/**
 * The contents of this file are subject to the license and copyright
 * detailed in the LICENSE and NOTICE files at the root of the source
 * tree and available online at
 *
 * http://www.dspace.org/license/
 */
package org.dspace.app.rest;

import java.io.File;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.servlet.Filter;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;

import org.dspace.app.rest.filter.DSpaceRequestContextFilter;
import org.dspace.app.rest.model.hateoas.DSpaceRelProvider;
import org.dspace.app.rest.utils.ApplicationConfig;
import org.dspace.app.util.DSpaceContextListener;
import org.dspace.servicemanager.DSpaceKernelImpl;
import org.dspace.servicemanager.DSpaceKernelInit;
import org.dspace.servicemanager.config.DSpaceConfigurationService;
import org.dspace.utils.servlet.DSpaceWebappServletFilter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.ServletContextInitializer;
import org.springframework.boot.web.support.SpringBootServletInitializer;
import org.springframework.context.annotation.Bean;
import org.springframework.core.annotation.Order;
import org.springframework.hateoas.RelProvider;

/**
 * Define the Spring Boot Application settings itself. This class takes the place 
 * of a web.xml file, and configures all Filters/Listeners as methods (see below).
 * <P>
 * NOTE: Requires a Servlet 3.0 container, e.g. Tomcat 7.0 or above.
 * <p>
 * NOTE: This extends SpringBootServletInitializer in order to allow us to build
 * a deployable WAR file with Spring Boot. See:
 * http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#howto-create-a-deployable-war-file
 *
 * @author Andrea Bollini (andrea.bollini at 4science.it)
 * @author Tim Donohue
 */
@SpringBootApplication
public class Application extends SpringBootServletInitializer
{
    private static final Logger log = LoggerFactory.getLogger(Application.class);

    @Autowired
    private ApplicationConfig configuration;
    
    /**
     * Override the default SpringBootServletInitializer.configure() method,
     * passing it this Application class.
     * <P>
     * This is necessary to allow us to build a deployable WAR, rather than
     * always relying on embedded Tomcat.
     * <P>
     * See: http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#howto-create-a-deployable-war-file
     * @param application
     * @return
     */
    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }

    @Bean
    public ServletContextInitializer contextInitializer() {
        return new ServletContextInitializer() {

        	private transient DSpaceKernelImpl kernelImpl;

            @Override
            public void onStartup(ServletContext servletContext)
                    throws ServletException {
                    servletContext.setInitParameter("dspace.dir",configuration.getDspaceHome());
                    
                    // start the kernel when the webapp starts
                    try {
                        this.kernelImpl = DSpaceKernelInit.getKernel(null);
                        if (! this.kernelImpl.isRunning()) {
                        	this.kernelImpl.start(getProvidedHome(configuration.getDspaceHome())); // init the kernel
                        }
                    } catch (Exception e) {
                        // failed to start so destroy it and log and throw an exception
                        try {
                            this.kernelImpl.destroy();
                        } catch (Exception e1) {
                            // nothing
                        }
                        String message = "Failure during filter init: " + e.getMessage();
                        System.err.println(message + ":" + e);
                        throw new RuntimeException(message, e);
                    }
            }
            
            /*
             * Find DSpace's "home" directory.
             * Initially look for JNDI Resource called "java:/comp/env/dspace.dir".
             * If not found, look for "dspace.dir" initial context parameter.
             */
            private String getProvidedHome(String dspaceHome){
            	String providedHome = null;
            	try {
        			Context ctx = new InitialContext();
        			providedHome = (String) ctx.lookup("java:/comp/env/" + DSpaceConfigurationService.DSPACE_HOME);
        		} catch (Exception e) {
        			// do nothing
        		}
        		
        		if (providedHome == null)
        		{
        			if(dspaceHome != null && !dspaceHome.equals("") && 
        					!dspaceHome.equals("${" + DSpaceConfigurationService.DSPACE_HOME + "}")){
        				File test = new File(dspaceHome);
        				if(test.exists() && new File(test,DSpaceConfigurationService.DSPACE_CONFIG_PATH).exists()) {
        					providedHome = dspaceHome;
                        }
        			}
        		}
        		return providedHome;
            }

        };
    }

    /**
     * Register the "DSpaceContextListener" so that it is loaded
     * for this Application.
     * @return DSpaceContextListener
     */
    @Bean
    @Order(2)
    protected DSpaceContextListener dspaceContextListener() {
        // This listener initializes the DSpace Context object
        // (and loads all DSpace configs)
        return new DSpaceContextListener();
    }
    
    /**
     * Register the DSpaceWebappServletFilter, which initializes the
     * DSpace RequestService / SessionService
     * 
     * @return DSpaceWebappServletFilter
     */
    @Bean
    @Order(1)
    protected Filter dspaceWebappServletFilter() {
        return new DSpaceWebappServletFilter();
    }
    
    /**
     * Register the DSpaceRequestContextFilter, a Filter which checks for open
     * Context objects *after* a request has been fully processed, and closes them
     *
     * @return DSpaceRequestContextFilter
     */
    @Bean
    @Order(2)
    protected Filter dspaceRequestContextFilter() {
        return new DSpaceRequestContextFilter();
    }
    
    @Bean
    protected RelProvider dspaceRelProvider() {
    	return new DSpaceRelProvider();
    }
}