/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.team.internal.ccvs.core;


import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;
import org.eclipse.core.runtime.IStatus;

/**
 * A tag in CVS gives a label  to a collection of revisions. The labels can represent a version, a branch, 
 * or a date.
 */
public class CVSTag {

	public final static int HEAD = 0;
	public final static int BRANCH = 1;
	public final static int VERSION = 2;
	public final static int DATE = 3;
	
	public static final CVSTag DEFAULT = new CVSTag();
	public static final CVSTag BASE = new CVSTag("BASE", VERSION); //$NON-NLS-1$
	
	protected String name;
	protected int type;
	
	private static final String DATE_TAG_NAME_FORMAT = "dd MMM yyyy HH:mm:ss Z";//$NON-NLS-1$
	private static final SimpleDateFormat tagNameFormat = new SimpleDateFormat(DATE_TAG_NAME_FORMAT, Locale.US);
	protected static synchronized String dateToTagName(Date date){
		tagNameFormat.setTimeZone(TimeZone.getTimeZone("GMT"));//$NON-NLS-1$
		return tagNameFormat.format(date); //$NON-NLS-1$
	}
	protected static Date tagNameToDate(String name){
		if (name == null) return null;		
		try {
			return tagNameFormat.parse(name);
		} catch (ParseException e) {
			CVSProviderPlugin.log(new CVSException("Tag name " + name + " is not of the expected format " + DATE_TAG_NAME_FORMAT, e));
			return null;
		}
	}
	
	public CVSTag() {
		this("HEAD", HEAD); //$NON-NLS-1$
	}

	public CVSTag(String name, int type) {		
		this.name = name;
		this.type = type;
	}
	//Write a date in local date tag format
	public CVSTag(Date date) {
		this(dateToTagName(date), DATE);
	}

	public boolean equals(Object other) {
		if(other == this) return true;
		if (!(other instanceof CVSTag)) return false;
			
		CVSTag tag = ((CVSTag)other);
		if (getType() != tag.getType()) return false;
		if (!getName().equals(tag.getName())) return false;
		return true;
	}
	
	public String getName() {
		return name;
	}

	public int getType() {
		// TODO: getType() will not return accurate types for Tags retrieved from the local CVS Entries file.  See Bug: 36758
		return type;
	}
	
	public int hashCode() {
		return name.hashCode();
	}
	
	public int compareTo(CVSTag other) {
		if(getType() == DATE && other.getType()== DATE){
			Date date1 = asDate();
			Date date2 = other.asDate();
			if(date1 == null || date2 == null)return -1;
			return date1.compareTo(date2);
		}
		return getName().compareTo(other.getName());
	}
	
	public static boolean equalTags(CVSTag tag1, CVSTag tag2) {
		if (tag1 == null) tag1 = CVSTag.DEFAULT;
		if (tag2 == null) tag2 = CVSTag.DEFAULT;
		return tag1.equals(tag2);
	}
	
	public static IStatus validateTagName(String tagName) {
		if (tagName == null)
			return new CVSStatus(CVSStatus.ERROR, Policy.bind("CVSTag.nullName")); //$NON-NLS-1$
		if (tagName.equals(""))  //$NON-NLS-1$
			return new CVSStatus(CVSStatus.ERROR, Policy.bind("CVSTag.emptyName")); //$NON-NLS-1$
		if (!Character. isLetter(tagName.charAt(0)))
			return new CVSStatus(CVSStatus.ERROR, Policy.bind("CVSTag.beginName")); //$NON-NLS-1$
		
		for (int i = 0; i < tagName.length(); i++) {
			char c = tagName.charAt(i);
			if ( Character.isSpaceChar(c) || c == '$' || c == ',' || c == '.' || c == ':' || c == ';' || c == '@' || c == '|')
				return new CVSStatus(CVSStatus.ERROR, Policy.bind("CVSTag.badCharName")); //$NON-NLS-1$
		}
		return new CVSStatus(CVSStatus.OK, Policy.bind("ok")); //$NON-NLS-1$
	}
	
	/**
	 * Return the date this tag represents or <code>null</code>
	 * if the tag is not of type DATE.
	 * @return the date of the tag or <code>null</code>
	 */
	public Date asDate(){
		return tagNameToDate(name);
	}

}