/*
    Copyright 2009 Dmitry Naumenko (dm.naumenko@gmail.com)
    
    This file is part of Java Diff Utills Library.

    Java Diff Utills Library is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    Java Diff Utills 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Java Diff Utills Library.  If not, see <http://www.gnu.org/licenses/>.
*/
package difflib;

import java.util.*;

/**
 * Describes the delta between original and revised texts.
 * 
 * @author <a href="dm.naumenko@gmail.com">Dmitry Naumenko</a>
 */
public abstract class Delta {
	private Chunk original;
	private Chunk revised;

	/**
	 * Construct the delta for original and revised chunks
	 * 
	 * @param original chunk describes the original text
	 * @param revised chunk describes the revised text
	 */
	public Delta(Chunk original, Chunk revised) {
		this.original = original;
		this.revised  = revised;
	}
	
    /**
     * Verifies that this delta can be used to patch the given text.
     * @param target the text to patch.
     * @throws PatchFailedException if the patch cannot be applied.
     */
    public abstract void verify(List<?> target) throws PatchFailedException;
	
	/**
	 * Applies this delta as the patch for a given target
	 * 
	 * @param target the given target
	 * @throws PatchFailedException  
	 */
	public abstract void applyTo(List<Object> target) throws PatchFailedException;
	
	/**
	 * Cancel this delta for a given revised text. The action is opposite to patch.
	 * 
	 * @param target the given revised text
	 */
	public abstract void restore(List<Object> target);
	
	/**
	 * @return the Chunk describing the original text
	 */
	public Chunk getOriginal() {
		return original;
	}
	/**
	 * @param original the Chunk describing the original text to set
	 */
	public void setOriginal(Chunk original) {
		this.original = original;
	}
	
	/**
	 * @return the Chunk describing the revised text
	 */
	public Chunk getRevised() {
		return revised;
	}
	/**
	 * @param revised the Chunk describing the revised text to set
	 */
	public void setRevised(Chunk revised) {
		this.revised = revised;
	}

	/* (non-Javadoc)
	 * @see java.lang.Object#hashCode()
	 */
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result
				+ ((original == null) ? 0 : original.hashCode());
		result = prime * result + ((revised == null) ? 0 : revised.hashCode());
		return result;
	}

	/* (non-Javadoc)
	 * @see java.lang.Object#equals(java.lang.Object)
	 */
	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Delta other = (Delta) obj;
		if (original == null) {
			if (other.original != null)
				return false;
		} else if (!original.equals(other.original))
			return false;
		if (revised == null) {
			if (other.revised != null)
				return false;
		} else if (!revised.equals(other.revised))
			return false;
		return true;
	}
	
	
}