package org.whispersystems.textsecure.api;

import android.util.Log;

import com.google.protobuf.ByteString;

import org.whispersystems.libaxolotl.InvalidKeyException;
import org.whispersystems.libaxolotl.SessionBuilder;
import org.whispersystems.libaxolotl.protocol.CiphertextMessage;
import org.whispersystems.libaxolotl.state.AxolotlStore;
import org.whispersystems.libaxolotl.state.PreKeyBundle;
import org.whispersystems.libaxolotl.util.guava.Optional;
import org.whispersystems.textsecure.api.crypto.TextSecureCipher;
import org.whispersystems.textsecure.api.crypto.UntrustedIdentityException;
import org.whispersystems.textsecure.api.messages.TextSecureAttachment;
import org.whispersystems.textsecure.api.messages.TextSecureAttachmentStream;
import org.whispersystems.textsecure.api.messages.TextSecureGroup;
import org.whispersystems.textsecure.api.messages.TextSecureMessage;
import org.whispersystems.textsecure.push.MismatchedDevices;
import org.whispersystems.textsecure.push.OutgoingPushMessage;
import org.whispersystems.textsecure.push.OutgoingPushMessageList;
import org.whispersystems.textsecure.push.PushAddress;
import org.whispersystems.textsecure.push.PushAttachmentData;
import org.whispersystems.textsecure.push.PushBody;
import org.whispersystems.textsecure.push.PushServiceSocket;
import org.whispersystems.textsecure.push.StaleDevices;
import org.whispersystems.textsecure.push.UnregisteredUserException;
import org.whispersystems.textsecure.push.exceptions.EncapsulatedExceptions;
import org.whispersystems.textsecure.push.exceptions.MismatchedDevicesException;
import org.whispersystems.textsecure.push.exceptions.StaleDevicesException;
import org.whispersystems.textsecure.util.Util;

import java.io.IOException;
import java.util.LinkedList;
import java.util.List;

import static org.whispersystems.textsecure.push.PushMessageProtos.IncomingPushMessageSignal.Type;
import static org.whispersystems.textsecure.push.PushMessageProtos.PushMessageContent;
import static org.whispersystems.textsecure.push.PushMessageProtos.PushMessageContent.AttachmentPointer;
import static org.whispersystems.textsecure.push.PushMessageProtos.PushMessageContent.GroupContext;

public class TextSecureMessageSender {

  private static final String TAG = TextSecureMessageSender.class.getSimpleName();

  private final PushServiceSocket       socket;
  private final AxolotlStore            store;
  private final Optional<EventListener> eventListener;

  public TextSecureMessageSender(String url, PushServiceSocket.TrustStore trustStore,
                                 String user, String password, AxolotlStore store,
                                 Optional<EventListener> eventListener)
  {
    this.socket        = new PushServiceSocket(url, trustStore, user, password);
    this.store         = store;
    this.eventListener = eventListener;
  }

  public void sendDeliveryReceipt(PushAddress recipient, long messageId) throws IOException {
    this.socket.sendReceipt(recipient.getNumber(), messageId, recipient.getRelay());
  }

  public void sendMessage(PushAddress recipient, TextSecureMessage message)
      throws UntrustedIdentityException, IOException
  {
    byte[] content = createMessageContent(message);
    sendMessage(recipient, message.getTimestamp(), content);

    if (message.isEndSession()) {
      store.deleteAllSessions(recipient.getRecipientId());

      if (eventListener.isPresent()) {
        eventListener.get().onSecurityEvent(recipient.getRecipientId());
      }
    }
  }

  public void sendMessage(List<PushAddress> recipients, TextSecureMessage message)
      throws IOException, EncapsulatedExceptions
  {
    byte[] content = createMessageContent(message);
    sendMessage(recipients, message.getTimestamp(), content);
  }

  private byte[] createMessageContent(TextSecureMessage message) throws IOException {
    PushMessageContent.Builder builder  = PushMessageContent.newBuilder();
    List<AttachmentPointer>    pointers = createAttachmentPointers(message.getAttachments());

    if (!pointers.isEmpty()) {
      builder.addAllAttachments(pointers);
    }

    if (message.getBody().isPresent()) {
      builder.setBody(message.getBody().get());
    }

    if (message.getGroupInfo().isPresent()) {
      builder.setGroup(createGroupContent(message.getGroupInfo().get()));
    }

    if (message.isEndSession()) {
      builder.setFlags(PushMessageContent.Flags.END_SESSION_VALUE);
    }

    return builder.build().toByteArray();
  }

  private GroupContext createGroupContent(TextSecureGroup group) throws IOException {
    GroupContext.Builder builder = GroupContext.newBuilder();
    builder.setId(ByteString.copyFrom(group.getGroupId()));

    if (group.getType() != TextSecureGroup.Type.DELIVER) {
      if      (group.getType() == TextSecureGroup.Type.UPDATE) builder.setType(GroupContext.Type.UPDATE);
      else if (group.getType() == TextSecureGroup.Type.QUIT)   builder.setType(GroupContext.Type.QUIT);
      else                                                     throw new AssertionError("Unknown type: " + group.getType());

      if (group.getName().isPresent()) builder.setName(group.getName().get());
      if (group.getMembers().isPresent()) builder.addAllMembers(group.getMembers().get());

      if (group.getAvatar().isPresent() && group.getAvatar().get().isStream()) {
        AttachmentPointer pointer = createAttachmentPointer(group.getAvatar().get().asStream());
        builder.setAvatar(pointer);
      }
    } else {
      builder.setType(GroupContext.Type.DELIVER);
    }

    return builder.build();
  }

  private void sendMessage(List<PushAddress> recipients, long timestamp, byte[] content)
      throws IOException, EncapsulatedExceptions
  {
    List<UntrustedIdentityException> untrustedIdentities = new LinkedList<>();
    List<UnregisteredUserException>  unregisteredUsers   = new LinkedList<>();

    for (PushAddress recipient : recipients) {
      try {
        sendMessage(recipient, timestamp, content);
      } catch (UntrustedIdentityException e) {
        Log.w(TAG, e);
        untrustedIdentities.add(e);
      } catch (UnregisteredUserException e) {
        Log.w(TAG, e);
        unregisteredUsers.add(e);
      }
    }

    if (!untrustedIdentities.isEmpty() || !unregisteredUsers.isEmpty()) {
      throw new EncapsulatedExceptions(untrustedIdentities, unregisteredUsers);
    }
  }

  private void sendMessage(PushAddress recipient, long timestamp, byte[] content)
      throws UntrustedIdentityException, IOException
  {
    for (int i=0;i<3;i++) {
      try {
        OutgoingPushMessageList messages = getEncryptedMessages(socket, recipient, timestamp, content);
        socket.sendMessage(messages);

        return;
      } catch (MismatchedDevicesException mde) {
        Log.w(TAG, mde);
        handleMismatchedDevices(socket, recipient, mde.getMismatchedDevices());
      } catch (StaleDevicesException ste) {
        Log.w(TAG, ste);
        handleStaleDevices(recipient, ste.getStaleDevices());
      }
    }
  }

  private List<AttachmentPointer> createAttachmentPointers(Optional<List<TextSecureAttachment>> attachments) throws IOException {
    List<AttachmentPointer> pointers = new LinkedList<>();

    if (!attachments.isPresent() || attachments.get().isEmpty()) {
      Log.w(TAG, "No attachments present...");
      return pointers;
    }

    for (TextSecureAttachment attachment : attachments.get()) {
      if (attachment.isStream()) {
        Log.w(TAG, "Found attachment, creating pointer...");
        pointers.add(createAttachmentPointer(attachment.asStream()));
      }
    }

    return pointers;
  }

  private AttachmentPointer createAttachmentPointer(TextSecureAttachmentStream attachment)
      throws IOException
  {
    byte[]             attachmentKey  = Util.getSecretBytes(64);
    PushAttachmentData attachmentData = new PushAttachmentData(attachment.getContentType(),
                                                               attachment.getInputStream(),
                                                               attachment.getLength(),
                                                               attachmentKey);

    long attachmentId = socket.sendAttachment(attachmentData);

    return AttachmentPointer.newBuilder()
                            .setContentType(attachment.getContentType())
                            .setId(attachmentId)
                            .setKey(ByteString.copyFrom(attachmentKey))
                            .build();
  }


  private OutgoingPushMessageList getEncryptedMessages(PushServiceSocket socket,
                                                       PushAddress recipient,
                                                       long timestamp,
                                                       byte[] plaintext)
      throws IOException, UntrustedIdentityException
  {
    PushBody masterBody = getEncryptedMessage(socket, recipient, plaintext);

    List<OutgoingPushMessage> messages = new LinkedList<>();
    messages.add(new OutgoingPushMessage(recipient, masterBody));

    for (int deviceId : store.getSubDeviceSessions(recipient.getRecipientId())) {
      PushAddress device = new PushAddress(recipient.getRecipientId(), recipient.getNumber(), deviceId, recipient.getRelay());
      PushBody    body   = getEncryptedMessage(socket, device, plaintext);

      messages.add(new OutgoingPushMessage(device, body));
    }

    return new OutgoingPushMessageList(recipient.getNumber(), timestamp, recipient.getRelay(), messages);
  }

  private PushBody getEncryptedMessage(PushServiceSocket socket, PushAddress recipient, byte[] plaintext)
      throws IOException, UntrustedIdentityException
  {
    if (!store.containsSession(recipient.getRecipientId(), recipient.getDeviceId())) {
      try {
        List<PreKeyBundle> preKeys = socket.getPreKeys(recipient);

        for (PreKeyBundle preKey : preKeys) {
          try {
            SessionBuilder sessionBuilder = new SessionBuilder(store, recipient.getRecipientId(), recipient.getDeviceId());
            sessionBuilder.process(preKey);
          } catch (org.whispersystems.libaxolotl.UntrustedIdentityException e) {
            throw new UntrustedIdentityException("Untrusted identity key!", recipient.getNumber(), preKey.getIdentityKey());
          }
        }

        if (eventListener.isPresent()) {
          eventListener.get().onSecurityEvent(recipient.getRecipientId());
        }
      } catch (InvalidKeyException e) {
        throw new IOException(e);
      }
    }

    TextSecureCipher  cipher               = new TextSecureCipher(store, recipient.getRecipientId(), recipient.getDeviceId());
    CiphertextMessage message              = cipher.encrypt(plaintext);
    int               remoteRegistrationId = cipher.getRemoteRegistrationId();

    if (message.getType() == CiphertextMessage.PREKEY_TYPE) {
      return new PushBody(Type.PREKEY_BUNDLE_VALUE, remoteRegistrationId, message.serialize());
    } else if (message.getType() == CiphertextMessage.WHISPER_TYPE) {
      return new PushBody(Type.CIPHERTEXT_VALUE, remoteRegistrationId, message.serialize());
    } else {
      throw new AssertionError("Unknown ciphertext type: " + message.getType());
    }
  }

  private void handleMismatchedDevices(PushServiceSocket socket, PushAddress recipient,
                                       MismatchedDevices mismatchedDevices)
      throws IOException, UntrustedIdentityException
  {
    try {
      for (int extraDeviceId : mismatchedDevices.getExtraDevices()) {
        store.deleteSession(recipient.getRecipientId(), extraDeviceId);
      }

      for (int missingDeviceId : mismatchedDevices.getMissingDevices()) {
        PushAddress  device = new PushAddress(recipient.getRecipientId(), recipient.getNumber(),
                                              missingDeviceId, recipient.getRelay());
        PreKeyBundle preKey = socket.getPreKey(device);

        try {
          SessionBuilder sessionBuilder = new SessionBuilder(store, device.getRecipientId(), device.getDeviceId());
          sessionBuilder.process(preKey);
        } catch (org.whispersystems.libaxolotl.UntrustedIdentityException e) {
          throw new UntrustedIdentityException("Untrusted identity key!", recipient.getNumber(), preKey.getIdentityKey());
        }
      }
    } catch (InvalidKeyException e) {
      throw new IOException(e);
    }
  }

  private void handleStaleDevices(PushAddress recipient, StaleDevices staleDevices) {
    long recipientId = recipient.getRecipientId();

    for (int staleDeviceId : staleDevices.getStaleDevices()) {
      store.deleteSession(recipientId, staleDeviceId);
    }
  }

  public static interface EventListener {
    public void onSecurityEvent(long recipientId);
  }

}