package login.view.util;

import javax.ejb.SessionBean;
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;

import login.view.bean.BeanNames;

import com.sun.faces.config.beans.ApplicationBean;

public class FacesUtils {
	/**
	 * 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);
	}
	
	/**
	 * Get <code>ApplicationBean</code>.
	 * <p>
	 * Specific for this application.
	 * 
	 * @return the application bean
	 */
	public static ApplicationBean getApplicationBean() {
		return (ApplicationBean)getManagedBean(BeanNames.APPLICATION_BEAN);
	} 
	
	/**
	 * Get <code>SessionBean</code>.
	 * <p>
	 * Specific for this applicaiton.
	 * 
	 * @return the session bean
	 */
	public static SessionBean getSessionBean() {
		return (SessionBean)getManagedBean(BeanNames.SESSION_BEAN);
	} 
	
	/**
	 * 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));
	}
	
	/**
	 * 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());
			}
		}
		else {
			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);
	}
	
	private 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 + "}";
	}
}