/*
Wotonomy: OpenStep design patterns for pure Java applications.
Copyright (C) 2000 Blacksmith, Inc.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see http://www.gnu.org
*/

package net.wotonomy.foundation;

/**
 * A pure java implementation of NSRange. An NSRange represents a range of
 * numbers having a starting location and spanning a length.
 *
 * @author michael@mpowers.net
 * @author $Author: cgruber $
 * @version $Revision: 920 $
 */
public class NSRange implements Cloneable {
	/**
	 * An empty range.
	 */
	public static final NSRange ZeroRange = new NSRange();

	protected int loc;
	protected int len;

	/**
	 * Default constructor produces an empty range.
	 */
	public NSRange() {
		this(0, 0);
	}

	/**
	 * Produces a range with the specified location and length.
	 */
	public NSRange(int location, int length) {
		loc = location;
		len = length;
	}

	/**
	 * Produces a range that has the same location and length as the specified
	 * range.
	 */
	public NSRange(NSRange aRange) {
		this(aRange.location(), aRange.length());
	}

	/**
	 * Returns the location of this range.
	 */
	public int location() {
		return loc;
	}

	/**
	 * Returns the length of this range.
	 */
	public int length() {
		return len;
	}

	/**
	 * Returns the maximum extent of the range. This number is one more than the
	 * last position in the range.
	 */
	public int maxRange() {
		return location() + length() - 1;
	}

	/**
	 * Returns whether this is an empty range, therefore whether the length is zero.
	 */
	public boolean isEmpty() {
		return (length() == 0);
	}

	/**
	 * Returns whether the specified location is contained within this range.
	 */
	public boolean locationInRange(int location) {
		if (location < location())
			return false;
		if (location >= maxRange())
			return false;
		return true;
	}

	/**
	 * Returns whether the specified range is equal to this range.
	 */
	public boolean isEqualToRange(NSRange aRange) {
		if (aRange == null)
			return false;
		return ((aRange.location() == location()) && (aRange.length() == length()));
	}

	/**
	 * Returns whether the specified object is equal to this range.
	 */
	@Override
	public boolean equals(Object anObject) {
		if (anObject instanceof NSRange)
			return isEqualToRange((NSRange) anObject);
		return false;
	}

	/**
	 * Returns a hashCode.
	 */
	@Override
	public int hashCode() {
		// TODO: Test this logic.
		return (location() << 2) & length(); // bitwise ops never my forte
	}

	/**
	 * Returns a string representation of this range.
	 */
	@Override
	public String toString() {
		return "[NSRange: location = " + location() + "; length = " + length() + "]";
	}

	/**
	 * Returns the union of this range and the specified range, if any. Gaps are
	 * filled, so the result is the smallest starting position and the largest
	 * ending position.
	 */
	public NSRange rangeByUnioningRange(NSRange aRange) {
		if (aRange == null)
			return this;

		// TODO: Test this logic.
		int resultLoc = Math.min(this.location(), aRange.location());
		int resultLen = Math.max(this.location() + this.length(), aRange.location() + aRange.length()) - resultLoc;
		return new NSRange(resultLoc, resultLen);
	}

	/**
	 * Returns the intersection of this range and the specified range, if any. If no
	 * intersection, returns an empty range.
	 */
	public NSRange rangeByIntersectingRange(NSRange aRange) {
		// TODO: Test this logic.
		if (!intersectsRange(aRange))
			return ZeroRange;
		int start = Math.max(this.location(), aRange.location());
		int end = Math.min(this.location() + this.length(), aRange.location() + aRange.length());
		return new NSRange(start, end - start);
	}

	/**
	 * Returns whether the specified range overlaps at any point with this range.
	 */
	public boolean intersectsRange(NSRange aRange) {
		// TODO: Test this logic.
		if (aRange == null)
			return false;
		if ((this.location() >= aRange.location()) && (this.location() < aRange.location() + aRange.length()))
			return true;
		if ((aRange.location() >= this.location()) && (aRange.location() < this.location() + this.length()))
			return true;
		return false;
	}

	/**
	 * Returns whether this range is completely contained within the specified
	 * range.
	 */
	public boolean isSubrangeOfRange(NSRange aRange) {
		// TODO: Test this logic.
		if (aRange == null)
			return false;
		if ((this.location() >= aRange.location()) && (this.maxRange() <= aRange.maxRange()))
			return true;
		return false;
	}

	/**
	 * Eliminates any intersections between this range and the specified range. This
	 * produces two ranges, either of which may be empty. These two ranges are
	 * returned by modifying the supplied second and third parameters.
	 */
	public void subtractRange(NSRange aRange, NSMutableRange firstResult, NSMutableRange secondResult) {
		if (aRange == null)
			return;

		// TODO: Test this logic.
		// no intersection: return this and aRange without calculation
		if (!intersectsRange(aRange)) {
			if (firstResult != null) {
				firstResult.setLocation(this.location());
				firstResult.setLength(this.length());
			}
			if (secondResult != null) {
				secondResult.setLocation(aRange.location());
				secondResult.setLength(aRange.location());
			}
			return;
		}

		// TODO: Test this logic.
		// this range is completely contained by other range
		if (isSubrangeOfRange(aRange)) {
			if (firstResult != null) {
				firstResult.setLocation(aRange.location());
				firstResult.setLength(this.location() - aRange.location());
			}
			if (secondResult != null) {
				secondResult.setLocation(this.maxRange());
				secondResult.setLength(aRange.maxRange() - this.maxRange() - 1); // test this
			}
			return;
		}

		// TODO: Test this logic.
		// other range is completely contained by this range
		if (aRange.isSubrangeOfRange(this)) {
			if (firstResult != null) {
				firstResult.setLocation(this.location());
				firstResult.setLength(aRange.location() - this.location());
			}
			if (secondResult != null) {
				secondResult.setLocation(aRange.maxRange());
				secondResult.setLength(this.maxRange() - aRange.maxRange() - 1); // test this
			}
			return;
		}

		// TODO: Test this logic.
		// ranges intersect: remove only the intersection

		NSRange firstRange, secondRange;
		if (this.location() <= aRange.location()) {
			firstRange = this;
			secondRange = aRange;
		} else {
			firstRange = aRange;
			secondRange = this;
		}

		if (firstResult != null) {
			firstResult.setLocation(firstRange.location());
			firstResult.setLength(secondRange.location() - firstRange.location());
		}
		if (secondResult != null) {
			secondResult.setLocation(firstRange.maxRange());
			secondResult.setLength(secondRange.maxRange() - aRange.maxRange() - 1); // test this
		}
		return;

	}

	/**
	 * Returns a copy of this range.
	 */
	@Override
	public Object clone() {
		return new NSRange(location(), length());
	}

	/**
	 * Parses a range from a string of the form "{x,y}" where x is the location and
	 * y is the length. If not parsable, an IllegalArgumentException is thrown.
	 */
	public static NSRange fromString(String aString) {
		// TODO: Test this logic.
		try {
			java.util.StringTokenizer tokens = new java.util.StringTokenizer(aString, "{,}");
			int loc = Integer.parseInt(tokens.nextToken());
			int len = Integer.parseInt(tokens.nextToken());
			return new NSRange(loc, len);
		} catch (Exception exc) {
			throw new IllegalArgumentException(exc.toString());
		}
	}

}

/*
 * $Log$ Revision 1.2 2006/02/16 13:15:00 cgruber Check in all sources in
 * eclipse-friendly maven-enabled packages.
 *
 * Revision 1.1.1.1 2000/12/21 15:47:42 mpowers Contributing wotonomy.
 *
 * Revision 1.3 2000/12/20 16:25:38 michael Added log to all files.
 *
 *
 */