package de.ldj.jspwiki.plugin;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Random;

import org.apache.log4j.Logger;

import com.ecyrd.jspwiki.WikiContext;
import com.ecyrd.jspwiki.WikiEngine;
import com.ecyrd.jspwiki.WikiPage;
import com.ecyrd.jspwiki.plugin.WikiPlugin;
import com.ecyrd.jspwiki.providers.ProviderException;

/**
 * The FortuneCookie will return a random line from a cookies page on each call.
 * 
 * @author Maik Scheibler
 */
public class FortuneCookie implements WikiPlugin {

	private static final String LINE_COMMENT = "//";
	private static final String BULLET_ITEM = "*";
	private static final String NUMBER_ITEM = "#";
	private static final String LINEBREAK = "\\\\";
	private static final Logger LOG = Logger.getLogger(FortuneCookie.class);
	private static final Random RANDOM = new Random(System.currentTimeMillis());
	private static List<String> m_fortuneCookies = new ArrayList<String>();
	private static Date m_pageLastModified;

	/**
	 * {@inheritDoc}
	 */
	public String execute(WikiContext context, Map params) {
		String cookiesPageName = (String) params.get("page");
		if (cookiesPageName == null || cookiesPageName.trim().isEmpty())
			return getErrorSpan("You need to specify a cookies page.");

		WikiEngine wikiEngine = context.getEngine();
		try {
			if (!wikiEngine.pageExists(cookiesPageName))
				return getErrorSpan("The cookies page '" + cookiesPageName
						+ "' could not be found.");
			WikiPage cookiesPage = wikiEngine.getPage(wikiEngine
					.getFinalPageName(cookiesPageName));

			synchronized (FortuneCookie.class) {
				if (m_pageLastModified == null
						|| m_pageLastModified.before(cookiesPage
								.getLastModified()))
					updateCookies(wikiEngine, cookiesPage);
			}
		} catch (ProviderException ex) {
			String message = "failed to aquire cookies final page name";
			LOG.error(message, ex);
			return getErrorSpan(message);
		} catch (IOException ex) {
			String message = "failed to read cookies page content";
			LOG.error(message, ex);
			return getErrorSpan(message);
		}

		if (m_fortuneCookies.isEmpty())
			return getErrorSpan("The cookies page does not contain any non empty lines.");
		String line = m_fortuneCookies.get(RANDOM.nextInt(m_fortuneCookies
				.size()));

		// translate the selected cookie from Wiki markup to HTML
		String htmlCookie = wikiEngine.textToHTML(context, line);
		return htmlCookie;
	}

	/**
	 * Updates the available cookies from the cookies page.
	 * 
	 * @param wikiEngine
	 *            of this wiki
	 * @param cookiesPage
	 *            which contains the cookies
	 * @throws IOException
	 *             in case the page content could not be read
	 */
	private void updateCookies(WikiEngine wikiEngine, WikiPage cookiesPage)
			throws IOException {
		m_fortuneCookies.clear();
		String pureCookiesText = wikiEngine.getPureText(cookiesPage);
		BufferedReader reader = new BufferedReader(new StringReader(
				pureCookiesText));
		String line = null;
		while ((line = reader.readLine()) != null) {
			line = line.trim();
			if (line.isEmpty() || line.startsWith(LINE_COMMENT))
				continue;
			// strip bullet, numeration or line breaks from the content
			if (line.startsWith(BULLET_ITEM) || line.startsWith(NUMBER_ITEM))
				line = line.substring(BULLET_ITEM.length());
			if (line.endsWith(LINEBREAK))
				line = line.substring(0, line.length() - LINEBREAK.length());
			m_fortuneCookies.add(line.trim());
		}
		m_pageLastModified = cookiesPage.getLastModified();
	}

	/**
	 * Creates an error message span.
	 * 
	 * @param errorMsg
	 *            to display
	 * @return the error as HTML
	 */
	private String getErrorSpan(String errorMsg) {
		return "<span class=\"error\">" + FortuneCookie.class.getName()
				+ ":<br/>" + errorMsg + "</span>";
	}
}