enum DataID {
  case row
}

let viewController = CollectionViewController(
  layout: UICollectionViewCompositionalLayout
    .list(using: .init(appearance: .plain)),
  items: {
    TextRow.itemModel(
      dataID: DataID.row,
      content: .init(title: "Tap me!"),
      style: .small)
      .didSelect { _ in
        // Handle selection
      }
  })

class CounterViewController: CollectionViewController {
  init() {
    let layout = UICollectionViewCompositionalLayout
      .list(using: .init(appearance: .plain))
    super.init(layout: layout)
    setItems(items, animated: false)
  }

  enum DataID {
    case row
  }

  var count = 0 {
    didSet {
      setItems(items, animated: true)
    }
  }

  @ItemModelBuilder
  var items: [ItemModeling] {
    TextRow.itemModel(
      dataID: DataID.row,
      content: .init(
        title: "Count \(count)",
        body: "Tap to increment"),
      style: .large)
      .didSelect { [weak self] _ in
        self?.count += 1
      }
  }
}

class BottomButtonViewController: UIViewController {
  override func viewDidLoad() {
    super.viewDidLoad()
    bottomBarInstaller.install()
  }

  lazy var bottomBarInstaller = BottomBarInstaller(
    viewController: self,
    bars: bars)

  @BarModelBuilder
  var bars: [BarModeling] {
    ButtonRow.barModel(
      content: .init(text: "Click me!"),
      behaviors: .init(didTap: {
        // Handle button selection
      }))
  }
}

class FormNavigationController: NavigationController {
  init() {
    super.init()
    setStack(stack, animated: false)
  }

  enum DataID {
    case step1, step2
  }

  var showStep2 = false {
    didSet {
      setStack(stack, animated: true)
    }
  }

  @NavigationModelBuilder
  var stack: [NavigationModel] {
    .root(dataID: DataID.step1) { [weak self] in
      Step1ViewController(didTapNext: {
        self?.showStep2 = true
      })
    }

    if showStep2 {
      NavigationModel(
        dataID: DataID.step2,
        makeViewController: {
          Step2ViewController(didTapNext: {
            // Navigate away from this step.
          })
        },
        remove: { [weak self] in
          self?.showStep2 = false
        })
    }
  }
}

class PresentationViewController: UIViewController {
  override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    setPresentation(presentation, animated: true)
  }

  enum DataID {
    case detail
  }

  var showDetail = true {
    didSet {
      setPresentation(presentation, animated: true)
    }
  }

  @PresentationModelBuilder
  var presentation: PresentationModel? {
    if showDetail {
      PresentationModel(
        dataID: DataID.detail,
        presentation: .system,
        makeViewController: { [weak self] in
          DetailViewController(didTapDismiss: {
            self?.showDetail = false
          })
        },
        dismiss: { [weak self] in
          self?.showDetail = false
        })
    }
  }
}

// Set of dataIDs to have consistent
// and unique IDs
enum DataID {
  case title
  case subtitle
  case action
}

// Groups are created declaratively
// just like Epoxy ItemModels
let group = VGroup(
  alignment: .leading,
  spacing: 8)
{
  Label.groupItem(
    dataID: DataID.title,
    content: "Title text",
    style: .title)
  Label.groupItem(
    dataID: DataID.subtitle,
    content: "Subtitle text",
    style: .subtitle)
  Button.groupItem(
    dataID: DataID.action,
    content: "Perform action",
    behaviors: .init { button in
      print("Button tapped! \(button)")
    },
    style: .standard)
}

// install your group in a view
group.install(in: view)

// constrain the group like you
// would a normal subview
group.constrainToMargins()

enum DataID {
  case icon
  case title
}

let group = HGroup(spacing: 8) {
  ImageView.groupItem(
    dataID: DataID.icon,
    content: UIImage(systemName: "person.fill")!,
    style: .init(size: .init(width: 24, height: 24)))
  Label.groupItem(
    dataID: DataID.title,
    content: "This is an IconRow")
}

group.install(in: view)
group.constrainToMargins()

enum DataID {
  case checkbox
  case titleSubtitleGroup
  case title
  case subtitle
}

HGroup(spacing: 8) {
  Checkbox.groupItem(
    dataID: DataID.checkbox,
    content: .init(isChecked: true),
    style: .standard)
  VGroupItem(
    dataID: DataID.titleSubtitleGroup,
    style: .init(spacing: 4))
  {
    Label.groupItem(
      dataID: DataID.title,
      content: "Build iOS App",
      style: .title)
    Label.groupItem(
      dataID: DataID.subtitle,
      content: "Use EpoxyLayoutGroups",
      style: .subtitle)
  }
}