 页脚地址：站内单斜杠路径，或 http(s) */
export function footerURLAllowed(raw: string): boolean {
  const u = raw.trim();
  if (!u || runeCount(u) > BRAND_LIMITS.footerURL) return false;
  if (/\s/.test(u) || u.includes("\\")) return false;
  if (/^(javascript|data):/i.test(u) || u.startsWith("//")) return false;
  if (isExternalFooterURL(u)) return true;
  return u.startsWith("/") && !u.startsWith("//");
}

export function normalizeFooterLinks(raw: unknown): FooterLink[] {
  if (!Array.isArray(raw)) return [];
  const out: FooterLink[] = [];
  for (const item of raw) {
    if (!item || typeof item !== "object") continue;
    const rec = item as { label?: unknown; url?: unknown; new_tab?: unknown };
    const label = String(rec.label ?? "").trim();
    const url = String(rec.url ?? "").trim();
    if (!label || runeCount(label) > BRAND_LIMITS.footerLabel) continue;
    if (!footerURLAllowed(url)) continue;
    const omitted = rec.new_tab === undefined || rec.new_tab === null;
    const newTab = omitted ? isExternalFooterURL(url) : rec.new_tab !== false;
    const align = normalizeFooterLinksAlign((rec as { align?: unknown }).align);
    out.push({ label, url, new_tab: newTab, align });
    if (out.length >= BRAND_LIMITS.footerLinks) break;
  }
  return out;
}

export function brandAccept(slot: BrandSlot): string {
  if (slot === "favicon") return "image/png,image/webp,image/svg+xml,.ico,image/x-icon";
  return "image/png,image/webp,image/svg+xml";
}

export function brandFileOk(slot: BrandSlot, file: File): string | null {
  const name = file.name.toLowerCase();
  const logo = slot !== "favicon";
  const okExt = logo
    ? /\.(png|webp|svg)$/.test(name)
    : /\.(png|webp|svg|ico)$/.test(name);
  if (!okExt) {
    return logo ? "Logo 仅支持 PNG / WebP / SVG" : "Favicon 仅支持 PNG / WebP / SVG / ICO";
  }
  const max = logo ? BRAND_LIMITS.logoBytes : BRAND_LIMITS.faviconBytes;
  if (file.size > max) {
    return logo ? "Logo 不能超过 2MB" : "Favicon 不能超过 512KB";
  }
  return null;
}