//
//  OpenVPNView+Import.swift
//  Passepartout
//
//  Created by Davide De Rosa on 12/8/24.
//  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/>.
//

import CommonLibrary
import CommonUtils
import PassepartoutKit
import SwiftUI

extension OpenVPNView {
    struct ImportModifier: ViewModifier {

        @Binding
        var draft: OpenVPNModule.Builder

        let impl: OpenVPNModule.Implementation?

        @Binding
        var isImporting: Bool

        @ObservedObject
        var errorHandler: ErrorHandler

        @State
        private var importURL: URL?

        @State
        private var importPassphrase: String?

        @State
        private var requiresPassphrase = false

        func body(content: Content) -> some View {
            content
                .fileImporter(
                    isPresented: $isImporting,
                    allowedContentTypes: [.item],
                    onCompletion: importConfiguration
                )
                .alert(
                    draft.moduleType.localizedDescription,
                    isPresented: $requiresPassphrase,
                    presenting: importURL,
                    actions: { url in
                        SecureField(
                            Strings.Placeholders.secret,
                            text: $importPassphrase ?? ""
                        )
                        Button(Strings.Alerts.Import.Passphrase.ok) {
                            importConfiguration(from: .success(url))
                        }
                        Button(Strings.Global.Actions.cancel, role: .cancel) {
                            isImporting = false
                        }
                    },
                    message: {
                        Text(Strings.Alerts.Import.Passphrase.message($0.lastPathComponent))
                    }
                )
        }
    }
}

private extension OpenVPNView.ImportModifier {
    func importConfiguration(from result: Result<URL, Error>) {
        do {
            let url = try result.get()
            guard url.startAccessingSecurityScopedResource() else {
                throw AppError.permissionDenied
            }
            defer {
                url.stopAccessingSecurityScopedResource()
            }
            importURL = url

            guard let impl else {
                fatalError("Requires OpenVPNModule implementation")
            }
            guard let parser = impl.importer as? StandardOpenVPNParser else {
                fatalError("OpenVPNModule importer should be StandardOpenVPNParser")
            }
            let parsed = try parser.parsed(fromURL: url, passphrase: importPassphrase)

            draft.configurationBuilder = parsed.configuration.builder()
        } catch StandardOpenVPNParserError.encryptionPassphrase,
                StandardOpenVPNParserError.unableToDecrypt {
            Task {
                // XXX: re-present same alert after artificial delay
                try? await Task.sleep(for: .milliseconds(500))
                importPassphrase = nil
                requiresPassphrase = true
            }
        } catch {
            pp_log(.app, .error, "Unable to import OpenVPN configuration: \(error)")
            errorHandler.handle(
                (error as? StandardOpenVPNParserError)?.asPassepartoutError ?? error,
                title: draft.moduleType.localizedDescription
            )
        }
    }
}