package com.btr.proxy.util;

import java.net.InetSocketAddress;
import java.net.Proxy;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;

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;

	/*************************************************************************
	 * 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) {
		return parseProxySettings(proxyVar, Proxy.Type.HTTP, 0);
	}
	
	public static FixedProxySelector parseProxySettings(String proxyVar, Proxy.Type fallback, int fallbackPort) {
		Proxy proxy = parseProxyString(proxyVar, fallback, fallbackPort);
		if (proxy == null)
			return null;
		return new FixedProxySelector(proxy);
	}
	
	public static Proxy parseProxyString(String proxyVar, Proxy.Type fallback, int fallbackPort) {
		if (proxyVar == null || proxyVar.trim().length() == 0) {
			return null;
		}
		
		Proxy.Type type;
		int port = -1;
		String host;
		
		int protoIdx = proxyVar.indexOf(":/");
		if (protoIdx == -1) {
			type = fallback;
		} else {
			String stype = proxyVar.substring(0, protoIdx);
			proxyVar = proxyVar.substring(protoIdx + 2);
			proxyVar = proxyVar.replaceAll("(^/+|/+$)", "");
			if (stype.isEmpty()) {
				type = fallback;
			} else if (stype.startsWith("socks")) {
				type = Proxy.Type.SOCKS;
			} else {
				type = Proxy.Type.HTTP;
			}
		}
		
		int portIdx = proxyVar.lastIndexOf(':');
		if (portIdx == -1) {
			host = proxyVar;
		} else {
			String portStr = proxyVar.substring(portIdx + 1).replaceAll("[^0-9]", "");
			if (!portStr.isEmpty()) {
				port = MiscUtil.parseInt(portStr);
			}
			host = proxyVar.substring(0, portIdx);
		}
			
		if (port == -1 && fallbackPort > 0) {
			port = fallbackPort;
		}
		if (port < 0 || port > 65535) {
			if (type == Proxy.Type.HTTP) {
				port = DEFAULT_HTTP_PROXY_PORT;
			} else if (type == Proxy.Type.SOCKS) {
				port = DEFAULT_SOCKS_PROXY_PORT;
			}
		}
		return new Proxy(type, InetSocketAddress.createUnresolved(host.trim(), port));
	}

	/*************************************************************************
	 * 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();
	}

}