upload.ts

import type { CloudinaryUploadWidgetOptions } from '@cloudinary-util/types';

/**
 * generateSignature
 * @description Makes a request to an endpoint to sign Cloudinary parameters as part of widget creation
 */

export interface GenerateSignatureCallback {
  fetch: Function;
  signatureEndpoint: string;
}

export function generateSignatureCallback({ signatureEndpoint, fetch: fetcher }: GenerateSignatureCallback): CloudinaryUploadWidgetOptions["uploadSignature"] {
  return function generateSignature(callback: (signature: string | null, error?: unknown) => void, paramsToSign: object) {
    if ( typeof signatureEndpoint === 'undefined' ) {
      throw Error('Failed to generate signature: signatureEndpoint property undefined.')
    }
    
    if ( typeof fetcher === 'undefined' ) {
      throw Error('Failed to generate signature: fetch property undefined.')
    }

    fetcher(signatureEndpoint, {
      method: 'POST',
      body: JSON.stringify({
        paramsToSign,
      }),
      headers: {
        'Content-Type': 'application/json'
      }
    })
      .then((response: { json: Function }) => response.json())
      .then((result: { signature: string }) => {
        callback(result.signature);
      })
      .catch((error: unknown) => {
        callback(null, error);
      })
  }
}