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package marcel.lang;

import lombok.AllArgsConstructor;
import lombok.Getter;
import marcel.lang.primitives.collections.lists.IntList;
import marcel.lang.primitives.collections.lists.IntLists;
import marcel.lang.primitives.iterators.AbstractIntIterator;
import marcel.lang.primitives.iterators.IntIterator;
import marcel.lang.primitives.iterators.IntIterators;

import java.util.NoSuchElementException;

public class IntRanges {

  public static IntRange ofExclusive(int from, int to) {
    return from <= to ? ofIncrExclusive(from, to) : ofDecrExclusive(from, to);
  }

  public static IntRange ofFromExclusive(int from, int to) {
    return from <= to ? ofIncrFromExclusive(from, to) : ofDecrFromExclusive(from, to);
  }

  public static IntRange ofToExclusive(int from, int to) {
    return from <= to ? ofIncrToExclusive(from, to) : ofDecrToExclusive(from, to);
  }

  public static IntRange of(int from, int to) {
    return from <= to ? ofIncr(from, to) : ofDecr(from, to);
  }

  public static IntRange ofDecrExclusive(int from, int to) {
    return from - to <= 1 ? new EmptyRange() : ofDecr(from - 1, to + 1);
  }
  public static IntRange ofDecrFromExclusive(int from, int to) {
    return from == to ? new EmptyRange() : ofDecr(from - 1, to);
  }
  public static IntRange ofDecrToExclusive(int from, int to) {
    return from == to ? new EmptyRange() : ofDecr(from, to + 1);
  }

  public static IntRange ofDecr(int from, int to) {
    if (from < to) {
      throw new IllegalArgumentException("From should be goe to");
    }
    return new IntRangeImpl(from, to, true);
  }

  public static IntRange ofIncrExclusive(int from, int to) {
    return to - from <= 1 ? new EmptyRange() : ofIncr(from + 1, to - 1);
  }
  public static IntRange ofIncrFromExclusive(int from, int to) {
    return from == to ? new EmptyRange() : ofIncr(from + 1, to);
  }
  public static IntRange ofIncrToExclusive(int from, int to) {
    return from == to ? new EmptyRange() : ofIncr(from, to - 1);
  }

  public static IntRange ofIncr(int from, int to) {
    if (from > to) {
      throw new IllegalArgumentException("From should be loe to");
    }
    return new IntRangeImpl(from, to, false);
  }

  @AllArgsConstructor
  private static class IntIncrRangeIterator extends AbstractIntIterator {

    private int current;
    private final int end;

    @Override
    public Integer next() {
      return current++;
    }

    @Override
    public boolean hasNext() {
      return current <= end;
    }
  }

  @AllArgsConstructor
  private static class IntDecrRangeIterator extends AbstractIntIterator {

    private int current;
    private final int end;

    @Override
    public Integer next() {
      return current--;
    }

    @Override
    public boolean hasNext() {
      return current >= end;
    }
  }

  @Getter
  @AllArgsConstructor
  private static final class IntRangeImpl extends AbstractIntRange {

    private final int from;
    private final int to;
    private boolean reverse;

    @Override
    public IntIterator iterator() {
      return reverse ? new IntDecrRangeIterator(from, to) : new IntIncrRangeIterator(from, to);
    }

    @Override
    public boolean isEmpty() {
      return false;
    }

    @Override
    public String toString() {
      return from + ".." + to;
    }
  }
  private static final class EmptyRange extends AbstractIntRange {

    @Override
    public int getFrom() {
      throw new NoSuchElementException();
    }

    @Override
    public int getTo() {
      throw new NoSuchElementException();
    }

    @Override
    public IntIterator iterator() {
      return IntIterators.EMPTY_ITERATOR;
    }

    @Override
    public boolean isEmpty() {
      return true;
    }

    @Override
    public boolean isReverse() {
      return false;
    }

    @Override
    public IntList toList() {
      return IntLists.EMPTY_LIST;
    }

    @Override
    public String toString() {
      return "..";
    }

    @Override
    public int size() {
      return 0;
    }
  }
}