//
//  VPNProviderServerView+iOS.swift
//  Passepartout
//
//  Created by Davide De Rosa on 10/9/24.
//  Copyright (c) 2024 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/>.
//

#if os(iOS)

import CommonAPI
import CommonLibrary
import PassepartoutKit
import SwiftUI

extension VPNProviderServerView {
    var contentView: some View {
        serversView
            .modifier(FiltersItemModifier {
                filtersView
            })
    }
}

private extension VPNProviderServerView {
    struct FiltersItemModifier<FiltersContent>: ViewModifier where FiltersContent: View {

        @ViewBuilder
        let filtersContent: FiltersContent

        @State
        private var isPresented = false

        func body(content: Content) -> some View {
            content
                .toolbar {
                    Button {
                        isPresented = true
                    } label: {
                        ThemeImage(.filters)
                    }
                    .themePopover(
                        isPresented: $isPresented,
                        size: .custom(width: 400, height: 400)
                    ) {
                        filtersContent
                            .modifier(FiltersViewModifier(isPresented: $isPresented))
                    }
                }
        }
    }

    struct FiltersViewModifier: ViewModifier {

        @Binding
        var isPresented: Bool

        func body(content: Content) -> some View {
            NavigationStack {
                content
                    .navigationTitle(Strings.Global.Nouns.filters)
                    .themeNavigationDetail()
                    .toolbar {
                        ToolbarItem(placement: .cancellationAction) {
                            Button {
                                isPresented = false
                            } label: {
                                ThemeCloseLabel()
                            }
                        }
                    }
            }
            .presentationDetents([.medium])
        }
    }
}

// MARK: - Subviews

extension VPNProviderServerView {
    struct ServersSubview: View {
        let servers: [VPNServer]

        let selectedServer: VPNServer?

        let isFiltering: Bool

        @ObservedObject
        var filtersViewModel: VPNFiltersView.Model

        @ObservedObject
        var favoritesManager: ProviderFavoritesManager

        let selectTitle: String

        let onSelect: (VPNServer) -> Void

        @State
        private var serversByCountryCode: [String: [VPNServer]] = [:]

        @State
        private var expandedCodes: Set<String> = []

        var body: some View {
            debugChanges()
            return listView
                .themeAnimation(on: isFiltering, category: .providers)
                .onChange(of: servers, perform: computeServersByCountry)
        }
    }
}

private extension VPNProviderServerView.ServersSubview {
    var listView: some View {
        List {
            Section {
                Toggle(Strings.Views.Providers.onlyFavorites, isOn: $filtersViewModel.onlyShowsFavorites)
            }
            Group {
                if isFiltering || !servers.isEmpty {
                    if isFiltering {
                        ProgressView()
                            .id(UUID())
                    } else {
                        ForEach(countryCodes, id: \.self, content: countryView)
                    }
                } else {
                    emptyView
                }
            }
            .themeSection(
                header: filtersViewModel.filters.categoryName ?? Strings.Views.Providers.Vpn.Category.any
            )
            .onLoad {
                if let selectedServer {
                    expandedCodes.insert(selectedServer.provider.countryCode)
                }
            }
        }
    }

    var emptyView: some View {
        Text(Strings.Views.Providers.Vpn.noServers)
    }
}

private extension VPNProviderServerView.ServersSubview {
    var countryCodes: [String] {
        filtersViewModel
            .countries
            .map(\.code)
    }

    func isExpandedCountry(_ code: String) -> Binding<Bool> {
        Binding {
            expandedCodes.contains(code)
        } set: {
            if $0 {
                expandedCodes.insert(code)
            } else {
                expandedCodes.remove(code)
            }
        }
    }

    func countryView(for code: String) -> some View {
        serversByCountryCode[code]
            .map { servers in
                DisclosureGroup(isExpanded: isExpandedCountry(code)) {
                    ForEach(servers, id: \.id, content: serverView)
                } label: {
                    ThemeCountryText(code)
                }
            }
    }

    func serverView(for server: VPNServer) -> some View {
        Button {
            onSelect(server)
        } label: {
            HStack {
                ThemeImage(.marked)
                    .opaque(server.id == selectedServer?.id)
                VStack(alignment: .leading) {
                    if let area = server.provider.area {
                        Text(area)
                            .font(.headline)
                    }
                    Text(server.hostname ?? server.serverId)
                        .font(.subheadline)
                        .truncationMode(.middle)
                }
                Spacer()
                FavoriteToggle(
                    value: server.serverId,
                    selection: $favoritesManager.serverIds
                )
            }
        }
    }

    func computeServersByCountry(_ servers: [VPNServer]) {
        var map: [String: [VPNServer]] = [:]
        servers.forEach {
            let code = $0.provider.countryCode
            var list = map[code] ?? []
            list.append($0)
            map[code] = list
        }
        serversByCountryCode = map
    }
}

// MARK: - Preview

#Preview {
    NavigationStack {
        VPNProviderServerView(
            apis: [API.bundled],
            moduleId: UUID(),
            providerId: .tunnelbear,
            configurationType: OpenVPN.Configuration.self,
            selectedEntity: nil,
            filtersWithSelection: false,
            selectTitle: "Select",
            onSelect: { _, _ in }
        )
    }
    .withMockEnvironment()
}

#endif