//
//  SessionProxy+PushReply.swift
//  TunnelKit
//
//  Created by Davide De Rosa on 25/07/2018.
//  Copyright © 2018 London Trust Media. All rights reserved.
//

import Foundation

extension SessionProxy {
    struct PushReply {
        private static let ifconfigRegexp = try! NSRegularExpression(pattern: "ifconfig [\\d\\.]+ [\\d\\.]+", options: [])

        private static let dnsRegexp = try! NSRegularExpression(pattern: "dhcp-option DNS [\\d\\.]+", options: [])

        private static let authTokenRegexp = try! NSRegularExpression(pattern: "auth-token [a-zA-Z0-9/=+]+", options: [])

        private static let peerIdRegexp = try! NSRegularExpression(pattern: "peer-id [0-9]+", options: [])
        
        let address: String

        let gatewayAddress: String
        
        let dnsServers: [String]
        
        let authToken: String?
        
        let peerId: UInt32?
        
        init?(message: String) throws {
            guard message.hasPrefix("PUSH_REPLY") else {
                return nil
            }
            
            var ifconfigComponents: [String]?
            var dnsServers = [String]()
            var authToken: String?
            var peerId: UInt32?

            PushReply.ifconfigRegexp.enumerateMatches(in: message, options: [], range: NSMakeRange(0, message.count)) { (result, flags, _) in
                guard let range = result?.range else { return }
                
                let match = (message as NSString).substring(with: range)
                ifconfigComponents = match.components(separatedBy: " ")
            }
            
            guard let addresses = ifconfigComponents, addresses.count >= 2 else {
                throw SessionError.malformedPushReply
            }
            
            PushReply.dnsRegexp.enumerateMatches(in: message, options: [], range: NSMakeRange(0, message.count)) { (result, flags, _) in
                guard let range = result?.range else { return }
                
                let match = (message as NSString).substring(with: range)
                let dnsEntryComponents = match.components(separatedBy: " ")
                
                dnsServers.append(dnsEntryComponents[2])
            }
            
            PushReply.authTokenRegexp.enumerateMatches(in: message, options: [], range: NSMakeRange(0, message.count)) { (result, flags, _) in
                guard let range = result?.range else { return }
                
                let match = (message as NSString).substring(with: range)
                let tokenComponents = match.components(separatedBy: " ")
                
                if (tokenComponents.count > 1) {
                    authToken = tokenComponents[1]
                }
            }
            
            PushReply.peerIdRegexp.enumerateMatches(in: message, options: [], range: NSMakeRange(0, message.count)) { (result, flags, _) in
                guard let range = result?.range else { return }
                
                let match = (message as NSString).substring(with: range)
                let tokenComponents = match.components(separatedBy: " ")
                
                if (tokenComponents.count > 1) {
                    peerId = UInt32(tokenComponents[1])
                }
            }

            address = addresses[1]
            gatewayAddress = addresses[2]
            self.dnsServers = dnsServers
            self.authToken = authToken
            self.peerId = peerId
        }
    }
}