package com.n1nja.utils;
import java.util.Iterator;
/**
 * Allows for Python-like {@code foreach} loop iteration with
 * {@link java.lang.Integer Integer}s. Use as follows.
 * <pre>
 * for ({@link java.lang.Integer Integer} l : new Range());
 * </pre>
 * @author Colin Haber
 * @version 0.1.0
 */
public class Range implements Iterable<Integer> {
	/**
	 * The default {@linkplain #start starting value} for {@link Range}s that
	 * do not explicitly define one.
	 * @since 0.1.0
	 * @see #Range(Integer)
	 */
	private static Integer DEFAULT_START = 0;
	/**
	 * The default {@linkplain #step step size} for {@link Range}s that do not
	 * explicitly define one.
	 * @since 0.1.0
	 * @see #Range(Integer)
	 * @see #Range(Integer, Integer)
	 */
	private static Integer DEFAULT_STEP = 1;
	/**
	 * The {@link Range}'s starting value, inclusive.
	 * @since 0.0.0
	 */
	private final Integer start;
	/**
	 * The {@link Range}'s ending value, non-inclusive.
	 * @since 0.0.0
	 */
	private final Integer end;
	/**
	 * The {@link Range}'s step (or interval) size.
	 * @since 0.0.0
	 */
	private final Integer step;
	/**
	 * Creates a {@link Range} from {@code 0}, inclusive, to {@code count},
	 * non-inclusive, with a {@linkplain #step} size of {@code 1}.
	 * @since 0.0.0
	 * @param count the {@link #end} value for this {@link Range},
	 * non-inclusive
	 */
	public Range(Integer count) {
		this(Range.DEFAULT_START, count);
	}
	/**
	 * Creates a {@link Range} from {@code start}, inclusive, to {@code end},
	 * non-inclusive, with a {@linkplain #step} size of {@code 1}.
	 * @since 0.0.0
	 * @param start the {@link #start} value for this {@link Range}, inclusive
	 * @param end the {@link #end} value for this {@link Range}, non-inclusive
	 */
	public Range(Integer start, Integer end) {
		this(start, end, Range.DEFAULT_STEP);
	}
	/**
	 * Creates a {@link Range} from {@code start}, inclusive, to {@code end},
	 * non-inclusive, with a {@linkplain #step} size of {@code step}.
	 * @since 0.0.0
	 * @param start the {@link #start} value for this {@link Range}, inclusive
	 * @param end the {@link #end} value for this {@link Range}, non-inclusive
	 * @param step the {@link #step} size for this {@link Range}
	 */
	public Range(Integer start, Integer end, Integer step) {
		this.start = start;
		this.end = end;
		this.step = step;
	}
	@Override
	public Iterator<Integer> iterator() {
		final Integer startVal = this.start;
		final Integer endVal = this.end;
		final Integer stepSize = this.step;
		return new Iterator<Integer>() {
			private final Integer start = startVal;
			private final Integer end = endVal;
			private final Integer step = stepSize;
			private Integer index;
			{
				if ((this.end - this.start != 0) && (Math.signum(this.end - this.start) != Math.signum(this.step))) {
					throw new IllegalArgumentException("Infinite looping statement detected.");
				}
				this.index = 0;
			}
			@Override
			public boolean hasNext() {
				return ((this.start < this.end) && (this.start + (this.step * this.index) < this.end) || ((this.start > this.end) && (this.start + (this.step * this.index) > this.end)));
			}
			@Override
			public synchronized Integer next() {
				Integer next = null;
				if (this.hasNext()) {
					next = this.start + (this.step * this.index);
					this.index++;
				}
				return next;
			}
			@Override
			public void remove() {
				throw new UnsupportedOperationException(this.getClass().getSimpleName() + " does not support remove().");
			}
		};
	}
}