const URL_PATTERN =
  /https?:\/\/[^\s<>"')\]]+\/(?:MindSpace|temp)\/([0-9a-f-]{36}|[a-z0-9._-]+)\/([^\s<>"')\]]+\.html)/gi;

export type MessageSaveKind = 'page' | 'article';

export type MessageSaveOwner = {
  userId?: string | null;
  username?: string | null;
};

export type MessageSaveActions = {
  kind: MessageSaveKind;
  previewUrl: string | null;
  links: Array<{ publicUrl: string; filename: string }>;
};

function decodeSegment(segment: string) {
  try {
    return decodeURIComponent(segment);
  } catch {
    return segment;
  }
}

function normalizeOwnerOptions(owner?: string | MessageSaveOwner): MessageSaveOwner {
  if (typeof owner === 'string') return { username: owner };
  return owner ?? {};
}

function normalizeStaticHtmlRelativePath(relativePath: string) {
  const parts = String(relativePath ?? '')
    .replace(/^\/+/, '')
    .split('/')
    .filter((part) => part && part !== '.' && part !== '..');
  if (parts.length === 0) return '';
  if (parts[0]?.toLowerCase() === 'public') return ['public', ...parts.slice(1)].join('/');
  if (parts.length === 1 && parts[0].toLowerCase().endsWith('.html')) return `public/${parts[0]}`;
  return parts.join('/');
}

function escapeRegExp(value: string) {
  return value.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

function encodeUrlPath(relativePath: string) {
  return relativePath
    .split('/')
    .filter(Boolean)
    .map((part) => encodeURIComponent(part))
    .join('/');
}

function canonicalizeStaticPageUrl(publicUrl: string, originalRelativePath: string) {
  const canonicalRelativePath = normalizeStaticHtmlRelativePath(originalRelativePath);
  const originalClean = originalRelativePath.replace(/^\/+/, '');
  if (!canonicalRelativePath || canonicalRelativePath === originalClean) return publicUrl;
  const suffix = escapeRegExp(encodeUrlPath(originalClean));
  return publicUrl.replace(new RegExp(`${suffix}$`), encodeUrlPath(canonicalRelativePath));
}

export function extractStaticPageLinks(content: string, owner?: string | MessageSaveOwner) {
  const { userId, username } = normalizeOwnerOptions(owner);
  const normalizedUserId = userId?.trim().toLowerCase();
  const normalizedUsername = username?.trim().toLowerCase();
  const links: Array<{ publicUrl: string; filename: string }> = [];
  const seen = new Set<string>();
  for (const match of content.matchAll(URL_PATTERN)) {
    const linkOwner = decodeSegment(match[1]).toLowerCase();
    const relativePath = decodeSegment(match[2]);
    const filename = relativePath.split('/').pop() ?? relativePath;
    if (normalizedUserId) {
      if (linkOwner !== normalizedUserId && linkOwner !== normalizedUsername) continue;
    } else if (normalizedUsername && linkOwner !== normalizedUsername) {
      continue;
    }
    const publicUrl = canonicalizeStaticPageUrl(match[0], relativePath);
    if (seen.has(publicUrl)) continue;
    seen.add(publicUrl);
    links.push({ publicUrl, filename });
  }
  return links;
}

export function getMessageSaveActions(content: string, owner?: string | MessageSaveOwner): MessageSaveActions {
  const links = extractStaticPageLinks(content, owner);
  return {
    kind: links.length > 0 ? 'page' : 'article',
    previewUrl: links[0]?.publicUrl ?? null,
    links,
  };
}