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package org.ff4j.web;

import static org.ff4j.web.bean.WebConstants.CSS_SESSIONATTRIBUTE_NAME;
import static org.ff4j.web.bean.WebConstants.FF4J_SESSIONATTRIBUTE_NAME;
import static org.ff4j.web.bean.WebConstants.SERVLETPARAM_CSS;
import static org.ff4j.web.bean.WebConstants.SERVLETPARAM_FF4JPROVIDER;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

/*
 * #%L
 * ff4j-web
 * %%
 * Copyright (C) 2013 - 2015 Ff4J
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;

import org.ff4j.FF4j;
import org.ff4j.web.controller.AbstractController;
import org.ff4j.web.controller.AuditController;
import org.ff4j.web.controller.FeatureUsageController;
import org.ff4j.web.controller.FeaturesController;
import org.ff4j.web.controller.HomeController;
import org.ff4j.web.controller.InfosController;
import org.ff4j.web.controller.NotFoundController;
import org.ff4j.web.controller.OperationsController;
import org.ff4j.web.controller.PropertiesController;
import org.ff4j.web.controller.SettingsController;
import org.ff4j.web.controller.StaticResourceController;
import org.ff4j.web.controller.TimeSeriesController;
import org.ff4j.web.thymeleaf.CustomMessageResolver;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.thymeleaf.TemplateEngine;
import org.thymeleaf.templatemode.TemplateMode;
import org.thymeleaf.templateresolver.ClassLoaderTemplateResolver;

/**
 * Servlet initialisation to put FF4J in HTTP Session.
 *
 * @author Cedrick LUNVEN
 */
public class FF4jServlet extends HttpServlet {

    /** Serial. */
    private static final long serialVersionUID = 8447941463286918975L;

    /** Logger for this class. */
    public static final Logger LOGGER = LoggerFactory.getLogger(FF4jServlet.class);

    /** instance of ff4j. */
    protected FF4j ff4j = null;

    /** initializing ff4j provider. */
    protected FF4jProvider ff4jProvider = null;

    /** Template engine. */
    protected TemplateEngine templateEngine = null;

    /** Static resource controller. */
    protected StaticResourceController staticResourceController;

    /** Simple Operation. */
    protected OperationsController operationsController;

    /** Mapping PATH <=> Controller */
    protected static Map < String , AbstractController > mapOfControllers = new HashMap();

    /**
     * Servlet initialization, init FF4J from "ff4jProvider" attribute Name.
     *
     * @param servletConfig
     *            current {@link ServletConfig} context
     * @throws ServletException
     *             error during servlet initialization
     */
    public void init(ServletConfig servletConfig) throws ServletException {
    	LOGGER.info("  __  __ _  _   _ ");
        LOGGER.info(" / _|/ _| || | (_)");
        LOGGER.info("| |_| |_| || |_| |");
        LOGGER.info("|  _|  _|__   _| |");
        LOGGER.info("|_| |_|    |_|_/ |");
        LOGGER.info("             |__/  v" + getClass().getPackage().getImplementationVersion());
        LOGGER.info(" ");

        if (ff4j == null) {
        	initializeFF4J(servletConfig);
        }

    	initializeTemplateEngine();

    	staticResourceController = new StaticResourceController(ff4j, templateEngine);
    	operationsController = new OperationsController(ff4j, templateEngine);

    	addController(new HomeController(ff4j, templateEngine));
    	addController(new InfosController(ff4j, templateEngine));
        
    	addController(new FeaturesController(ff4j, templateEngine));
    	addController(new PropertiesController(ff4j, templateEngine));
    	addController(new SettingsController(ff4j, templateEngine));
    	addController(new NotFoundController(ff4j, templateEngine));
        
    	addController(new AuditController(ff4j, templateEngine));
        addController(new FeatureUsageController(ff4j, templateEngine));
        addController(new TimeSeriesController(ff4j, templateEngine));
    }

    /**
     * Syntaxic to add controller to map.
     *
     * @param ac
     *      current controller
     */
    private void addController(AbstractController ac) {
    	mapOfControllers.put(ac.getSuccessView(), ac);
    }

    /**
     * Initialize FF4J configuration.
     *
     * @param servletConfig
     * 		current servlet configuration
     */
    private void initializeFF4J(ServletConfig servletConfig) {
    	String className = servletConfig.getInitParameter(SERVLETPARAM_FF4JPROVIDER);
	    try {
	    	Class c = Class.forName(className);
            Method method = c.getMethod("getInstance");
            Object o = method.invoke(null);
	        ff4jProvider = (FF4jProvider) o;
	        LOGGER.info("ff4j context has been successfully initialized - {} feature(s)", ff4jProvider.getFF4j().getFeatures().size());
	    } catch (ClassNotFoundException e) {
	    	throw new IllegalArgumentException("Cannot load ff4jProvider as " + ff4jProvider, e);
	    } catch (NoSuchMethodException e) {
            throw new IllegalArgumentException("No static method getInstance in " + ff4jProvider, e);
        } catch (InvocationTargetException e) {
            throw new IllegalArgumentException("Failed to invoke getInstance in " + ff4jProvider, e);
        } catch (IllegalAccessException e) {
	    	throw new IllegalArgumentException("No public constructor for  " + ff4jProvider + " as ff4jProvider", e);
	    } catch (ClassCastException ce) {
	    	throw new IllegalArgumentException("ff4jProvider expected instance of " + FF4jProvider.class, ce);
	    }

	    ff4j = ff4jProvider.getFF4j();
	    servletConfig.getServletContext().setAttribute(FF4J_SESSIONATTRIBUTE_NAME, ff4j);
	    LOGGER.debug("Servlet has been initialized and ff4j store in session with {} ", ff4j.getFeatures().size());
	    String cssFile = servletConfig.getInitParameter(SERVLETPARAM_CSS);
	    if (cssFile != null) {
	    	LOGGER.debug("A custom CSS has been defined [" + cssFile + "]");
	        servletConfig.getServletContext().setAttribute(CSS_SESSIONATTRIBUTE_NAME, cssFile);
	    }
    }

    /**
     * Initialize Thymeleaf.
     */
    private void initializeTemplateEngine() {
    	ClassLoaderTemplateResolver templateResolver = new ClassLoaderTemplateResolver();
	    templateResolver.setTemplateMode(TemplateMode.HTML);
	    templateResolver.setPrefix("views/view-");
	    templateResolver.setSuffix(".html");
	    templateResolver.setCacheTTLMs(3600000L);

	    templateEngine = new TemplateEngine();
        templateEngine.setTemplateResolver(templateResolver);
        templateEngine.addMessageResolver(new CustomMessageResolver());
        LOGGER.info("Thymeleaf has been initialized");
    }
    
    /**
     * Getter accessor for attribute 'ff4j'.
     *
     * @return current value of 'ff4j'
     */
    public FF4j getFf4j() {
        if (ff4j == null) {
            throw new IllegalStateException("Console Servlet has not been initialized, please set 'load-at-startup' to 1");
        }
        return ff4j;
    }

    /**
     * Setter accessor for attribute 'ff4j'.
     * @param ff4j
     *      new value for 'ff4j '
     */
    public void setFf4j(FF4j ff4j) {
        this.ff4j = ff4j;
    }


}