MVI large reducer

TicketsPresenter.java

public class TicketsPresenter extends BasePresenter<TicketsView, TicketsModel> {

    private final DisplayErrorUsecase displayErrorUsecase;
    private final LoadTicketsPageUsecase loadTicketsPageUsecase;
    private final ArchiveTicketUsecase archiveTicketUsecase;
    private final RenewTicketUsecase renewTicketUsecase;
    private final DeleteTicketUsecase deleteTicketUsecase;
    private final DeleteAllArchivedTicketsUsecase deleteAllArchivedTicketsUsecase;

    @Inject TicketsPresenter(DisplayErrorUsecase displayErrorUsecase,
                             LoadTicketsPageUsecase loadTicketsPageUsecase,
                             ArchiveTicketUsecase archiveTicketUsecase,
                             RenewTicketUsecase renewTicketUsecase,
                             DeleteTicketUsecase deleteTicketUsecase,
                             DeleteAllArchivedTicketsUsecase deleteAllArchivedTicketsUsecase) {
        this.displayErrorUsecase = displayErrorUsecase;
        this.loadTicketsPageUsecase = loadTicketsPageUsecase;
        this.archiveTicketUsecase = archiveTicketUsecase;
        this.renewTicketUsecase = renewTicketUsecase;
        this.deleteTicketUsecase = deleteTicketUsecase;
        this.deleteAllArchivedTicketsUsecase = deleteAllArchivedTicketsUsecase;
    }

    @Override protected void bindIntents() {

        final Observable<Result> allIntents = Observable.merge(Arrays.asList(
                intent(TicketsView::displayErrorActions).compose(displayErrorUsecase),
                intent(TicketsView::loadFirstPageSignal).compose(loadTicketsPageUsecase),
                intent(TicketsView::loadFreshPageSignal).compose(loadTicketsPageUsecase),
                intent(TicketsView::loadNextPageSignal).compose(loadTicketsPageUsecase),
                intent(TicketsView::archiveTicket).compose(archiveTicketUsecase),
                intent(TicketsView::renewTicket).compose(renewTicketUsecase),
                intent(TicketsView::deleteTicket).compose(deleteTicketUsecase),
                intent(TicketsView::deleteAllArchivedTicketsSignal).compose(deleteAllArchivedTicketsUsecase)
        ));

        final Observable<TicketsModel> modelObservable = allIntents
                .scan(TicketsModel.builder().build(), this::reduceModel)
                .doOnNext(model -> Timber.v("render: %s", model))
                .observeOn(AndroidSchedulers.mainThread());

        subscribeViewState(modelObservable, TicketsView::render);
    }

    @Override protected TicketsModel reduceModel(TicketsModel model, Result result) {
        final TicketsModel.Builder builder = model.toBuilder();

        if (result instanceof DisplayErrorUsecase.Result) {
            return builder
                    .error(null)
                    .build();
        }

        if (result instanceof LoadTicketsPageUsecase.Result) {
            final LoadTicketsPageUsecase.Result res = (LoadTicketsPageUsecase.Result) result;
            switch (res.status()) {
                case INITIAL_PAGE:
                    if (res.success()) builder.items(res.data());
                    return builder
                            .firstPageLoading(res.loading())
                            .firstPageError(res.error())
                            .build();
                case REFRESH_PAGE:
                    if (res.success()) builder.items(res.data());
                    return builder
                            .freshPageLoading(res.loading())
                            .freshPageError(res.error())
                            .build();
                case NEXT_PAGE:
                    if (res.success()) {
                        final List<ItemViewModel> data = new ArrayList<>();
                        data.addAll(model.items());
                        data.addAll(res.data());
                        builder.items(data);
                    }
                    return builder
                            .nextPageLoading(res.loading())
                            .nextPageError(res.error())
                            .build();
            }
        }

        if (result instanceof ArchiveTicketUsecase.Result || result instanceof DeleteTicketUsecase.Result) {
            //noinspection unchecked
            final LceResult<Ticket> res = ((LceResult) result);
            if (res.success()) {
                final List<ItemViewModel> data = new ArrayList<>(model.items());
                data.remove(new TicketItemViewModel(res.data()));
                builder.items(data);
            }
            return builder
                    .loading(res.loading())
                    .error(res.error())
                    .build();
        }

        if (result instanceof RenewTicketUsecase.Result) {
            final RenewTicketUsecase.Result res = (RenewTicketUsecase.Result) result;
            if (res.success()) {
                final List<ItemViewModel> data = new ArrayList<>(model.items());
                data.remove(new TicketItemViewModel(res.oldTicket()));
                builder.items(data);
            }
            return builder
                    .loading(res.loading())
                    .error(res.error())
                    .build();
        }

        if (result instanceof DeleteAllArchivedTicketsUsecase.Result) {
            final DeleteAllArchivedTicketsUsecase.Result res = (DeleteAllArchivedTicketsUsecase.Result) result;
            if (res.success()) builder.items(Collections.emptyList());
            return builder
                    .error(res.error())
                    .loading(res.loading())
                    .build();
        }

        throw new IllegalStateException("Can not reduce model for result " + result.getClass().getName());
    }
}