import { POST_MEDIA_PUBLIC_PREFIX } from "#server/constants/media";

const MD_IMG_RE = /!\[[^\]]*]\(([^)]+)\)/g;

function normalizeUrl(raw: string): string {
  const t = raw.trim().replace(/^<|>$/g, "").split(/\s+/)[0] ?? "";
  if (t.startsWith(POST_MEDIA_PUBLIC_PREFIX)) {
    return t;
  }
  return "";
}

/** 从 markdown 中提取本站图片 URL（去重，顺序稳定） */
export function extractMediaUrlsFromMarkdown(markdown: string): string[] {
  const out: string[] = [];
  const seen = new Set<string>();
  let m: RegExpExecArray | null;
  const re = new RegExp(MD_IMG_RE.source, MD_IMG_RE.flags);
  while ((m = re.exec(markdown)) !== null) {
    const u = normalizeUrl(m[1] ?? "");
    if (u && !seen.has(u)) {
      seen.add(u);
      out.push(u);
    }
  }
  return out;
}

export function extractMediaUrlsFromCover(coverUrl: string | null | undefined): string[] {
  if (!coverUrl) {
    return [];
  }
  const u = normalizeUrl(coverUrl);
  return u ? [u] : [];
}

export function mergePostMediaUrls(bodyMarkdown: string, coverUrl: string | null | undefined): string[] {
  const a = extractMediaUrlsFromMarkdown(bodyMarkdown);
  const b = extractMediaUrlsFromCover(coverUrl);
  const seen = new Set<string>(a);
  for (const u of b) {
    if (!seen.has(u)) {
      seen.add(u);
      a.push(u);
    }
  }
  return a;
}

export function mergeProfileMediaUrls(bioMarkdown: string | null | undefined, avatar: string | null | undefined): string[] {
  return mergePostMediaUrls(bioMarkdown ?? "", avatar ?? null);
}

/** `/public/assets/foo.webp` → `foo.webp` */
export function publicAssetUrlToStorageKey(url: string): string | null {
  const t = url.trim();
  if (!t.startsWith(POST_MEDIA_PUBLIC_PREFIX)) {
    return null;
  }
  const key = t.slice(POST_MEDIA_PUBLIC_PREFIX.length).replace(/^\/+/, "");
  if (!key || key.includes("..") || key.includes("/") || key.includes("\\")) {
    return null;
  }
  return key;
}