package org.expressme.webwind.container;



import java.util.ArrayList;

import java.util.List;

import java.util.Map;

import java.util.Set;



import javax.servlet.ServletContext;



import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.expressme.webwind.Config;

import org.expressme.webwind.ConfigException;

import org.expressme.webwind.Destroyable;

import org.expressme.webwind.guice.ServletContextAware;



import com.google.inject.Binding;

import com.google.inject.Guice;

import com.google.inject.Injector;

import com.google.inject.Key;

import com.google.inject.Module;

import com.google.inject.Stage;



/**

 * Create Guice 2.0 Injector instance, and bind it on ServletContext with 

 * name of <code>Injector.class.getName()</code>.

 * 

 * @author Michael Liao (askxuefeng@gmail.com)

 */

public class GuiceContainerFactory implements ContainerFactory {



    private Log log = LogFactory.getLog(getClass());



    private Injector injector;



    public List<Object> findAllBeans() {

        Map<Key<?>, Binding<?>> map = injector.getBindings();

        Set<Key<?>> keys = map.keySet();

        List<Object> list = new ArrayList<Object>(keys.size());

        for (Key<?> key : keys) {

            Object bean = injector.getInstance(key);

            list.add(bean);

        }

        return list;

    }



    public void init(final Config config) {

        String value = config.getInitParameter("modules");

        if (value==null)

            throw new ConfigException("Init guice failed. Missing parameter '<modules>'.");

        String[] ss = value.split(",");

        List<Module> moduleList = new ArrayList<Module>(ss.length);

        for (String s : ss) {

            Module m = initModule(s, config.getServletContext());

            if (m!=null)

                moduleList.add(m);

        }

        if (moduleList.isEmpty())

            throw new ConfigException("No module found.");

        this.injector = Guice.createInjector(Stage.PRODUCTION, moduleList);

        config.getServletContext().setAttribute(Injector.class.getName(), this.injector);

    }



    Module initModule(String s, ServletContext servletContext) {

        s = trim(s);

        if (s.length()>0) {

            if (log.isDebugEnabled())

                log.debug("Initializing module '" + s + "'...");

            try {

                Object o = Class.forName(s).newInstance();

                if (o instanceof Module) {

                    if (o instanceof ServletContextAware) {

                        ((ServletContextAware) o).setServletContext(servletContext);

                    }

                    return (Module) o;

                }

                throw new ConfigException("Class '" + s + "' does not implement '" + Module.class.getName() + "'.");

            }

            catch(InstantiationException e) {

                throw new ConfigException("Cannot instanciate class '" + s + "'.", e);

            }

            catch(IllegalAccessException e) {

                throw new ConfigException("Cannot instanciate class '" + s + "'.", e);

            }

            catch(ClassNotFoundException e) {

                throw new ConfigException("Cannot instanciate class '" + s + "'.", e);

            }

        }

        return null;

    }



    String trim(String s) {

        while (s.length()>0) {

            char c = s.charAt(0);

            if (" \t\r\n".indexOf(c)!=(-1))

                s = s.substring(1);

            else

                break;

        }

        while (s.length()>0) {

            char c = s.charAt(s.length()-1);

            if (" \t\r\n".indexOf(c)!=(-1))

                s = s.substring(0, s.length()-1);

            else

                break;

        }

        return s;

    }



    public void destroy() {

        List<Object> beans = findAllBeans();

        for (Object bean : beans) {

            if (bean instanceof Destroyable) {

                ((Destroyable)bean).destroy();

            }

        }

    }



}