//
//  KillSwitchClient.swift
//  PrivadoVPN
//
//  Created by Juraldinio on 7/30/20.
//  Copyright © 2020 Privado LLC. All rights reserved.
//

import Foundation

protocol KillSwitchClientDelegate: AnyObject {
    func clientChangeState(state: XPCClientState)
}

final class KillSwitchClient {
    
    enum KillSwitchError: Error {
        case unowned
        case writeError
    }
    
    weak var delegate: KillSwitchClientDelegate?
    private weak var client: (XPCFirewallClient & XPCSystemClient)?
    
    var state: XPCClientState { self.client?.state ?? .undefined }
    
    // MARK: - Init
    
    init(client: (XPCFirewallClient & XPCSystemClient)?) {
        
        self.client = client
        
        self.client?.stateEmitter.addReaction { [weak self] state -> ShouldContinueReceiveNotifications in
            self?.delegate?.clientChangeState(state: state)
            return self.isExist
        }
        
    }
    
    // MARK: - Client operations
    
    @discardableResult
    func flushDNS() -> Future<Bool> {
        
        return Future(value: self.client)
            .flatMap { client in
                client.flushDNS()
            }
    }
    
    func resolveDNS(name: String) -> Future<String> {
        
        return Future(value: self.client)
            .flatMap { client in
                client.resolveDNS(name: name)
            }
    }
    
    @discardableResult
    func changeDNS(dns: [String], port: String) -> Future<Bool> {
        
        return Future(value: self.client)
            .flatMap { client in
                client.changeDNS(servers: dns, hardware: port)
            }
    }
    
    @discardableResult
    func changeDNSs(dns: [String], ports: [String]) -> Future<Bool> {
        return ports.reduce(nil as Future<Bool>?) { result, port in
            if let future = result {
                return future.flatMap { _ in self.changeDNS(dns: dns, port: port) }
            } else {
                return self.changeDNS(dns: dns, port: port)
            }
        } ?? Future(value: true)
    }
    
    @discardableResult
    func currentDNS(hardware: [String]) -> Future<[String: [String]]> {
        
        return Future(value: self.client)
            .flatMap { client in
                client.currentDNS(hardware: hardware)
            }
    }
    
    @discardableResult
    func hardwarePorts() -> Future<[HardwarePort]> {
        
        return Future(value: self.client)
            .flatMap { client in
                client.hardwarePorts()
            }
    }
    
    func firewall(check rules: [String]) -> Future<Bool> {
        
        let content = rules.joined(separator: "\n") + "\n"
        
        return Future(value: URL.randomFile())
            .flatMap { [weak self] url in
                
                do {
                    try content.write(to: url, atomically: true, encoding: .utf8)
                } catch {
                    return Future(error: KillSwitchError.writeError)
                }
                
                guard let client = self?.client else {
                    return Future(error: KillSwitchError.unowned)
                }
                
                return client
                    .firewallActivate(rulesPath: url.absoluteString, validate: true)
                    .onResult { _ in
                        url.remove()
                    }
            }
    }
    
    @discardableResult
    func firewall(activate rules: [String]) -> Future<Bool> {
        
        let content = rules.joined(separator: "\n") + "\n"
        return Future(value: URL.randomFile())
            .flatMap { [weak self] url in
                
                do {
                    try content.write(to: url, atomically: true, encoding: .utf8)
                } catch {
                    return Future(error: KillSwitchError.writeError)
                }
                
                guard let client = self?.client else {
                    return Future(error: KillSwitchError.unowned)
                }
                
                return client
                    .firewallActivate(rulesPath: url.absoluteString, validate: false)
                    .onResult { _ in
                        url.remove()
                    }
            }
    }
    
    @discardableResult
    func firewallDeactivate() -> Future<Bool> {
        
        return Future(value: self.client)
            .flatMap { client in
                client.firewallDeactivate()
            }
    }
    
    func firewallEnable(_ enable: Bool) -> Future<Bool> {
        
        return Future(value: self.client)
            .map({ success in
                Future(value: success)
            }, failure: { _ in
                let error = NSError(domain: PrivadoConstants.Hive.error,
                                    code: PrivadoConstants.Hive.ErrorCode.xpcEmptyRemoteObject,
                                    userInfo: nil)
                return Future(error: error)
            }).flatMap { client in
                client.firewallEnable(enable)
            }
    }
    
    @discardableResult
    func firewallState() -> Future<Bool> {
        
        return Future(value: self.client)
            .map({ success in
                Future(value: success)
            }, failure: { _ in
                let error = NSError(domain: PrivadoConstants.Hive.error,
                                    code: PrivadoConstants.Hive.ErrorCode.xpcEmptyRemoteObject,
                                    userInfo: nil)
                return Future(error: error)
            }).flatMap { client in
                client.firewallState()
            }
    }
    
}