import { HttpException, HttpStatus, Injectable } from '@nestjs/common';
import type {
  EnrollmentErrorCode,
  EnrollmentFailure,
  EnrollmentResult,
} from './enrollment.repository.js';

/**
 * Maps enrollment result unions onto the closed HTTP status set (design
 * docs/plans/2026-08-29-agent-enrollment-command-design.md §3.3, contract 5
 * §4.2). Every refusal body carries the correlation id (contract 5 §4.3
 * end-to-end traceability) alongside the enum code. `not_found` carries one
 * fixed message for every cause — missing agent and unauthorized caller are
 * indistinguishable on the wire (§3.2).
 */
const HTTP_STATUS: Record<EnrollmentErrorCode, HttpStatus> = {
  validation_failed: HttpStatus.BAD_REQUEST,
  authentication_failed: HttpStatus.UNAUTHORIZED,
  authorization_refused: HttpStatus.FORBIDDEN,
  not_found: HttpStatus.NOT_FOUND,
  conflict: HttpStatus.CONFLICT,
  precondition_failed: HttpStatus.UNPROCESSABLE_ENTITY,
  internal_fault: HttpStatus.INTERNAL_SERVER_ERROR,
};

@Injectable()
export class EnrollmentService {
  unwrap<T>(result: EnrollmentResult<T>): { ok: true; correlationId: string } & T {
    if (result.ok) return result;
    throw this.toException(result);
  }

  private toException(failure: EnrollmentFailure): HttpException {
    const status = HTTP_STATUS[failure.error];
    return new HttpException(
      {
        statusCode: status,
        error: failure.error,
        message: failure.message,
        correlationId: failure.correlationId,
      },
      status,
    );
  }
}