export type ChatMarkdownProps = {
  children: string;
  streaming?: boolean;
};

const protocolPattern = /^([a-z][a-z\d+.-]*):/i;
const safeProtocols = new Set(["http", "https", "mailto", "tel"]);
const hexColorPattern = /^#(?:[0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[0-9a-fA-F]{8})$/;
const numericCitationPattern = /^\[?(\d{1,3})\]?$/;

export function sanitizeMarkdownUrl(url: string, allowRelative = false): string | undefined {
  const value = url.trim();
  const protocol = value.match(protocolPattern)?.[1]?.toLowerCase();

  if (protocol) return safeProtocols.has(protocol) ? value : undefined;
  if (
    allowRelative &&
    (value.startsWith("/") ||
      value.startsWith("./") ||
      value.startsWith("../") ||
      value.startsWith("#"))
  ) {
    return value;
  }
  return undefined;
}

export function isExternalMarkdownUrl(url: string | undefined): boolean {
  if (!url) return false;
  const protocol = url.trim().match(protocolPattern)?.[1]?.toLowerCase();
  return Boolean(protocol && safeProtocols.has(protocol));
}

export function parseCitationBadgeLabel(
  label: string | undefined,
  href: string | undefined,
): string | undefined {
  if (!label || !href || !isExternalMarkdownUrl(href)) return undefined;
  const trimmed = label.trim();
  const numeric = trimmed.match(numericCitationPattern);
  if (numeric?.[1]) return numeric[1];
  return undefined;
}

export function citationDomainLabel(href: string | undefined): string | undefined {
  if (!href) return undefined;
  try {
    const parsed = new URL(href.trim());
    if (parsed.protocol !== "http:" && parsed.protocol !== "https:") return undefined;
    return parsed.hostname.toLowerCase().replace(/^www\./, "");
  } catch {
    return undefined;
  }
}

export function parseHexColorToken(value: string | undefined): string | undefined {
  if (!value) return undefined;
  const trimmed = value.trim();
  return hexColorPattern.test(trimmed) ? trimmed : undefined;
}

export function closeUnterminatedFence(markdown: string): string {
  let openFence: { marker: "`" | "~"; length: number } | undefined;

  for (const line of markdown.split("\n")) {
    const match = line.match(/^ {0,3}(`{3,}|~{3,})(.*)$/);
    if (!match?.[1]) continue;

    const marker = match[1][0] as "`" | "~";
    if (!openFence) {
      openFence = { marker, length: match[1].length };
      continue;
    }

    if (
      marker === openFence.marker &&
      match[1].length >= openFence.length &&
      (match[2] ?? "").trim() === ""
    ) {
      openFence = undefined;
    }
  }

  return openFence ? `${markdown}\n${openFence.marker.repeat(openFence.length)}` : markdown;
}