/*
 * Copyright 2015 Christian Basler
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package ch.dissem.bitmessage;

import ch.dissem.bitmessage.entity.*;
import ch.dissem.bitmessage.entity.payload.*;
import ch.dissem.bitmessage.exception.ApplicationException;
import ch.dissem.bitmessage.ports.*;
import ch.dissem.bitmessage.utils.Singleton;
import ch.dissem.bitmessage.utils.TTL;
import ch.dissem.bitmessage.utils.UnixTime;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.TreeSet;

/**
 * The internal context should normally only be used for port implementations. If you need it in your client
 * implementation, you're either doing something wrong, something very weird, or the BitmessageContext should
 * get extended.
 * <p>
 * On the other hand, if you need the BitmessageContext in a port implementation, the same thing might apply.
 * </p>
 */
public class InternalContext {
    private final static Logger LOG = LoggerFactory.getLogger(InternalContext.class);

    public final static long NETWORK_NONCE_TRIALS_PER_BYTE = 1000;
    public final static long NETWORK_EXTRA_BYTES = 1000;

    private final Cryptography cryptography;
    private final Inventory inventory;
    private final NodeRegistry nodeRegistry;
    private final NetworkHandler networkHandler;
    private final AddressRepository addressRepository;
    private final MessageRepository messageRepository;
    private final ProofOfWorkRepository proofOfWorkRepository;
    private final ProofOfWorkEngine proofOfWorkEngine;
    private final CustomCommandHandler customCommandHandler;
    private final ProofOfWorkService proofOfWorkService;
    private final Labeler labeler;
    private final NetworkHandler.MessageListener networkListener;

    private final TreeSet<Long> streams = new TreeSet<>();
    private final int port;
    private final long clientNonce;
    private long connectionTTL;
    private int connectionLimit;

    public InternalContext(BitmessageContext.Builder builder) {
        this.cryptography = builder.cryptography;
        this.inventory = builder.inventory;
        this.nodeRegistry = builder.nodeRegistry;
        this.networkHandler = builder.networkHandler;
        this.addressRepository = builder.addressRepo;
        this.messageRepository = builder.messageRepo;
        this.proofOfWorkRepository = builder.proofOfWorkRepository;
        this.proofOfWorkService = new ProofOfWorkService();
        this.proofOfWorkEngine = builder.proofOfWorkEngine;
        this.clientNonce = cryptography.randomNonce();
        this.customCommandHandler = builder.customCommandHandler;
        this.port = builder.port;
        this.connectionLimit = builder.connectionLimit;
        this.connectionTTL = builder.connectionTTL;
        this.labeler = builder.labeler;
        this.networkListener = new DefaultMessageListener(labeler, builder.listener);

        Singleton.initialize(cryptography);

        // TODO: streams of new identities and subscriptions should also be added. This works only after a restart.
        for (BitmessageAddress address : addressRepository.getIdentities()) {
            streams.add(address.getStream());
        }
        for (BitmessageAddress address : addressRepository.getSubscriptions()) {
            streams.add(address.getStream());
        }
        if (streams.isEmpty()) {
            streams.add(1L);
        }

        init(cryptography, inventory, nodeRegistry, networkHandler, addressRepository, messageRepository,
            proofOfWorkRepository, proofOfWorkService, proofOfWorkEngine, customCommandHandler, builder.labeler,
            networkListener);
        for (BitmessageAddress identity : addressRepository.getIdentities()) {
            streams.add(identity.getStream());
        }
    }

    private void init(Object... objects) {
        for (Object o : objects) {
            if (o instanceof ContextHolder) {
                ((ContextHolder) o).setContext(this);
            }
        }
    }

    public Cryptography getCryptography() {
        return cryptography;
    }

    public Inventory getInventory() {
        return inventory;
    }

    public NodeRegistry getNodeRegistry() {
        return nodeRegistry;
    }

    public NetworkHandler getNetworkHandler() {
        return networkHandler;
    }

    public AddressRepository getAddressRepository() {
        return addressRepository;
    }

    public MessageRepository getMessageRepository() {
        return messageRepository;
    }

    public ProofOfWorkRepository getProofOfWorkRepository() {
        return proofOfWorkRepository;
    }

    public ProofOfWorkEngine getProofOfWorkEngine() {
        return proofOfWorkEngine;
    }

    public ProofOfWorkService getProofOfWorkService() {
        return proofOfWorkService;
    }

    public Labeler getLabeler() {
        return labeler;
    }

    public NetworkHandler.MessageListener getNetworkListener() {
        return networkListener;
    }

    public long[] getStreams() {
        long[] result = new long[streams.size()];
        int i = 0;
        for (long stream : streams) {
            result[i++] = stream;
        }
        return result;
    }

    public int getPort() {
        return port;
    }

    public void send(final Plaintext plaintext) {
        if (plaintext.getAckMessage() != null) {
            long expires = UnixTime.now(+plaintext.getTTL());
            LOG.info("Expires at " + expires);
            proofOfWorkService.doProofOfWorkWithAck(plaintext, expires);
        } else {
            send(plaintext.getFrom(), plaintext.getTo(), new Msg(plaintext), plaintext.getTTL());
        }
    }

    public void send(final BitmessageAddress from, BitmessageAddress to, final ObjectPayload payload,
                     final long timeToLive) {
        try {
            final BitmessageAddress recipient = (to != null ? to : from);
            long expires = UnixTime.now(+timeToLive);
            LOG.info("Expires at " + expires);
            final ObjectMessage object = new ObjectMessage.Builder()
                .stream(recipient.getStream())
                .expiresTime(expires)
                .payload(payload)
                .build();
            if (object.isSigned()) {
                object.sign(from.getPrivateKey());
            }
            if (payload instanceof Broadcast) {
                ((Broadcast) payload).encrypt();
            } else if (payload instanceof Encrypted) {
                object.encrypt(recipient.getPubkey());
            }
            proofOfWorkService.doProofOfWork(to, object);
        } catch (IOException e) {
            throw new ApplicationException(e);
        }
    }

    public void sendPubkey(final BitmessageAddress identity, final long targetStream) {
        try {
            long expires = UnixTime.now(TTL.pubkey());
            LOG.info("Expires at " + expires);
            final ObjectMessage response = new ObjectMessage.Builder()
                .stream(targetStream)
                .expiresTime(expires)
                .payload(identity.getPubkey())
                .build();
            response.sign(identity.getPrivateKey());
            response.encrypt(cryptography.createPublicKey(identity.getPublicDecryptionKey()));
            // TODO: remember that the pubkey is just about to be sent, and on which stream!
            proofOfWorkService.doProofOfWork(response);
        } catch (IOException e) {
            throw new ApplicationException(e);
        }
    }

    /**
     * Be aware that if the pubkey already exists in the inventory, the metods will not request it and the callback
     * for freshly received pubkeys will not be called. Instead the pubkey is added to the contact and stored on DB.
     */
    public void requestPubkey(final BitmessageAddress contact) {
        BitmessageAddress stored = addressRepository.getAddress(contact.getAddress());

        tryToFindMatchingPubkey(contact);
        if (contact.getPubkey() != null) {
            if (stored != null) {
                stored.setPubkey(contact.getPubkey());
                addressRepository.save(stored);
            } else {
                addressRepository.save(contact);
            }
            return;
        }

        if (stored == null) {
            addressRepository.save(contact);
        }

        long expires = UnixTime.now(TTL.getpubkey());
        LOG.info("Expires at " + expires);
        final ObjectMessage request = new ObjectMessage.Builder()
            .stream(contact.getStream())
            .expiresTime(expires)
            .payload(new GetPubkey(contact))
            .build();
        proofOfWorkService.doProofOfWork(request);
    }

    private void tryToFindMatchingPubkey(BitmessageAddress address) {
        BitmessageAddress stored = addressRepository.getAddress(address.getAddress());
        if (stored != null) {
            address.setAlias(stored.getAlias());
            address.setSubscribed(stored.isSubscribed());
        }
        for (ObjectMessage object : inventory.getObjects(address.getStream(), address.getVersion(), ObjectType.PUBKEY)) {
            try {
                Pubkey pubkey = (Pubkey) object.getPayload();
                if (address.getVersion() == 4) {
                    V4Pubkey v4Pubkey = (V4Pubkey) pubkey;
                    if (Arrays.equals(address.getTag(), v4Pubkey.getTag())) {
                        v4Pubkey.decrypt(address.getPublicDecryptionKey());
                        if (object.isSignatureValid(v4Pubkey)) {
                            address.setPubkey(v4Pubkey);
                            addressRepository.save(address);
                            break;
                        } else {
                            LOG.info("Found pubkey for " + address + " but signature is invalid");
                        }
                    }
                } else {
                    if (Arrays.equals(pubkey.getRipe(), address.getRipe())) {
                        address.setPubkey(pubkey);
                        addressRepository.save(address);
                        break;
                    }
                }
            } catch (Exception e) {
                LOG.debug(e.getMessage(), e);
            }
        }
    }

    public void resendUnacknowledged() {
        List<Plaintext> messages = messageRepository.findMessagesToResend();
        for (Plaintext message : messages) {
            send(message);
            messageRepository.save(message);
        }
    }

    public long getClientNonce() {
        return clientNonce;
    }

    public long getConnectionTTL() {
        return connectionTTL;
    }

    public int getConnectionLimit() {
        return connectionLimit;
    }

    public CustomCommandHandler getCustomCommandHandler() {
        return customCommandHandler;
    }

    public interface ContextHolder {
        void setContext(InternalContext context);
    }
}