/**

* @license

* Copyright 2018 Google Inc. 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 * as tfc from '@tensorflow/tfjs-core';

/**

* Convert an ArrayBuffer to a Buffer.

*/

export function toBuffer(ab: ArrayBuffer): Buffer {

const view = new Uint8Array(ab);

return Buffer.from(view); // copies data

}

/**

* Convert a Buffer or an Array of Buffers to an ArrayBuffer.

*

* If the input is an Array of Buffers, they will be concatenated in the

* specified order to form the output ArrayBuffer.

*/

export function toArrayBuffer(buf: Buffer|Buffer[]): ArrayBuffer {

if (Array.isArray(buf)) {

// An Array of Buffers.

let totalLength = 0;

for (const buffer of buf) {

totalLength += buffer.length;

}

const ab = new ArrayBuffer(totalLength);

const view = new Uint8Array(ab);

let pos = 0;

for (const buffer of buf) {

pos += buffer.copy(view, pos);

}

return ab;

} else {

// A single Buffer. Return a copy of the underlying ArrayBuffer slice.

return buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength);

}

}

// TODO(cais): Use explicit tfc.io.ModelArtifactsInfo return type below once it

// is available.

/**

* Populate ModelArtifactsInfo fields for a model with JSON topology.

* @param modelArtifacts

* @returns A ModelArtifactsInfo object.

*/

export function getModelArtifactsInfoForJSON(

modelArtifacts: tfc.io.ModelArtifacts) {

if (modelArtifacts.modelTopology instanceof ArrayBuffer) {

throw new Error('Expected JSON model topology, received ArrayBuffer.');

}

return {

dateSaved: new Date(),

modelTopologyType: 'JSON',

modelTopologyBytes: modelArtifacts.modelTopology == null ?

0 :

Buffer.byteLength(JSON.stringify(modelArtifacts.modelTopology), 'utf8'),

weightSpecsBytes: modelArtifacts.weightSpecs == null ?

0 :

Buffer.byteLength(JSON.stringify(modelArtifacts.weightSpecs), 'utf8'),

weightDataBytes: modelArtifacts.weightData == null ?

0 :

modelArtifacts.weightData.byteLength,

};

}