/* 
    * Copyright 2012 Marek Romanowski
    * 
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    * 
    *   http://www.apache.org/licenses/LICENSE-2.0
    * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package pl.matsuo.maven.skins.msb4;
  
  import org.apache.maven.doxia.site.decoration.DecorationModel;
  import org.apache.maven.project.MavenProject;
  import org.apache.velocity.tools.ToolContext;
  import org.apache.velocity.tools.config.DefaultKey;
  import org.apache.velocity.tools.generic.SafeConfig;
  import org.apache.velocity.tools.generic.ValueParser;
  import org.codehaus.plexus.util.xml.Xpp3Dom;
  
  /**
   * An Apache Velocity tool that simplifies retrieval of custom configuration values for a
   * Maven Site.
   * <p>
   * The tool is configured to access Maven site configuration of a skin inside {@code <custom>}
   * element of site descriptor. It supports global properties (defined at skin level) and per-page
   * properties (defined in {@code <page><mypage>} element). The per-page properties override the
   * global ones.
   * </p>
   * <p>
   * A sample configuration would be like that:
   * </p>
   * 
   * <pre>
   * {@code
   * <custom>
   *   <msb4Skin>
   *     <prop1>value1</prop1>
   *     <prop2>
   *       <prop21>value2</prop21>
   *     </prop2>
   *     <pages>
   *       <mypage project="myproject">
   *         <prop1>override value1</prop1>
   *       </mypage>
   *     </pages>
   *   </msb4Skin>
   * </custom>
   * }
   * </pre>
   * <p>
   * To get the value of {@code prop1}, one would simply use {@code $config.prop1}. This would return
   * "override value1". Then {@code $config.prop2} would return "value2" - the global value.
   * </p>
   * <p>
   * The tool allows querying the value easily, falling back from page to global configuration to
   * {@code null}, if none is available. It also provides convenience accessors for common values.
   * </p>
   * <p>
   * Note
   * </p>
   * 
   * @author Andrius Velykis
   * @since 1.0
   */
  @DefaultKey("config")
  public class SkinConfigTool extends SafeConfig {
  
  	public static final String DEFAULT_KEY = "config";
  
  	/** By default use Msb4 skin configuration tag */
  	public static final String SKIN_KEY = "msb4Skin";
  
  	private String key = DEFAULT_KEY;
  	private String skinKey = SKIN_KEY;
  
  	/* Create dummy nodes to avoid null checks */
  	private Xpp3Dom globalProperties = new Xpp3Dom("");
  	private Xpp3Dom pageProperties = new Xpp3Dom("");
  	private String namespace = "";
  	
  	private String projectId = null;
  	private String fileId = null;
  //	private String fileShortId = null;
  
  	/**
  	 * {@inheritDoc}
  	 * 
  	 * @see SafeConfig#configure(ValueParser)
  	 */
  	@Override
  	protected void configure(ValueParser values) {
  		String altkey = values.getString("key");
  		if (altkey != null) {
 			setKey(altkey);
 		}
 
 		// allow changing skin key in the configuration
 		String altSkinKey = values.getString("skinKey");
 		if (altSkinKey != null) {
 			this.skinKey = altSkinKey;
 		}
 
 		// retrieve the decoration model from Velocity context
 		Object velocityContext = values.get("velocityContext");
 
 		if (!(velocityContext instanceof ToolContext)) {
 			return;
 		}
 
 		ToolContext ctxt = (ToolContext) velocityContext;
 		
 		Object projectObj = ctxt.get("project");
 		if (projectObj instanceof MavenProject) {
 			MavenProject project = (MavenProject) projectObj;
 			String artifactId = project.getArtifactId();
 			// use artifactId "sluggified" as the projectId
 			projectId = HtmlTool.slug(artifactId);
 		}
 		
 		// calculate the page ID from the current file name
 		Object currentFileObj = ctxt.get("currentFileName");
 		if (currentFileObj instanceof String) {
 
 			String currentFile = (String) currentFileObj;
 
 			// drop the extension
 			int lastDot = currentFile.lastIndexOf(".");
 			if (lastDot >= 0) {
 				currentFile = currentFile.substring(0, lastDot);
 			}
 			
 			// get the short ID (in case of nested files)
 //			String fileName = new File(currentFile).getName();
 //			fileShortId = HtmlTool.slug(fileName);
 			
 			// full file ID includes the nested dirs
 			// replace nesting "/" with "-"
 			fileId = HtmlTool.slug(currentFile.replace("/", "-").replace("\\", "-"));
 		}
 		
 		Object decorationObj = ctxt.get("decoration");
 
 		if (!(decorationObj instanceof DecorationModel)) {
 			return;
 		}
 
 		DecorationModel decoration = (DecorationModel) decorationObj;
 		Object customObj = decoration.getCustom();
 
 		if (!(customObj instanceof Xpp3Dom)) {
 			return;
 		}
 
 		// Now that we have the custom node, get the global properties
 		// under the skin tag
 		Xpp3Dom customNode = (Xpp3Dom) customObj;
 		Xpp3Dom skinNode = customNode.getChild(skinKey);
 		String namespaceKey = ":" + skinKey;
 		
 		if (skinNode == null) {
 			// try searching with any namespace
 			for (Xpp3Dom child : customNode.getChildren()) {
 				if (child.getName().endsWith(namespaceKey)) {
 					skinNode = child;
 					break;
 				}
 			}
 		}
 		
 		if (skinNode != null) {
 			globalProperties = skinNode;
 			
 			if (skinNode.getName().endsWith(namespaceKey)) {
 				// extract the namespace (including the colon)
 				namespace = skinNode.getName().substring(0, skinNode.getName().length() - namespaceKey.length() + 1);
 			}
 
 			// for page properties, retrieve the file name and drop the `.html`
 			// extension - this will be used, i.e. `index` instead of `index.html`
 			Xpp3Dom pagesNode = getChild(skinNode, "pages");
 			if (pagesNode != null) {
 
 				// Get the page for the file
 				// TODO try fileShortId as well?
 				Xpp3Dom page = getChild(pagesNode, fileId);
 
 				// Now check if the project artifact ID is set, and if so, if it matches the
 				// current project. This allows preventing accidental reuse of parent page
 				// configs in children modules
 				if (page != null && projectId != null) {
 					String pageProject = page.getAttribute("project");
 					if (pageProject != null && !projectId.equals(pageProject)) {
 						// project ID indicated, and is different - do not use the config
 						page = null;
 					}
 				}
 
 				if (page != null) {
 					pageProperties = page;
 				}
 			}
 		}
 	}
 	
 	/**
 	 * Retrieves the child node. Tests both default name and with namespace.
 	 * 
 	 * @param parentNode
 	 * @param name
 	 * @return value
 	 */
 	private Xpp3Dom getChild(Xpp3Dom parentNode, String name) {
 		Xpp3Dom child = parentNode.getChild(name);
 		if (child != null) {
 			return child;
 		}
 		
 		return parentNode.getChild(namespace + name);
 	}
 
 	/**
 	 * Sets the key under which this tool has been configured.
 	 * 
 	 * @param key sets key
 	 * @since 1.0
 	 */
 	protected void setKey(String key) {
 		if (key == null) {
 			throw new NullPointerException("SkinConfigTool key cannot be null");
 		}
 		this.key = key;
 	}
 
 	/**
 	 * Should return the key under which this tool has been configured. The default is `config`.
 	 * 
 	 * @return key
 	 * @since 1.0
 	 */
 	public String getKey() {
 		return this.key;
 	}
 
 	/**
 	 * Default accessor for config properties. Instead of using {@code $config.get("myproperty")},
 	 * one can utilise Velocity fallback onto the default getter and use {@code $config.myproperty}.
 	 * 
 	 * @param property
 	 *            the property of interest
 	 * @return configuration node if found in the following sequence:
 	 *         <ol>
 	 *         <li>In page configuration</li>
 	 *         <li>In global configuration</li>
 	 *         <li>{@code null} otherwise</li>
 	 *         </ol>
 	 * @since 1.0
 	 */
 	public Xpp3Dom get(String property) {
 
 		// first try page properties
 		Xpp3Dom propNode = getChild(pageProperties, property);
 		if (propNode == null) {
 			// try global
 			propNode = getChild(globalProperties, property);
 		}
 
 		return propNode;
 	}
 
 	/**
 	 * Retrieves the text value of the given {@code property}, e.g. as in
 	 * {@code <myprop>value</myprop>}.
 	 * 
 	 * @param property
 	 *            the property of interest
 	 * @return the configuration value if found in page or globally, {@code null} otherwise.
 	 * @see #get(String)
 	 * @since 1.0
 	 */
 	public String value(String property) {
 
 		Xpp3Dom propNode = get(property);
 
 		if (propNode == null) {
 			// not found
 			return null;
 		}
 
 		return propNode.getValue();
 	}
 
 	/**
 	 * A convenience method to check if the value of the {@code property} is {@code "true"}.
 	 * 
 	 * @param property
 	 *            the property of interest
 	 * @return {@code true} if the configuration value is set either in page or globally, and is
 	 *         equal to {@code "true"}.
 	 * @see #get(String)
 	 * @since 1.0
 	 */
 	public boolean is(String property) {
 		return "true".equals(value(property));
 	}
 
 	/**
 	 * A convenience method to check if the value of the {@code property} is {@code "false"}. Useful
 	 * for properties that are enabled by default - checks if the property is set to {@code "false"}
 	 * explicitly.
 	 * 
 	 * @param property
 	 *            the property of interest
 	 * @return {@code true} if the configuration value is set either in page or globally, and is
 	 *         equal to {@code "false"}. Note that this will return {@code false} if property is not
 	 *         set at all.
 	 * @see #get(String)
 	 * @since 1.0
 	 */
 	public boolean not(String property) {
 		return "false".equals(value(property));
 	}
 
 	/**
 	 * A convenience method to check if the {@code property} is set to a specific value.
 	 * 
 	 * @param property
 	 *            the property of interest
 	 * @param value
 	 *            the property value to check
 	 * @return {@code true} if the configuration value is set either in page or globally, and is
 	 *         equal to {@code value}.
 	 * @see #get(String)
 	 * @since 1.0
 	 */
 	public boolean isValue(String property, String value) {
 		return value != null && value.equals(value(property));
 	}
 	
 	public String getProjectId() {
 		return projectId;
 	}
 	
 	public String getFileId() {
 		return fileId;
 	}
 
 }