simplexmq/src/Simplex/Messaging/Agent/Store.hs

{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveAnyClass #-}
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE NamedFieldPuns #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# OPTIONS_GHC -fno-warn-unticked-promoted-constructors #-}

module Simplex.Messaging.Agent.Store where

import Control.Exception (Exception)
import qualified Data.Attoparsec.ByteString.Char8 as A
import Data.ByteString.Char8 (ByteString)
import Data.Int (Int64)
import Data.Kind (Type)
import Data.List (find)
import Data.List.NonEmpty (NonEmpty)
import qualified Data.List.NonEmpty as L
import Data.Maybe (isJust)
import Data.Time (UTCTime)
import Data.Type.Equality
import Simplex.Messaging.Agent.Protocol
import Simplex.Messaging.Agent.RetryInterval (RI2State)
import qualified Simplex.Messaging.Crypto as C
import Simplex.Messaging.Crypto.Ratchet (PQEncryption, PQSupport, RatchetX448)
import Simplex.Messaging.Encoding.String
import Simplex.Messaging.Protocol
  ( MsgBody,
    MsgFlags,
    MsgId,
    NotifierId,
    NtfPrivateAuthKey,
    NtfPublicAuthKey,
    RcvDhSecret,
    RcvNtfDhSecret,
    RcvPrivateAuthKey,
    SndPrivateAuthKey,
    SndPublicAuthKey,
    SenderCanSecure,
    VersionSMPC,
  )
import qualified Simplex.Messaging.Protocol as SMP

-- * Queue types

data QueueStored = QSStored | QSNew

data SQueueStored (q :: QueueStored) where
  SQSStored :: SQueueStored 'QSStored
  SQSNew :: SQueueStored 'QSNew

data DBQueueId (q :: QueueStored) where
  DBQueueId :: Int64 -> DBQueueId 'QSStored
  DBNewQueue :: DBQueueId 'QSNew

deriving instance Show (DBQueueId q)

type RcvQueue = StoredRcvQueue 'QSStored

type NewRcvQueue = StoredRcvQueue 'QSNew

-- | A receive queue. SMP queue through which the agent receives messages from a sender.
data StoredRcvQueue (q :: QueueStored) = RcvQueue
  { userId :: UserId,
    connId :: ConnId,
    server :: SMPServer,
    -- | recipient queue ID
    rcvId :: SMP.RecipientId,
    -- | key used by the recipient to authorize transmissions
    rcvPrivateKey :: RcvPrivateAuthKey,
    -- | shared DH secret used to encrypt/decrypt message bodies from server to recipient
    rcvDhSecret :: RcvDhSecret,
    -- | private DH key related to public sent to sender out-of-band (to agree simple per-queue e2e)
    e2ePrivKey :: C.PrivateKeyX25519,
    -- | public sender's DH key and agreed shared DH secret for simple per-queue e2e
    e2eDhSecret :: Maybe C.DhSecretX25519,
    -- | sender queue ID
    sndId :: SMP.SenderId,
    -- | sender can secure the queue
    sndSecure :: SenderCanSecure,
    -- | queue status
    status :: QueueStatus,
    -- | database queue ID (within connection)
    dbQueueId :: DBQueueId q,
    -- | True for a primary or a next primary queue of the connection (next if dbReplaceQueueId is set)
    primary :: Bool,
    -- | database queue ID to replace, Nothing if this queue is not replacing another, `Just Nothing` is used for replacing old queues
    dbReplaceQueueId :: Maybe Int64,
    rcvSwchStatus :: Maybe RcvSwitchStatus,
    -- | SMP client version
    smpClientVersion :: VersionSMPC,
    -- | credentials used in context of notifications
    clientNtfCreds :: Maybe ClientNtfCreds,
    deleteErrors :: Int
  }
  deriving (Show)

rcvQueueInfo :: RcvQueue -> RcvQueueInfo
rcvQueueInfo rq@RcvQueue {server, rcvSwchStatus} =
  RcvQueueInfo {rcvServer = server, rcvSwitchStatus = rcvSwchStatus, canAbortSwitch = canAbortRcvSwitch rq}

canAbortRcvSwitch :: RcvQueue -> Bool
canAbortRcvSwitch = maybe False canAbort . rcvSwchStatus
  where
    canAbort = \case
      RSSwitchStarted -> True
      RSSendingQADD -> True
      -- if switch is in RSSendingQUSE, a race condition with sender deleting the original queue is possible
      RSSendingQUSE -> False
      -- if switch is in RSReceivedMessage status, aborting switch (deleting new queue)
      -- will break the connection because the sender would have original queue deleted
      RSReceivedMessage -> False

data ClientNtfCreds = ClientNtfCreds
  { -- | key pair to be used by the notification server to authorize transmissions
    ntfPublicKey :: NtfPublicAuthKey,
    ntfPrivateKey :: NtfPrivateAuthKey,
    -- | queue ID to be used by the notification server for NSUB command
    notifierId :: NotifierId,
    -- | shared DH secret used to encrypt/decrypt notification metadata (NMsgMeta) from server to recipient
    rcvNtfDhSecret :: RcvNtfDhSecret
  }
  deriving (Show)

type SndQueue = StoredSndQueue 'QSStored

type NewSndQueue = StoredSndQueue 'QSNew

-- | A send queue. SMP queue through which the agent sends messages to a recipient.
data StoredSndQueue (q :: QueueStored) = SndQueue
  { userId :: UserId,
    connId :: ConnId,
    server :: SMPServer,
    -- | sender queue ID
    sndId :: SMP.SenderId,
    -- | sender can secure the queue
    sndSecure :: SenderCanSecure,
    -- | key pair used by the sender to authorize transmissions
    -- TODO combine keys to key pair so that types match
    sndPublicKey :: SndPublicAuthKey,
    sndPrivateKey :: SndPrivateAuthKey,
    -- | DH public key used to negotiate per-queue e2e encryption
    e2ePubKey :: Maybe C.PublicKeyX25519,
    -- | shared DH secret agreed for simple per-queue e2e encryption
    e2eDhSecret :: C.DhSecretX25519,
    -- | queue status
    status :: QueueStatus,
    -- | database queue ID (within connection)
    dbQueueId :: DBQueueId q,
    -- | True for a primary or a next primary queue of the connection (next if dbReplaceQueueId is set)
    primary :: Bool,
    -- | ID of the queue this one is replacing
    dbReplaceQueueId :: Maybe Int64,
    sndSwchStatus :: Maybe SndSwitchStatus,
    -- | SMP client version
    smpClientVersion :: VersionSMPC
  }
  deriving (Show)

sndQueueInfo :: SndQueue -> SndQueueInfo
sndQueueInfo SndQueue {server, sndSwchStatus} =
  SndQueueInfo {sndServer = server, sndSwitchStatus = sndSwchStatus}

instance SMPQueue RcvQueue where
  qServer RcvQueue {server} = server
  {-# INLINE qServer #-}
  queueId RcvQueue {rcvId} = rcvId
  {-# INLINE queueId #-}

instance SMPQueue NewRcvQueue where
  qServer RcvQueue {server} = server
  {-# INLINE qServer #-}
  queueId RcvQueue {rcvId} = rcvId
  {-# INLINE queueId #-}

instance SMPQueue SndQueue where
  qServer SndQueue {server} = server
  {-# INLINE qServer #-}
  queueId SndQueue {sndId} = sndId
  {-# INLINE queueId #-}

findQ :: SMPQueue q => (SMPServer, SMP.QueueId) -> NonEmpty q -> Maybe q
findQ = find . sameQueue
{-# INLINE findQ #-}

removeQ :: SMPQueue q => (SMPServer, SMP.QueueId) -> NonEmpty q -> Maybe (q, [q])
removeQ = removeQP . sameQueue
{-# INLINE removeQ #-}

removeQP :: (q -> Bool) -> NonEmpty q -> Maybe (q, [q])
removeQP p qs = case L.break p qs of
  (_, []) -> Nothing
  (qs1, q : qs2) -> Just (q, qs1 <> qs2)

sndAddress :: RcvQueue -> (SMPServer, SMP.SenderId)
sndAddress RcvQueue {server, sndId} = (server, sndId)
{-# INLINE sndAddress #-}

findRQ :: (SMPServer, SMP.SenderId) -> NonEmpty RcvQueue -> Maybe RcvQueue
findRQ sAddr = find $ sameQAddress sAddr . sndAddress
{-# INLINE findRQ #-}

switchingRQ :: NonEmpty RcvQueue -> Maybe RcvQueue
switchingRQ = find $ isJust . rcvSwchStatus
{-# INLINE switchingRQ #-}

updatedQs :: SMPQueueRec q => q -> NonEmpty q -> NonEmpty q
updatedQs q = L.map $ \q' -> if dbQId q == dbQId q' then q else q'
{-# INLINE updatedQs #-}

class SMPQueue q => SMPQueueRec q where
  qUserId :: q -> UserId
  qConnId :: q -> ConnId
  dbQId :: q -> Int64
  dbReplaceQId :: q -> Maybe Int64

instance SMPQueueRec RcvQueue where
  qUserId RcvQueue {userId} = userId
  {-# INLINE qUserId #-}
  qConnId RcvQueue {connId} = connId
  {-# INLINE qConnId #-}
  dbQId RcvQueue {dbQueueId = DBQueueId qId} = qId
  {-# INLINE dbQId #-}
  dbReplaceQId RcvQueue {dbReplaceQueueId} = dbReplaceQueueId
  {-# INLINE dbReplaceQId #-}

instance SMPQueueRec SndQueue where
  qUserId SndQueue {userId} = userId
  {-# INLINE qUserId #-}
  qConnId SndQueue {connId} = connId
  {-# INLINE qConnId #-}
  dbQId SndQueue {dbQueueId = DBQueueId qId} = qId
  {-# INLINE dbQId #-}
  dbReplaceQId SndQueue {dbReplaceQueueId} = dbReplaceQueueId
  {-# INLINE dbReplaceQId #-}

-- * Connection types

-- | Type of a connection.
data ConnType = CNew | CRcv | CSnd | CDuplex | CContact deriving (Eq, Show)

-- | Connection of a specific type.
--
-- - RcvConnection is a connection that only has a receive queue set up,
--   typically created by a recipient initiating a duplex connection.
--
-- - SndConnection is a connection that only has a send queue set up, typically
--   created by a sender joining a duplex connection through a recipient's invitation.
--
-- - DuplexConnection is a connection that has both receive and send queues set up,
--   typically created by upgrading a receive or a send connection with a missing queue.
data Connection (d :: ConnType) where
  NewConnection :: ConnData -> Connection CNew
  RcvConnection :: ConnData -> RcvQueue -> Connection CRcv
  SndConnection :: ConnData -> SndQueue -> Connection CSnd
  DuplexConnection :: ConnData -> NonEmpty RcvQueue -> NonEmpty SndQueue -> Connection CDuplex
  ContactConnection :: ConnData -> RcvQueue -> Connection CContact

deriving instance Show (Connection d)

toConnData :: Connection d -> ConnData
toConnData = \case
  NewConnection cData -> cData
  RcvConnection cData _ -> cData
  SndConnection cData _ -> cData
  DuplexConnection cData _ _ -> cData
  ContactConnection cData _ -> cData

updateConnection :: ConnData -> Connection d -> Connection d
updateConnection cData = \case
  NewConnection _ -> NewConnection cData
  RcvConnection _ rq -> RcvConnection cData rq
  SndConnection _ sq -> SndConnection cData sq
  DuplexConnection _ rqs sqs -> DuplexConnection cData rqs sqs
  ContactConnection _ rq -> ContactConnection cData rq

data SConnType :: ConnType -> Type where
  SCNew :: SConnType CNew
  SCRcv :: SConnType CRcv
  SCSnd :: SConnType CSnd
  SCDuplex :: SConnType CDuplex
  SCContact :: SConnType CContact

connType :: SConnType c -> ConnType
connType SCNew = CNew
connType SCRcv = CRcv
connType SCSnd = CSnd
connType SCDuplex = CDuplex
connType SCContact = CContact

deriving instance Show (SConnType d)

instance TestEquality SConnType where
  testEquality SCRcv SCRcv = Just Refl
  testEquality SCSnd SCSnd = Just Refl
  testEquality SCDuplex SCDuplex = Just Refl
  testEquality SCContact SCContact = Just Refl
  testEquality _ _ = Nothing

-- | Connection of an unknown type.
-- Used to refer to an arbitrary connection when retrieving from store.
data SomeConn = forall d. SomeConn (SConnType d) (Connection d)

deriving instance Show SomeConn

data ConnData = ConnData
  { connId :: ConnId,
    userId :: UserId,
    connAgentVersion :: VersionSMPA,
    enableNtfs :: Bool,
    lastExternalSndId :: PrevExternalSndId,
    deleted :: Bool,
    ratchetSyncState :: RatchetSyncState,
    pqSupport :: PQSupport
  }
  deriving (Eq, Show)

-- this function should be mirrored in the clients
ratchetSyncAllowed :: ConnData -> Bool
ratchetSyncAllowed ConnData {ratchetSyncState, connAgentVersion} =
  connAgentVersion >= ratchetSyncSMPAgentVersion && (ratchetSyncState `elem` ([RSAllowed, RSRequired] :: [RatchetSyncState]))

-- this function should be mirrored in the clients
ratchetSyncSendProhibited :: ConnData -> Bool
ratchetSyncSendProhibited ConnData {ratchetSyncState} =
  ratchetSyncState `elem` ([RSRequired, RSStarted, RSAgreed] :: [RatchetSyncState])

data PendingCommand = PendingCommand
  { cmdId :: AsyncCmdId,
    corrId :: ACorrId,
    userId :: UserId,
    connId :: ConnId,
    command :: AgentCommand
  }

data AgentCmdType = ACClient | ACInternal

instance StrEncoding AgentCmdType where
  strEncode = \case
    ACClient -> "CLIENT"
    ACInternal -> "INTERNAL"
  strP =
    A.takeTill (== ' ') >>= \case
      "CLIENT" -> pure ACClient
      "INTERNAL" -> pure ACInternal
      _ -> fail "bad AgentCmdType"

data AgentCommand
  = AClientCommand ACommand
  | AInternalCommand InternalCommand

instance StrEncoding AgentCommand where
  strEncode = \case
    AClientCommand cmd -> strEncode (ACClient, Str $ serializeCommand cmd)
    AInternalCommand cmd -> strEncode (ACInternal, cmd)
  strP =
    strP_ >>= \case
      ACClient -> AClientCommand <$> dbCommandP
      ACInternal -> AInternalCommand <$> strP

data AgentCommandTag
  = AClientCommandTag ACommandTag
  | AInternalCommandTag InternalCommandTag
  deriving (Show)

instance StrEncoding AgentCommandTag where
  strEncode = \case
    AClientCommandTag t -> strEncode (ACClient, t)
    AInternalCommandTag t -> strEncode (ACInternal, t)
  strP =
    strP_ >>= \case
      ACClient -> AClientCommandTag <$> strP
      ACInternal -> AInternalCommandTag <$> strP

data InternalCommand
  = ICAck SMP.RecipientId MsgId
  | ICAckDel SMP.RecipientId MsgId InternalId
  | ICAllowSecure SMP.RecipientId (Maybe SMP.SndPublicAuthKey)
  | ICDuplexSecure SMP.RecipientId SMP.SndPublicAuthKey
  | ICDeleteConn
  | ICDeleteRcvQueue SMP.RecipientId
  | ICQSecure SMP.RecipientId SMP.SndPublicAuthKey
  | ICQDelete SMP.RecipientId

data InternalCommandTag
  = ICAck_
  | ICAckDel_
  | ICAllowSecure_
  | ICDuplexSecure_
  | ICDeleteConn_
  | ICDeleteRcvQueue_
  | ICQSecure_
  | ICQDelete_
  deriving (Show)

instance StrEncoding InternalCommand where
  strEncode = \case
    ICAck rId srvMsgId -> strEncode (ICAck_, rId, srvMsgId)
    ICAckDel rId srvMsgId mId -> strEncode (ICAckDel_, rId, srvMsgId, mId)
    ICAllowSecure rId sndKey -> strEncode (ICAllowSecure_, rId, sndKey)
    ICDuplexSecure rId sndKey -> strEncode (ICDuplexSecure_, rId, sndKey)
    ICDeleteConn -> strEncode ICDeleteConn_
    ICDeleteRcvQueue rId -> strEncode (ICDeleteRcvQueue_, rId)
    ICQSecure rId senderKey -> strEncode (ICQSecure_, rId, senderKey)
    ICQDelete rId -> strEncode (ICQDelete_, rId)
  strP =
    strP >>= \case
      ICAck_ -> ICAck <$> _strP <*> _strP
      ICAckDel_ -> ICAckDel <$> _strP <*> _strP <*> _strP
      ICAllowSecure_ -> ICAllowSecure <$> _strP <*> _strP
      ICDuplexSecure_ -> ICDuplexSecure <$> _strP <*> _strP
      ICDeleteConn_ -> pure ICDeleteConn
      ICDeleteRcvQueue_ -> ICDeleteRcvQueue <$> _strP
      ICQSecure_ -> ICQSecure <$> _strP <*> _strP
      ICQDelete_ -> ICQDelete <$> _strP

instance StrEncoding InternalCommandTag where
  strEncode = \case
    ICAck_ -> "ACK"
    ICAckDel_ -> "ACK_DEL"
    ICAllowSecure_ -> "ALLOW_SECURE"
    ICDuplexSecure_ -> "DUPLEX_SECURE"
    ICDeleteConn_ -> "DELETE_CONN"
    ICDeleteRcvQueue_ -> "DELETE_RCV_QUEUE"
    ICQSecure_ -> "QSECURE"
    ICQDelete_ -> "QDELETE"
  strP =
    A.takeTill (== ' ') >>= \case
      "ACK" -> pure ICAck_
      "ACK_DEL" -> pure ICAckDel_
      "ALLOW_SECURE" -> pure ICAllowSecure_
      "DUPLEX_SECURE" -> pure ICDuplexSecure_
      "DELETE_CONN" -> pure ICDeleteConn_
      "DELETE_RCV_QUEUE" -> pure ICDeleteRcvQueue_
      "QSECURE" -> pure ICQSecure_
      "QDELETE" -> pure ICQDelete_
      _ -> fail "bad InternalCommandTag"

agentCommandTag :: AgentCommand -> AgentCommandTag
agentCommandTag = \case
  AClientCommand cmd -> AClientCommandTag $ aCommandTag cmd
  AInternalCommand cmd -> AInternalCommandTag $ internalCmdTag cmd

internalCmdTag :: InternalCommand -> InternalCommandTag
internalCmdTag = \case
  ICAck {} -> ICAck_
  ICAckDel {} -> ICAckDel_
  ICAllowSecure {} -> ICAllowSecure_
  ICDuplexSecure {} -> ICDuplexSecure_
  ICDeleteConn -> ICDeleteConn_
  ICDeleteRcvQueue {} -> ICDeleteRcvQueue_
  ICQSecure {} -> ICQSecure_
  ICQDelete _ -> ICQDelete_

-- * Confirmation types

data NewConfirmation = NewConfirmation
  { connId :: ConnId,
    senderConf :: SMPConfirmation,
    ratchetState :: RatchetX448
  }

data AcceptedConfirmation = AcceptedConfirmation
  { confirmationId :: ConfirmationId,
    connId :: ConnId,
    senderConf :: SMPConfirmation,
    ratchetState :: RatchetX448,
    ownConnInfo :: ConnInfo
  }

-- * Invitations

data NewInvitation = NewInvitation
  { contactConnId :: ConnId,
    connReq :: ConnectionRequestUri 'CMInvitation,
    recipientConnInfo :: ConnInfo
  }

data Invitation = Invitation
  { invitationId :: InvitationId,
    contactConnId :: ConnId,
    connReq :: ConnectionRequestUri 'CMInvitation,
    recipientConnInfo :: ConnInfo,
    ownConnInfo :: Maybe ConnInfo,
    accepted :: Bool
  }

-- * Message integrity validation types

-- | Corresponds to `last_external_snd_msg_id` in `connections` table
type PrevExternalSndId = Int64

-- | Corresponds to `last_rcv_msg_hash` in `connections` table
type PrevRcvMsgHash = MsgHash

-- | Corresponds to `last_snd_msg_hash` in `connections` table
type PrevSndMsgHash = MsgHash

-- * Message data containers

data RcvMsgData = RcvMsgData
  { msgMeta :: MsgMeta,
    msgType :: AgentMessageType,
    msgFlags :: MsgFlags,
    msgBody :: MsgBody,
    internalRcvId :: InternalRcvId,
    internalHash :: MsgHash,
    externalPrevSndHash :: MsgHash,
    encryptedMsgHash :: MsgHash
  }

data RcvMsg = RcvMsg
  { internalId :: InternalId,
    msgMeta :: MsgMeta,
    msgType :: AgentMessageType,
    msgBody :: MsgBody,
    internalHash :: MsgHash,
    msgReceipt :: Maybe MsgReceipt, -- if this message is a delivery receipt
    userAck :: Bool
  }

data SndMsgData = SndMsgData
  { internalId :: InternalId,
    internalSndId :: InternalSndId,
    internalTs :: InternalTs,
    msgType :: AgentMessageType,
    msgFlags :: MsgFlags,
    msgBody :: MsgBody,
    pqEncryption :: PQEncryption,
    internalHash :: MsgHash,
    prevMsgHash :: MsgHash
  }

data SndMsg = SndMsg
  { internalId :: InternalId,
    internalSndId :: InternalSndId,
    msgType :: AgentMessageType,
    internalHash :: MsgHash,
    msgReceipt :: Maybe MsgReceipt
  }

data PendingMsgData = PendingMsgData
  { msgId :: InternalId,
    msgType :: AgentMessageType,
    msgFlags :: MsgFlags,
    msgBody :: MsgBody,
    pqEncryption :: PQEncryption,
    msgRetryState :: Maybe RI2State,
    internalTs :: InternalTs
  }
  deriving (Show)

-- internal Ids are newtypes to prevent mixing them up
newtype InternalRcvId = InternalRcvId {unRcvId :: Int64} deriving (Eq, Show)

type ExternalSndId = Int64

type ExternalSndTs = UTCTime

type BrokerId = MsgId

type BrokerTs = UTCTime

newtype InternalSndId = InternalSndId {unSndId :: Int64} deriving (Eq, Show)

-- | Base message data independent of direction.
data MsgBase = MsgBase
  { connId :: ConnId,
    -- | Monotonically increasing id of a message per connection, internal to the agent.
    -- Internal Id preserves ordering between both received and sent messages, and is needed
    -- to track the order of the conversation (which can be different for the sender / receiver)
    -- and address messages in commands. External [sender] Id cannot be used for this purpose
    -- due to a possibility of implementation errors in different agents.
    internalId :: InternalId,
    internalTs :: InternalTs,
    msgBody :: MsgBody,
    -- | Hash of the message as computed by agent.
    internalHash :: MsgHash
  }
  deriving (Eq, Show)

newtype InternalId = InternalId {unId :: Int64} deriving (Eq, Show)

instance StrEncoding InternalId where
  strEncode = strEncode . unId
  strP = InternalId <$> strP

type InternalTs = UTCTime

type AsyncCmdId = Int64

-- * Store errors

-- | Agent store error.
data StoreError
  = -- | IO exceptions in store actions.
    SEInternal ByteString
  | -- | Database busy
    SEDatabaseBusy ByteString
  | -- | Failed to generate unique random ID
    SEUniqueID
  | -- | User ID not found
    SEUserNotFound
  | -- | Connection not found (or both queues absent).
    SEConnNotFound
  | -- | Server not found.
    SEServerNotFound
  | -- | Connection already used.
    SEConnDuplicate
  | -- | Confirmed snd queue already exists.
    SESndQueueExists
  | -- | Wrong connection type, e.g. "send" connection when "receive" or "duplex" is expected, or vice versa.
    -- 'upgradeRcvConnToDuplex' and 'upgradeSndConnToDuplex' do not allow duplex connections - they would also return this error.
    SEBadConnType ConnType
  | -- | Confirmation not found.
    SEConfirmationNotFound
  | -- | Invitation not found
    SEInvitationNotFound
  | -- | Message not found
    SEMsgNotFound
  | -- | Command not found
    SECmdNotFound
  | -- | Currently not used. The intention was to pass current expected queue status in methods,
    -- as we always know what it should be at any stage of the protocol,
    -- and in case it does not match use this error.
    SEBadQueueStatus
  | -- | connection does not have associated double-ratchet state
    SERatchetNotFound
  | -- | connection does not have associated x3dh keys
    SEX3dhKeysNotFound
  | -- | Used to wrap agent errors inside store operations to avoid race conditions
    SEAgentError AgentErrorType
  | -- | XFTP Server not found.
    SEXFTPServerNotFound
  | -- | XFTP File not found.
    SEFileNotFound
  | -- | XFTP Deleted snd chunk replica not found.
    SEDeletedSndChunkReplicaNotFound
  | -- | Error when reading work item that suspends worker - do not use!
    SEWorkItemError ByteString
  | -- | Servers stats not found.
    SEServersStatsNotFound
  deriving (Eq, Show, Exception)