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/*
 * Copyright 2015 Objectos, Fábrica de Software LTDA.
 *
 * 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.
 */
package br.com.objectos.way.code;

import java.util.Collection;

/**
 * @author [email protected] (Marcio Endo)
 */
public class Index {

  private final int value;
  private final int total;

  private Index(int value, int total) {
    this.value = value;
    this.total = total;
  }

  public static Builder builder(Collection collection) {
    int total = collection.size();
    return new Builder(total);
  }

  public static Index of(int index, int total) {
    return new Index(index, total);
  }

  public int get() {
    return value;
  }

  public boolean first() {
    return value == 0;
  }

  public boolean last() {
    return value == total - 1;
  }

  @Override
  public String toString() {
    return value + "/" + total;
  }

  @Override
  public final int hashCode() {
    return value * 31 + total;
  }

  @Override
  public final boolean equals(final Object obj) {
    if (obj == this) {
      return true;
    }
    if (obj instanceof Index) {
      final Index that = (Index) obj;
      return value == that.value
          && total == that.total;
    } else {
      return false;
    }
  }

  public static class Builder {

    private int value;
    private final int total;

    private Builder(int total) {
      this.total = total;
    }

    public Index next() {
      return new Index(value++, total);
    }

  }

}