PetShop.swift

import SwiftUI

@main
struct PetShopApp: App {
    /// ペットショップ
    @StateObject private var shop: PetShop = .init()
    
    var body: some Scene {
        WindowGroup {
            ContentView(shop: shop)
        }
    }
}

struct ContentView: View {
    /// ペットショップ
    @ObservedObject var shop: PetShop
    
    var body: some View {
        NavigationView {
            List {
                ForEach(shop.dogs) { dog in
                    DogCell(dog: dog)
                } // ForEach
                .onMove(perform: moveDogs)
                .onDelete(perform: deleteDog)
                
                HStack {
                    Spacer()
                    Text("\(shop.dogs.count) dogs")
                        .foregroundColor(.secondary)
                    Spacer()
                } // HStack
            } // List
            .navigationTitle("Dogs")
            .toolbar {
                #if os(iOS)
                ToolbarItem(placement: .navigationBarTrailing) {
                    EditButton()
                } // ToolbarItem
                #endif
                ToolbarItem(placement: .automatic) {
                    Button("Add", action: makeDog)
                } // ToolbarItem
            } // toolbar
            
            Text("Select a dog")
                .font(.largeTitle)
        } // NavigationView
    } // body
    
    /// 犬を追加
    func makeDog() {
        withAnimation {
            // ドーベルマンを追加
            shop.dogs.append(.init(name: "Doberman", age: 1, popularity: false))
        }
    }
    
    /// 犬を移動
    func moveDogs(from: IndexSet, to: Int) {
        withAnimation {
            shop.dogs.move(fromOffsets: from, toOffset: to)
        }
    }
    
    /// 犬を削除
    func deleteDog(offsets: IndexSet) {
        withAnimation {
            shop.dogs.remove(atOffsets: offsets)
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView(shop: testShop)
    }
}

/// 犬セル
struct DogCell: View {
    /// 犬情報
    let dog: Dog
        
    var body: some View {
        NavigationLink(destination: DogDetail(dog: dog)) {
            Image(dog.thumbnailName)
                .resizable()
                .frame(width:40, height: 40)
                .aspectRatio(contentMode: .fill)
                .cornerRadius(8.0)
            
            VStack(alignment: .leading) {
                Text(dog.name)
                Text("\(dog.age) years old")
                    .font(.subheadline)
                    .foregroundColor(.secondary)
            } // VStack
        } // NavigationLink
    } // body
}

struct DogCell_Previews: PreviewProvider {
    static var previews: some View {
        DogCell(dog: testData[0])
            .previewLayout(.sizeThatFits)
    }
}

/// 犬詳細画面
struct DogDetail: View {
    /// 犬情報
    let dog: Dog
    /// ズームした
    @State private var zoomed: Bool = false
    
    var body: some View {
        VStack {
            Spacer(minLength: 0)
            
            Image(dog.imageName)
                .resizable()
                .aspectRatio(contentMode: zoomed ? .fill : .fit)
                .onTapGesture {
                    withAnimation {
                        zoomed.toggle()
                    }
                }
            
            Spacer(minLength: 0)
            
            if dog.popularity && !zoomed {
                HStack {
                    Spacer()
                    Label("Popularity", systemImage: "star.fill")
                    Spacer()
                } // HStack
                .padding(.all)
                .font(Font.headline.smallCaps())
                .background(Color.red)
                .foregroundColor(.yellow)
                .transition(.move(edge: .bottom))
            }
        } // VStack
        .edgesIgnoringSafeArea(.bottom)
        .navigationTitle(dog.name)
    } // body
}

struct DogDetail_Previews: PreviewProvider {
    static var previews: some View {
        NavigationView {
            DogDetail(dog: testData[0])
        }
    }
}

/// ペットショップ
class PetShop: ObservableObject {
    @Published var dogs: [Dog]
    
    init(dogs: [Dog] = []) {
        self.dogs = dogs
    }
}
/// テストショップ
let testShop: PetShop = PetShop(dogs: testData)

/// 犬モデル
struct Dog: Identifiable {
    /// ID
    var id:UUID = UUID()
    /// 名前
    var name: String
    /// 年齢
    var age: Int
    /// 人気
    var popularity: Bool
    /// 画像名
    var imageName: String {
        name
    }
    /// サムネイル画像名
    var thumbnailName: String {
        name + "Thumb"
    }
}
/// テストデータ
let testData: [Dog] = [
    .init(name: "Kaiken", age: 2, popularity: false),
    .init(name: "Great Pyrenees", age: 2, popularity: true),
    .init(name: "Akitainu", age: 1, popularity: false),
    .init(name: "Doberman", age: 3, popularity: false),
    .init(name: "Shetland Sheepdog", age: 1, popularity: false),
]