package eu.siacs.conversations.utils;

import de.measite.minidns.Client;
import de.measite.minidns.DNSMessage;
import de.measite.minidns.Record;
import de.measite.minidns.Record.TYPE;
import de.measite.minidns.Record.CLASS;
import de.measite.minidns.record.SRV;
import de.measite.minidns.record.A;
import de.measite.minidns.record.AAAA;
import de.measite.minidns.record.Data;
import de.measite.minidns.util.NameUtil;
import eu.siacs.conversations.Config;
import eu.siacs.conversations.xmpp.jid.Jid;

import java.io.IOException;
import java.net.InetAddress;
import java.net.SocketTimeoutException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Random;
import java.util.TreeMap;

import android.os.Bundle;
import android.util.Log;

public class DNSHelper {
	protected static Client client = new Client();

	public static Bundle getSRVRecord(final Jid jid) throws IOException {
        final String host = jid.getDomainpart();
		String dns[] = client.findDNS();

		if (dns != null) {
			for (String dnsserver : dns) {
				InetAddress ip = InetAddress.getByName(dnsserver);
				Bundle b = queryDNS(host, ip);
				if (b.containsKey("values")) {
					return b;
				}
			}
		}
		return queryDNS(host, InetAddress.getByName("8.8.8.8"));
	}

	public static Bundle queryDNS(String host, InetAddress dnsServer) {
		Bundle bundle = new Bundle();
		try {
			String qname = "_xmpp-client._tcp." + host;
			Log.d(Config.LOGTAG, "using dns server: " + dnsServer.getHostAddress() + " to look up " + host);
			DNSMessage message = client.query(qname, TYPE.SRV, CLASS.IN, dnsServer.getHostAddress());

			TreeMap<Integer, ArrayList<SRV>> priorities = new TreeMap<>();
			TreeMap<String, ArrayList<String>> ips4 = new TreeMap<>();
			TreeMap<String, ArrayList<String>> ips6 = new TreeMap<>();

			for (Record[] rrset : new Record[][] { message.getAnswers(), message.getAdditionalResourceRecords() }) {
				for (Record rr : rrset) {
					Data d = rr.getPayload();
					if (d instanceof SRV && NameUtil.idnEquals(qname, rr.getName())) {
						SRV srv = (SRV) d;
						if (!priorities.containsKey(srv.getPriority())) {
							priorities.put(srv.getPriority(),new ArrayList<SRV>());
						}
						priorities.get(srv.getPriority()).add(srv);
					}
					if (d instanceof A) {
						A a = (A) d;
						if (!ips4.containsKey(rr.getName())) {
							ips4.put(rr.getName(), new ArrayList<String>());
						}
						ips4.get(rr.getName()).add(a.toString());
					}
					if (d instanceof AAAA) {
						AAAA aaaa = (AAAA) d;
						if (!ips6.containsKey(rr.getName())) {
							ips6.put(rr.getName(), new ArrayList<String>());
						}
						ips6.get(rr.getName()).add("[" + aaaa.toString() + "]");
					}
				}
			}

			ArrayList<SRV> result = new ArrayList<>();
			for (ArrayList<SRV> s : priorities.values()) {
				result.addAll(s);
			}

			ArrayList<Bundle> values = new ArrayList<>();
			if (result.size() == 0) {
				DNSMessage response;
				response = client.query(host, TYPE.A, CLASS.IN, dnsServer.getHostAddress());
				for(int i = 0; i < response.getAnswers().length; ++i) {
					values.add(createNamePortBundle(host,5222,response.getAnswers()[i].getPayload()));
				}
				response = client.query(host, TYPE.AAAA, CLASS.IN, dnsServer.getHostAddress());
				for(int i = 0; i < response.getAnswers().length; ++i) {
					values.add(createNamePortBundle(host,5222,response.getAnswers()[i].getPayload()));
				}
				bundle.putParcelableArrayList("values", values);
				return bundle;
			}
			for (SRV srv : result) {
				if (ips6.containsKey(srv.getName())) {
					values.add(createNamePortBundle(srv.getName(),srv.getPort(),ips6));
				} else {
					DNSMessage response = client.query(srv.getName(), TYPE.AAAA, CLASS.IN, dnsServer.getHostAddress());
					for(int i = 0; i < response.getAnswers().length; ++i) {
						values.add(createNamePortBundle(srv.getName(),srv.getPort(),response.getAnswers()[i].getPayload()));
					}
				}
				if (ips4.containsKey(srv.getName())) {
					values.add(createNamePortBundle(srv.getName(),srv.getPort(),ips4));
				} else {
					DNSMessage response = client.query(srv.getName(), TYPE.A, CLASS.IN, dnsServer.getHostAddress());
					for(int i = 0; i < response.getAnswers().length; ++i) {
						values.add(createNamePortBundle(srv.getName(),srv.getPort(),response.getAnswers()[i].getPayload()));
					}
				}
				values.add(createNamePortBundle(srv.getName(), srv.getPort()));
			}
			bundle.putParcelableArrayList("values", values);
		} catch (SocketTimeoutException e) {
			bundle.putString("error", "timeout");
		} catch (Exception e) {
			Log.d(Config.LOGTAG,e.getMessage());
			bundle.putString("error", "unhandled");
		}
		return bundle;
	}

	private static Bundle createNamePortBundle(String name, int port) {
		Bundle namePort = new Bundle();
		namePort.putString("name", name);
		namePort.putInt("port", port);
		return namePort;
	}

	private static Bundle createNamePortBundle(String name, int port, TreeMap<String, ArrayList<String>> ips) {
		Bundle namePort = new Bundle();
		namePort.putString("name", name);
		namePort.putInt("port", port);
		if (ips!=null) {
			ArrayList<String> ip = ips.get(name);
			Collections.shuffle(ip, new Random());
			namePort.putString("ip", ip.get(0));
		}
		return namePort;
	}

	private static Bundle createNamePortBundle(String name, int port, Data data) {
		Bundle namePort = new Bundle();
		namePort.putString("name", name);
		namePort.putInt("port", port);
		if (data instanceof A) {
			namePort.putString("ip", data.toString());
		} else if (data instanceof AAAA) {
			namePort.putString("ip","["+data.toString()+"]");
		}
		return namePort;
	}

	final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();

	public static String bytesToHex(byte[] bytes) {
		char[] hexChars = new char[bytes.length * 2];
		for (int j = 0; j < bytes.length; j++) {
			int v = bytes[j] & 0xFF;
			hexChars[j * 2] = hexArray[v >>> 4];
			hexChars[j * 2 + 1] = hexArray[v & 0x0F];
		}
		return new String(hexChars);
	}
}