package eu.siacs.conversations.services;

import android.support.annotation.NonNull;
import android.util.Log;

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import eu.siacs.conversations.Config;
import eu.siacs.conversations.entities.Account;
import eu.siacs.conversations.entities.Room;
import eu.siacs.conversations.http.HttpConnectionManager;
import eu.siacs.conversations.http.services.MuclumbusService;
import eu.siacs.conversations.parser.IqParser;
import eu.siacs.conversations.utils.LanguageUtils;
import eu.siacs.conversations.utils.UIHelper;
import eu.siacs.conversations.xmpp.OnIqPacketReceived;
import eu.siacs.conversations.xmpp.XmppConnection;
import eu.siacs.conversations.xmpp.stanzas.IqPacket;
import okhttp3.OkHttpClient;
import okhttp3.ResponseBody;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
import rocks.xmpp.addr.Jid;

public class ChannelDiscoveryService {

    private final XmppConnectionService service;


    private MuclumbusService muclumbusService;

    private final Cache<String, List<Room>> cache;

    ChannelDiscoveryService(XmppConnectionService service) {
        this.service = service;
        this.cache = CacheBuilder.newBuilder().expireAfterWrite(5, TimeUnit.MINUTES).build();
    }

    void initializeMuclumbusService() {
        final OkHttpClient.Builder builder = new OkHttpClient.Builder();

        if (service.useTorToConnect()) {
            try {
                builder.proxy(HttpConnectionManager.getProxy());
            } catch (IOException e) {
                throw new RuntimeException("Unable to use Tor proxy", e);
            }
        }
        Retrofit retrofit = new Retrofit.Builder()
                .client(builder.build())
                .baseUrl(Config.CHANNEL_DISCOVERY)
                .addConverterFactory(GsonConverterFactory.create())
                .callbackExecutor(Executors.newSingleThreadExecutor())
                .build();
        this.muclumbusService = retrofit.create(MuclumbusService.class);
    }

    void cleanCache() {
        cache.invalidateAll();
    }

    void discover(@NonNull final String query, Method method, OnChannelSearchResultsFound onChannelSearchResultsFound) {
        List<Room> result = cache.getIfPresent(key(method, query));
        if (result != null) {
            onChannelSearchResultsFound.onChannelSearchResultsFound(result);
            return;
        }
        if (method == Method.LOCAL_SERVER) {
            discoverChannelsLocalServers(query, onChannelSearchResultsFound);
        } else {
            if (query.isEmpty()) {
                discoverChannelsJabberNetwork(onChannelSearchResultsFound);
            } else {
                discoverChannelsJabberNetwork(query, onChannelSearchResultsFound);
            }
        }
    }

    private void discoverChannelsJabberNetwork(OnChannelSearchResultsFound listener) {
        Call<MuclumbusService.Rooms> call = muclumbusService.getRooms(1);
        try {
            call.enqueue(new Callback<MuclumbusService.Rooms>() {
                @Override
                public void onResponse(@NonNull Call<MuclumbusService.Rooms> call, @NonNull Response<MuclumbusService.Rooms> response) {
                    final MuclumbusService.Rooms body = response.body();
                    if (body == null) {
                        listener.onChannelSearchResultsFound(Collections.emptyList());
                        logError(response);
                        return;
                    }
                    cache.put(key(Method.JABBER_NETWORK, ""), body.items);
                    listener.onChannelSearchResultsFound(body.items);
                }

                @Override
                public void onFailure(@NonNull Call<MuclumbusService.Rooms> call, @NonNull Throwable throwable) {
                    Log.d(Config.LOGTAG, "Unable to query muclumbus on " + Config.CHANNEL_DISCOVERY, throwable);
                    listener.onChannelSearchResultsFound(Collections.emptyList());
                }
            });
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void discoverChannelsJabberNetwork(final String query, OnChannelSearchResultsFound listener) {
        MuclumbusService.SearchRequest searchRequest = new MuclumbusService.SearchRequest(query);
        Call<MuclumbusService.SearchResult> searchResultCall = muclumbusService.search(searchRequest);

        searchResultCall.enqueue(new Callback<MuclumbusService.SearchResult>() {
            @Override
            public void onResponse(@NonNull Call<MuclumbusService.SearchResult> call, @NonNull Response<MuclumbusService.SearchResult> response) {
                final MuclumbusService.SearchResult body = response.body();
                if (body == null) {
                    listener.onChannelSearchResultsFound(Collections.emptyList());
                    logError(response);
                    return;
                }
                cache.put(key(Method.JABBER_NETWORK, query), body.result.items);
                listener.onChannelSearchResultsFound(body.result.items);
            }

            @Override
            public void onFailure(@NonNull Call<MuclumbusService.SearchResult> call, @NonNull Throwable throwable) {
                Log.d(Config.LOGTAG, "Unable to query muclumbus on " + Config.CHANNEL_DISCOVERY, throwable);
                listener.onChannelSearchResultsFound(Collections.emptyList());
            }
        });
    }

    private void discoverChannelsLocalServers(final String query, final OnChannelSearchResultsFound listener) {
        final Map<Jid, Account> localMucService = getLocalMucServices();
        Log.d(Config.LOGTAG, "checking with " + localMucService.size() + " muc services");
        if (localMucService.size() == 0) {
            listener.onChannelSearchResultsFound(Collections.emptyList());
            return;
        }
        if (!query.isEmpty()) {
            final List<Room> cached = cache.getIfPresent(key(Method.LOCAL_SERVER, ""));
            if (cached != null) {
                final List<Room> results = copyMatching(cached, query);
                cache.put(key(Method.LOCAL_SERVER, query), results);
                listener.onChannelSearchResultsFound(results);
            }
        }
        final AtomicInteger queriesInFlight = new AtomicInteger();
        final List<Room> rooms = new ArrayList<>();
        for (Map.Entry<Jid, Account> entry : localMucService.entrySet()) {
            IqPacket itemsRequest = service.getIqGenerator().queryDiscoItems(entry.getKey());
            queriesInFlight.incrementAndGet();
            service.sendIqPacket(entry.getValue(), itemsRequest, (account, itemsResponse) -> {
                if (itemsResponse.getType() == IqPacket.TYPE.RESULT) {
                    final List<Jid> items = IqParser.items(itemsResponse);
                    for (Jid item : items) {
                        IqPacket infoRequest = service.getIqGenerator().queryDiscoInfo(item);
                        queriesInFlight.incrementAndGet();
                        service.sendIqPacket(account, infoRequest, new OnIqPacketReceived() {
                            @Override
                            public void onIqPacketReceived(Account account, IqPacket infoResponse) {
                                if (infoResponse.getType() == IqPacket.TYPE.RESULT) {
                                    final Room room = IqParser.parseRoom(infoResponse);
                                    if (room != null) {
                                        rooms.add(room);
                                    }
                                    if (queriesInFlight.decrementAndGet() <= 0) {
                                        finishDiscoSearch(rooms, query, listener);
                                    }
                                } else {
                                    queriesInFlight.decrementAndGet();
                                }
                            }
                        });
                    }
                }
                if (queriesInFlight.decrementAndGet() <= 0) {
                    finishDiscoSearch(rooms, query, listener);
                }
            });
        }
    }

    private void finishDiscoSearch(List<Room> rooms, String query, OnChannelSearchResultsFound listener) {
        Collections.sort(rooms);
        cache.put(key(Method.LOCAL_SERVER, ""), rooms);
        if (query.isEmpty()) {
            listener.onChannelSearchResultsFound(rooms);
        } else {
            List<Room> results = copyMatching(rooms, query);
            cache.put(key(Method.LOCAL_SERVER, query), results);
            listener.onChannelSearchResultsFound(rooms);
        }
    }

    private static List<Room> copyMatching(List<Room> haystack, String needle) {
        ArrayList<Room> result = new ArrayList<>();
        for (Room room : haystack) {
            if (room.contains(needle)) {
                result.add(room);
            }
        }
        return result;
    }

    private Map<Jid, Account> getLocalMucServices() {
        final HashMap<Jid, Account> localMucServices = new HashMap<>();
        for (Account account : service.getAccounts()) {
            if (account.isEnabled()) {
                final XmppConnection xmppConnection = account.getXmppConnection();
                if (xmppConnection == null) {
                    continue;
                }
                for (final String mucService : xmppConnection.getMucServers()) {
                    Jid jid = Jid.of(mucService);
                    if (!localMucServices.containsKey(jid)) {
                        localMucServices.put(jid, account);
                    }
                }
            }
        }
        return localMucServices;
    }

    private static String key(Method method, String query) {
        return String.format("%s\00%s", method, query);
    }

    private static void logError(final Response response) {
        final ResponseBody errorBody = response.errorBody();
        Log.d(Config.LOGTAG, "code from muclumbus=" + response.code());
        if (errorBody == null) {
            return;
        }
        try {
            Log.d(Config.LOGTAG, "error body=" + errorBody.string());
        } catch (IOException e) {
            //ignored
        }
    }

    public interface OnChannelSearchResultsFound {
        void onChannelSearchResultsFound(List<Room> results);
    }

    public enum Method {
        JABBER_NETWORK,
        LOCAL_SERVER
    }
}