/*
	WhatsNew - a plugin based on RecentChangesPlugin for:
	
    JSPWiki - a JSP-based WikiWiki clone.

    by Janne Jalkanen (Janne.Jalkanen@iki.fi)
 */

import java.util.Calendar;
import java.util.Collection;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import com.ecyrd.jspwiki.TextUtil;
import com.ecyrd.jspwiki.WikiContext;
import com.ecyrd.jspwiki.WikiEngine;
import com.ecyrd.jspwiki.WikiPage;
import com.ecyrd.jspwiki.attachment.Attachment;
import com.ecyrd.jspwiki.plugin.PluginException;
import com.ecyrd.jspwiki.plugin.WikiPlugin;

import org.apache.ecs.xhtml.a;
import org.apache.ecs.xhtml.li;
import org.apache.ecs.xhtml.ul;
import org.apache.log4j.Logger;

/**
 *  Returns the Recent Changes in the form of a simple bullet list.
 *
 *  Parameters: since=number of days
 *              entries=max number of entries,
 *              width=max width in characters
 *              suffix=string on which to split off page name suffixes
 *
 *  @author Janne Jalkanen
 *  @author Andre van Dalen
 *  @version 0.1
 */
public class WhatsNewPlugin implements WikiPlugin {

	/** The logger. */
	private static Logger log = Logger.getLogger(WhatsNewPlugin.class);

	/** Name of the 'since' parameter. */
	private static final String PARAM_SINCE 		= "since";

	/** Name of the 'entries' parameter. */
	private static final String PARAM_MAX_ENTRIES	= "entries";

	/** Name of the 'width' parameter. */
	private static final String PARAM_MAX_WIDTH	= "width";

	/** Name of the 'suffix' parameter. */
	private static final String PARAM_SUFFIX	= "suffix";

	/** String constant for truncation filler. */
	private static final String DOTS = "..";

	/** How many days we show by default. */
	private static final int DEFAULT_SINCE = 365;

	/** How many entries we show by default. */
	private static final int DEFAULT_MAX_ENTRIES = 16;

	/** What character width we show by default. */
	private static final int DEFAULT_MAX_WIDTH = 64;

	/**
	 * @see com.ecyrd.jspwiki.plugin.WikiPlugin#execute(com.ecyrd.jspwiki.WikiContext, java.util.Map)
	 */
	public String execute(WikiContext context, Map params) throws PluginException {

		WikiEngine engine	= context.getEngine();
		Calendar sincedate 	= new GregorianCalendar();
		final int since	= TextUtil.parseIntParameter((String) params.get(PARAM_SINCE), DEFAULT_SINCE);
		int maxEntries		= TextUtil.parseIntParameter((String) params.get(PARAM_MAX_ENTRIES), DEFAULT_MAX_ENTRIES);
		final int maxWidth	= TextUtil.parseIntParameter((String) params.get(PARAM_MAX_WIDTH), DEFAULT_MAX_WIDTH);
		String suffix		= (String) params.get(PARAM_SUFFIX);

		sincedate.add(Calendar.DAY_OF_MONTH, -since);

		if (log.isDebugEnabled()) {
			log.debug("Calculating recent changes from " + sincedate.getTime());
		}

		Collection changes = engine.getRecentChanges();
		String result = "";

		if (null != changes) {
			Set seen = new HashSet(maxEntries);

			ul ul = new ul();
			ul.setClass("whatsnew");

			for (Iterator i = changes.iterator(); i.hasNext() && 0 < maxEntries;) {
				WikiPage pageref = (WikiPage) i.next();

				Date lastmod = pageref.getLastModified();

				if (lastmod.before(sincedate.getTime())) {
					break;
				}

				String name = (pageref instanceof Attachment) ?
								((Attachment) pageref).getParentName() :
								pageref.getName();
				
				final int suffixOffset = (null == suffix) ? 0 : name.indexOf(suffix);
				
				if (0 < suffixOffset) {
					name = name.substring(0, suffixOffset);
				}
				
				if (!seen.contains(name)) {
					seen.add(name);
					maxEntries--;

					String link = context.getURL(WikiContext.VIEW, name);
					String title = fitToWidth(engine.beautifyTitle(name), maxWidth);

					a linkel = new a(link, title);

					linkel.setClass("wikipage");

					li line = new li().addElement(linkel);

					ul.addElement(line);
				}
			}

			ul.setPrettyPrint(true);

			result = ul.toString();
		}

		return result;
	}

	/**
	 * Fit a wiki-like string to a maximum width.
	 * 
	 * @param value The string the compress if its too long.
	 * @param maxWidth The maximum width in characters.
	 * @return String, the input value compressed to maxWidth characters.
	 */
	public String fitToWidth(String value, int maxWidth) {
		String result = value;
		
		if (0 < maxWidth && maxWidth < result.length()) {
			// first change AaaaBbbbCcc into AaaaB..Cccc by replacing chacacters before the last
			// Capitalised word with .. 
			final int diff = result.length() - maxWidth + DOTS.length();
			
			final boolean oneChar = (diff > result.length() - 1);

			int offset = result.length();
			
			while (0 < offset) {
				if (Character.isUpperCase(result.charAt(--offset))) {
					break;
				}
			}
			
			if (0 < offset) {
				final boolean smallGap = oneChar || (1 >= offset - diff);
				
				result = result.substring(0, smallGap ? 1 : offset - diff) +
							DOTS +
							result.substring(oneChar || !smallGap ? offset : 1 + diff);
			}
			
			// if that didn't get the desired result, truncate what we got
			if (maxWidth < result.length()) {
				result = result.substring(0, maxWidth);
			}
		}
		return result;
	}
}