/**

* @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 {DataSource} from '../datasource';

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

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

import {urlChunkIterator} from '../iterators/url_chunk_iterator';

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

import {FileDataSource} from './file_data_source';

/*

* Represents a URL readable as a stream of binary data chunks.

*/

export class URLDataSource extends DataSource {

/**

* Create a `URLDataSource`.

*

* @param url A source URL string, or a `Request` object.

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

* such as {chunksize: 1024}.

*/

constructor(

protected readonly url: RequestInfo,

protected readonly fileOptions: FileChunkIteratorOptions = {}) {

super();

}

// TODO(soergel): provide appropriate caching options. Currently this

// will download the URL anew for each call to iterator(). Since we have

// to treat the downloaded file as a blob/buffer anyway, we may as well retain

// it-- but that raises GC issues. Also we may want a persistent disk cache.

async iterator(): Promise<ByteChunkIterator> {

if (isLocalPath(this.url)) {

return (new FileDataSource(this.url as string, this.fileOptions))

.iterator();

} else {

return urlChunkIterator(this.url, this.fileOptions);

}

}

}