com.semanticcms.core.servlet.Theme Maven / Gradle / Ivy

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/*
 * semanticcms-core-servlet - Java API for modeling web page content and relationships in a Servlet environment.
 * Copyright (C) 2016, 2017, 2019, 2020  AO Industries, Inc.
 *     [email protected]
 *     7262 Bull Pen Cir
 *     Mobile, AL 36695
 *
 * This file is part of semanticcms-core-servlet.
 *
 * semanticcms-core-servlet is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * semanticcms-core-servlet is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with semanticcms-core-servlet.  If not, see .
 */
package com.semanticcms.core.servlet;

import com.aoindustries.encoding.Doctype;
import com.aoindustries.encoding.Serialization;
import com.aoindustries.encoding.servlet.DoctypeEE;
import com.aoindustries.encoding.servlet.SerializationEE;
import com.aoindustries.web.resources.registry.Registry;
import com.semanticcms.core.model.Page;
import java.io.IOException;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.SkipPageException;

/**
 * A theme is responsible for the overall view of the site.
 */
abstract public class Theme {

	/**
	 * The request-scope attribute that will store the currently active theme.
	 */
	private static final String REQUEST_ATTRIBUTE = Theme.class.getName();

	/**
	 * Gets the current theme on the given request or {@code null} when none active.
	 */
	public static Theme getTheme(ServletRequest request) {
		return (Theme)request.getAttribute(REQUEST_ATTRIBUTE);
	}

	/**
	 * Sets the current theme on the given request or {@code null} for none active.
	 */
	public static void setTheme(ServletRequest request, Theme theme) {
		request.setAttribute(REQUEST_ATTRIBUTE, theme);
	}

	/**
	 * Two themes with the same name are considered equal.
	 */
	@Override
	public boolean equals(Object obj) {
		if(!(obj instanceof Theme)) return false;
		Theme o = (Theme)obj;
		return getName().equals(o.getName());
	}

	/**
	 * Consistent with equals, hashCode based on name.
	 */
	@Override
	public int hashCode() {
		return getName().hashCode();
	}

	/**
	 * @see  #getDisplay()
	 */
	@Override
	public String toString() {
		return getDisplay();
	}

	/**
	 * Gets the display name for this theme.
	 */
	abstract public String getDisplay();

	/**
	 * Gets the unique name of this theme.
	 */
	abstract public String getName();

	/**
	 * Checks if this is the default theme.
	 */
	final public boolean isDefault() {
		return SemanticCMS.DEFAULT_THEME_NAME.equals(getName());
	}

	/**
	 * Configures the {@linkplain com.aoindustries.web.resources.servlet.RegistryEE.Request request-scope web resources} that this theme uses.
	 * 
	 * Implementers should call super.configureResources(…) as a matter of convention, despite this default implementation doing nothing.
	 * 
	 */
	public void configureResources(ServletContext servletContext, HttpServletRequest req, HttpServletResponse resp, View view, Page page, Registry requestRegistry) {
		// Do nothing
	}

	/**
	 * Renders the theme.
	 * 
	 * Both the {@link Serialization} and {@link Doctype} may have been set
	 * on the request, and these must be considered in the HTML generation.
	 * 
	 *
	 * @see SerializationEE#get(javax.servlet.ServletContext, javax.servlet.http.HttpServletRequest)
	 * @see DoctypeEE#get(javax.servlet.ServletContext, javax.servlet.ServletRequest)
	 *
	 * TODO: Is SkipPageException acceptable at the view rendering stage?
	 */
	abstract public void doTheme(
		ServletContext servletContext,
		HttpServletRequest request,
		HttpServletResponse response,
		View view,
		Page page
	) throws ServletException, IOException, SkipPageException;
}