session-ios/SessionSnodeKit/Jobs/GetSnodePoolJob.swift

// Copyright © 2022 Rangeproof Pty Ltd. All rights reserved.

import Foundation
import Combine
import GRDB
import SignalCoreKit
import SessionUtilitiesKit

public enum GetSnodePoolJob: JobExecutor {
    public static let maxFailureCount: Int = -1
    public static let requiresThreadId: Bool = false
    public static let requiresInteractionId: Bool = false
    
    public static func run(
        _ job: Job,
        queue: DispatchQueue,
        success: @escaping (Job, Bool, Dependencies) -> (),
        failure: @escaping (Job, Error?, Bool, Dependencies) -> (),
        deferred: @escaping (Job, Dependencies) -> (),
        using dependencies: Dependencies
    ) {
        // If we already have cached Snodes then we still want to trigger the 'SnodeAPI.getSnodePool'
        // but we want to succeed this job immediately (since it's marked as blocking), this allows us
        // to block if we have no Snode pool and prevent other jobs from failing but avoids having to
        // wait if we already have a potentially valid snode pool
        guard !SnodeAPI.hasCachedSnodesIncludingExpired() else {
            SNLog("[GetSnodePoolJob] Has valid cached pool, running async instead")
            SnodeAPI
                .getSnodePool()
                .subscribe(on: DispatchQueue.global(qos: .default))
                .sinkUntilComplete()
            return success(job, false, dependencies)
        }
        
        // If we don't have a user yet then generate a dummy secret key to populate the snode
        // pool from the seed node (so we can do so before account creation on first launch)
        let ed25519SecretKey: [UInt8] = (Identity.fetchUserEd25519KeyPair()?.secretKey ??
            (try! Identity.generate(from: try! Randomness.generateRandomBytes(numberBytes: 16))).ed25519KeyPair.secretKey
        )
        
        // If we don't have the snode pool cached then we should also try to build the path (this will
        // speed up the onboarding process for new users because it can run before the user is created)
        SnodeAPI.getSnodePool(ed25519SecretKey: ed25519SecretKey, using: dependencies)
            .flatMap { _ in BuildPathsJob.runIfNeeded(ed25519SecretKey: ed25519SecretKey, using: dependencies) }
            .subscribe(on: queue)
            .receive(on: queue)
            .sinkUntilComplete(
                receiveCompletion: { result in
                    switch result {
                        case .finished:
                            SNLog("[GetSnodePoolJob] Completed")
                            success(job, false, dependencies)
                            
                        case .failure(let error):
                            SNLog("[GetSnodePoolJob] Failed due to error: \(error)")
                            failure(job, error, false, dependencies)
                    }
                }
            )
    }
    
    public static func run(using dependencies: Dependencies = Dependencies()) {
        GetSnodePoolJob.run(
            Job(variant: .getSnodePool),
            queue: .global(qos: .background),
            success: { _, _, _ in },
            failure: { _, _, _, _ in },
            deferred: { _, _ in },
            using: dependencies
        )
    }
}