SideStore/SideStoreApp/Sources/SideStoreAppKit/Operations/UpdatePatronsOperation.swift

//
//  UpdatePatronsOperation.swift
//  AltStore
//
//  Created by Riley Testut on 4/11/22.
//  Copyright © 2022 Riley Testut. All rights reserved.
//

import CoreData
import Foundation

import SideStoreCore

private extension URL {
    #if STAGING
        static let patreonInfo = URL(string: "https://f000.backblazeb2.com/file/altstore-staging/altstore/patreon.json")!
    #else
        static let patreonInfo = URL(string: "https://cdn.altstore.io/file/altstore/altstore/patreon.json")!
    #endif
}

extension UpdatePatronsOperation {
    private struct Response: Decodable {
        var version: Int
        var accessToken: String
        var refreshID: String
    }
}

final class UpdatePatronsOperation: ResultOperation<Void> {
    let context: NSManagedObjectContext

    init(context: NSManagedObjectContext = DatabaseManager.shared.persistentContainer.newBackgroundContext()) {
        self.context = context
    }

    override func main() {
        super.main()

        let dataTask = URLSession.shared.dataTask(with: .patreonInfo) { data, response, error in
            do {
                if let response = response as? HTTPURLResponse {
                    guard response.statusCode != 404 else {
                        self.finish(.failure(URLError(.fileDoesNotExist, userInfo: [NSURLErrorKey: URL.patreonInfo])))
                        return
                    }
                }

                guard let data = data else { throw error! }

                let response = try SideStoreCore.JSONDecoder().decode(Response.self, from: data)
                Keychain.shared.patreonCreatorAccessToken = response.accessToken

                let previousRefreshID = UserDefaults.shared.patronsRefreshID
                guard response.refreshID != previousRefreshID else {
                    self.finish(.success(()))
                    return
                }

                PatreonAPI.shared.fetchPatrons { result in
                    self.context.perform {
                        do {
                            let patrons = try result.get()
                            let managedPatrons = patrons.map { ManagedPatron(patron: $0, context: self.context) }

                            let patronIDs = Set(managedPatrons.map { $0.identifier })
                            let nonFriendZonePredicate = NSPredicate(format: "NOT (%K IN %@)", #keyPath(ManagedPatron.identifier), patronIDs)

                            let nonFriendZonePatrons = ManagedPatron.all(satisfying: nonFriendZonePredicate, in: self.context)
                            for managedPatron in nonFriendZonePatrons {
                                self.context.delete(managedPatron)
                            }

                            try self.context.save()

                            UserDefaults.shared.patronsRefreshID = response.refreshID

                            self.finish(.success(()))

                            print("Updated Friend Zone Patrons!")
                        } catch {
                            self.finish(.failure(error))
                        }
                    }
                }
            } catch {
                self.finish(.failure(error))
            }
        }

        dataTask.resume()
    }
}