dependency-error.ts

import type { CxModule } from './module';

/**
 * An error indicating context module dependency load failure.
 */
export class CxDependencyError extends ReferenceError {

  /**
   * Constructs context module dependency load error.
   *
   * @param module - A module failed to load.
   * @param reasons - An array of dependency/reason pairs caused the load failure.
   * @param message - An error message.
   */
  constructor(
    readonly module: CxModule,
    readonly reasons: readonly (readonly [CxModule, unknown?])[] = [],
    message: string = CxDependencyError$defaultMessage(module, reasons),
  ) {
    super(message);
  }

  override get name(): string {
    return 'CxDependencyError';
  }

}

function CxDependencyError$defaultMessage(
  module: CxModule,
  dependencies: readonly (readonly [CxModule, unknown?])[],
): string {
  const reasons = dependencies.reduce((out, [dep, reason]) => {
    if (out) {
      out += ', ';
    } else {
      out = ': ';
    }
    if (reason !== undefined) {
      out += `${dep} failed to load (${reason})`;
    } else {
      out += `${dep} not loaded`;
    }

    return out;
  }, '');

  return `Failed to load ${module}${reasons}`;
}