/**
 * @license
 * Copyright 2020 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 {whereImpl} from '../backends/where_impl';
import {Tensor, Tensor2D} from '../tensor';
import {convertToTensor} from '../tensor_util_env';
import {TensorLike} from '../types';

/**
 * Returns the coordinates of true elements of condition.
 *
 * The coordinates are returned in a 2-D tensor where the first dimension (rows)
 * represents the number of true elements, and the second dimension (columns)
 * represents the coordinates of the true elements. Keep in mind, the shape of
 * the output tensor can vary depending on how many true values there are in
 * input. Indices are output in row-major order. The resulting tensor has the
 * shape `[numTrueElems, condition.rank]`.
 *
 * This is analogous to calling the python `tf.where(cond)` without an x or y.
 *
 * ```js
 * const cond = tf.tensor1d([false, false, true], 'bool');
 * const result = await tf.whereAsync(cond);
 * result.print();
 * ```
 *
 * @doc {heading: 'Operations', subheading: 'Logical'}
 */
async function whereAsync_(condition: Tensor|TensorLike): Promise<Tensor2D> {
  const $condition =
      convertToTensor(condition, 'condition', 'whereAsync', 'bool');
  const vals = await $condition.data();
  const res = whereImpl($condition.shape, vals);
  if (condition !== $condition) {
    $condition.dispose();
  }
  return res;
}

export const whereAsync = whereAsync_;