import SwiftUI
import Combine

let initToDos = [
    ToDo(title: "タスク1", done: false),
    ToDo(title: "タスク2", done: true),
]

struct ToDo : Identifiable{
    let id = UUID()
    var title: String
    var done: Bool
}

struct ToDoList {
    var todos: [ToDo] = initToDos
    var completedToDos: [ToDo]  {
        get{
            return todos.filter { $0.done }
        }
    }
    var unCompletedToDos: [ToDo]  {
        get{
            return todos.filter { !$0.done }
        }
    }
    func toggle(id: UUID){
        // TODO
        
    }
    func append(title: String){
        // TODO
    }
}

struct ContentView: View {
    var body: some View {
        VStack{
            ToDoView()
        }
    }
}

class AsyncState<Data>: ObservableObject {
    var f: () -> Data
    @Published var isLoading = false
    @Published var error: Error?
    @Published var data: Data?
    
    init(f: @escaping () -> Data) {
        self.f = f
    }
    
    func get() {
        self.isLoading = true
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 1) {// 1s sleep
            self.data = self.f()
            self.isLoading = false
        }
    }
}

struct ToDoView: View {
    @StateObject private var state =  AsyncState<ToDoList> {
        return ToDoList() // APIコール
    }
    var body: some View {
        ZStack {
            VStack{
                Button(action: { state.todoList?.append(title: "新タスク") }){ Text("追加") }
                Text("全ToDo")
                ToDoListView(todos: state.todoList?.todos ?? [],
                             toggle: state.todoList?.toggle)
                Text("未完了ToDo")
                ToDoListView(todos: state.todoList?.unCompletedToDos ?? [],
                             toggle: state.todoList?.toggle)
                Text("完了済みToDo")
                ToDoListView(todos: state.todoList?.completedToDos ?? [],
                             toggle: state.todoList?.toggle)
            }.onAppear {
                state.get()
            }
            if state.isLoading {
                ProgressView()
            }
        }
    }
}

struct ToDoListView: View {
    let todos: [ToDo]
    let toggle: ((UUID) -> Void)?
    var body: some View {
        VStack{
            List {
                ForEach(todos) { todo in
                    ToDoRow(todo: todo, toggle: toggle)
                }
            }
        }
    }
}

struct ToDoRow: View {
    let todo: ToDo
    let toggle: ((UUID) -> Void)?
    var body: some View {
        HStack {
            Text(todo.title)
            Spacer()
            Button(action: { toggle?(todo.id) }){
                if (todo.done) {
                    Image(systemName: "checkmark.square.fill")
                        .foregroundColor(.green)
                }else {
                    Image(systemName: "square")
                }
                
            }
        }
    }
}


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