/**
 * Service Unavailable Error
 *
 * Error thrown when the gas-free backend service is unavailable
 *
 * @module features/gas-free/errors/ServiceUnavailableError
 */

import { GasFreeError, GasFreeErrorCode } from './GasFreeError';

/**
 * ServiceUnavailableError class
 *
 * Thrown when the gas-free service is down or unreachable.
 */
export class ServiceUnavailableError extends GasFreeError {
  /** Service URL that was unavailable */
  public readonly serviceUrl: string;

  /** HTTP status code (if available) */
  public readonly statusCode?: number;

  /** Number of retries attempted */
  public readonly retriesAttempted?: number;

  /**
   * Create a ServiceUnavailableError
   *
   * @param serviceUrl - Service URL
   * @param message - Error message
   * @param statusCode - HTTP status code (if available)
   * @param retriesAttempted - Number of retries attempted
   * @param originalError - Original error
   */
  constructor(
    serviceUrl: string,
    message?: string,
    statusCode?: number,
    retriesAttempted?: number,
    originalError?: Error
  ) {
    const errorMessage =
      message ||
      `Gas-Free service at '${serviceUrl}' is unavailable` +
        (statusCode ? ` (HTTP ${statusCode})` : '') +
        (retriesAttempted ? ` after ${retriesAttempted} retries` : '');

    super(errorMessage, GasFreeErrorCode.SERVICE_UNAVAILABLE, originalError, {
      serviceUrl,
      statusCode,
      retriesAttempted,
    });

    this.name = 'ServiceUnavailableError';
    this.serviceUrl = serviceUrl;
    this.statusCode = statusCode;
    this.retriesAttempted = retriesAttempted;

    // Maintains proper stack trace for where our error was thrown (only available on V8)
    if (Error.captureStackTrace) {
      Error.captureStackTrace(this, ServiceUnavailableError);
    }
  }

  /**
   * Create error for network timeout
   */
  static timeout(
    serviceUrl: string,
    timeoutMs: number,
    retriesAttempted?: number
  ): ServiceUnavailableError {
    return new ServiceUnavailableError(
      serviceUrl,
      `Request timed out after ${timeoutMs}ms`,
      undefined,
      retriesAttempted
    );
  }

  /**
   * Create error for HTTP status code
   */
  static httpError(
    serviceUrl: string,
    statusCode: number,
    statusText?: string
  ): ServiceUnavailableError {
    return new ServiceUnavailableError(serviceUrl, statusText, statusCode);
  }

  /**
   * Convert error to JSON
   */
  toJSON(): Record<string, unknown> {
    return {
      ...super.toJSON(),
      serviceUrl: this.serviceUrl,
      statusCode: this.statusCode,
      retriesAttempted: this.retriesAttempted,
    };
  }
}