Message.ts

// message.ts
import { createOpaqueAPI } from ‘@iadvize-oss/opaque-type’;
import { createFoldObject } from ‘@iadvize-oss/foldable-helpers’;

type $Text = {
  text: string;
}

type $Image = {
  url: string;
  description: string;
}

const TextOpaqueAPI  = createOpaqueAPI<
  'Text',
  $Text,
>('Text’);

const ImageOpaqueAPI = createOpaqueAPI<
  ‘Image’,
  $Image,
>('Image’);

// opaque types
export type Text = ReturnType<typeof TextOpaqueAPI.toOpaque>;
export type Image = ReturnType<typeof ImageOpaqueAPI.toOpaque>;

// union of opaque types
export type Message = Text | Image;

// constructors

export function createText(text: string): Text {
  return TextOpaqueAPI.toOpaque({ text });
}
export function createImage({ url, description }): Image {
  return ImageOpaqueAPI.toOpaque({ url, description  });
}

// queries

export function text(message: Text): string {
  const $message = TextOpaqueAPI.fromOpaque(message);
  return $message.text;
}

export function url(message: Image): string {
  const $message = ImageOpaqueAPI.fromOpaque(message);
  return $message.url;
}

export function description(message: Image): string {
  const $message = ImageOpaqueAPI.fromOpaque(message);
  return $message.description;
}

export function isText(message: Message): message is Text {
  return TextOpaqueAPIisOpaque(message);
}

export function isImage(message: Message): message is Image {
  return ImageOpaqueAPIisOpaque(message);
}

// transformations

export function addSignature(signature: string) {
  return (message: Text): Text  => {
    const $message = TextOpaqueAPI.fromOpaque(message);
    const newText = `${$message.text} - ${signature}`;
    return TextOpaqueAPI.toOpaque({ text: newText  });
  };
}

export function withBitlyUrl(message: Image): Image {
  const $message = ImageOpaqueAPI.fromOpaque(message);
  const newUrl = convertToBitly($message.url);
  return ImageOpaqueAPI.toOpaque({ ...$message, url: newUrl  });
}

// fold function from @iadvize-oss/foldable-helpers
const fold = createFoldObject({ 
  Text: isText,
  Image: isImage
});