import javax.faces.FactoryFinder;
import javax.faces.application.Application;
import javax.faces.application.ApplicationFactory;
import javax.faces.application.FacesMessage;
import javax.faces.context.FacesContext;
import javax.faces.el.ValueBinding;
import javax.faces.webapp.UIComponentTag;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
/**
 * Utility class for JavaServer Faces.
 *
 */
public class FacesUtil {
    /**
     * Get servlet context.
     *
     * @return the servlet context
     */
    public static ServletContext getServletContext() {
        return (ServletContext) FacesContext.getCurrentInstance()
                .getExternalContext().getContext();
    }
    /**
     * Get managed bean based on the bean name.
     *
     * @param beanName
     *            the bean name
     * @return the managed bean associated with the bean name
     */
    public static Object getManagedBean(String beanName) {
        Object o = getValueBinding(getJsfEl(beanName)).getValue(
                FacesContext.getCurrentInstance());
        return o;
    }
    /**
     * Remove the managed bean based on the bean name.
     *
     * @param beanName
     *            the bean name of the managed bean to be removed
     */
    public static void resetManagedBean(String beanName) {
        getValueBinding(getJsfEl(beanName)).setValue(
                FacesContext.getCurrentInstance(), null);
    }
    /**
     * Store the managed bean inside the session scope.
     *
     * @param beanName
     *            the name of the managed bean to be stored
     * @param managedBean
     *            the managed bean to be stored
     */
    public static void setManagedBeanInSession(String beanName,
            Object managedBean) {
        FacesContext.getCurrentInstance().getExternalContext().getSessionMap()
                .put(beanName, managedBean);
    }
    /**
     * Get parameter value from request scope.
     *
     * @param name
     *            the name of the parameter
     * @return the parameter value
     */
    public static String getRequestParameter(String name) {
        return (String) FacesContext.getCurrentInstance().getExternalContext()
                .getRequestParameterMap().get(name);
    }
    /**
     * Add information message.
     *
     * @param msg
     *            the information message
     */
    public static void addInfoMessage(String msg) {
        addInfoMessage(null, msg);
    }
    /**
     * Add information message to a sepcific client.
     *
     * @param clientId
     *            the client id
     * @param msg
     *            the information message
     */
    public static void addInfoMessage(String clientId, String msg) {
        FacesContext.getCurrentInstance().addMessage(clientId,
                new FacesMessage(FacesMessage.SEVERITY_INFO, msg, msg));
    }
    /**
     * Add error message.
     *
     * @param msg
     *            the error message
     */
    public static void addErrorMessage(String msg) {
        addErrorMessage(null, msg);
    }
    /**
     * Add error message to a sepcific client.
     *
     * @param clientId
     *            the client id
     * @param msg
     *            the error message
     */
    public static void addErrorMessage(String clientId, String msg) {
        FacesContext.getCurrentInstance().addMessage(clientId,
                new FacesMessage(FacesMessage.SEVERITY_ERROR, msg, msg));
    }
    /**
     * Add warning message.
     *
     * @param msg
     *            the warning message
     */
    public static void addWarningMessage(String msg) {
        addWarningMessage(null, msg);
    }
    /**
     * Add warning message to a sepcific client.
     *
     * @param clientId
     *            the client id
     * @param msg
     *            the warning message
     */
    public static void addWarningMessage(String clientId, String msg) {
        FacesContext.getCurrentInstance().addMessage(clientId,
                new FacesMessage(FacesMessage.SEVERITY_WARN, msg, msg));
    }
    /**
     * Evaluate the integer value of a JSF expression.
     *
     * @param el
     *            the JSF expression
     * @return the integer value associated with the JSF expression
     */
    public static Integer evalInt(String el) {
        if (el == null) {
            return null;
        }
        if (UIComponentTag.isValueReference(el)) {
            Object value = getElValue(el);
            if (value == null) {
                return null;
            } else if (value instanceof Integer) {
                return (Integer) value;
            } else {
                return new Integer(value.toString());
            }
        }
        return new Integer(el);
    }
    private static Application getApplication() {
        ApplicationFactory appFactory = (ApplicationFactory) FactoryFinder
                .getFactory(FactoryFinder.APPLICATION_FACTORY);
        return appFactory.getApplication();
    }
    private static ValueBinding getValueBinding(String el) {
        return getApplication().createValueBinding(el);
    }
    public static HttpServletRequest getServletRequest() {
        return (HttpServletRequest) FacesContext.getCurrentInstance()
                .getExternalContext().getRequest();
    }
    private static Object getElValue(String el) {
        return getValueBinding(el).getValue(FacesContext.getCurrentInstance());
    }
    private static String getJsfEl(String value) {
        return "#{" + value + "}";
    }
}