/**
 * @license
 * Copyright 2020 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 {ENGINE} from '../engine';
import {Tensor} from '../tensor';
import {DataType, Rank, ShapeMap} from '../types';
import {sizeFromShape} from '../util';

import {op} from './operation';

/**
 * Creates a `tf.Tensor` with values sampled from a random number generator
 * function defined by the user.
 *
 * @param shape An array of integers defining the output tensor shape.
 * @param randFunction A random number generator function which is called
 * for each element in the output tensor.
 * @param dtype The data type of the output tensor. Defaults to 'float32'.
 */
function rand_<R extends Rank>(
    shape: ShapeMap[R], randFunction: () => number,
    dtype?: DataType): Tensor<R> {
  const size = sizeFromShape(shape);
  let values = null;
  if (dtype == null || dtype === 'float32') {
    values = new Float32Array(size);
  } else if (dtype === 'int32') {
    values = new Int32Array(size);
  } else if (dtype === 'bool') {
    values = new Uint8Array(size);
  } else {
    throw new Error(`Unknown data type ${dtype}`);
  }
  for (let i = 0; i < size; i++) {
    values[i] = randFunction();
  }
  return ENGINE.makeTensor(values, shape, dtype) as Tensor<R>;
}

export const rand = op({rand_});