package ddth.dasp.framework.spring;

import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.osgi.context.BundleContextAware;

import ddth.dasp.common.DaspGlobal;

/**
 * This class provide an application-wide access to Spring's ApplicationContext.
 * Use {@link ApplicationContextProvider#getApplicationContext()} to obtain the
 * ApplicationContext instance.
 * <p>
 * Note: This class is a Spring bean and must be initialized in the
 * Spring-Configuration file:
 * </p>
 * 
 * <pre>
 * <bean id="contextApplicationContextProvider" class="...ApplicationContextProvider" lazy-init="false" init-method="init" destroy-method="destroy" />
 * </pre>
 * <p>
 * In code:
 * </p>
 * 
 * <pre>
 * ApplicationContext appContext = ApplicationContextProvider.getApplicationContext(bundleId);
 * </pre>
 * 
 * @author NBThanh <btnguyen2k@gmail.com>
 */
public class ApplicationContextProvider implements ApplicationContextAware, BundleContextAware {

    private static String calcKey(long bundleId) {
        return "SPRING_APP_CONTEXT_" + bundleId;
    }

    public static ApplicationContext getApplicationContext(Bundle bundle) {
        return getApplicationContext(bundle.getBundleId());
    }

    public static ApplicationContext getApplicationContext(long bundleId) {
        return (ApplicationContext) DaspGlobal.getGlobalVar(calcKey(bundleId));
    }

    private ApplicationContext applicationContext;
    private Bundle bundle;
    private String KEY;

    public void init() {
        DaspGlobal.setGlobalVar(KEY, applicationContext);
    }

    public void destroy() {
        DaspGlobal.removeGlobalVar(KEY);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void setBundleContext(BundleContext bundleContext) {
        this.bundle = bundleContext.getBundle();
        KEY = calcKey(bundle.getBundleId());
    }
}