//// Loki: Refer to Docs/SessionReset.md for explanations
//
//#import "SessionCipher+Loki.h"
//#import "NSNotificationCenter+OWS.h"
//#import "PreKeyWhisperMessage.h"
//#import "OWSPrimaryStorage+Loki.h"
//#import "TSContactThread.h"
//#import <YapDatabase/YapDatabase.h>
//
//NSString *const kNSNotificationName_SessionAdopted = @"kNSNotificationName_SessionAdopted";
//NSString *const kNSNotificationKey_ContactPubKey = @"kNSNotificationKey_ContactPubKey";
//
//@interface SessionCipher ()
//
//@property (nonatomic, readonly) NSString *recipientId;
//@property (nonatomic, readonly) int deviceId;
//
//@property (nonatomic, readonly) id<SessionStore> sessionStore;
//@property (nonatomic, readonly) id<PreKeyStore> prekeyStore;
//
//@end
//
//@implementation SessionCipher (Loki)
//
//- (NSData *)throws_lokiDecrypt:(id<CipherMessage>)whisperMessage protocolContext:(nullable id)protocolContext
//{
//    // Our state before we decrypt the message
//    SessionState *_Nullable state = [self getCurrentState:protocolContext];
//    
//    // Verify incoming friend request messages
//    if (!state) {
//        [self throws_validatePreKeysForFriendRequestAcceptance:whisperMessage protocolContext:protocolContext];
//    }
//    
//    // While decrypting our state may change internally
//    NSData *plainText = [self throws_decrypt:whisperMessage protocolContext:protocolContext];
//    
//   
//    // Loki: Handle any session resets
//    [self handleSessionReset:whisperMessage previousState:state protocolContext:protocolContext];
//    
//    return plainText;
//}
//
///// Get the current session state
//- (SessionState *_Nullable)getCurrentState:(nullable id)protocolContext {
//    SessionRecord *record = [self.sessionStore loadSession:self.recipientId deviceId:self.deviceId protocolContext:protocolContext];
//    SessionState *state = record.sessionState;
//    
//    // Check if session is initialized
//    if (!state.hasSenderChain) { return nil; }
//    
//    return state;
//}
//
///// Handle any Loki session reset stuff
//- (void)handleSessionReset:(id<CipherMessage>)whisperMessage previousState:(SessionState *_Nullable)previousState protocolContext:(nullable id)protocolContext
//{
//    // Don't bother doing anything if we didn't have a session before
//    if (!previousState) { return; }
//    
//    OWSAssertDebug([protocolContext isKindOfClass:[YapDatabaseReadWriteTransaction class]]);
//    YapDatabaseReadWriteTransaction *transaction = protocolContext;
//    
//    // Get the thread
//    TSContactThread *thread = [TSContactThread getThreadWithContactId:self.recipientId transaction:transaction];
//    if (!thread) { return; }
//    
//    // Bail early if no session reset is in progress
//    if (thread.sessionResetState == TSContactThreadSessionResetStateNone) { return; }
//    
//    BOOL sessionResetReceived = thread.sessionResetState == TSContactThreadSessionResetStateRequestReceived;
//    SessionState *_Nullable currentState = [self getCurrentState:protocolContext];
//    
//    // Check if our previous state and our current state differ
//    if (!currentState || ![currentState.aliceBaseKey isEqualToData:previousState.aliceBaseKey]) {
//        
//        if (sessionResetReceived) {
//            // The other user used an old session to contact us.
//            // Wait for them to use a new one
//            [self restoreSession:previousState protocolContext:protocolContext];
//        } else {
//            // Our session reset went through successfully
//            // We had initiated a session reset and got a different session back from the user
//            [self deleteAllSessionsExcept:currentState protocolContext:protocolContext];
//            [self notifySessionAdopted];
//        }
//        
//    } else if (sessionResetReceived) {
//        // Our session reset went through successfully
//        // We got a message with the same session from the other user
//        [self deleteAllSessionsExcept:previousState protocolContext:protocolContext];
//        [self notifySessionAdopted];
//    }
//}
//
///// Send a notification about a new session being adopted
//- (void)notifySessionAdopted
//{
//    NSDictionary *userInfo = @{ kNSNotificationKey_ContactPubKey : self.recipientId };
//    [NSNotificationCenter.defaultCenter postNotificationNameAsync:kNSNotificationName_SessionAdopted object:nil userInfo:userInfo];
//}
//
///// Delete all other sessions except the given one
//- (void)deleteAllSessionsExcept:(SessionState *)state protocolContext:(nullable id)protocolContext
//{
//    SessionRecord *record = [self.sessionStore loadSession:self.recipientId deviceId:self.deviceId protocolContext:protocolContext];
//    [record removePreviousSessionStates];
//    
//    SessionState *newState = state == nil ? [SessionState new] : state;
//    [record setState:newState];
//    
//    [self.sessionStore storeSession:self.recipientId deviceId:self.deviceId session:record protocolContext:protocolContext];
//}
//
///// Set the given session as the active one while archiving the old one
//- (void)restoreSession:(SessionState *)state protocolContext:(nullable id)protocolContext
//{
//    SessionRecord *record = [self.sessionStore loadSession:self.recipientId deviceId:self.deviceId protocolContext:protocolContext];
//    
//    // Remove the state from previous session states
//    [record.previousSessionStates enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(SessionState *obj, NSUInteger idx, BOOL *stop) {
//        if ([state.aliceBaseKey isEqualToData:obj.aliceBaseKey]) {
//            [record.previousSessionStates removeObjectAtIndex:idx];
//            *stop = YES;
//        }
//    }];
//    
//    // Promote it so the previous state gets archived
//    [record promoteState:state];
//    
//    [self.sessionStore storeSession:self.recipientId deviceId:self.deviceId session:record protocolContext:protocolContext];
//}
//
///// Check that we have matching pre keys in the case of a `PreKeyWhisperMessage`.
///// This is so that we don't trigger a false friend request accept on unknown contacts.
//- (void)throws_validatePreKeysForFriendRequestAcceptance:(id<CipherMessage>)whisperMessage protocolContext:(nullable id)protocolContext {
//    OWSAssertDebug([protocolContext isKindOfClass:[YapDatabaseReadTransaction class]]);
//    YapDatabaseReadTransaction *transaction = protocolContext;
//    
//    // Ignore anything that isn't a `PreKeyWhisperMessage`
//    if (![whisperMessage isKindOfClass:[PreKeyWhisperMessage class]]) { return; }
//
//    // Check the pre key store
//    if (![self.prekeyStore isKindOfClass:[OWSPrimaryStorage class]]) { return; }
//    
//    PreKeyWhisperMessage *preKeyMessage = whisperMessage;
//    OWSPrimaryStorage *primaryStorage = self.prekeyStore;
//    
//    PreKeyRecord *_Nullable storedPreKey = [primaryStorage getPreKeyForContact:self.recipientId transaction:transaction];
//    if (!storedPreKey) {
//        OWSRaiseException(@"Loki", @"Received a friend request from a public key for which no pre key bundle was created.");
//    }
//    
//    if (storedPreKey.Id != preKeyMessage.prekeyID) {
//        OWSRaiseException(@"Loki", @"Received a PreKeyWhisperMessage (friend request accept) from an unknown source.");
//    }
//}
//
//@end