session-android/libsession/src/main/java/org/session/libsession/messaging/sending_receiving/MessageSenderClosedGroupHandler.kt

@file:Suppress("NAME_SHADOWING")

package org.session.libsession.messaging.sending_receiving

import com.google.protobuf.ByteString
import nl.komponents.kovenant.Promise
import nl.komponents.kovenant.deferred
import org.session.libsession.messaging.MessagingModuleConfiguration
import org.session.libsession.messaging.messages.control.ClosedGroupControlMessage
import org.session.libsession.messaging.sending_receiving.MessageSender.Error
import org.session.libsession.messaging.sending_receiving.notifications.PushNotificationAPI
import org.session.libsession.messaging.sending_receiving.pollers.ClosedGroupPollerV2
import org.session.libsession.utilities.Address
import org.session.libsession.utilities.GroupUtil
import org.session.libsession.utilities.TextSecurePreferences
import org.session.libsignal.crypto.ecc.Curve
import org.session.libsignal.crypto.ecc.ECKeyPair
import org.session.libsignal.utilities.guava.Optional
import org.session.libsignal.messages.SignalServiceGroup
import org.session.libsignal.protos.SignalServiceProtos
import org.session.libsignal.utilities.hexEncodedPublicKey
import org.session.libsignal.utilities.removing05PrefixIfNeeded
import org.session.libsignal.utilities.Hex
import org.session.libsignal.utilities.ThreadUtils
import org.session.libsignal.utilities.Log
import java.util.*
import java.util.concurrent.ConcurrentHashMap

const val groupSizeLimit = 100

val pendingKeyPairs = ConcurrentHashMap<String, Optional<ECKeyPair>>()

fun MessageSender.create(name: String, members: Collection<String>): Promise<String, Exception> {
    val deferred = deferred<String, Exception>()
    ThreadUtils.queue {
        // Prepare
        val context = MessagingModuleConfiguration.shared.context
        val storage = MessagingModuleConfiguration.shared.storage
        val userPublicKey = storage.getUserPublicKey()!!
        val membersAsData = members.map { ByteString.copyFrom(Hex.fromStringCondensed(it)) }
        // Generate the group's public key
        val groupPublicKey = Curve.generateKeyPair().hexEncodedPublicKey // Includes the "05" prefix
        // Generate the key pair that'll be used for encryption and decryption
        val encryptionKeyPair = Curve.generateKeyPair()
        // Create the group
        val groupID = GroupUtil.doubleEncodeGroupID(groupPublicKey)
        val admins = setOf( userPublicKey )
        val adminsAsData = admins.map { ByteString.copyFrom(Hex.fromStringCondensed(it)) }
        storage.createGroup(groupID, name, LinkedList(members.map { Address.fromSerialized(it) }),
            null, null, LinkedList(admins.map { Address.fromSerialized(it) }), System.currentTimeMillis())
        storage.setProfileSharing(Address.fromSerialized(groupID), true)
        // Send a closed group update message to all members individually
        val closedGroupUpdateKind = ClosedGroupControlMessage.Kind.New(ByteString.copyFrom(Hex.fromStringCondensed(groupPublicKey)), name, encryptionKeyPair, membersAsData, adminsAsData)
        val sentTime = System.currentTimeMillis()
        for (member in members) {
            val closedGroupControlMessage = ClosedGroupControlMessage(closedGroupUpdateKind)
            closedGroupControlMessage.sentTimestamp = sentTime
            try {
                sendNonDurably(closedGroupControlMessage, Address.fromSerialized(member)).get()
            } catch (e: Exception) {
                deferred.reject(e)
                return@queue
            }
        }

        // Add the group to the user's set of public keys to poll for
        storage.addClosedGroupPublicKey(groupPublicKey)
        // Store the encryption key pair
        storage.addClosedGroupEncryptionKeyPair(encryptionKeyPair, groupPublicKey)
        // Notify the user
        val threadID = storage.getOrCreateThreadIdFor(Address.fromSerialized(groupID))
        storage.insertOutgoingInfoMessage(context, groupID, SignalServiceGroup.Type.CREATION, name, members, admins, threadID, sentTime)
        // Notify the PN server
        PushNotificationAPI.performOperation(PushNotificationAPI.ClosedGroupOperation.Subscribe, groupPublicKey, userPublicKey)
        // Start polling
        ClosedGroupPollerV2.shared.startPolling(groupPublicKey)
        // Fulfill the promise
        deferred.resolve(groupID)
    }
    // Return
    return deferred.promise
}

fun MessageSender.update(groupPublicKey: String, members: List<String>, name: String) {
    val context = MessagingModuleConfiguration.shared.context
    val storage = MessagingModuleConfiguration.shared.storage
    val groupID = GroupUtil.doubleEncodeGroupID(groupPublicKey)
    val group = storage.getGroup(groupID) ?: run {
        Log.d("Loki", "Can't update nonexistent closed group.")
        throw Error.NoThread
    }
    // Update name if needed
    if (name != group.title) { setName(groupPublicKey, name) }
    // Add members if needed
    val addedMembers = members - group.members.map { it.serialize() }
    if (!addedMembers.isEmpty()) { addMembers(groupPublicKey, addedMembers) }
    // Remove members if needed
    val removedMembers = group.members.map { it.serialize() } - members
    if (removedMembers.isEmpty()) { removeMembers(groupPublicKey, removedMembers) }
}

fun MessageSender.setName(groupPublicKey: String, newName: String) {
    val context = MessagingModuleConfiguration.shared.context
    val storage = MessagingModuleConfiguration.shared.storage
    val groupID = GroupUtil.doubleEncodeGroupID(groupPublicKey)
    val group = storage.getGroup(groupID) ?: run {
        Log.d("Loki", "Can't change name for nonexistent closed group.")
        throw Error.NoThread
    }
    val members = group.members.map { it.serialize() }.toSet()
    val admins = group.admins.map { it.serialize() }
    // Send the update to the group
    val kind = ClosedGroupControlMessage.Kind.NameChange(newName)
    val sentTime = System.currentTimeMillis()
    val closedGroupControlMessage = ClosedGroupControlMessage(kind)
    closedGroupControlMessage.sentTimestamp = sentTime
    send(closedGroupControlMessage, Address.fromSerialized(groupID))
    // Update the group
    storage.updateTitle(groupID, newName)
    // Notify the user
    val infoType = SignalServiceGroup.Type.NAME_CHANGE
    val threadID = storage.getOrCreateThreadIdFor(Address.fromSerialized(groupID))
    storage.insertOutgoingInfoMessage(context, groupID, infoType, newName, members, admins, threadID, sentTime)
}

fun MessageSender.addMembers(groupPublicKey: String, membersToAdd: List<String>) {
    val context = MessagingModuleConfiguration.shared.context
    val storage = MessagingModuleConfiguration.shared.storage
    val groupID = GroupUtil.doubleEncodeGroupID(groupPublicKey)
    val group = storage.getGroup(groupID) ?: run {
        Log.d("Loki", "Can't add members to nonexistent closed group.")
        throw Error.NoThread
    }
    if (membersToAdd.isEmpty()) {
        Log.d("Loki", "Invalid closed group update.")
        throw Error.InvalidClosedGroupUpdate
    }
    val updatedMembers = group.members.map { it.serialize() }.toSet() + membersToAdd
    // Save the new group members
    storage.updateMembers(groupID, updatedMembers.map { Address.fromSerialized(it) })
    val membersAsData = updatedMembers.map { ByteString.copyFrom(Hex.fromStringCondensed(it)) }
    val newMembersAsData = membersToAdd.map { ByteString.copyFrom(Hex.fromStringCondensed(it)) }
    val admins = group.admins.map { it.serialize() }
    val adminsAsData = admins.map { ByteString.copyFrom(Hex.fromStringCondensed(it)) }
    val encryptionKeyPair = storage.getLatestClosedGroupEncryptionKeyPair(groupPublicKey) ?: run {
        Log.d("Loki", "Couldn't get encryption key pair for closed group.")
        throw Error.NoKeyPair
    }
    val name = group.title
    // Send the update to the group
    val memberUpdateKind = ClosedGroupControlMessage.Kind.MembersAdded(newMembersAsData)
    val sentTime = System.currentTimeMillis()
    val closedGroupControlMessage = ClosedGroupControlMessage(memberUpdateKind)
    closedGroupControlMessage.sentTimestamp = sentTime
    send(closedGroupControlMessage, Address.fromSerialized(groupID))
    // Send closed group update messages to any new members individually
    for (member in membersToAdd) {
        val closedGroupNewKind = ClosedGroupControlMessage.Kind.New(ByteString.copyFrom(Hex.fromStringCondensed(groupPublicKey)), name, encryptionKeyPair, membersAsData, adminsAsData)
        val closedGroupControlMessage = ClosedGroupControlMessage(closedGroupNewKind)
        closedGroupControlMessage.sentTimestamp = sentTime
        send(closedGroupControlMessage, Address.fromSerialized(member))
    }
    // Notify the user
    val infoType = SignalServiceGroup.Type.MEMBER_ADDED
    val threadID = storage.getOrCreateThreadIdFor(Address.fromSerialized(groupID))
    storage.insertOutgoingInfoMessage(context, groupID, infoType, name, membersToAdd, admins, threadID, sentTime)
}

fun MessageSender.removeMembers(groupPublicKey: String, membersToRemove: List<String>) {
    val context = MessagingModuleConfiguration.shared.context
    val storage = MessagingModuleConfiguration.shared.storage
    val userPublicKey = storage.getUserPublicKey()!!
    val groupID = GroupUtil.doubleEncodeGroupID(groupPublicKey)
    val group = storage.getGroup(groupID) ?: run {
        Log.d("Loki", "Can't remove members from nonexistent closed group.")
        throw Error.NoThread
    }
    if (membersToRemove.isEmpty() || membersToRemove.contains(userPublicKey)) {
        Log.d("Loki", "Invalid closed group update.")
        throw Error.InvalidClosedGroupUpdate
    }
    val admins = group.admins.map { it.serialize() }
    if (!admins.contains(userPublicKey)) {
        Log.d("Loki", "Only an admin can remove members from a group.")
        throw Error.InvalidClosedGroupUpdate
    }
    val updatedMembers = group.members.map { it.serialize() }.toSet() - membersToRemove
    if (membersToRemove.any { it in admins } && updatedMembers.isNotEmpty()) {
        Log.d("Loki", "Can't remove admin from closed group unless the group is destroyed entirely.")
        throw Error.InvalidClosedGroupUpdate
    }
    // Save the new group members
    storage.updateMembers(groupID, updatedMembers.map { Address.fromSerialized(it) })
    // Update the zombie list
    val oldZombies = storage.getZombieMembers(groupID)
    storage.setZombieMembers(groupID, oldZombies.minus(membersToRemove).map { Address.fromSerialized(it) })
    val removeMembersAsData = membersToRemove.map { ByteString.copyFrom(Hex.fromStringCondensed(it)) }
    val name = group.title
    // Send the update to the group
    val memberUpdateKind = ClosedGroupControlMessage.Kind.MembersRemoved(removeMembersAsData)
    val sentTime = System.currentTimeMillis()
    val closedGroupControlMessage = ClosedGroupControlMessage(memberUpdateKind)
    closedGroupControlMessage.sentTimestamp = sentTime
    send(closedGroupControlMessage, Address.fromSerialized(groupID))
    // Send the new encryption key pair to the remaining group members.
    // At this stage we know the user is admin, no need to test.
    generateAndSendNewEncryptionKeyPair(groupPublicKey, updatedMembers)
    // Notify the user
    // We don't display zombie members in the notification as users have already been notified when those members left
    val notificationMembers = membersToRemove.minus(oldZombies)
    if (notificationMembers.isNotEmpty()) {
        // No notification to display when only zombies have been removed
        val infoType = SignalServiceGroup.Type.MEMBER_REMOVED
        val threadID = storage.getOrCreateThreadIdFor(Address.fromSerialized(groupID))
        storage.insertOutgoingInfoMessage(context, groupID, infoType, name, notificationMembers, admins, threadID, sentTime)
    }
}

fun MessageSender.leave(groupPublicKey: String, notifyUser: Boolean = true): Promise<Unit, Exception> {
    val deferred = deferred<Unit, Exception>()
    ThreadUtils.queue {
        val context = MessagingModuleConfiguration.shared.context
        val storage = MessagingModuleConfiguration.shared.storage
        val userPublicKey = TextSecurePreferences.getLocalNumber(context)!!
        val groupID = GroupUtil.doubleEncodeGroupID(groupPublicKey)
        val group = storage.getGroup(groupID) ?: return@queue deferred.reject(Error.NoThread)
        val updatedMembers = group.members.map { it.serialize() }.toSet() - userPublicKey
        val admins = group.admins.map { it.serialize() }
        val name = group.title
        // Send the update to the group
        val closedGroupControlMessage = ClosedGroupControlMessage(ClosedGroupControlMessage.Kind.MemberLeft())
        val sentTime = System.currentTimeMillis()
        closedGroupControlMessage.sentTimestamp = sentTime
        storage.setActive(groupID, false)
        sendNonDurably(closedGroupControlMessage, Address.fromSerialized(groupID)).success {
            // Notify the user
            val infoType = SignalServiceGroup.Type.QUIT
            val threadID = storage.getOrCreateThreadIdFor(Address.fromSerialized(groupID))
            if (notifyUser) {
                storage.insertOutgoingInfoMessage(context, groupID, infoType, name, updatedMembers, admins, threadID, sentTime)
            }
            // Remove the group private key and unsubscribe from PNs
            MessageReceiver.disableLocalGroupAndUnsubscribe(groupPublicKey, groupID, userPublicKey)
            deferred.resolve(Unit)
        }.fail {
            storage.setActive(groupID, true)
        }
    }
    return deferred.promise
}

fun MessageSender.generateAndSendNewEncryptionKeyPair(groupPublicKey: String, targetMembers: Collection<String>) {
    // Prepare
    val storage = MessagingModuleConfiguration.shared.storage
    val userPublicKey = storage.getUserPublicKey()!!
    val groupID = GroupUtil.doubleEncodeGroupID(groupPublicKey)
    val group = storage.getGroup(groupID) ?: run {
        Log.d("Loki", "Can't update nonexistent closed group.")
        throw Error.NoThread
    }
    if (!group.admins.map { it.toString() }.contains(userPublicKey)) {
        Log.d("Loki", "Can't distribute new encryption key pair as non-admin.")
        throw Error.InvalidClosedGroupUpdate
    }
    // Generate the new encryption key pair
    val newKeyPair = Curve.generateKeyPair()
    // Replace call will not succeed if no value already set
    pendingKeyPairs.putIfAbsent(groupPublicKey,Optional.absent())
    do {
        // Make sure we set the pending key pair or wait until it is not null
    } while (!pendingKeyPairs.replace(groupPublicKey,Optional.absent(),Optional.fromNullable(newKeyPair)))
    // Distribute it
    sendEncryptionKeyPair(groupPublicKey, newKeyPair, targetMembers)?.success {
        // Store it * after * having sent out the message to the group
        storage.addClosedGroupEncryptionKeyPair(newKeyPair, groupPublicKey)
        pendingKeyPairs[groupPublicKey] = Optional.absent()
    }
}

fun MessageSender.sendEncryptionKeyPair(groupPublicKey: String, newKeyPair: ECKeyPair, targetMembers: Collection<String>, targetUser: String? = null, force: Boolean = true): Promise<Unit, Exception>? {
    val destination = targetUser ?: GroupUtil.doubleEncodeGroupID(groupPublicKey)
    val proto = SignalServiceProtos.KeyPair.newBuilder()
    proto.publicKey = ByteString.copyFrom(newKeyPair.publicKey.serialize().removing05PrefixIfNeeded())
    proto.privateKey = ByteString.copyFrom(newKeyPair.privateKey.serialize())
    val plaintext = proto.build().toByteArray()
    val wrappers = targetMembers.map { publicKey ->
        val ciphertext = MessageEncrypter.encrypt(plaintext, publicKey)
        ClosedGroupControlMessage.KeyPairWrapper(publicKey, ByteString.copyFrom(ciphertext))
    }
    val kind = ClosedGroupControlMessage.Kind.EncryptionKeyPair(ByteString.copyFrom(Hex.fromStringCondensed(groupPublicKey)), wrappers)
    val sentTime = System.currentTimeMillis()
    val closedGroupControlMessage = ClosedGroupControlMessage(kind)
    closedGroupControlMessage.sentTimestamp = sentTime
    return if (force) {
        MessageSender.sendNonDurably(closedGroupControlMessage, Address.fromSerialized(destination))
    } else {
        MessageSender.send(closedGroupControlMessage, Address.fromSerialized(destination))
        null
    }
}

fun MessageSender.sendLatestEncryptionKeyPair(publicKey: String, groupPublicKey: String) {
    val storage = MessagingModuleConfiguration.shared.storage
    val groupID = GroupUtil.doubleEncodeGroupID(groupPublicKey)
    val group = storage.getGroup(groupID) ?: run {
        Log.d("Loki", "Can't send encryption key pair for nonexistent closed group.")
        throw Error.NoThread
    }
    val members = group.members.map { it.serialize() }
    if (!members.contains(publicKey)) {
        Log.d("Loki", "Refusing to send latest encryption key pair to non-member.")
        return
    }
    // Get the latest encryption key pair
    val encryptionKeyPair = pendingKeyPairs[groupPublicKey]?.orNull()
        ?: storage.getLatestClosedGroupEncryptionKeyPair(groupPublicKey) ?: return
    // Send it
    val proto = SignalServiceProtos.KeyPair.newBuilder()
    proto.publicKey = ByteString.copyFrom(encryptionKeyPair.publicKey.serialize().removing05PrefixIfNeeded())
    proto.privateKey = ByteString.copyFrom(encryptionKeyPair.privateKey.serialize())
    val plaintext = proto.build().toByteArray()
    val ciphertext = MessageEncrypter.encrypt(plaintext, publicKey)
    Log.d("Loki", "Sending latest encryption key pair to: $publicKey.")
    val wrapper = ClosedGroupControlMessage.KeyPairWrapper(publicKey, ByteString.copyFrom(ciphertext))
    val kind = ClosedGroupControlMessage.Kind.EncryptionKeyPair(ByteString.copyFrom(Hex.fromStringCondensed(groupPublicKey)), listOf(wrapper))
    val closedGroupControlMessage = ClosedGroupControlMessage(kind)
    MessageSender.send(closedGroupControlMessage, Address.fromSerialized(publicKey))
}