HomeView.swift

class HomeViewModel: ObservableObject {
    @Published var articles: [Article] = []
    private let cacheFile = "articles.json"
    private var cancellables = Set<AnyCancellable>()
    struct ListArticleParams {
        let limit: Int
        let offset: Int
        let useCache: Bool
    }

    var loadArticle = PassthroughSubject<HomeViewModel.ListArticleParams, Never>()

    init() {
        let emptyArticle: [Article] = []
        self.loadArticle
            .debounce(for: 0.5, scheduler: RunLoop.main)
            .flatMap { params -> AnyPublisher<[Article], Error> in
                if params.useCache {
                    let out: AnyPublisher<([Article], Int), Error> = DefaultStorage.readPublisher(fileName: self.cacheFile)
                    return out.map { articles, _ in articles }.eraseToAnyPublisher()
                }

                return DefaultHTTPClient.listArticles(limit: params.limit, offset: params.offset)
                    .map { $0.articles }
                    .flatMap { DefaultStorage.writePublisher(input: $0, fileName: self.cacheFile) }
                    .eraseToAnyPublisher()
            }

            .replaceError(with: emptyArticle)
            .receive(on: DispatchQueue.main)
            .assign(to: &self.$articles)
    }
}

struct HomeView: View {
    @EnvironmentObject var appState: AppState
    @ObservedObject var viewModel = HomeViewModel()

    var body: some View {
        VStack {
            Text("Home page ").font(/*@START_MENU_TOKEN@*/ .title/*@END_MENU_TOKEN@*/)
            ForEach(viewModel.articles, id: \.uuid) { article in
                Text("title: \(article.slug)")
            }
            Button {
                viewModel.loadArticle.send(HomeViewModel.ListArticleParams(limit: 0, offset: 10, useCache: false))
            } label: {
                Text("Load")
            }
        }
    }
}

#Preview {
    HomeView()
}