package eu.siacs.conversations.xmpp.jingle;

import android.util.Log;
import com.google.common.base.Strings;
import com.google.common.collect.ImmutableSet;
import com.google.common.primitives.Ints;
import eu.siacs.conversations.Config;
import eu.siacs.conversations.utils.IP;
import eu.siacs.conversations.xml.Element;
import eu.siacs.conversations.xml.Namespace;
import im.conversations.android.xmpp.model.stanza.Iq;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import org.webrtc.PeerConnection;

public final class IceServers {

    public static Set<PeerConnection.IceServer> parse(final Iq response) {
        if (response.getType() != Iq.Type.RESULT) {
            return Collections.emptySet();
        }
        final var builder = new ImmutableSet.Builder<PeerConnection.IceServer>();
        final Element services =
                response.findChild("services", Namespace.EXTERNAL_SERVICE_DISCOVERY);
        final List<Element> children =
                services == null ? Collections.emptyList() : services.getChildren();
        for (final Element child : children) {
            if ("service".equals(child.getName())) {
                final String type = child.getAttribute("type");
                final String host = child.getAttribute("host");
                final String sport = child.getAttribute("port");
                final Integer port = sport == null ? null : Ints.tryParse(sport);
                final String transport = child.getAttribute("transport");
                final String username = child.getAttribute("username");
                final String password = child.getAttribute("password");
                if (Strings.isNullOrEmpty(host) || port == null) {
                    continue;
                }
                if (port < 0 || port > 65535) {
                    continue;
                }

                if (Arrays.asList("stun", "stuns", "turn", "turns").contains(type)
                        && Arrays.asList("udp", "tcp").contains(transport)) {
                    if (Arrays.asList("stuns", "turns").contains(type) && "udp".equals(transport)) {
                        Log.w(
                                Config.LOGTAG,
                                "skipping invalid combination of udp/tls in external services");
                        continue;
                    }

                    // STUN URLs do not support a query section since M110
                    final String uri;
                    if (Arrays.asList("stun", "stuns").contains(type)) {
                        uri = String.format("%s:%s:%s", type, IP.wrapIPv6(host), port);
                    } else {
                        uri =
                                String.format(
                                        "%s:%s:%s?transport=%s",
                                        type, IP.wrapIPv6(host), port, transport);
                    }

                    final PeerConnection.IceServer.Builder iceServerBuilder =
                            PeerConnection.IceServer.builder(uri);
                    iceServerBuilder.setTlsCertPolicy(
                            PeerConnection.TlsCertPolicy.TLS_CERT_POLICY_INSECURE_NO_CHECK);
                    if (username != null && password != null) {
                        iceServerBuilder.setUsername(username);
                        iceServerBuilder.setPassword(password);
                    } else if (Arrays.asList("turn", "turns").contains(type)) {
                        // The WebRTC spec requires throwing an
                        // InvalidAccessError when username (from libwebrtc
                        // source coder)
                        // https://chromium.googlesource.com/external/webrtc/+/master/pc/ice_server_parsing.cc
                        Log.w(
                                Config.LOGTAG,
                                "skipping "
                                        + type
                                        + "/"
                                        + transport
                                        + " without username and password");
                        continue;
                    }
                    final PeerConnection.IceServer iceServer = iceServerBuilder.createIceServer();
                    Log.w(Config.LOGTAG, "discovered ICE Server: " + iceServer);
                    builder.add(iceServer);
                }
            }
        }
        return builder.build();
    }
}