@Named
@ViewScoped
public class ClearDynaFormController implements Serializable {

    protected static final Set<VisitHint> VISIT_HINTS = EnumSet.of(VisitHint.SKIP_UNRENDERED);
    private static final long serialVersionUID = 20130504L;

    private DynaFormModel model;
    private List<Condition> conditions;

    @PostConstruct
    protected void initialize() {
        model = new DynaFormModel();
        conditions = new ArrayList<>();

        // 1. condition and row
        Condition condition = new Condition("model", 2, "eq", "mercedes", 0);
        conditions.add(condition);

        DynaFormRow row = model.createRegularRow();
        row.addControl(condition, "column");
        row.addControl(condition, "offset");
        row.addControl(condition, "operator");
        row.addControl(condition, "value");
        row.addControl(condition, "clear");

        // 2. condition and row
        condition = new Condition("manufacturer", 1, "not", "chrysler group", 1);
        conditions.add(condition);

        row = model.createRegularRow();
        row.addControl(condition, "column");
        row.addControl(condition, "offset");
        row.addControl(condition, "operator");
        row.addControl(condition, "value");
        row.addControl(condition, "clear");

        // 3. condition and row
        condition = new Condition("year", 0, "lt", "2010", 2);
        conditions.add(condition);

        row = model.createRegularRow();
        row.addControl(condition, "column");
        row.addControl(condition, "offset");
        row.addControl(condition, "operator");
        row.addControl(condition, "value");
        row.addControl(condition, "clear");
    }

    public static void clearInputs(final int index) {
        final FacesContext fc = FacesContext.getCurrentInstance();
        final DynaForm dynaForm = (DynaForm) fc.getViewRoot().findComponent(":mainForm:dynaForm");

        // Ids of components to be visited
        final String[] ids = new String[] {"tableColumn", "inputValue", "inputOffset", "valueOperator"};

        final VisitTaskExecutor visitTaskExecutor = new ClearInputsExecutor(fc.getELContext(), ids, index);

        // clear inputs in the visit callback
        final ExecutableVisitCallback visitCallback = new ExecutableVisitCallback(visitTaskExecutor);
        dynaForm.visitTree(VisitContext.createVisitContext(fc, null, VISIT_HINTS), visitCallback);
    }

    public void removeCondition(final Condition condition) {
        model.removeRegularRow(condition.getIndex());
        conditions.remove(condition);

        // re-index conditions
        int idx = 0;
        for (final Condition cond : conditions) {
            cond.setIndex(idx);
            idx++;
        }
    }

    public String getConditions() {
        final StringBuilder sb = new StringBuilder();
        for (final Condition condition : conditions) {
            sb.append(condition.toString());
            sb.append("<br/>");
        }

        return sb.toString();
    }

    public DynaFormModel getModel() {
        return model;
    }
}
            

public class Condition implements Serializable {

    private static final long serialVersionUID = 1L;
    private String tableColumn;
    private int inputOffset;
    private String valueOperator;
    private String inputValue;
    private int index; // internal index in the list of all conditions

    public Condition() {
    }

    public Condition(String tableColumn, int inputOffset, String valueOperator, String inputValue, int index) {
        this.tableColumn = tableColumn;
        this.inputOffset = inputOffset;
        this.valueOperator = valueOperator;
        this.inputValue = inputValue;
        this.index = index;
    }

    public String getTableColumn() {
        return tableColumn;
    }

    public void setTableColumn(String tableColumn) {
        this.tableColumn = tableColumn;
    }

    public int getInputOffset() {
        return inputOffset;
    }

    public void setInputOffset(int inputOffset) {
        this.inputOffset = inputOffset;
    }

    public String getValueOperator() {
        return valueOperator;
    }

    public void setValueOperator(String valueOperator) {
        this.valueOperator = valueOperator;
    }

    public String getInputValue() {
        return inputValue;
    }

    public void setInputValue(String inputValue) {
        this.inputValue = inputValue;
    }

    public int getIndex() {
        return index;
    }

    public void setIndex(int index) {
        this.index = index;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        Condition condition = (Condition) o;

        if (index != condition.index) {
            return false;
        }
        if (inputOffset != condition.inputOffset) {
            return false;
        }
        if (inputValue != null ? !inputValue.equals(condition.inputValue) : condition.inputValue != null) {
            return false;
        }
        if (tableColumn != null ? !tableColumn.equals(condition.tableColumn) : condition.tableColumn != null) {
            return false;
        }
        if (valueOperator != null ? !valueOperator.equals(condition.valueOperator) : condition.valueOperator != null) {
            return false;
        }

        return true;
    }

    @Override
    public int hashCode() {
        int result = tableColumn != null ? tableColumn.hashCode() : 0;
        result = 31 * result + inputOffset;
        result = 31 * result + (valueOperator != null ? valueOperator.hashCode() : 0);
        result = 31 * result + (inputValue != null ? inputValue.hashCode() : 0);
        result = 31 * result + index;
        return result;
    }

    @Override
    public String toString() {
        return "Condition {"
                    + "tableColumn='" + tableColumn + '\''
                    + ", inputOffset=" + inputOffset
                    + ", valueOperator='" + valueOperator + '\''
                    + ", inputValue='" + inputValue + '\''
                    + '}';
    }
}
            

public class ClearInputsExecutor implements VisitTaskExecutor {

    private static final String INDEX_ATTR = "rcIndex";

    private ELContext elContext;
    private String[] ids;
    private int index;

    public ClearInputsExecutor(ELContext elContext, String[] ids, int index) {
        this.elContext = elContext;
        this.ids = ids;
        this.index = index;
    }

    /**
     * @see org.primefaces.extensions.util.visitcallback.VisitTaskExecutor
     */
    @Override
    public VisitResult execute(UIComponent component) {
        UIInput input = (UIInput) component;
        String id = input.getId();

        // reset UI
        input.resetValue();

        // reset value in bean
        if ("tableColumn".equals(id) || "inputValue".equals(id)) {
            ValueExpression ve = input.getValueExpression("value");
            if (ve != null) {
                ve.setValue(elContext, StringUtils.EMPTY);
            }
        }
        else if ("inputOffset".equals(id)) {
            ValueExpression ve = input.getValueExpression("value");
            if (ve != null) {
                ve.setValue(elContext, 0);
            }
        }
        else if ("valueOperator".equals(id)) {
            ValueExpression ve = input.getValueExpression("value");
            if (ve != null) {
                ve.setValue(elContext, "eq");
            }
        }

        // update the corresponding input during response
        PrimeFaces.current().ajax().update(input.getClientId());

        // delete handled id from the list, so that similar inputs should not be executed again
        ArrayUtils.removeElement(ids, id);

        return ids.length != 0 ? VisitResult.REJECT : VisitResult.COMPLETE;
    }

    /**
     * @see org.primefaces.extensions.util.visitcallback.VisitTaskExecutor
     */
    @Override
    public boolean shouldExecute(UIComponent component) {
        if (component instanceof EditableValueHolder && ArrayUtils.contains(ids, component.getId())) {
            Integer idx = (Integer) component.getAttributes().get(INDEX_ATTR);
            if (idx != null && index == idx) {
                return true;
            }
        }

        return false;
    }
}