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/*
 * Copyright 2015-16, Yahoo! Inc.
 * Licensed under the terms of the Apache License 2.0. See LICENSE file at the project root for terms.
 */

package com.yahoo.sketches.quantiles;

import static com.yahoo.sketches.quantiles.Util.LS;
import static com.yahoo.sketches.quantiles.Util.TAB;

/**
 * For building a new QuantilesSketch.
 *
 * @author Lee Rhodes
 */
public class DoublesSketchBuilder {
  private int bK;

  /**
   * Constructor for building a new QuantilesSketch. The default configuration is
   * 
   * k: {@value DoublesSketch#DEFAULT_K}
   * This produces a normalized rank error of about 1.7%
   * Seed: 0
   * Memory: null
   * 
   */
  public DoublesSketchBuilder() {
    bK = DoublesSketch.DEFAULT_K;
  }

  /**
   * Sets the parameter k that determines the accuracy and size of the sketch
   * @param k determines the accuracy and size of the sketch.
   * k must be greater than 0 and less than 65536.
   * It is recommended that k be a power of 2 to enable merging of sketches with
   * different values of k. However, in this case it is only possible to merge from
   * larger values of k to smaller values.
   * @return this builder
   */
  public DoublesSketchBuilder setK(int k) {
    Util.checkK(k);
    bK = k;
    return this;
  }

  /**
   * Gets the current configured value of k
   * @return the current configured value of k
   */
  public int getK() {
    return bK;
  }

  /**
   * Returns a QuantilesSketch with the current configuration of this Builder.
   * @return a QuantilesSketch
   */
  public DoublesSketch build() {
    return HeapDoublesSketch.newInstance(bK);
  }

  /**
   * Returns a QuantilesSketch with the current configuration of this Builder and the
   * given parameter k.
   * @param k determines the accuracy and size of the sketch.
   * k must be greater than 0 and less than 65536.
   * It is recommended that k be a power of 2 to enable merging of sketches with
   * different values of k. However, in this case it is only possible to merge from
   * larger values of k to smaller values.
   *
   * @return a QuantilesSketch
   */
  public DoublesSketch build(int k) {
    setK(k);
    return build();
  }

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("QuantileSketchBuilder configuration:").append(LS);
    sb.append("K:").append(TAB).append(bK).append(LS);
    return sb.toString();
  }

}