package com.mousetech.gourmetj;

import java.io.InputStream;

import javax.faces.application.FacesMessage;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;
import javax.faces.context.Flash;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class JSFUtils {

	/* Logger */

	private static final Logger log =
			LoggerFactory.getLogger(JSFUtils.class);

	private static ExternalContext getExternalContext() {
		FacesContext facesContext =
				FacesContext.getCurrentInstance();
		ExternalContext externalContext =
				facesContext.getExternalContext();
		return externalContext;
	}

	/**
	 * Obtain resource as Stream. The caller must close this
	 * stream after use.
	 * 
	 * @param pathName Path of the resource. For example,
	 *                 "/WEB-INF/classes/xys.properties".
	 * @return InputStream or <code>null</code>, if no such
	 *         resource exists.
	 */
	public static InputStream getResourceStream(
			String pathName) {
		InputStream response = getExternalContext()
			.getResourceAsStream(pathName);
		return response;
	}

	// ===
	/**
	 * Post an info-level message to the FacesContext where the
	 * &lt;h:messages&gt; tag can display it.
	 * 
	 * @param string Message text
	 */
	public static void addInfoMessage(String string) {
		FacesMessage message = new FacesMessage(
				FacesMessage.SEVERITY_INFO, string, string);
		FacesContext.getCurrentInstance().addMessage(null,
			message);
	}

	/**
	 * Post an error-level message to the FacesContext where the
	 * &lt;h:messages&gt; tag can display it.
	 * 
	 * @param string Message text
	 */
	public static void addErrorMessage(String string) {
		FacesMessage message = new FacesMessage(
				FacesMessage.SEVERITY_ERROR, string, string);
		FacesContext.getCurrentInstance().addMessage(null,
			message);
	}

	public static void addErrorMessage(String string,
			Exception e) {
		if (e instanceof NullPointerException) {
			addErrorMessage(
				"Internal logic error (NullPointerException)");
		} else {
			addErrorMessage(string);
		}
		log.error(string, e);
	}

	public static Flash flashScope() {
		return (FacesContext.getCurrentInstance()
			.getExternalContext().getFlash());
	}

	/**
	 * Look in Flash scope for item.
	 * 
	 * @param key Item to retrieve
	 * @return Item, or null if not in Flash OR Flash not active 
	 */
	public static Object getFlash(String key) {
		Flash flash = flashScope();
		try {
			return flash.get(key);
		} catch ( NullPointerException nex ) {
			// If session is expired, flash.get() will fail!
			return null;
		}
	}

	public static void putFlash(String key, Object value) {
		flashScope().put(key, value);
	}
}