TaskContainer.swift

import SwiftUI

extension ContainerValues {
    @Entry var taskCompleted: Bool = false
}

struct TaskContainer<Content: View>: View {
    var content: Content
    init(@ViewBuilder content: () -> Content) {
        self.content = content()
    }

    var body: some View {
        ZStack {
            Group(sections: content) { sections in
                ForEach(sections) { section in
                    Group(subviews: section.content) { subviews in
                        if let firstIncomplete = subviews.first(where: { !$0.containerValues.taskCompleted }) {
                            firstIncomplete
                        }
                    }
                }
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .ignoresSafeArea()
    }
}

struct TaskView<Content: View>: View {
    @State private var completed = false
    let content: (_ complete: @escaping () -> Void) -> Content

    init(@ViewBuilder content: @escaping (_ complete: @escaping () -> Void) -> Content) {
        self.content = content
    }

    var body: some View {
        content { completed = true }
            .containerValue(\.taskCompleted, completed)
    }
}

// MARK: - Example tasks, using TaskView directly would be annoying. Would be nice to protocol constrain tho

struct SleepTaskView: View {
    let seconds: Double
    var body: some View {
        TaskView { complete in
            Color.clear
                .task {
                    try? await Task.sleep(nanoseconds: UInt64(seconds * 1_000_000_000))
                    complete()
                }
        }
    }
}

struct TapToContinueTask: View {
    let label: String
    var body: some View {
        TaskView { complete in
            Button(label) { complete() }
                .buttonStyle(.borderedProminent)
        }
    }
}

struct ContentView: View {
    var body: some View {
        TaskContainer {
            Section {
                SleepTaskView(seconds: 0.5)
                TapToContinueTask(label: "Tap to Continue")
            }
            Section {
                SleepTaskView(seconds: 5)
                TapToContinueTask(label: "Tap to Continue (again)")
            }
        }
    }
}

#Preview { ContentView() }