import RxSwift
import RxRelay
// 1
import RxDataSources

class TodoListViewModel {
    private let addButtonPublishRelay = PublishRelay<Void>()
    // 2
    private let todoListCellViewModelsBehaviorRelay = BehaviorRelay<[TodoListCellViewModel]>(value: [])

    var addButtonObserver: AnyObserver<Void> {
        return AnyObserver {
            guard let element = $0.element else { return }
            self.addButtonPublishRelay.accept(element)
        }
    }

    // 3
    let dataSource = RxTableViewSectionedReloadDataSource<TodoListSection>(configureCell: {dataSource, tableView, indexPath, item in
        guard let cell = tableView.dequeueReusableCell(withIdentifier: "TodoListTableViewCell") as? TodoListTableViewCell else { return UITableViewCell() }
        cell.bind(to: item)

        return cell
    })

    // 4
    init() {
        dataSource.titleForHeaderInSection = { dataSource, index in
            return dataSource.sectionModels[index].header
        }
    }
}