/**

* @license

* Copyright 2018 Google LLC. All Rights Reserved.

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

*

* http://www.apache.org/licenses/LICENSE-2.0

*

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*

* =============================================================================

*/

import {env} from '@tensorflow/tfjs-core';

import {DataSource} from '../datasource';

import {ByteChunkIterator} from '../iterators/byte_chunk_iterator';

import {FileChunkIterator, FileChunkIteratorOptions} from '../iterators/file_chunk_iterator';

import {FileElement} from '../types';

import {isLocalPath} from '../util/source_util';

/**

* Represents a file, blob, or Uint8Array readable as a stream of binary data

* chunks.

*/

export class FileDataSource extends DataSource {

/**

* Create a `FileDataSource`.

*

* @param input Local file path, or `File`/`Blob`/`Uint8Array` object to

* read. Local file only works in node environment.

* @param options Options passed to the underlying `FileChunkIterator`s,

* such as {chunksize: 1024}.

*/

constructor(

protected input: FileElement|string,

protected readonly options: FileChunkIteratorOptions = {}) {

super();

}

async iterator(): Promise<ByteChunkIterator> {

if (isLocalPath(this.input) && env().get('IS_NODE')) {

// tslint:disable-next-line:no-require-imports

const fs = require('fs');

this.input = fs.readFileSync((this.input as string).substr(7));

}

// TODO(kangyizhang): Add LocalFileChunkIterator to split local streaming

// with file in browser.

return new FileChunkIterator(this.input as FileElement, this.options);

}

}