package com.btr.proxy.util;

import java.net.Proxy;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.btr.proxy.selector.fixed.FixedProxySelector;
import com.btr.proxy.selector.pac.PacProxySelector;
import com.btr.proxy.selector.pac.PacScriptSource;
import com.btr.proxy.selector.pac.UrlPacScriptSource;

/*****************************************************************************
 * Small helper class for some common utility methods.
 *
 * @author Bernd Rosstauscher (proxyvole@rosstauscher.de) Copyright 2009
 ****************************************************************************/

public class ProxyUtil {
	
	public static final int DEFAULT_PROXY_PORT = 80;
	
	private static List<Proxy> noProxyList;
    private static Pattern pattern = Pattern.compile("\\w*?:?/*([^:/]+):?(\\d*)/?");
	
	/*************************************************************************
	 * Parse host and port out of a proxy variable.
	 * @param proxyVar the proxy string. example: http://192.168.10.9:8080/
	 * @return a FixedProxySelector using this settings, null on parse error.
	 ************************************************************************/
	
	public static FixedProxySelector parseProxySettings(String proxyVar) {
		if (proxyVar == null || proxyVar.trim().length() == 0) {
			return null;
		}
		Matcher matcher = pattern.matcher(proxyVar);
		if (matcher.matches()) {
		    String host = matcher.group(1);
		    int port;
		    if (!"".equals(matcher.group(2))) {
		        port = Integer.parseInt(matcher.group(2));
		    } else {
		        port = DEFAULT_PROXY_PORT;
		    }
            return new FixedProxySelector(host.trim(), port);
		} else {
		    return null;
		}
	}
	
	/*************************************************************************
	 * Gets an unmodifiable proxy list that will have as it's only entry an DIRECT proxy.
	 * @return a list with a DIRECT proxy in it.
	 ************************************************************************/
	
	public static synchronized List<Proxy> noProxyList() {
		if (noProxyList == null) {
			ArrayList<Proxy> list = new ArrayList<Proxy>(1);
			list.add(Proxy.NO_PROXY);
			noProxyList = Collections.unmodifiableList(list);
		}
		return noProxyList;
	}
	
	/*************************************************************************
	 * Build a PAC proxy selector for the given URL.
	 * @param url to fetch the PAC script from.
	 * @return a PacProxySelector or null if it is not possible to build a working
	 * selector.
	 ************************************************************************/
	
	public static PacProxySelector buildPacSelectorForUrl(String url) {
		PacProxySelector result = null;
		PacScriptSource pacSource = new UrlPacScriptSource(url);
		if (pacSource.isScriptValid()) {
			result = new PacProxySelector(pacSource);
		}
		return result;
	}
	

}