/**
 * Operator-facing pairing artifacts derived from a freshly-issued pairing code:
 *   - the ready-to-run `web-terminal-agent pair <code> --install --zone <zone>` command line, and
 *   - a QR PNG data: URL of the code (rendered with the `qrcode` dep) for phone scanning.
 * Pure/deterministic given the code + zone (except the QR, which is a stable render of the code).
 */
import QRCode from 'qrcode'

/** Build the exact command an operator runs on the new host to enroll it into the tunnel. */
export function buildPairCommand(code: string, zone: string): string {
  return `web-terminal-agent pair ${code} --install --zone ${zone}`
}

/** Render a QR PNG data: URL encoding the pairing code (for scanning on the phone client). */
export async function buildQrDataUrl(code: string): Promise<string> {
  return QRCode.toDataURL(code, { errorCorrectionLevel: 'M', margin: 1, width: 256 })
}

export interface PairingArtifacts {
  readonly code: string
  readonly expiresAt: string
  readonly pairCommand: string
  readonly qrDataUrl: string
}

/** Combine an issued code with its operator-facing command + QR into the /api/pairing-codes payload. */
export async function buildPairingArtifacts(
  issued: { readonly code: string; readonly expiresAt: string },
  zone: string,
): Promise<PairingArtifacts> {
  return {
    code: issued.code,
    expiresAt: issued.expiresAt,
    pairCommand: buildPairCommand(issued.code, zone),
    qrDataUrl: await buildQrDataUrl(issued.code),
  }
}