//
// Copyright © 2021 osy. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import SwiftUI

@available(macOS 11, *)
struct VMWizardView: View {
    @StateObject var wizardState = VMWizardState()
    @Environment(\.presentationMode) private var presentationMode: Binding<PresentationMode>
    @EnvironmentObject private var data: UTMData
    
    /// SwiftUI BUG: on macOS 12, when VoiceOver is enabled and isBusy changes
    /// the disable state of a button being clicked, the app crashes
    private var isNeverDisabledWorkaround: Bool {
        #if os(macOS)
        if #available(macOS 12, *) {
            if #unavailable(macOS 13) {
                return false
            }
        }
        return true
        #else
        return true
        #endif
    }
    
    var body: some View {
        Group {
            switch wizardState.currentPage {
            case .start:
                VMWizardStartView(wizardState: wizardState)
                    .transition(wizardState.slide)
            case .operatingSystem:
                VMWizardOSView(wizardState: wizardState)
                    .transition(wizardState.slide)
            case .otherBoot:
                VMWizardOSOtherView(wizardState: wizardState)
                    .transition(wizardState.slide)
            case .macOSBoot:
                if #available(macOS 12, *) {
                    VMWizardOSMacView(wizardState: wizardState)
                        .transition(wizardState.slide)
                }
            case .linuxBoot:
                VMWizardOSLinuxView(wizardState: wizardState)
                    .transition(wizardState.slide)
            case .windowsBoot:
                VMWizardOSWindowsView(wizardState: wizardState)
                    .transition(wizardState.slide)
            case .classicMacOSBoot:
                VMWizardOSClassicMacView(wizardState: wizardState)
                    .transition(wizardState.slide)
            case .hardware:
                VMWizardHardwareView(wizardState: wizardState)
                    .transition(wizardState.slide)
            case .drives:
                VMWizardDrivesView(wizardState: wizardState)
                    .transition(wizardState.slide)
            case .sharing:
                VMWizardSharingView(wizardState: wizardState)
                    .transition(wizardState.slide)
            case .summary:
                VMWizardSummaryView(wizardState: wizardState)
                    .transition(wizardState.slide)
            }
        }
        .padding(.top)
        .frame(width: 450, height: 450)
        .toolbar {
            ToolbarItem(placement: .automatic) {
                if wizardState.currentPage != .start {
                    Button("Cancel") {
                        presentationMode.wrappedValue.dismiss()
                    }
                }
            }
            ToolbarItem(placement: .cancellationAction) {
                if wizardState.currentPage != .start {
                    Button("Go Back") {
                        wizardState.back()
                    }
                } else {
                    Button("Cancel") {
                        presentationMode.wrappedValue.dismiss()
                    }
                }
            }
            ToolbarItem(placement: .confirmationAction) {
                if wizardState.hasNextButton {
                    Button("Continue") {
                        wizardState.next()
                    }
                } else if wizardState.currentPage == .summary {
                    Button("Save") {
                        presentationMode.wrappedValue.dismiss()
                        data.busyWorkAsync {
                            let config = try await wizardState.generateConfig()
                            #if arch(arm64)
                            if #available(macOS 12, *), await wizardState.isPendingIPSWDownload, let appleConfig = config as? UTMAppleConfiguration {
                                await data.downloadIPSW(using: appleConfig)
                                return
                            }
                            #endif
                            if let qemuConfig = config as? UTMQemuConfiguration {
                                let vm = try await data.create(config: qemuConfig)
                                await MainActor.run {
                                    if wizardState.isGuestToolsInstallRequested {
                                        NotificationCenter.default.post(name: NSNotification.InstallGuestTools, object: vm.wrapped!)
                                    }
                                }
                            } else if let appleConfig = config as? UTMAppleConfiguration {
                                _ = try await data.create(config: appleConfig)
                            }
                            if await wizardState.isOpenSettingsAfterCreation {
                                await data.showSettingsForCurrentVM()
                            }
                        }
                    }
                }
            }
        }.alert(item: $wizardState.alertMessage) { msg in
            Alert(title: Text(msg.message))
        }
        .disabled(wizardState.isBusy && isNeverDisabledWorkaround)
    }
}

@available(macOS 11, *)
struct VMWizardView_Previews: PreviewProvider {
    static var previews: some View {
        VMWizardView()
    }
}