package com.btr.proxy.util;

import java.net.Proxy;
import java.net.ProxySelector;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;
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;
import com.btr.proxy.util.Logger.LogLevel;

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

public class ProxyUtil {

	public static final int DEFAULT_HTTP_PROXY_PORT = 80;
	
	public static final int DEFAULT_SOCKS_PROXY_PORT = 1080;

	private static List<Proxy> noProxyList;
	private static Pattern pattern = Pattern.compile("^\\s*(\\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 ProxySelector parseProxySettings(String proxyVar) {
		return parseProxySettings(proxyVar, Proxy.Type.HTTP, 0);
	}
	
	public static ProxySelector parseProxySettings(String proxyVar, Proxy.Type fallback, int fallbackPort) {
		if (proxyVar == null || proxyVar.trim().length() == 0) {
			return null;
		}
		Matcher matcher = pattern.matcher(proxyVar);
		if (matcher.matches()) {
			String host = matcher.group(2);
			int port = -1;
			if (!"".equals(matcher.group(3))) {
				port = Integer.parseInt(matcher.group(3));
			}
			String stype = matcher.group(1).toLowerCase();
			Proxy.Type type;
			if (stype.isEmpty()) {
				type = fallback;
			} else if (stype.startsWith("socks")) {
				type = Proxy.Type.SOCKS;
			} else {
				type = Proxy.Type.HTTP;
			}
			if (port == -1 && fallbackPort > 0) {
				port = fallbackPort;
			}
			if (port == -1) {
				if (type == Proxy.Type.HTTP) {
					port = DEFAULT_HTTP_PROXY_PORT;
				} else if (type == Proxy.Type.SOCKS) {
					port = DEFAULT_SOCKS_PROXY_PORT;
				}
			}
			return new FixedProxySelector(type, 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(final String url) {
		Logger.log(ProxyUtil.class, LogLevel.TRACE, "Fetching PAC script from {0}", url);
		final AtomicReference<PacProxySelector> result = new AtomicReference<>();
		Thread t = new Thread() {
			@Override
			public void run() {
				PacScriptSource pacSource = new UrlPacScriptSource(url);
				if (pacSource.isScriptValid()) {
					result.set(new PacProxySelector(pacSource));
				}
			}
		};
		t.start();
		try {
			t.join(2500);
		} catch (InterruptedException e) {
			Thread.currentThread().interrupt();
		}
		return result.get();
	}

}