import { randomBytes } from "node:crypto";

export type LinkTokenPayloadV1 = {
  v: 1;
  nonce: string;
  exp: number;
};

const TOKEN_TTL_SEC = Number(process.env.TELEGRAM_LINK_TOKEN_TTL_SEC || 10 * 60);

export function requireBotUsername() {
  const botUsername = String(process.env.TELEGRAM_BOT_USERNAME || "").trim().replace(/^@/, "");
  if (!botUsername) {
    throw createError({ statusCode: 500, statusMessage: "TELEGRAM_BOT_USERNAME is required" });
  }
  return botUsername;
}

export function issueLinkToken(input: { teamId: string; userId: string }) {
  void input;
  // Telegram deep-link `start` parameter is limited, keep token very short.
  const token = randomBytes(12).toString("hex");
  const payload: LinkTokenPayloadV1 = {
    v: 1,
    nonce: token,
    exp: Math.floor(Date.now() / 1000) + Math.max(60, TOKEN_TTL_SEC),
  };
  return { token, payload };
}

export function verifyLinkToken(token: string): LinkTokenPayloadV1 | null {
  const raw = String(token || "").trim();
  if (!/^[a-f0-9]{24}$/.test(raw)) return null;
  return {
    v: 1,
    nonce: raw,
    exp: 0,
  };
}

export function extractLinkTokenFromStartText(text: string) {
  const trimmed = String(text || "").trim();
  if (!trimmed.startsWith("/start")) return null;
  const parts = trimmed.split(/\s+/).filter(Boolean);
  if (parts.length < 2) return null;
  const arg = parts[1] || "";
  if (!arg.startsWith("link_")) return null;
  return arg.slice("link_".length);
}

export function buildTelegramStartUrl(token: string) {
  const botUsername = requireBotUsername();
  return `https://t.me/${botUsername}?start=link_${token}`;
}

export function getTelegramChatIdFromUpdate(update: any): string | null {
  const candidates = [
    update?.message?.chat?.id,
    update?.business_message?.chat?.id,
    update?.edited_business_message?.chat?.id,
    update?.business_connection?.user_chat_id,
  ];
  for (const c of candidates) {
    if (c == null) continue;
    const v = String(c).trim();
    if (v) return v;
  }
  return null;
}

export function getBusinessConnectionFromUpdate(update: any): {
  id: string;
  userChatId: string | null;
  isEnabled: boolean | null;
  canReply: boolean | null;
  raw: any;
} | null {
  const bc = (update?.business_connection ?? null) as any;
  if (!bc || typeof bc !== "object") return null;

  const id = String(bc.id ?? "").trim();
  if (!id) return null;

  const userChatId = bc.user_chat_id != null ? String(bc.user_chat_id) : null;
  const isEnabled = typeof bc.is_enabled === "boolean" ? bc.is_enabled : null;
  const canReply = typeof bc.can_reply === "boolean"
    ? bc.can_reply
    : typeof bc.rights?.can_reply === "boolean"
      ? bc.rights.can_reply
      : null;

  return {
    id,
    userChatId,
    isEnabled,
    canReply,
    raw: bc,
  };
}