/**
 * Copyright (c) 2020-present, Goldman Sachs
 *
 * 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 seedrandom from 'seedrandom';

export class Randomizer {
  private rng = seedrandom();

  /**
   * This method is exposed to allow setting seeds in test.
   * NOTE: Disable this during production for security.
   */
  setSeed(seed?: string): void {
    // eslint-disable-next-line no-process-env
    if (process.env.NODE_ENV === 'production') {
      return;
    }
    this.rng = seedrandom(seed);
  }

  /**
   * Get a random float in internal [0,1]
   */
  getRandomFloat(): number {
    // NOTE: the randomizer library we use automatically guarantee the value lies within the interval [0,1]
    // but we do this just in case
    return Math.abs(this.rng.quick() % 1);
  }

  /**
   * Get a random double in internal [0,1]
   */
  getRandomDouble(): number {
    // NOTE: the randomizer library we use automatically guarantee the value lies within the interval [0,1]
    // but we do this just in case
    return Math.abs(this.rng.double() % 1);
  }

  getRandomSignedInteger(): number {
    return this.rng.int32();
  }

  /**
   * Return whole number in internal [0, max] if `max` is specified, or otherwise, [0, Infinity)
   */
  getRandomWholeNumber(max?: number): number {
    return max !== undefined
      ? Math.abs(Math.floor(this.getRandomFloat() * Math.floor(max)))
      : Math.abs(this.getRandomSignedInteger());
  }

  getRandomItemInCollection<T>(collection: T[]): T | undefined {
    return collection[this.getRandomWholeNumber(collection.length - 1)];
  }

  getRandomDate(start: Date, end: Date): Date {
    return new Date(
      start.getTime() +
        Math.floor(this.getRandomFloat() * (end.getTime() - start.getTime())),
    );
  }
}