package de.blinkt.openvpn;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map.Entry;
import java.util.Vector;

//! Openvpn Config FIle Parser, probably not 100% accurate but close enough

// And rember, this is valid :)
// --<foo>
// bar
// </foo>
public class ConfigParser {


	private HashMap<String,Vector<String>> options = new HashMap<String, Vector<String>>();
	public void parseConfig(InputStream inputStream) throws IOException, ConfigParseError {


		InputStreamReader fr = new InputStreamReader(inputStream);
		BufferedReader br =new BufferedReader(fr);

		@SuppressWarnings("unused")
		int lineno=0;

		while (true){
			String line = br.readLine();
			if(line==null)
				break;
			lineno++;
			Vector<String> args = parseline(line);
			if(args.size() ==0)
				continue;



			if(args.get(0).startsWith("--"))
				args.set(0, args.get(0).substring(2));

			checkinlinefile(args,br);

			options.put(args.get(0), args);
		}
	}

	private void checkinlinefile(Vector<String> args, BufferedReader br) throws IOException, ConfigParseError {
		String arg0 = args.get(0);
		// CHeck for <foo>
		if(arg0.startsWith("<") && arg0.endsWith(">")) {
			String argname = arg0.substring(1, arg0.length()-1);
			String inlinefile = VpnProfile.INLINE_TAG;

			String endtag = String.format("</%s>",argname);
			do {
				String line = br.readLine();
				if(line==null){
					throw new ConfigParseError(String.format("No endtag </%s> for starttag <%s> found",argname,argname));
				}
				if(line.equals(endtag))
					break;
				else {
					inlinefile+=line;
					inlinefile+= "\n";					
				}
			} while(true);

			args.clear();
			args.add(argname);
			args.add(inlinefile);
		}

	}

	enum linestate {
		initial,
		readin_single_quote
		, reading_quoted, reading_unquoted, done}

	private boolean space(char c) {
		// I really hope nobody is using zero bytes inside his/her config file
		// to sperate parameter but here we go:
		return Character.isSpace(c) || c == '\0';

	}

	public class ConfigParseError extends Exception {
		private static final long serialVersionUID = -60L;

		public ConfigParseError(String msg) {
			super(msg);
		}
	}


	// adapted openvpn's parse function to java
	private Vector<String> parseline(String line) throws ConfigParseError {
		Vector<String> parameters = new Vector<String>(); 

		if (line.length()==0)
			return parameters;


		linestate state = linestate.initial;
		boolean backslash = false;
		char out=0;

		int pos=0;
		String currentarg="";

		do { 
			// Emulate the c parsing ...
			char in;
			if(pos < line.length())
				in = line.charAt(pos);
			else 
				in = '\0';

			if (!backslash && in == '\\' && state != linestate.readin_single_quote)
			{
				backslash = true;
			}
			else
			{
				if (state == linestate.initial)
				{
					if (!space (in))
					{
						if (in == ';' || in == '#') /* comment */
							break;
						if (!backslash && in == '\"')
							state = linestate.reading_quoted;
						else if (!backslash && in == '\'')
							state = linestate.readin_single_quote;
						else
						{
							out = in;
							state = linestate.reading_unquoted;
						}
					}
				}
				else if (state == linestate.reading_unquoted)
				{
					if (!backslash && space (in))
						state = linestate.done;
					else
						out = in;
				}
				else if (state == linestate.reading_quoted)
				{
					if (!backslash && in == '\"')
						state = linestate.done;
					else
						out = in;
				}
				else if (state == linestate.readin_single_quote)
				{
					if (in == '\'')
						state = linestate.done;
					else
						out = in;
				}

				if (state == linestate.done)
				{
					/* ASSERT (parm_len > 0); */
					state = linestate.initial;
					parameters.add(currentarg);
					currentarg = "";
					out =0;
				}

				if (backslash && out!=0)
				{
					if (!(out == '\\' || out == '\"' || space (out)))
					{
						throw new ConfigParseError("Options warning: Bad backslash ('\\') usage");
					}
				}
				backslash = false;
			}

			/* store parameter character */
			if (out!=0)
			{
				currentarg+=out;
			}
		} while (pos++ < line.length());

		return parameters;
	}


	final String[] unsupportedOptions = { "config", 
			"connection", 
			"proto-force", 
			"remote-random",
			"tls-server"

	};

	// Ignore all scripts
	// in most cases these won't work and user who wish to execute scripts will
	// figure out themselves
	final String[] ignoreOptions = { "tls-client",
			"askpass",
			"auth-nocache",
			"up",
			"down",
			"route-up",
			"ipchange",
			"route-up",
			"auth-user-pass-verify"
	};
	// Missing
	// proto tcp-client|udp

	VpnProfile convertProfile() throws ConfigParseError{
		VpnProfile np = new VpnProfile("converted Profile");
		// Pull, client, tls-client
		np.clearDefaults();

		if(options.containsKey("client") || options.containsKey("pull")) {
			np.mUsePull=true;
			options.remove("pull");
			options.remove("client");
		}

		Vector<String> secret = getOption("secret", 1, 2);
		if(secret!=null) 
		{
			np.mAuthenticationType=VpnProfile.TYPE_STATICKEYS;
			np.mUseTLSAuth=true;
			np.mTLSAuthFilename=secret.get(1);
			if(secret.size()==3)
				np.mTLSAuthDirection=secret.get(2);
		}

		Vector<String> tlsauth = getOption("tls-auth", 1, 2);
		if(tlsauth!=null) 
		{
			np.mUseTLSAuth=true;
			np.mTLSAuthFilename=tlsauth.get(1);
			if(tlsauth.size()==3)
				np.mTLSAuthDirection=tlsauth.get(2);
		}

		Vector<String> direction = getOption("key-direction", 1, 1);
		if(direction!=null)
			np.mTLSAuthDirection=direction.get(1);

		if(options.containsKey("redirect-gateway")) {
			options.remove("redirect-gateway");
			np.mUseDefaultRoute=true;
		} else {
			np.mUseDefaultRoute=true;
		}

		Vector<String> dev =getOption("dev",1,1);
		Vector<String> devtype =getOption("dev-type",1,1);

		if( (devtype !=null && devtype.get(1).equals("tun")) ||  
				(dev!=null && dev.get(1).startsWith("tun")) || 
				(devtype ==null && dev == null) ) {
			//everything okay 
		} else {
			throw new ConfigParseError("Sorry. Only tun mode is supported. See the FAQ for more detail");
		}



		Vector<String> mode =getOption("mode",1,1);
		if (mode != null){
			if(!mode.get(1).equals("p2p"))
				throw new ConfigParseError("Invalid mode for --mode specified, need p2p");
		}

		// Parse remote config
		Vector<String> remote = getOption("remote",1,3);
		if(remote != null){
			switch (remote.size()) {
			case 4:
				String proto = remote.get(3);
				if(proto.equals("udp"))
					np.mUseUdp=true;
				else if (proto.equals("tcp"))
					np.mUseUdp=false;
				else
					throw new ConfigParseError("remote protocol must be tcp or udp");
			case 3:
				np.mServerPort = remote.get(2);
			case 2:
				np.mServerName = remote.get(1);
			}
		}
		
		Vector<String> proto = getOption("proto, ", 1,1);
		if(proto!=null){
			if(proto.get(1).equals("udp"))
				np.mUseUdp=true;
			else if (proto.get(1).equals("tcp-client"))
				np.mUseUdp=false;
			else 
				throw new ConfigParseError("Unsupported option to --proto " + proto.get(1));
					
		}
		
		Vector<String> dhcpoption = getOption("dhcp-options", 1, 3);
		if(dhcpoption!=null) {
			String type=dhcpoption.get(1);

		}
		
		if(getOption("remote-random-hostname", 0, 0)!=null)
			np.mUseRandomHostname=true;

		if(getOption("float", 0, 0)!=null)
			np.mUseFloat=true;

		if(getOption("comp-lzo", 0, 1)!=null)
			np.mUseLzo=true;

		Vector<String> cipher = getOption("cipher", 1, 1);
		if(cipher!=null)
			np.mCipher= cipher.get(1);

		Vector<String> ca = getOption("ca",1,1);
		if(ca!=null){
			np.mCaFilename = ca.get(1);
		}

		Vector<String> cert = getOption("cert",1,1);
		if(cert!=null){
			np.mClientCertFilename = cert.get(1);
			np.mAuthenticationType = VpnProfile.TYPE_CERTIFICATES;
		}
		Vector<String> key= getOption("key",1,1);
		if(key!=null)
			np.mClientKeyFilename=key.get(1);

		Vector<String> pkcs12 = getOption("pkcs12",1,1);
		if(pkcs12!=null) {
			np.mPKCS12Filename = pkcs12.get(1);
			np.mAuthenticationType = VpnProfile.TYPE_KEYSTORE;
		}

		Vector<String> tlsremote = getOption("tls-remote",1,1);
		if(tlsremote!=null){
			np.mRemoteCN = tlsremote.get(1);
			np.mCheckRemoteCN=true;
		} 
		
		Vector<String> verb = getOption("verb",1,1);
		if(verb!=null){
			np.mVerb=verb.get(1);
		}

		// Check the other options

		for(String option:unsupportedOptions)
			if(options.containsKey(option))
				throw new ConfigParseError(String.format("Unsupported Option %s encountered in config file. Aborting",option));

		for(String option:ignoreOptions)
			// removing an item which is not in the map is no error
			options.remove(option);

		if(options.size()> 0) {
			String custom = "# These Options were found in the config file but not parsed:\n";
			for(Entry<String, Vector<String>> option:options.entrySet()) {
				for (String arg : option.getValue()) {
					custom+= arg + " ";
				}
				custom+="\n";
			}
			np.mCustomConfigOptions = custom;
			np.mUseCustomConfig=true;

		}


		fixup(np);

		return np;
	}

	private void fixup(VpnProfile np) {
		if(np.mRemoteCN.equals(np.mServerName)) {
			np.mRemoteCN="";
		}
	}

	private Vector<String> getOption(String option, int minarg, int maxarg) throws ConfigParseError {
		Vector<String> args = options.get(option);
		if(args==null)
			return null;
		if(args.size()< (minarg+1) || args.size() > maxarg+1) {
			String err = String.format("Option %s has %d parameters, expected between %d and %d",
					option,args.size()-1,minarg,maxarg );
			throw new ConfigParseError(err);
		}
		options.remove(option);
		return args;
	}

}