package org.etk.kernel.container;

import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Set;

import javax.servlet.RequestDispatcher;
import javax.servlet.Servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;


/**
 * This class is used to merge all the {@link ServletContext} related to a given
 * portal container. It will used the {@link WebAppInitContext} that have been
 * defined in the related portal container. It will always consider that the
 * {@link WebAppInitContext} with the highest priority has always right, in
 * other words for example in the method getInitParameter, it will try to get
 * the init parameter in the {@link WebAppInitContext} of the highest priority,
 * if it cans not find it, it will try the {@link WebAppInitContext} with the
 * second highest priority and so on. The priority of the
 * {@link WebAppInitContext} is the order given by the method
 * PortalContainer.getWebAppInitContexts(), the last {@link WebAppInitContext}
 * is the one with the highest priority.
 * 
 * Created by The eXo Platform SAS Author : Nicolas Filotto
 * nicolas.filotto@exoplatform.com 14 sept. 2009
 */
class PortalContainerContext implements ServletContext {

	/**
	 * The related portal container
	 */
	private final ApplicationContainer container;

	PortalContainerContext(ApplicationContainer container) {
		this.container = container;
	}

	private WebAppInitContext[] getWebAppInitContexts() {
		final Set<WebAppInitContext> contexts = container.getWebAppInitContexts();
		final WebAppInitContext[] aContexts = new WebAppInitContext[contexts.size()];
		return (WebAppInitContext[]) contexts.toArray(aContexts);
	}

	private ServletContext getPortalContext() {
		return container.portalContext;
	}

	/**
	 * {@inheritDoc}
	 */
	public Object getAttribute(String name) {
		return getPortalContext().getAttribute(name);
	}

	/**
	 * {@inheritDoc}
	 */
	@SuppressWarnings("unchecked")
	public Enumeration getAttributeNames() {
		return getPortalContext().getAttributeNames();
	}

	/**
	 * {@inheritDoc}
	 */
	public ServletContext getContext(String uripath) {
		return getPortalContext().getContext(uripath);
	}

	/**
	 * {@inheritDoc}
	 */
	public String getInitParameter(String name) {
		final WebAppInitContext[] contexts = getWebAppInitContexts();
		for (int i = contexts.length - 1; i >= 0; i--) {
			final ServletContext context = contexts[i].getServletContext();
			String param = context.getInitParameter(name);
			if (param != null) {
				return param;
			}
		}
		return null;
	}

	/**
	 * {@inheritDoc}
	 */
	@SuppressWarnings("unchecked")
	public Enumeration<String> getInitParameterNames() {
		final Set<WebAppInitContext> contexts = container
				.getWebAppInitContexts();
		Set<String> names = null;
		for (WebAppInitContext context : contexts) {
			Enumeration<String> eNames = context.getServletContext()
					.getAttributeNames();
			if (eNames != null) {
				if (names == null) {
					names = new HashSet<String>();
				}
				names.addAll(Collections.list(eNames));
			}
		}
		if (names == null) {
			return null;
		}
		return Collections.enumeration(names);
	}

	/**
	 * {@inheritDoc}
	 */
	public int getMajorVersion() {
		return getPortalContext().getMajorVersion();
	}

	/**
	 * {@inheritDoc}
	 */
	public String getMimeType(String file) {
		final WebAppInitContext[] contexts = getWebAppInitContexts();
		for (int i = contexts.length - 1; i >= 0; i--) {
			final ServletContext context = contexts[i].getServletContext();
			String mimeType = context.getMimeType(file);
			if (mimeType != null) {
				return mimeType;
			}
		}
		return null;
	}

	/**
	 * {@inheritDoc}
	 */
	public int getMinorVersion() {
		return getPortalContext().getMinorVersion();
	}

	/**
	 * {@inheritDoc}
	 */
	public RequestDispatcher getNamedDispatcher(String name) {
		return getPortalContext().getNamedDispatcher(name);
	}

	/**
	 * {@inheritDoc}
	 */
	public String getRealPath(String path) {
		final WebAppInitContext[] contexts = getWebAppInitContexts();
		for (int i = contexts.length - 1; i >= 0; i--) {
			final ServletContext context = contexts[i].getServletContext();
			final InputStream is = context.getResourceAsStream(path);
			if (is != null) {
				// The resource exists within this servlet context
				return context.getRealPath(path);
			}
		}
		return null;
	}

	/**
	 * {@inheritDoc}
	 */
	public RequestDispatcher getRequestDispatcher(String path) {
		final WebAppInitContext[] contexts = getWebAppInitContexts();
		for (int i = contexts.length - 1; i >= 0; i--) {
			final ServletContext context = contexts[i].getServletContext();
			final InputStream is = context.getResourceAsStream(path);
			if (is != null) {
				// The resource exists within this servlet context
				return context.getRequestDispatcher(path);
			}
		}
		return null;
	}

	/**
	 * {@inheritDoc}
	 */
	public URL getResource(String path) throws MalformedURLException {
		final WebAppInitContext[] contexts = getWebAppInitContexts();
		for (int i = contexts.length - 1; i >= 0; i--) {
			final ServletContext context = contexts[i].getServletContext();
			final URL url = context.getResource(path);
			if (url != null) {
				return url;
			}
		}
		return null;
	}

	/**
	 * {@inheritDoc}
	 */
	public InputStream getResourceAsStream(String path) {
		final WebAppInitContext[] contexts = getWebAppInitContexts();
		for (int i = contexts.length - 1; i >= 0; i--) {
			final ServletContext context = contexts[i].getServletContext();
			final InputStream is = context.getResourceAsStream(path);
			if (is != null) {
				return is;
			}
		}
		return null;
	}

	/**
	 * {@inheritDoc}
	 */
	@SuppressWarnings("unchecked")
	public Set<String> getResourcePaths(String path) {
		final Set<WebAppInitContext> contexts = container
				.getWebAppInitContexts();
		Set<String> paths = null;
		for (WebAppInitContext context : contexts) {
			Set<String> sPaths = context.getServletContext().getResourcePaths(
					path);
			if (sPaths != null) {
				if (paths == null) {
					paths = new LinkedHashSet<String>();
				}
				paths.addAll(sPaths);
			}
		}
		return paths;
	}

	/**
	 * {@inheritDoc}
	 */
	public String getServerInfo() {
		return getPortalContext().getServerInfo();
	}

	/**
	 * {@inheritDoc}
	 */
	@SuppressWarnings("deprecation")
	public Servlet getServlet(String name) throws ServletException {
		return getPortalContext().getServlet(name);
	}

	/**
	 * {@inheritDoc}
	 */
	public String getServletContextName() {
		return getPortalContext().getServletContextName();
	}

	/**
	 * {@inheritDoc}
	 */
	@SuppressWarnings({ "deprecation", "unchecked" })
	public Enumeration getServletNames() {
		return getPortalContext().getServletNames();
	}

	/**
	 * {@inheritDoc}
	 */
	@SuppressWarnings({ "deprecation", "unchecked" })
	public Enumeration getServlets() {
		return getPortalContext().getServlets();
	}

	/**
	 * {@inheritDoc}
	 */
	public void log(String message) {
		getPortalContext().log(message);
	}

	/**
	 * {@inheritDoc}
	 */
	@SuppressWarnings("deprecation")
	public void log(Exception exception, String message) {
		getPortalContext().log(exception, message);
	}

	/**
	 * {@inheritDoc}
	 */
	public void log(String message, Throwable throwable) {
		getPortalContext().log(message, throwable);
	}

	/**
	 * {@inheritDoc}
	 */
	public void removeAttribute(String name) {
		getPortalContext().removeAttribute(name);
	}

	/**
	 * {@inheritDoc}
	 */
	public void setAttribute(String name, Object object) {
		getPortalContext().setAttribute(name, object);
	}

	/**
	 * {@inheritDoc}
	 */
	public String getContextPath() {
		return getPortalContext().getContextPath();
	}
}