/**

 * Copyright (c) Meta Platforms, Inc. and affiliates.

 *

 * This source code is licensed under the MIT license found in the

 * LICENSE file in the root directory of this source tree.

 *

 * @flow

 */

import nullthrows from 'nullthrows';

import InvalidProfileError from './InvalidProfileError';

export const readInputData = (file: File): Promise<string> => {

  if (!file.name.endsWith('.json')) {

    throw new InvalidProfileError(

      'Invalid file type. Only JSON performance profiles are supported',

    );

  }

  const fileReader = new FileReader();

  return new Promise((resolve, reject) => {

    fileReader.onload = () => {

      const result = nullthrows(fileReader.result);

      if (typeof result === 'string') {

        resolve(result);

      }

      reject(new InvalidProfileError('Input file was not read as a string'));

    };

    fileReader.onerror = () => reject(fileReader.error);

    fileReader.readAsText(file);

  });

};