/*
 * Copyright (c) 2022 BWI GmbH
 *
 * 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

enum OnBoardingSplashScreenAlertType {
    case showServerMaintenanceAlert, showServerMaintenanceDefaultAlert, showInvalidAppVersionAlert, showDowntimeTimeAlert
}

@available(iOS 14.0, *)
/// The splash screen shown at the beginning of the onboarding flow.
struct OnboardingBwiSplashScreen: View {

    // MARK: - Properties
    
    // MARK: Private
    
    @Environment(\.theme) private var theme
    @Environment(\.layoutDirection) private var layoutDirection
    private let service = ServerDowntimeDefaultService()
    
    /// The dimensions of the stack with the action buttons and page indicator.
    @State private var overlayFrame: CGRect = .zero
    @State private var isFetchingDowntime = false
    @State private var showAlert = false
    @State private var activeAlert: OnBoardingSplashScreenAlertType = .showInvalidAppVersionAlert

    // MARK: Public
    
    @ObservedObject var viewModel: OnboardingBwiSplashScreenViewModel.Context
    
    /// The main action buttons.
    var startButton: some View {
        Button(action: startButtonAction) {
            if isFetchingDowntime {
                ProgressView()
            } else {
                Text(BWIL10n.splashScreenStart)
                    .font(theme.fonts.body.bold())
                    .frame(minWidth: 0, maxWidth: .infinity, minHeight: 32)
            }
        }
            .foregroundColor(.white)
            .background(theme.colors.accent)
            .cornerRadius(5)
            .padding([.leading, .trailing], 20)
    }
    
    var footer: some View {
        Image("powered_by_BWI_blk")
            .resizable()
            .aspectRatio(contentMode: .fit)
            .frame(width: 140, alignment: .center)
    }
    
    var body: some View {
        ZStack {
            VStack(spacing: 30) {
                startButton
                    .padding()
                Spacer()
                footer
                    .padding()
            }
        }
        .navigationTitle("")
        .navigationBarHidden(true)
        .alert(isPresented: $showAlert, content: {
            switch activeAlert {
            case .showInvalidAppVersionAlert:
                return Alert(title: Text(BWIL10n.bwiOutdatedVersionWarningTitle),
                             message: Text(BWIL10n.bwiOutdatedVersionWarningMessage(AppInfo.current.displayName)),
                             dismissButton: .destructive(Text(BWIL10n.bwiOutdatedVersionAppstoreButton), action: {
                           let iTunesLink = "itms://itunes.apple.com/app/BwMessenger/id1518548153?mt=8"
                           UIApplication.shared.open(URL(string: iTunesLink)!, options: [:], completionHandler: nil)
                       }))
            case .showDowntimeTimeAlert:
                return Alert(title: Text(BWIL10n.downtimeTitle),
                             message: Text(ServerDowntimeDefaultService().downtimeText() != "" ? BWIL10n.downtimeDefaultMessage + "\n\n" + ServerDowntimeDefaultService().downtimeText() : BWIL10n.downtimeDefaultMessage),
                            dismissButton: .destructive(Text(BWIL10n.downtimeAlertDismissButton)) {
                            return
                        })
            case .showServerMaintenanceAlert:
                return Alert(title: Text(BWIL10n.downtimeTitle),
                            message: Text(ServerDowntimeDefaultService().downtimeText()),
                            dismissButton: .destructive(Text(BWIL10n.downtimeAlertDismissButton)) {
                            viewModel.send(viewAction: .login)
                        })
            case .showServerMaintenanceDefaultAlert:
                return Alert(title: Text(BWIL10n.downtimeTitle),
                             message: Text(BWIL10n.downtimeDefaultMessage),
                             dismissButton: .destructive(Text(BWIL10n.downtimeAlertDismissButton)) {
                           viewModel.send(viewAction: .login)
                       })
            }
        })
    }
    
    private func startButtonAction() {
        if BWIBuildSettings.shared.enableMaintenanceInfoOnWelcomeScreen {
            isFetchingDowntime = true   // show progresview
            
            if BWIBuildSettings.shared.useTestDataForDowntime {
                service.fetchDowntimes {
                    self.isFetchingDowntime = false // hide progressview
                    self.showAlertIfNeeded()
                }
            } else {
                service.fetchDowntimesWithDirectRequest { success in
                    DispatchQueue.main.async {
                        self.isFetchingDowntime = false   // hide progressview
                        if success {
                            self.showAlertIfNeeded()
                        } else {
                            showAlert = true
                            activeAlert = .showServerMaintenanceDefaultAlert
                        }
                    }
                }
            }
        } else {
            viewModel.send(viewAction: .login)
        }
    }
    
    
    private func showAlertIfNeeded() {
        switch service.nextDowntimeType() {
        case .none:
            viewModel.send(viewAction: .login)
            break
        case .ongoing:
            showAlert = true
            activeAlert = .showDowntimeTimeAlert
            break
        case .warning:
            // only show active downtimes
            viewModel.send(viewAction: .login)
            // showAlert = true
            // activeAlert = .showServerMaintenanceAlert
            break
        }
    }
}

// MARK: - Previews

@available(iOS 14.0, *)
struct OnboardingBwiSplashScreen_Previews: PreviewProvider {
    static let stateRenderer = MockOnboardingBwiSplashScreenScreenState.stateRenderer
    static var previews: some View {
        stateRenderer.screenGroup()
    }
}