package org.thoughtcrime.securesms.service;

import android.content.Context;

import org.jetbrains.annotations.NotNull;
import org.session.libsession.messaging.messages.control.ExpirationTimerUpdate;
import org.session.libsession.messaging.messages.signal.IncomingMediaMessage;
import org.session.libsession.messaging.messages.signal.OutgoingExpirationUpdateMessage;
import org.session.libsession.utilities.Address;
import org.session.libsession.utilities.GroupUtil;
import org.session.libsession.utilities.SSKEnvironment;
import org.session.libsession.utilities.TextSecurePreferences;
import org.session.libsession.utilities.recipients.Recipient;
import org.session.libsignal.messages.SignalServiceGroup;
import org.session.libsignal.utilities.Log;
import org.session.libsignal.utilities.guava.Optional;
import org.thoughtcrime.securesms.database.MmsDatabase;
import org.thoughtcrime.securesms.database.SmsDatabase;
import org.thoughtcrime.securesms.database.model.MessageRecord;
import org.thoughtcrime.securesms.dependencies.DatabaseComponent;
import org.thoughtcrime.securesms.mms.MmsException;

import java.io.IOException;
import java.util.Comparator;
import java.util.TreeSet;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

public class ExpiringMessageManager implements SSKEnvironment.MessageExpirationManagerProtocol {

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

  private final TreeSet<ExpiringMessageReference> expiringMessageReferences = new TreeSet<>(new ExpiringMessageComparator());
  private final Executor                          executor                  = Executors.newSingleThreadExecutor();

  private final SmsDatabase smsDatabase;
  private final MmsDatabase mmsDatabase;
  private final Context     context;

  public ExpiringMessageManager(Context context) {
    this.context     = context.getApplicationContext();
    this.smsDatabase = DatabaseComponent.get(context).smsDatabase();
    this.mmsDatabase = DatabaseComponent.get(context).mmsDatabase();

    executor.execute(new LoadTask());
    executor.execute(new ProcessTask());
  }

  public void scheduleDeletion(long id, boolean mms, long expiresInMillis) {
    scheduleDeletion(id, mms, System.currentTimeMillis(), expiresInMillis);
  }

  public void scheduleDeletion(long id, boolean mms, long startedAtTimestamp, long expiresInMillis) {
    long expiresAtMillis = startedAtTimestamp + expiresInMillis;

    synchronized (expiringMessageReferences) {
      expiringMessageReferences.add(new ExpiringMessageReference(id, mms, expiresAtMillis));
      expiringMessageReferences.notifyAll();
    }
  }

  public void checkSchedule() {
    synchronized (expiringMessageReferences) {
      expiringMessageReferences.notifyAll();
    }
  }

  @Override
  public void setExpirationTimer(@NotNull ExpirationTimerUpdate message) {
    String userPublicKey = TextSecurePreferences.getLocalNumber(context);
    String senderPublicKey = message.getSender();

    // Notify the user
    if (senderPublicKey == null || userPublicKey.equals(senderPublicKey)) {
      // sender is self or a linked device
      insertOutgoingExpirationTimerMessage(message);
    } else {
      insertIncomingExpirationTimerMessage(message);
    }

    if (message.getId() != null) {
      DatabaseComponent.get(context).smsDatabase().deleteMessage(message.getId());
    }
  }

  private void insertIncomingExpirationTimerMessage(ExpirationTimerUpdate message) {
    MmsDatabase database = DatabaseComponent.get(context).mmsDatabase();

    String senderPublicKey = message.getSender();
    Long sentTimestamp = message.getSentTimestamp();
    String groupId = message.getGroupPublicKey();
    int duration = message.getDuration();

    Optional<SignalServiceGroup> groupInfo = Optional.absent();
    Address address = Address.fromSerialized(senderPublicKey);
    Recipient recipient = Recipient.from(context, address, false);

    // if the sender is blocked, we don't display the update, except if it's in a closed group
    if (recipient.isBlocked() && groupId == null) return;

    try {
      if (groupId != null) {
        String groupID = GroupUtil.doubleEncodeGroupID(groupId);
        groupInfo = Optional.of(new SignalServiceGroup(GroupUtil.getDecodedGroupIDAsData(groupID), SignalServiceGroup.GroupType.SIGNAL));

        Address groupAddress = Address.fromSerialized(groupID);
        recipient = Recipient.from(context, groupAddress, false);
      }

      IncomingMediaMessage mediaMessage = new IncomingMediaMessage(address, sentTimestamp, -1,
              duration * 1000L, true,
              false,
              Optional.absent(),
              groupInfo,
              Optional.absent(),
              Optional.absent(),
              Optional.absent(),
              Optional.absent(),
              Optional.absent());
      //insert the timer update message
      database.insertSecureDecryptedMessageInbox(mediaMessage, -1);

      //set the timer to the conversation
      DatabaseComponent.get(context).recipientDatabase().setExpireMessages(recipient, duration);

    } catch (IOException | MmsException ioe) {
      Log.e("Loki", "Failed to insert expiration update message.");
    }
  }

  private void insertOutgoingExpirationTimerMessage(ExpirationTimerUpdate message) {
    MmsDatabase database = DatabaseComponent.get(context).mmsDatabase();

    Long sentTimestamp = message.getSentTimestamp();
    String groupId = message.getGroupPublicKey();
    int duration = message.getDuration();

    Address address = Address.fromSerialized((message.getSyncTarget() != null && !message.getSyncTarget().isEmpty()) ? message.getSyncTarget() : message.getRecipient());
    Recipient recipient = Recipient.from(context, address, false);

    try {
      OutgoingExpirationUpdateMessage timerUpdateMessage = new OutgoingExpirationUpdateMessage(recipient, sentTimestamp, duration * 1000L, groupId);
      database.insertSecureDecryptedMessageOutbox(timerUpdateMessage, -1, sentTimestamp);

      if (groupId != null) {
        // we need the group ID as recipient for setExpireMessages below
        recipient = Recipient.from(context, Address.fromSerialized(GroupUtil.doubleEncodeGroupID(groupId)), false);
      }
      //set the timer to the conversation
      DatabaseComponent.get(context).recipientDatabase().setExpireMessages(recipient, duration);

    } catch (MmsException | IOException ioe) {
      Log.e("Loki", "Failed to insert expiration update message.");
    }
  }

  @Override
  public void disableExpirationTimer(@NotNull ExpirationTimerUpdate message) {
    setExpirationTimer(message);
  }

  @Override
  public void startAnyExpiration(long timestamp, @NotNull String author) {
    MessageRecord messageRecord = DatabaseComponent.get(context).mmsSmsDatabase().getMessageFor(timestamp, author);
    if (messageRecord != null) {
      boolean mms = messageRecord.isMms();
      Recipient recipient = messageRecord.getRecipient();
      if (recipient.getExpireMessages() <= 0) return;
      if (mms) {
        mmsDatabase.markExpireStarted(messageRecord.getId());
      } else {
        smsDatabase.markExpireStarted(messageRecord.getId());
      }
      scheduleDeletion(messageRecord.getId(), mms, recipient.getExpireMessages() * 1000);
    }
  }

  private class LoadTask implements Runnable {

    public void run() {
      SmsDatabase.Reader smsReader = smsDatabase.readerFor(smsDatabase.getExpirationStartedMessages());
      MmsDatabase.Reader mmsReader = mmsDatabase.getExpireStartedMessages();

      MessageRecord messageRecord;

      while ((messageRecord = smsReader.getNext()) != null) {
        expiringMessageReferences.add(new ExpiringMessageReference(messageRecord.getId(),
                                                                   messageRecord.isMms(),
                                                                   messageRecord.getExpireStarted() + messageRecord.getExpiresIn()));
      }

      while ((messageRecord = mmsReader.getNext()) != null) {
        expiringMessageReferences.add(new ExpiringMessageReference(messageRecord.getId(),
                                                                   messageRecord.isMms(),
                                                                   messageRecord.getExpireStarted() + messageRecord.getExpiresIn()));
      }

      smsReader.close();
      mmsReader.close();
    }
  }

  @SuppressWarnings("InfiniteLoopStatement")
  private class ProcessTask implements Runnable {
    public void run() {
      while (true) {
        ExpiringMessageReference expiredMessage = null;

        synchronized (expiringMessageReferences) {
          try {
            while (expiringMessageReferences.isEmpty()) expiringMessageReferences.wait();

            ExpiringMessageReference nextReference = expiringMessageReferences.first();
            long                     waitTime      = nextReference.expiresAtMillis - System.currentTimeMillis();

            if (waitTime > 0) {
              ExpirationListener.setAlarm(context, waitTime);
              expiringMessageReferences.wait(waitTime);
            } else {
              expiredMessage = nextReference;
              expiringMessageReferences.remove(nextReference);
            }

          } catch (InterruptedException e) {
            Log.w(TAG, e);
          }
        }

        if (expiredMessage != null) {
          if (expiredMessage.mms) mmsDatabase.deleteMessage(expiredMessage.id);
          else                    smsDatabase.deleteMessage(expiredMessage.id);
        }
      }
    }
  }

  private static class ExpiringMessageReference {
    private final long    id;
    private final boolean mms;
    private final long    expiresAtMillis;

    private ExpiringMessageReference(long id, boolean mms, long expiresAtMillis) {
      this.id = id;
      this.mms = mms;
      this.expiresAtMillis = expiresAtMillis;
    }

    @Override
    public boolean equals(Object other) {
      if (other == null) return false;
      if (!(other instanceof ExpiringMessageReference)) return false;

      ExpiringMessageReference that = (ExpiringMessageReference)other;
      return this.id == that.id && this.mms == that.mms && this.expiresAtMillis == that.expiresAtMillis;
    }

    @Override
    public int hashCode() {
      return (int)this.id ^ (mms ? 1 : 0) ^ (int)expiresAtMillis;
    }
  }

  private static class ExpiringMessageComparator implements Comparator<ExpiringMessageReference> {
    @Override
    public int compare(ExpiringMessageReference lhs, ExpiringMessageReference rhs) {
      if      (lhs.expiresAtMillis < rhs.expiresAtMillis) return -1;
      else if (lhs.expiresAtMillis > rhs.expiresAtMillis) return 1;
      else if (lhs.id < rhs.id)                           return -1;
      else if (lhs.id > rhs.id)                           return 1;
      else if (!lhs.mms && rhs.mms)                       return -1;
      else if (lhs.mms && !rhs.mms)                       return 1;
      else                                                return 0;
    }
  }

}