//
//  NetworkSettingsViewController.swift
//  Passepartout-iOS
//
//  Created by Davide De Rosa on 4/29/19.
//  Copyright (c) 2021 Davide De Rosa. All rights reserved.
//
//  https://github.com/passepartoutvpn
//
//  This file is part of Passepartout.
//
//  Passepartout is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  Passepartout is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with Passepartout.  If not, see <http://www.gnu.org/licenses/>.
//

import UIKit
import PassepartoutCore
import TunnelKit
import SwiftyBeaver
import Convenience

private let log = SwiftyBeaver.self

private enum FieldTag: Int {
    case dnsAddress = 100
    
    case dnsDomain = 200
    
    case proxyAddress = 301

    case proxyPort = 302
    
    case proxyAutoConfigurationURL = 303
    
    case proxyBypass = 400
}

private struct Offsets {
    static let dnsAddress = 0
    
    static let dnsDomain = 0
    
    static let proxyBypass = 3
}

class NetworkSettingsViewController: UITableViewController {
    var profile: ConnectionProfile?
    
    private lazy var networkChoices = ProfileNetworkChoices.with(profile: profile)
    
    private lazy var clientNetworkSettings = profile?.clientNetworkSettings
    
    private let networkSettings = ProfileNetworkSettings()
    
    // MARK: StrongTableHost
    
    let model: StrongTableModel<SectionType, RowType> = StrongTableModel()
    
    func reloadModel() {
        model.clear()
        
        // sections (candidate)
        var sections: [SectionType] = []
        sections.append(.choices)
        if networkChoices.gateway != .server {
            sections.append(.manualGateway)
        }
        if networkChoices.dns != .server {
            sections.append(.manualDNSServers)
            sections.append(.manualDNSDomains)
        }
        if networkChoices.proxy != .server {
            sections.append(.manualProxy)
        }
        if networkChoices.mtu != .server {
            sections.append(.manualMTU)
        }
        
        // headers
        model.setHeader("", forSection: .choices)
        model.setHeader(L10n.Core.NetworkSettings.Gateway.title, forSection: .manualGateway)
        model.setHeader(L10n.Core.NetworkSettings.Proxy.title, forSection: .manualProxy)
        model.setHeader(L10n.Core.NetworkSettings.Mtu.title, forSection: .manualMTU)
        
        // footers
//        model.setFooter(L10n.Core.Configuration.Sections.Reset.footer, for: .reset)
        
        // rows
        model.set([.gateway, .dns, .proxy, .mtu], forSection: .choices)
        model.set([.gatewayIPv4, .gatewayIPv6], forSection: .manualGateway)
        model.set([.mtuBytes], forSection: .manualMTU)

        var dnsServers: [RowType] = Array(repeating: .dnsAddress, count: networkSettings.dnsServers?.count ?? 0)
        if networkChoices.dns == .manual {
            dnsServers.append(.dnsAddAddress)
        }
        model.set(dnsServers, forSection: .manualDNSServers)

        var dnsDomains: [RowType] = Array(repeating: .dnsDomain, count: networkSettings.dnsSearchDomains?.count ?? 0)
        if networkChoices.dns == .manual {
            dnsDomains.append(.dnsAddDomain)
        }
        model.set(dnsDomains, forSection: .manualDNSDomains)
        
        var proxyRows: [RowType] = Array(repeating: .proxyBypass, count: networkSettings.proxyBypassDomains?.count ?? 0)
        proxyRows.insert(.proxyAddress, at: 0)
        proxyRows.insert(.proxyPort, at: 1)
        proxyRows.insert(.proxyAutoConfigurationURL, at: 2)
        if networkChoices.proxy == .manual {
            proxyRows.append(.proxyAddBypass)
        }
        model.set(proxyRows, forSection: .manualProxy)

        // refine sections before add (DNS is tricky)
        if !dnsServers.isEmpty {
            model.setHeader(L10n.Core.NetworkSettings.Dns.title, forSection: .manualDNSServers)
        } else if !dnsDomains.isEmpty {
            sections.removeAll { $0 == .manualDNSServers }
            model.setHeader(L10n.Core.NetworkSettings.Dns.title, forSection: .manualDNSDomains)
        } else {
            sections.removeAll { $0 == .manualDNSServers }
            sections.removeAll { $0 == .manualDNSDomains }
        }
        for s in sections {
            model.add(s)
        }
    }
    
    // MARK: UIViewController
    
    override func viewDidLoad() {
        super.viewDidLoad()

        updateGateway(networkChoices.gateway)
        updateDNS(networkChoices.dns)
        updateProxy(networkChoices.proxy)
        updateMTU(networkChoices.mtu)
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        reloadModel()
        tableView.reloadData()
    }
    
    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)

        commitChanges()
    }
    
    // MARK: Actions
    
    private func updateGateway(_ choice: NetworkChoice) {
        networkChoices.gateway = choice
        switch networkChoices.gateway {
        case .client:
            if let settings = clientNetworkSettings {
                networkSettings.copyGateway(from: settings)
            }
            
        case .server:
            break

        case .manual:
            if let settings = profile?.manualNetworkSettings {
                networkSettings.copyGateway(from: settings)
            }
        }
    }
    
    private func updateDNS(_ choice: NetworkChoice) {
        networkChoices.dns = choice
        switch networkChoices.dns {
        case .client:
            if let settings = clientNetworkSettings {
                networkSettings.copyDNS(from: settings)
            }
            
        case .server:
            break
            
        case .manual:
            if let settings = profile?.manualNetworkSettings {
                networkSettings.copyDNS(from: settings)
            }
        }
    }
    
    private func updateProxy(_ choice: NetworkChoice) {
        networkChoices.proxy = choice
        switch networkChoices.proxy {
        case .client:
            if let settings = clientNetworkSettings {
                networkSettings.copyProxy(from: settings)
            }
            
        case .server:
            break
            
        case .manual:
            if let settings = profile?.manualNetworkSettings {
                networkSettings.copyProxy(from: settings)
            }
        }
    }
    
    private func updateMTU(_ choice: NetworkChoice) {
        networkChoices.mtu = choice
        switch networkChoices.mtu {
        case .client:
            if let settings = clientNetworkSettings {
                networkSettings.copyMTU(from: settings)
            }
            
        case .server:
            break
            
        case .manual:
            if let settings = profile?.manualNetworkSettings {
                networkSettings.copyMTU(from: settings)
            }
        }
    }
    
    private func commitTextField(_ field: UITextField) {

        // DNS: servers, domains
        // Proxy: address, port, PAC, bypass domains

        let text = field.text ?? ""

        if field.tag >= FieldTag.dnsAddress.rawValue && field.tag < FieldTag.dnsDomain.rawValue {
            let i = field.tag - FieldTag.dnsAddress.rawValue
            if let _ = networkSettings.dnsServers {
                networkSettings.dnsServers?[i] = text
            } else {
                networkSettings.dnsServers = [text]
            }
        } else if field.tag >= FieldTag.dnsDomain.rawValue && field.tag < FieldTag.proxyAddress.rawValue {
            let i = field.tag - FieldTag.dnsDomain.rawValue
            if let _ = networkSettings.dnsSearchDomains {
                networkSettings.dnsSearchDomains?[i] = text
            } else {
                networkSettings.dnsSearchDomains = [text]
            }
        } else if field.tag == FieldTag.proxyAddress.rawValue {
            networkSettings.proxyAddress = field.text
        } else if field.tag == FieldTag.proxyPort.rawValue {
            networkSettings.proxyPort = UInt16(field.text ?? "0")
        } else if field.tag == FieldTag.proxyAutoConfigurationURL.rawValue {
            if let string = field.text {
                networkSettings.proxyAutoConfigurationURL = URL(string: string)
            } else {
                networkSettings.proxyAutoConfigurationURL = nil
            }
        } else if field.tag >= FieldTag.proxyBypass.rawValue {
            let i = field.tag - FieldTag.proxyBypass.rawValue
            if let _ = networkSettings.proxyBypassDomains {
                networkSettings.proxyBypassDomains?[i] = text
            } else {
                networkSettings.proxyBypassDomains = [text]
            }
        }
        
        log.debug("Network settings: \(networkSettings)")
    }
    
    private func commitChanges() {
        let settings = profile?.manualNetworkSettings ?? ProfileNetworkSettings()
        profile?.networkChoices = networkChoices
        if networkChoices.gateway == .manual {
            settings.copyGateway(from: networkSettings)
        }
        if networkChoices.dns == .manual {
            settings.copyDNS(from: networkSettings)
        }
        if networkChoices.proxy == .manual {
            settings.copyProxy(from: networkSettings)
        }
        if networkChoices.mtu == .manual {
            settings.copyMTU(from: networkSettings)
        }
        profile?.manualNetworkSettings = settings
    }
}

// MARK: -

extension NetworkSettingsViewController {
    enum SectionType: Int {
        case choices
        
        case manualGateway
        
        case manualDNSServers
        
        case manualDNSDomains
        
        case manualProxy

        case manualMTU
    }
    
    enum RowType: Int {
        case gateway
        
        case dns
        
        case proxy
        
        case mtu
        
        case gatewayIPv4

        case gatewayIPv6
        
        case dnsAddress
        
        case dnsAddAddress
        
        case dnsDomain
        
        case dnsAddDomain
        
        case proxyAddress
        
        case proxyPort
        
        case proxyAutoConfigurationURL
        
        case proxyBypass

        case proxyAddBypass

        case mtuBytes
    }
    
    override func numberOfSections(in tableView: UITableView) -> Int {
        return model.numberOfSections
    }
    
    override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        return model.header(forSection: section)
    }
    
    override func tableView(_ tableView: UITableView, titleForFooterInSection section: Int) -> String? {
        return model.footer(forSection: section)
    }
    
    override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
        return model.headerHeight(for: section)
    }
    
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return model.numberOfRows(forSection: section)
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let row = model.row(at: indexPath)
        
        switch row {
        case .gateway:
            let cell = Cells.setting.dequeue(from: tableView, for: indexPath)
            cell.leftText = L10n.Core.NetworkSettings.Gateway.title
            cell.rightText = networkChoices.gateway.description
            return cell

        case .dns:
            let cell = Cells.setting.dequeue(from: tableView, for: indexPath)
            cell.leftText = L10n.Core.NetworkSettings.Dns.title
            cell.rightText = networkChoices.dns.description
            return cell

        case .proxy:
            let cell = Cells.setting.dequeue(from: tableView, for: indexPath)
            cell.leftText = L10n.Core.NetworkSettings.Proxy.title
            cell.rightText = networkChoices.proxy.description
            return cell
            
        case .mtu:
            let cell = Cells.setting.dequeue(from: tableView, for: indexPath)
            cell.leftText = L10n.Core.NetworkSettings.Mtu.title
            cell.rightText = networkChoices.mtu.description
            return cell

        case .gatewayIPv4:
            let cell = Cells.toggle.dequeue(from: tableView, for: indexPath, tag: row.rawValue, delegate: self)
            cell.caption = "IPv4"
            cell.toggle.isEnabled = (networkChoices.gateway == .manual)
            cell.isOn = networkSettings.gatewayPolicies?.contains(.IPv4) ?? false
            return cell

        case .gatewayIPv6:
            let cell = Cells.toggle.dequeue(from: tableView, for: indexPath, tag: row.rawValue, delegate: self)
            cell.caption = "IPv6"
            cell.toggle.isEnabled = (networkChoices.gateway == .manual)
            cell.isOn = networkSettings.gatewayPolicies?.contains(.IPv6) ?? false
            return cell
            
        case .dnsAddress:
            let i = indexPath.row - Offsets.dnsAddress
            
            let cell = Cells.field.dequeue(from: tableView, for: indexPath)
            cell.caption = L10n.Core.Global.Captions.address
            cell.field.tag = FieldTag.dnsAddress.rawValue + i
            cell.field.placeholder = L10n.Core.Global.Values.none
            cell.field.text = networkSettings.dnsServers?[i]
            cell.field.clearButtonMode = .always
            cell.field.keyboardType = .numbersAndPunctuation
            cell.captionWidth = 160.0
            cell.delegate = self
            cell.field.isEnabled = (networkChoices.dns == .manual)
            return cell

        case .dnsAddAddress:
            let cell = Cells.setting.dequeue(from: tableView, for: indexPath)
            cell.applyAction(.current)
            cell.leftText = L10n.App.NetworkSettings.Cells.AddDnsServer.caption
            return cell
            
        case .dnsDomain:
            let i = indexPath.row - Offsets.dnsDomain

            let cell = Cells.field.dequeue(from: tableView, for: indexPath)
            cell.caption = L10n.Core.NetworkSettings.Dns.Cells.Domain.caption
            cell.field.tag = FieldTag.dnsDomain.rawValue + i
            cell.field.placeholder = L10n.Core.Global.Values.none
            cell.field.text = networkSettings.dnsSearchDomains?[i]
            cell.field.clearButtonMode = .always
            cell.field.keyboardType = .asciiCapable
            cell.captionWidth = 160.0
            cell.delegate = self
            cell.field.isEnabled = (networkChoices.dns == .manual)
            return cell
            
        case .dnsAddDomain:
            let cell = Cells.setting.dequeue(from: tableView, for: indexPath)
            cell.applyAction(.current)
            cell.leftText = L10n.App.NetworkSettings.Cells.AddDnsDomain.caption
            return cell
            
        case .proxyAddress:
            let cell = Cells.field.dequeue(from: tableView, for: indexPath)
            cell.caption = L10n.Core.Global.Captions.address
            cell.field.tag = FieldTag.proxyAddress.rawValue
            cell.field.placeholder = L10n.Core.Global.Values.none
            cell.field.text = networkSettings.proxyAddress
            cell.field.clearButtonMode = .always
            cell.field.keyboardType = .numbersAndPunctuation
            cell.captionWidth = 160.0
            cell.delegate = self
            cell.field.isEnabled = (networkChoices.proxy == .manual)
            return cell

        case .proxyPort:
            let cell = Cells.field.dequeue(from: tableView, for: indexPath)
            cell.caption = L10n.Core.Global.Captions.port
            cell.field.tag = FieldTag.proxyPort.rawValue
            cell.field.placeholder = L10n.Core.Global.Values.none
            cell.field.text = networkSettings.proxyPort?.description
            cell.field.clearButtonMode = .always
            cell.field.keyboardType = .numberPad
            cell.captionWidth = 160.0
            cell.delegate = self
            cell.field.isEnabled = (networkChoices.proxy == .manual)
            return cell
            
        case .proxyAutoConfigurationURL:
            let cell = Cells.field.dequeue(from: tableView, for: indexPath)
            cell.caption = "PAC"
            cell.field.tag = FieldTag.proxyAutoConfigurationURL.rawValue
            cell.field.placeholder = L10n.Core.Global.Values.none
            cell.field.text = networkSettings.proxyAutoConfigurationURL?.absoluteString
            cell.field.clearButtonMode = .always
            cell.field.keyboardType = .asciiCapable
            cell.captionWidth = 160.0
            cell.delegate = self
            cell.field.isEnabled = (networkChoices.proxy == .manual)
            return cell

        case .proxyBypass:
            let i = indexPath.row - Offsets.proxyBypass
            
            let cell = Cells.field.dequeue(from: tableView, for: indexPath)
            cell.caption = L10n.App.NetworkSettings.Cells.ProxyBypass.caption
            cell.field.tag = FieldTag.proxyBypass.rawValue + i
            cell.field.placeholder = L10n.Core.Global.Values.none
            cell.field.text = networkSettings.proxyBypassDomains?[i]
            cell.field.clearButtonMode = .always
            cell.field.keyboardType = .asciiCapable
            cell.captionWidth = 160.0
            cell.delegate = self
            cell.field.isEnabled = (networkChoices.proxy == .manual)
            return cell

        case .proxyAddBypass:
            let cell = Cells.setting.dequeue(from: tableView, for: indexPath)
            cell.applyAction(.current)
            cell.leftText = L10n.App.NetworkSettings.Cells.AddProxyBypass.caption
            return cell

        case .mtuBytes:
            let cell = Cells.setting.dequeue(from: tableView, for: indexPath)
            cell.leftText = L10n.Core.NetworkSettings.Mtu.Cells.Bytes.caption
            cell.rightText = networkSettings.mtuBytes?.description ?? "Default"
            return cell
        }
    }
    
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let cell = tableView.cellForRow(at: indexPath)

        switch model.row(at: indexPath) {
        case .gateway:
            let vc = SingleOptionViewController<NetworkChoice>()
            vc.applyTint(.current)
            vc.title = (cell as? SettingTableViewCell)?.leftText
            vc.options = NetworkChoice.choices(for: profile)
            vc.descriptionBlock = { $0.description }
            
            vc.selectedOption = networkChoices.gateway
            vc.selectionBlock = { [weak self] in
                self?.updateGateway($0)
                self?.navigationController?.popViewController(animated: true)
            }
            navigationController?.pushViewController(vc, animated: true)

        case .dns:
            let vc = SingleOptionViewController<NetworkChoice>()
            vc.applyTint(.current)
            vc.title = (cell as? SettingTableViewCell)?.leftText
            vc.options = NetworkChoice.choices(for: profile)
            vc.descriptionBlock = { $0.description }

            vc.selectedOption = networkChoices.dns
            vc.selectionBlock = { [weak self] in
                self?.updateDNS($0)
                self?.navigationController?.popViewController(animated: true)
            }
            navigationController?.pushViewController(vc, animated: true)

        case .proxy:
            let vc = SingleOptionViewController<NetworkChoice>()
            vc.applyTint(.current)
            vc.title = (cell as? SettingTableViewCell)?.leftText
            vc.options = NetworkChoice.choices(for: profile)
            vc.descriptionBlock = { $0.description }

            vc.selectedOption = networkChoices.proxy
            vc.selectionBlock = { [weak self] in
                self?.updateProxy($0)
                self?.navigationController?.popViewController(animated: true)
            }
            navigationController?.pushViewController(vc, animated: true)

        case .mtu:
            let vc = SingleOptionViewController<NetworkChoice>()
            vc.applyTint(.current)
            vc.title = (cell as? SettingTableViewCell)?.leftText
            vc.options = NetworkChoice.choices(for: profile)
            vc.descriptionBlock = { $0.description }

            vc.selectedOption = networkChoices.mtu
            vc.selectionBlock = { [weak self] in
                self?.updateMTU($0)
                self?.navigationController?.popViewController(animated: true)
            }
            navigationController?.pushViewController(vc, animated: true)

        case .dnsAddAddress:
            tableView.deselectRow(at: indexPath, animated: true)
            
            var dnsServers = networkSettings.dnsServers ?? []
            dnsServers.append("")
            networkSettings.dnsServers = dnsServers
            reloadModel()
            tableView.insertRows(at: [indexPath], with: .automatic)

        case .dnsAddDomain:
            tableView.deselectRow(at: indexPath, animated: true)
            
            var dnsSearchDomains = networkSettings.dnsSearchDomains ?? []
            dnsSearchDomains.append("")
            networkSettings.dnsSearchDomains = dnsSearchDomains
            reloadModel()
            tableView.insertRows(at: [indexPath], with: .automatic)

        case .proxyAddBypass:
            tableView.deselectRow(at: indexPath, animated: true)
            
            var bypassDomains = networkSettings.proxyBypassDomains ?? []
            bypassDomains.append("")
            networkSettings.proxyBypassDomains = bypassDomains
            reloadModel()
            tableView.insertRows(at: [indexPath], with: .automatic)
            
        case .mtuBytes:
            guard networkChoices.mtu == .manual else {
                break
            }
            let vc = SingleOptionViewController<Int>()
            vc.applyTint(.current)
            vc.title = (cell as? SettingTableViewCell)?.leftText
            vc.options = ProfileNetworkSettings.mtuOptions
            vc.descriptionBlock = { $0.description }
            
            vc.selectedOption = networkSettings.mtuBytes
            vc.selectionBlock = { [weak self] in
                self?.networkSettings.mtuBytes = $0
                self?.navigationController?.popViewController(animated: true)
            }
            navigationController?.pushViewController(vc, animated: true)

        default:
            break
        }
    }
    
    private func handle(row: RowType, cell: ToggleTableViewCell) {
        switch row {
        case .gatewayIPv4:
            guard networkChoices.gateway == .manual else {
                return
            }
            var policies = networkSettings.gatewayPolicies ?? []
            if cell.toggle.isOn {
                policies.append(.IPv4)
            } else {
                policies.removeAll { $0 == .IPv4 }
            }
            policies.sort { $0.rawValue < $1.rawValue }
            networkSettings.gatewayPolicies = policies

        case .gatewayIPv6:
            guard networkChoices.gateway == .manual else {
                return
            }
            var policies = networkSettings.gatewayPolicies ?? []
            if cell.toggle.isOn {
                policies.append(.IPv6)
            } else {
                policies.removeAll { $0 == .IPv6 }
            }
            policies.sort { $0.rawValue < $1.rawValue }
            networkSettings.gatewayPolicies = policies

        default:
            break
        }
    }
    
    override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
        switch model.row(at: indexPath) {
        case .dnsAddress, .dnsDomain, .proxyBypass:
            return true

        default:
            return false
        }
    }
    
    override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
        switch model.row(at: indexPath) {
        case .dnsAddress:
            networkSettings.dnsServers?.remove(at: indexPath.row - Offsets.dnsAddress)

        case .dnsDomain:
            networkSettings.dnsSearchDomains?.remove(at: indexPath.row - Offsets.dnsDomain)

        case .proxyBypass:
            networkSettings.proxyBypassDomains?.remove(at: indexPath.row - Offsets.proxyBypass)
            
        default:
            break
        }

        reloadModel()
        tableView.deleteRows(at: [indexPath], with: .automatic)
    }
}

extension NetworkSettingsViewController: ToggleTableViewCellDelegate {
    func toggleCell(_ cell: ToggleTableViewCell, didToggleToValue value: Bool) {
        guard let item = RowType(rawValue: cell.tag) else {
            return
        }
        handle(row: item, cell: cell)
    }
}

extension NetworkSettingsViewController: FieldTableViewCellDelegate {
    func fieldCellDidEdit(_ cell: FieldTableViewCell) {
        commitTextField(cell.field)
    }
    
    func fieldCellDidEnter(_: FieldTableViewCell) {
    }
}

extension NetworkChoice: CustomStringConvertible {
    public var description: String {
        switch self {
        case .client:
            return L10n.Core.NetworkChoice.client
            
        case .server:
            return L10n.Core.NetworkChoice.server
            
        case .manual:
            return L10n.Core.Global.Values.manual
        }
    }
}