//
//  OrganizerView+Profiles.swift
//  Passepartout
//
//  Created by Davide De Rosa on 5/3/22.
//  Copyright (c) 2022 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 SwiftUI
import PassepartoutCore

extension OrganizerView {
    struct ProfilesList: View {
        @ObservedObject private var profileManager: ProfileManager

        @ObservedObject private var providerManager: ProviderManager

        // just to observe changes in profiles eligibility
        @ObservedObject private var productManager: ProductManager
        
        @State private var isFirstLaunch = true

        @State private var presentedProfileId: UUID?

        private var presentedAndLoadedProfileId: Binding<UUID?> {
            .init {
                presentedProfileId
            } set: {
                guard $0 != presentedProfileId else {
                    return
                }
                guard let id = $0 else {
                    presentedProfileId = nil
                    return
                }
                presentedProfileId = id

                // load profile contextually with navigation
                do {
                    try profileManager.loadCurrentProfile(withId: id)
                } catch {
                    pp_log.error("Unable to load profile: \(error)")
                }
            }
        }

        init() {
            profileManager = .shared
            providerManager = .shared
            productManager = .shared
        }
        
        var body: some View {
            debugChanges()
            return Group {
                mainView
                if !profileManager.hasProfiles {
                    emptyView
                }
            }

            // events
            .onAppear {
                performMigrationsIfNeeded()
            }.onChange(of: profileManager.headers) {
                dismissSelectionIfDeleted(headers: $0)
            }.onReceive(profileManager.didCreateProfile) {
                presentedAndLoadedProfileId.wrappedValue = $0.id
            }
        }
        
        private var mainView: some View {
            List {
                if profileManager.hasProfiles {
                    if #available(iOS 15, *), themeIdiom == .pad {
                        // FIXME: iPad multitasking, navigation binding does not clear on pop without Section
                        Section {
                            profilesView
                        } header: {
                            Text(L10n.Global.Strings.profiles)
                        }
                    } else {
                        profilesView
                    }
                }
            }.themeAnimation(on: profileManager.headers)
        }
        
        private var profilesView: some View {
            ForEach(sortedHeaders, content: profileRow(forHeader:))
                .onDelete(perform: removeProfiles)
        }

        private var emptyView: some View {
            VStack {
                Text(L10n.Organizer.Empty.noProfiles)
                    .themeInformativeTextStyle()
            }
        }

        private func profileRow(forHeader header: Profile.Header) -> some View {
            NavigationLink(tag: header.id, selection: presentedAndLoadedProfileId) {
                ProfileView()
            } label: {
                profileLabel(forHeader: header)
            }.contextMenu {
                profileMenu(forHeader: header)
            }.onAppear {
                presentIfActiveProfile(header.id)
            }
        }
        
        private func profileLabel(forHeader header: Profile.Header) -> some View {
            ProfileRow(
                header: header,
                isActive: profileManager.isActiveProfile(header.id)
            )
        }

        @ViewBuilder
        private func profileMenu(forHeader header: Profile.Header) -> some View {
            ProfileView.DuplicateButton(
                header: header,
                switchCurrentProfile: false
            )
        }

        private var sortedHeaders: [Profile.Header] {
            profileManager.headers
                .sorted {
                    if profileManager.isActiveProfile($0.id) {
                        return true
                    } else if profileManager.isActiveProfile($1.id) {
                        return false
                    } else {
                        return $0 < $1
                    }
                }
        }

        private func presentIfActiveProfile(_ id: UUID) {
            guard id == profileManager.activeProfileId else {
                return
            }
            presentActiveProfile()
        }
        
        private func presentActiveProfile() {
            guard isFirstLaunch else {
                return
            }
            isFirstLaunch = false

            guard let activeProfileId = profileManager.activeProfileId else {
                return
            }

            // FIXME: iPad portrait/compact, preselecting profile on launch adds ProfileView() twice
            // can notice becase "Back" needs to be tapped twice to show sidebar
            if themeIdiom != .pad {
                presentedProfileId = activeProfileId
            }
        }
        
        private func removeProfiles(at offsets: IndexSet) {
            let currentHeaders = sortedHeaders
            var toDelete: [UUID] = []
            offsets.forEach {
                toDelete.append(currentHeaders[$0].id)
            }
            removeProfiles(withIds: toDelete)
        }

        private func removeProfiles(withIds toDelete: [UUID]) {

            // clear selection before removal to avoid triggering a bogus navigation push
            if toDelete.contains(profileManager.currentProfile.value.id) {
                presentedProfileId = nil
            }

            withAnimation {
                profileManager.removeProfiles(withIds: toDelete)
            }
        }
        
        private func performMigrationsIfNeeded() {
            Task {
                await AppManager.shared.doMigrations(profileManager)
            }
        }
        
        private func dismissSelectionIfDeleted(headers: [Profile.Header]) {
            if let _ = presentedProfileId, !profileManager.isCurrentProfileExisting() {
                presentedProfileId = nil
            }
        }
    }
}