package org.mercury_im.messenger.core.xmpp;

import org.jivesoftware.smack.AbstractXMPPConnection;
import org.jivesoftware.smack.ConnectionListener;
import org.jivesoftware.smack.ReconnectionListener;
import org.jivesoftware.smack.ReconnectionManager;
import org.jivesoftware.smack.SmackException;
import org.jivesoftware.smack.XMPPConnection;
import org.jivesoftware.smack.XMPPException;
import org.jivesoftware.smack.sasl.SASLErrorException;
import org.mercury_im.messenger.core.xmpp.exception.InvalidCredentialsException;
import org.mercury_im.messenger.core.xmpp.exception.ServerUnreachableException;
import org.mercury_im.messenger.core.xmpp.state.ConnectivityState;
import org.mercury_im.messenger.entity.Account;
import org.mercury_im.messenger.core.xmpp.state.ConnectionState;

import java.io.IOException;
import java.util.UUID;
import java.util.logging.Level;
import java.util.logging.Logger;

import io.reactivex.Completable;
import io.reactivex.Observable;
import io.reactivex.subjects.BehaviorSubject;
import lombok.Getter;

public class MercuryConnection {

    private static final Logger LOGGER = Logger.getLogger("MercuryConnection");

    @Getter
    private XMPPConnection connection;

    @Getter
    private final Account account;

    private final BehaviorSubject<ConnectionState> state;

    public MercuryConnection(XMPPConnection connection, Account account) {
        this.connection = connection;
        this.account = account;

        this.state = BehaviorSubject.createDefault(new ConnectionState(account.getId(), this,
                ConnectivityState.disconnected, false, false));
        connection.addConnectionListener(connectionListener);
    }

    public UUID getAccountId() {
        return getAccount().getId();
    }

    public Observable<ConnectionState> observeConnection() {
        return state;
    }

    public Completable connect() {
        return Completable.fromAction(this::doConnect)
                .doOnError(error -> LOGGER.log(Level.WARNING, "Connection error for account " + account, error));
    }

    private void doConnect() throws ServerUnreachableException {
        state.onNext(state.getValue().withConnectivity(ConnectivityState.connecting));
        AbstractXMPPConnection connection = (AbstractXMPPConnection) getConnection();
        if (connection.isConnected()) {
            return;
        }
        try {
            LOGGER.log(Level.INFO, "Connected!");
            connection.connect();
        } catch (SmackException.EndpointConnectionException e) {
            connection.disconnect();
            throw new ServerUnreachableException("Cannot connect to server " + connection.getXMPPServiceDomain().asUnescapedString(), e);
        } catch (IOException | InterruptedException | XMPPException | SmackException e) {
            throw new AssertionError("Unexpected exception.", e);
        }
    }

    public Completable login() {
        return Completable.fromAction(this::doLogin)
                .doOnError(error -> LOGGER.log(Level.WARNING, "Login error for account " + account, error));
    }

    private void doLogin() throws InvalidCredentialsException {
        if (connection.isAuthenticated()) {
            return;
        }
        try {
            ((AbstractXMPPConnection) getConnection()).login();
        } catch (SASLErrorException e) {
            throw new InvalidCredentialsException("Credentials of account " + account.getId() + " are invalid.", e);
        } catch (InterruptedException | XMPPException | SmackException | IOException e) {
            throw new AssertionError("Unexpected exception.", e);
        }
    }

    public Completable shutdown() {
        return Completable.fromAction(this::doShutdown)
                .doOnError(error -> LOGGER.log(Level.WARNING, "Shutdown error for account " + account, error));
    }

    public void doShutdown() {
        if (connection.isConnected()) {
            ((AbstractXMPPConnection) getConnection()).disconnect();
        } else {
            ((AbstractXMPPConnection) getConnection()).instantShutdown();
        }
    }

    private final ConnectionListener connectionListener = new ConnectionListener() {
        @Override
        public void connected(XMPPConnection connection) {
            state.onNext(state.getValue()
                    .withConnectivity(ConnectivityState.connected)
                    .withAuthenticated(false));
        }

        @Override
        public void authenticated(XMPPConnection connection, boolean resumed) {
            state.onNext(state.getValue()
                    .withConnectivity(ConnectivityState.connected)
                    .withAuthenticated(true)
                    .withResumed(resumed));
            if (!resumed) {
                initialConnectionSetup();
            }
        }

        @Override
        public void connectionClosed() {
            state.onNext(state.getValue()
                    .withConnectivity(ConnectivityState.disconnected)
                    .withAuthenticated(false));
        }

        @Override
        public void connectionClosedOnError(Exception e) {
            state.onNext(state.getValue()
                    .withConnectivity(ConnectivityState.disconnected)
                    .withAuthenticated(false));
        }
    };

    private void initialConnectionSetup() {
        ReconnectionManager.getInstanceFor((AbstractXMPPConnection) getConnection())
                .addReconnectionListener(new ReconnectionListener() {
                    @Override
                    public void reconnectingIn(int seconds) {
                        LOGGER.log(Level.FINER, "Reconnecting connection " + getAccount().getAddress() + " in " + seconds + " seconds.");
                    }

                    @Override
                    public void reconnectionFailed(Exception e) {
                        LOGGER.log(Level.WARNING, "Reconnection of connection " + getAccount().getAddress() + " failed.", e);
                    }
                });
    }
}