Enum mapper

Mapia now includes a lightweight enum mapper that works entirely at the type level. It enforces that every value in the source enum has a matching destination entry (and vice versa) by assuming a consistent suffix pattern such as VIEWER → VIEWER_ENUM. Because the mapping is described with EnumAutoSuffixMapping, the compiler rejects missing entries, stray keys, or misspelled destinations before you ever run the code.

Bidirectional guarantees

The helper stores both directions (forward and reverse) so you can reuse the same mapper to go from API enums to internal enums and back again.

Default suffix (_ENUM)

import { enumMapper } from 'mapia';

enum ApiRole {
  VIEWER = 'VIEWER',
  READER = 'READER',
}

enum InternalRole {
  VIEWER_ENUM = 'VIEWER_ENUM',
  READER_ENUM = 'READER_ENUM',
}

const roleMapper = enumMapper(ApiRole, InternalRole, {
  VIEWER: InternalRole.VIEWER_ENUM,
  READER: InternalRole.READER_ENUM,
});

const viewerEnum = roleMapper.toDestination(ApiRole.VIEWER); // VIEWER_ENUM
const readerRole = roleMapper.toSource(InternalRole.READER_ENUM); // READER

Because enumMapper returns an EnumMapperResult, you also get forward/reverse lookup objects if you prefer direct key-based access instead of helper methods.

Custom suffixes

If the destination enum uses a different suffix (for example _CUSTOM), pass it as the fourth argument. All keys still autocomplete and the type check ensures both enums remain symmetric.

enum HttpStatus {
  OK = 'OK',
  NOT_OK = 'NOT_OK',
}

enum HttpStatusCode {
  OK_CUSTOM = 'OK_CUSTOM',
  NOT_OK_CUSTOM = 'NOT_OK_CUSTOM',
}

const statusMapper = enumMapper(
  HttpStatus,
  HttpStatusCode,
  {
    OK: HttpStatusCode.OK_CUSTOM,
    NOT_OK: HttpStatusCode.NOT_OK_CUSTOM,
  },
  '_CUSTOM',
);

statusMapper.toDestination(HttpStatus.NOT_OK); // NOT_OK_CUSTOM
statusMapper.toSource(HttpStatusCode.OK_CUSTOM); // OK