session-ios/SessionMessagingKit/Sending & Receiving/Message Handling/MessageReceiver+MessageRequests.swift

// Copyright © 2022 Rangeproof Pty Ltd. All rights reserved.
//
// stringlint:disable

import Foundation
import Combine
import GRDB
import SessionUtilitiesKit
import SessionNetworkingKit

extension MessageReceiver {
    internal static func handleMessageRequestResponse(
        _ db: ObservingDatabase,
        message: MessageRequestResponse,
        decodedMessage: DecodedMessage,
        currentUserSessionIds: Set<String>,
        using dependencies: Dependencies
    ) throws -> InsertedInteractionInfo? {
        let userSessionId = dependencies[cache: .general].sessionId
        var blindedContactIds: [String] = []
        
        // Ignore messages which were sent from the current user
        guard message.sender != userSessionId.hexString else { throw MessageError.ignorableMessage }
        guard let senderId: String = message.sender else { throw MessageError.missingRequiredField("sender") }
        
        // Update profile if needed
        if let profile = message.profile {
            try Profile.updateIfNeeded(
                db,
                publicKey: senderId,
                displayNameUpdate: .contactUpdate(profile.displayName),
                displayPictureUpdate: .contactUpdateTo(profile, fallback: .none),
                proUpdate: .contactUpdate(Profile.ProState(decodedMessage.decodedPro)),
                profileUpdateTimestamp: profile.updateTimestampSeconds,
                currentUserSessionIds: currentUserSessionIds,
                using: dependencies
            )
        }
        
        // Need to handle a `MessageRequestResponse` sent to a blinded thread (ie. check if the sender matches
        // the blinded ids of any threads)
        let blindedThreadIds: Set<String> = (try? SessionThread
            .select(.id)
            .filter(SessionThread.Columns.variant == SessionThread.Variant.contact)
            .filter(
                (
                    SessionThread.Columns.id > SessionId.Prefix.blinded15.rawValue &&
                    SessionThread.Columns.id < SessionId.Prefix.blinded15.endOfRangeString
                ) ||
                (
                    SessionThread.Columns.id > SessionId.Prefix.blinded25.rawValue &&
                    SessionThread.Columns.id < SessionId.Prefix.blinded25.endOfRangeString
                )
            )
            .asRequest(of: String.self)
            .fetchSet(db))
            .defaulting(to: [])
        let pendingBlindedIdLookups: [BlindedIdLookup] = (try? BlindedIdLookup
            .filter(blindedThreadIds.contains(BlindedIdLookup.Columns.blindedId))
            .fetchAll(db))
            .defaulting(to: [])
        let earliestCreationTimestamp: TimeInterval = (try? SessionThread
            .filter(blindedThreadIds.contains(SessionThread.Columns.id))
            .select(max(SessionThread.Columns.creationDateTimestamp))
            .fetchOne(db))
            .defaulting(to: (dependencies[cache: .snodeAPI].currentOffsetTimestampMs() / 1000))
        
        // Prep the unblinded thread
        let unblindedThread: SessionThread = try SessionThread.upsert(
            db,
            id: senderId,
            variant: .contact,
            values: SessionThread.TargetValues(
                creationDateTimestamp: .setTo(earliestCreationTimestamp),
                shouldBeVisible: .useExisting
            ),
            using: dependencies
        )
        
        // Loop through all blinded threads and extract any interactions relating to the user accepting
        // the message request
        try pendingBlindedIdLookups.forEach { blindedIdLookup in
            // If the sessionId matches the blindedId then this thread needs to be converted to an
            // un-blinded thread
            guard
                dependencies[singleton: .crypto].verify(
                    .sessionId(
                        senderId,
                        matchesBlindedId: blindedIdLookup.blindedId,
                        serverPublicKey: blindedIdLookup.openGroupPublicKey
                    )
                )
            else { return }
            
            // Update the lookup
            try blindedIdLookup
                .with(sessionId: senderId)
                .upserted(db)
            
            // Add the `blindedId` to an array so we can remove them at the end of processing
            blindedContactIds.append(blindedIdLookup.blindedId)
            
            // Update all interactions to be on the new thread
            // Note: Pending `MessageSendJobs` _shouldn't_ be an issue as even if they are sent after the
            // un-blinding of a thread, the logic when handling the sent messages should automatically
            // assign them to the correct thread
            try Interaction
                .filter(Interaction.Columns.threadId == blindedIdLookup.blindedId)
                .updateAll(db, Interaction.Columns.threadId.set(to: unblindedThread.id))
            
            _ = try SessionThread.deleteOrLeave(
                db,
                type: .deleteContactConversationAndContact, // Blinded contact isn't synced anyway
                threadId: blindedIdLookup.blindedId,
                threadVariant: .contact,
                using: dependencies
            )
            
            // Notify about unblinding event
            db.addContactEvent(
                id: blindedIdLookup.blindedId,
                change: .unblinded(blindedId: blindedIdLookup.blindedId, unblindedId: senderId)
            )
        }
        
        // Update the `didApproveMe` state of the sender
        let senderHadAlreadyApprovedMe: Bool = (try? Contact
            .select(.didApproveMe)
            .filter(id: senderId)
            .asRequest(of: Bool.self)
            .fetchOne(db))
            .defaulting(to: false)
        try updateContactApprovalStatusIfNeeded(
            db,
            senderSessionId: senderId,
            threadId: nil,
            using: dependencies
        )
        
        // If there were blinded contacts which have now been resolved to this contact then we should remove
        // the blinded contact and we also need to assume that the 'sender' is a newly created contact and
        // hence need to update it's `isApproved` state
        if !blindedContactIds.isEmpty {
            _ = try? Contact
                .filter(ids: blindedContactIds)
                .deleteAll(db)
            
            try updateContactApprovalStatusIfNeeded(
                db,
                senderSessionId: userSessionId.hexString,
                threadId: unblindedThread.id,
                using: dependencies
            )
        }
        
        /// Notify the user of their approval
        ///
        /// We want to do this last as it'll mean the un-blinded thread gets updated and the contact approval status will have been
        /// updated at this point (which will mean the `isMessageRequest` will return correctly after this is saved)
        ///
        /// **Notes:**
        /// - We only want to add the control message if the sender hadn't already approved the current user (this is to prevent spam
        ///   if the sender deletes and re-accepts message requests from the current user)
        /// - This will always appear in the un-blinded thread
        if !senderHadAlreadyApprovedMe {
            let interaction: Interaction = try Interaction(
                serverHash: message.serverHash,
                threadId: unblindedThread.id,
                threadVariant: unblindedThread.variant,
                authorId: senderId,
                variant: .infoMessageRequestAccepted,
                timestampMs: (
                    message.sentTimestampMs.map { Int64($0) } ??
                    dependencies[cache: .snodeAPI].currentOffsetTimestampMs()
                ),
                using: dependencies
            ).inserted(db)
            
            return interaction.id.map {
                (unblindedThread.id, unblindedThread.variant, $0, .infoMessageRequestAccepted, true, 0)
            }
        }
        
        return nil
    }
    
    internal static func updateContactApprovalStatusIfNeeded(
        _ db: ObservingDatabase,
        senderSessionId: String,
        threadId: String?,
        using dependencies: Dependencies
    ) throws {
        let userSessionId: SessionId = dependencies[cache: .general].sessionId
        
        // If the sender of the message was the current user
        if senderSessionId == userSessionId.hexString {
            // Retrieve the contact for the thread the message was sent to (excluding 'NoteToSelf'
            // threads) and if the contact isn't flagged as approved then do so
            guard
                let threadId: String = threadId,
                let thread: SessionThread = try? SessionThread.fetchOne(db, id: threadId),
                !thread.isNoteToSelf(using: dependencies)
            else { return }
            
            // Sending a message to someone flags them as approved so create the contact record if
            // it doesn't exist
            let contact: Contact = Contact.fetchOrCreate(db, id: threadId, using: dependencies)
            
            guard !contact.isApproved else { return }
            
            try? contact.upsert(db)
            _ = try? Contact
                .filter(id: threadId)
                .updateAllAndConfig(
                    db,
                    Contact.Columns.isApproved.set(to: true),
                    using: dependencies
                )
            db.addContactEvent(id: threadId, change: .isApproved(true))
        }
        else {
            // The message was sent to the current user so flag their 'didApproveMe' as true (can't send a message to
            // someone without approving them)
            let contact: Contact = Contact.fetchOrCreate(db, id: senderSessionId, using: dependencies)
            
            guard !contact.didApproveMe else { return }

            try? contact.upsert(db)
            _ = try? Contact
                .filter(id: senderSessionId)
                .updateAllAndConfig(
                    db,
                    Contact.Columns.didApproveMe.set(to: true),
                    using: dependencies
                )
            db.addContactEvent(id: senderSessionId, change: .didApproveMe(true))
        }
    }
}