app-icon.swift

//
//  AppearanceSheet.swift
//  PeePooBoobRelease
//
//  Created by Adam Whitcroft on 2022-10-07.
//

import SwiftUI

struct AppearanceSheet: View {
    // MARK: Dismiss
    // Is this view visible or not
    @Environment(\.dismiss) private var dismiss
    @StateObject var viewModel = ChangeAppIconViewModel()
    
    var body: some View {
        ScrollView {
            VStack(spacing: 16) {
                // Section title
                SectionTitleView(title: "App icon")
                // App icon selector
                InsetContentCard {
                    ForEach(ChangeAppIconViewModel.AppIcon.allCases) { appIcon in
                        HStack(spacing: 16) {
                            Image(uiImage: appIcon.preview)
                                .resizable()
                                .aspectRatio(contentMode: .fit)
                                .frame(width: 60, height: 60)
                                .cornerRadius(12)
                            Text(appIcon.description)
                        }
                        .onTapGesture {
                            withAnimation {
                                viewModel.updateAppIcon(to: appIcon)
                            }
                        }
                    }
                }
            }
            .padding()
        }
        .navigationTitle("")
        .navigationBarTitleDisplayMode(.inline)
        .navigationBarBackButtonHidden(true)
        .toolbar {
            ToolbarItem(placement: .navigationBarLeading) {
                Button {
                    dismiss()
                } label: {}
                    .buttonStyle(RoundButtonStyleSmall(iconName: "chevron.left", iconColor: .secondary))
            }
            ToolbarItem(placement: .principal) {
                Text(Strings.SheetTitleAppearance)
                    .font(.system(.body, design: .rounded).weight(.bold))
            }
        }
    }
}

enum AppIcon: String, CaseIterable, Identifiable {
    case primary = "AppIcon"
    case primaryInverted = "AppIcon-Inverted"
    case red = "AppIcon-Red"
    case redInverted = "AppIcon-Red-Inverted"
    // etc...

    var id: String { rawValue }
    
    var iconName: String? {
        switch self {
        case .primary:
            // `nil` resets back to the primary `AppIcon` icon
            return nil
        default:
            return rawValue
        }
    }

    var description: String {
        switch self {
        case .primary:
            return "Default"
        case .primaryInverted:
            return "Something about primary inverted here..."
        case .red:
            return "Something about red here..."
        case .redInverted:
            return "Something about red inverted here..."
        }
    }

    var preview: UIImage {
        UIImage(named: rawValue + "-Preview") ?? UIImage()
    }
}

final class ChangeAppIconViewModel: ObservableObject {
    @Published private(set) var selectedAppIcon: AppIcon

    init() {
        if let iconName = UIApplication.shared.alternateIconName, let appIcon = AppIcon(rawValue: iconName) {
            selectedAppIcon = appIcon
        } else {
            selectedAppIcon = .primary
        }
    }

    func updateAppIcon(to icon: AppIcon) {
        let previousAppIcon = selectedAppIcon
        selectedAppIcon = icon

        Task { @MainActor in
            guard UIApplication.shared.alternateIconName != icon.iconName else {
                // No need to update since we're already using this icon.
                return
            }

            do {
                try await UIApplication.shared.setAlternateIconName(icon.iconName)
            } catch {
                // We're only logging the error here and not actively handling the app icon failure
                // since it's very unlikely to fail.
                print("Updating icon to \(String(describing: icon.iconName)) failed.")

                // Restore previous app icon
                selectedAppIcon = previousAppIcon
            }
        }
    }
}