function xmlEscape(value: string): string {
  return value
    .replace(/&/g, "&")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&apos;");
}

export interface GatewayParams {
  gatewayName: string;
  host: string;
  proxy?: string;
  realm?: string;
  register: boolean;
  username?: string;
  password?: string;
  fromUser?: string;
  fromDomain?: string;
  registerProxy?: string;
  outboundProxy?: string;
  expireSeconds: number;
  retrySeconds: number;
  callerIdName?: string;
  callerIdNumber?: string;
  dtmfMode: "RFC2833" | "INFO" | "INBAND";
  ping: boolean;
  pingFrequency: number;
  transport: "UDP" | "TCP" | "TLS";
}

const DTMF_VALUES: Record<GatewayParams["dtmfMode"], string> = {
  RFC2833: "rfc2833",
  INFO: "info",
  INBAND: "inband",
};

/**
 * XML de gateway do Sofia (agente.md secao 41). Escrito em
 * sip_profiles/external/<trunk_id>.xml pelo b2bcall-fs-config e carregado
 * via `sofia profile external rescan` — o profile "external" já vem com
 * `<X-PRE-PROCESS cmd="include" data="external/*.xml"/>` na config vanilla.
 */
export function buildGatewayXml(params: GatewayParams): string {
  const lines: string[] = [];
  const param = (name: string, value: string | number | boolean | undefined) => {
    if (value === undefined || value === "") return;
    lines.push(`    <param name="${name}" value="${xmlEscape(String(value))}"/>`);
  };

  param("username", params.username);
  param("password", params.password);
  param("realm", params.realm ?? params.host);
  param("proxy", params.proxy ?? params.host);
  param("register", params.register);
  param("expire-seconds", params.expireSeconds);
  param("retry-seconds", params.retrySeconds);
  param("from-user", params.fromUser ?? params.username);
  param("from-domain", params.fromDomain ?? params.host);
  param("register-proxy", params.registerProxy);
  param("outbound-proxy", params.outboundProxy);
  param("caller-id-in-from", true);
  param("extension", params.fromUser ?? params.username);
  param("dtmf-type", DTMF_VALUES[params.dtmfMode]);
  param("register-transport", params.transport.toLowerCase());
  if (params.ping) {
    param("ping", params.pingFrequency);
  }

  return `<include>
  <gateway name="${xmlEscape(params.gatewayName)}">
${lines.join("\n")}
  </gateway>
</include>`;
}