const LNBITS_URL = process.env.LNBITS_URL;
const LNBITS_API_KEY = process.env.LNBITS_API_KEY;

function getBaseUrl(): string {
  if (!LNBITS_URL) {
    throw new Error("LNBITS_URL environment variable is not set");
  }
  return LNBITS_URL.replace(/\/$/, "");
}

function getHeaders(): Record<string, string> {
  if (!LNBITS_API_KEY) {
    throw new Error("LNBITS_API_KEY environment variable is not set");
  }
  return {
    "Content-Type": "application/json",
    "X-Api-Key": LNBITS_API_KEY,
  };
}

export interface LNbitsInvoice {
  paymentHash: string;
  paymentRequest: string;
}

export interface LNbitsInvoiceStatus {
  paid: boolean;
  paidAt?: Date;
}

export async function createInvoice(
  amountSats: number,
  memo: string,
): Promise<LNbitsInvoice> {
  const baseUrl = getBaseUrl();
  const response = await fetch(`${baseUrl}/api/v1/payments`, {
    method: "POST",
    headers: getHeaders(),
    body: JSON.stringify({
      out: false,
      amount: amountSats,
      memo,
    }),
  });

  if (!response.ok) {
    const body = await response.text();
    throw new Error(`LNbits createInvoice failed (${response.status}): ${body}`);
  }

  const data = (await response.json()) as {
    payment_hash: string;
    payment_request: string;
  };

  return {
    paymentHash: data.payment_hash,
    paymentRequest: data.payment_request,
  };
}

export async function checkInvoicePaid(
  paymentHash: string,
): Promise<LNbitsInvoiceStatus> {
  const baseUrl = getBaseUrl();
  const response = await fetch(`${baseUrl}/api/v1/payments/${paymentHash}`, {
    method: "GET",
    headers: getHeaders(),
  });

  if (!response.ok) {
    const body = await response.text();
    throw new Error(`LNbits checkInvoice failed (${response.status}): ${body}`);
  }

  const data = (await response.json()) as {
    paid: boolean;
    details?: { time?: number };
  };

  return {
    paid: data.paid,
    paidAt: data.paid && data.details?.time
      ? new Date(data.details.time * 1000)
      : undefined,
  };
}