export interface BookmarkLite {
  title: string;
  url: string;
  description?: string;
  icon?: string;
  category?: string;
  sortOrder?: number;
}

export function hostnameOf(raw: string): string {
  try {
    const u = new URL(raw.includes("://") ? raw : `https://${raw}`);
    return u.hostname.replace(/^www\./, "");
  } catch {
    return "";
  }
}

export function faviconFallback(url: string, size = 64): string {
  const host = hostnameOf(url);
  if (!host) return "";
  return `https://www.google.com/s2/favicons?domain=${host}&sz=${size}`;
}

export function normalizeURL(raw: string): string {
  const trimmed = raw.trim();
  if (!trimmed) return "";
  if (/^https?:\/\//i.test(trimmed)) return trimmed;
  return `https://${trimmed}`;
}

export function exportToJSON(bookmarks: BookmarkLite[]): string {
  return JSON.stringify(
    {
      exportedAt: new Date().toISOString(),
      bookmarks: bookmarks.map((b) => ({
        title: b.title,
        url: b.url,
        description: b.description ?? "",
        icon: b.icon ?? "",
        category: b.category ?? "默认",
        sortOrder: b.sortOrder ?? 0,
      })),
    },
    null,
    2,
  );
}

export function downloadFile(filename: string, content: string, mime = "application/json") {
  const blob = new Blob([content], { type: `${mime};charset=utf-8` });
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url;
  a.download = filename;
  a.click();
  setTimeout(() => URL.revokeObjectURL(url), 1000);
}

export function parseImport(text: string): BookmarkLite[] {
  const trimmed = text.trim();
  if (!trimmed) return [];

  if (trimmed.startsWith("{") || trimmed.startsWith("[")) {
    return parseJSON(trimmed);
  }
  if (trimmed.toLowerCase().includes("<!doctype netscape-bookmark") || trimmed.toLowerCase().includes("<dl")) {
    return parseNetscapeHTML(trimmed);
  }

  return parseJSON(trimmed);
}

function parseJSON(raw: string): BookmarkLite[] {
  try {
    const parsed = JSON.parse(raw);
    const list: unknown[] = Array.isArray(parsed)
      ? parsed
      : Array.isArray((parsed as { bookmarks?: unknown[] })?.bookmarks)
        ? (parsed as { bookmarks: unknown[] }).bookmarks
        : [];
    return list
      .map((item) => {
        const i = item as Record<string, unknown>;
        return {
          title: String(i.title ?? i.name ?? "").trim(),
          url: String(i.url ?? i.href ?? "").trim(),
          description: i.description ? String(i.description) : "",
          icon: i.icon ? String(i.icon) : "",
          category: i.category ? String(i.category) : "默认",
          sortOrder: typeof i.sortOrder === "number" ? i.sortOrder : 0,
        };
      })
      .filter((b) => b.title && b.url);
  } catch {
    return [];
  }
}

function parseNetscapeHTML(raw: string): BookmarkLite[] {
  if (typeof DOMParser === "undefined") return [];
  const doc = new DOMParser().parseFromString(raw, "text/html");
  const out: BookmarkLite[] = [];

  const walk = (node: Element, currentCategory: string) => {
    const children = Array.from(node.children);
    for (let i = 0; i < children.length; i++) {
      const el = children[i];
      const tag = el.tagName.toLowerCase();
      if (tag === "dt") {
        const inner = el.firstElementChild;
        if (!inner) continue;
        const innerTag = inner.tagName.toLowerCase();
        if (innerTag === "a") {
          const a = inner as HTMLAnchorElement;
          const href = a.getAttribute("href") || "";
          const title = (a.textContent || "").trim() || href;
          const icon = a.getAttribute("icon") || "";
          if (href && /^https?:\/\//i.test(href)) {
            out.push({
              title,
              url: href,
              description: "",
              icon,
              category: currentCategory || "默认",
              sortOrder: 0,
            });
          }
        } else if (innerTag === "h3") {
          const folderName = (inner.textContent || "").trim() || currentCategory;
          const dl = el.querySelector("dl");
          if (dl) walk(dl, folderName);
        }
      } else if (tag === "dl") {
        walk(el, currentCategory);
      }
    }
  };

  const root = doc.querySelector("dl");
  if (root) walk(root, "默认");
  return out;
}