package org.greenstone.gsdl3.core;

import org.greenstone.gsdl3.util.*;
import org.greenstone.gsdl3.action.*;
// XML classes
import org.w3c.dom.Node; 
import org.w3c.dom.NodeList; 
import org.w3c.dom.Document; 
import org.w3c.dom.Element;
import org.xml.sax.InputSource;

// other java classes
import java.io.File;
import java.io.StringWriter;
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.util.HashMap;
import java.util.Enumeration;

import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.*;
import javax.xml.transform.stream.*;
import org.apache.log4j.*;
import org.apache.xerces.dom.*;
import org.apache.xerces.parsers.DOMParser;

/** A receptionist that uses xslt to transform the page_data before returning it. . Receives requests consisting
 * of an xml representation of cgi args, and returns the page of data - in 
 * html by default. The requests are processed by the appropriate action class
 *
 * @see Action
 */
public class TransformingReceptionist extends Receptionist{
    
    static Logger logger = Logger.getLogger(org.greenstone.gsdl3.core.TransformingReceptionist.class.getName());
	
	/** The preprocess.xsl file is in a fixed location */
	static final String preprocess_xsl_filename = GlobalProperties.getGSDL3Home() + File.separatorChar 
		+ "ui" + File.separatorChar + "xslt" + File.separatorChar + "preProcess.xsl";	
		
    /** the list of xslt to use for actions */
    protected HashMap xslt_map = null;
    
    /** a transformer class to transform xml using xslt */
    protected XMLTransformer transformer=null;

	protected TransformerFactory transformerFactory=null;
	protected DOMParser parser = null;
    public TransformingReceptionist() {
	super();
	this.xslt_map = new HashMap();
	this.transformer = new XMLTransformer();
		try {
			transformerFactory = org.apache.xalan.processor.TransformerFactoryImpl.newInstance();
			this.converter = new XMLConverter();
			//transformerFactory.setURIResolver(new MyUriResolver()) ;

			parser = new DOMParser();
			parser.setFeature("http://xml.org/sax/features/validation", false);
			// don't try and load external DTD - no need if we are not validating, and may cause connection errors if a proxy is not set up.
			parser.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
			// a performance test showed that having this on lead to increased 
			// memory use for small-medium docs, and not much gain for large 
			// docs.
			// http://www.sosnoski.com/opensrc/xmlbench/conclusions.html
			parser.setFeature("http://apache.org/xml/features/dom/defer-node-expansion", false);
			parser.setFeature("http://apache.org/xml/features/continue-after-fatal-error", true);
			// setting a handler for when fatal errors, errors or warnings happen during xml parsing
			// call XMLConverter's getParseErrorMessage() to get the errorstring that can be rendered as web page
			this.parser.setErrorHandler(new XMLConverter.ParseErrorHandler());
		}
		catch (Exception e) {
			e.printStackTrace();
		}

    }
    
    /** configures the receptionist - overwrite this to set up the xslt map*/
    public boolean configure() {
	
		if (this.config_params==null) {
		    logger.error(" config variables must be set before calling configure");
		    return false;
		}
		if (this.mr==null) {	   
		    logger.error(" message router must be set  before calling configure");
		    return false;
		}
		
		// find the config file containing a list of actions
		File interface_config_file = new File(GSFile.interfaceConfigFile(GSFile.interfaceHome(GlobalProperties.getGSDL3Home(), (String)this.config_params.get(GSConstants.INTERFACE_NAME))));
		if (!interface_config_file.exists()) {
		    logger.error(" interface config file: "+interface_config_file.getPath()+" not found!");
		    return false;
		}
		Document config_doc = this.converter.getDOM(interface_config_file, "utf-8");
		if (config_doc == null) {
		    logger.error(" could not parse interface config file: "+interface_config_file.getPath());
		    return false;
		}
		Element config_elem = config_doc.getDocumentElement();
		String base_interface = config_elem.getAttribute("baseInterface");
		setUpBaseInterface(base_interface);
		setUpInterfaceOptions(config_elem);

		Element action_list = (Element)GSXML.getChildByTagName(config_elem, GSXML.ACTION_ELEM+GSXML.LIST_MODIFIER);
		NodeList actions = action_list.getElementsByTagName(GSXML.ACTION_ELEM);

		for (int i=0; i<actions.getLength(); i++) {
		    Element action = (Element) actions.item(i);
		    String class_name = action.getAttribute("class");
		    String action_name = action.getAttribute("name");
		    Action ac = null;
		    try {
				ac = (Action)Class.forName("org.greenstone.gsdl3.action."+class_name).newInstance();
		    } catch (Exception e) {
				logger.error(" couldn't load in action "+class_name);
				e.printStackTrace();
				continue;
		    }
		    ac.setConfigParams(this.config_params);
		    ac.setMessageRouter(this.mr);
		    ac.configure();
		    ac.getActionParameters(this.params);
		    this.action_map.put(action_name, ac);

		    // now do the xslt map
		    String xslt = action.getAttribute("xslt");
		    if (!xslt.equals("")) {
				this.xslt_map.put(action_name, xslt);
		    }
		    NodeList subactions = action.getElementsByTagName(GSXML.SUBACTION_ELEM);
		    for (int j=0; j<subactions.getLength(); j++) {
				Element subaction = (Element)subactions.item(j);
				String subname = subaction.getAttribute(GSXML.NAME_ATT);
				String subxslt = subaction.getAttribute("xslt");
				
				String map_key = action_name+":"+subname;
				logger.debug("adding in to xslt map, "+map_key+"->"+subxslt);
				this.xslt_map.put(map_key, subxslt);
		    }
		}
		Element lang_list = (Element)GSXML.getChildByTagName(config_elem, "languageList");
		if (lang_list == null) {
		    logger.error(" didn't find a language list in the config file!!");
		} else {
		    this.language_list = (Element) this.doc.importNode(lang_list, true);
		}

		return true;
    }


    protected Node postProcessPage(Element page) {
		// might need to add some data to the page
		addExtraInfo(page);
		// transform the page using xslt
		Node transformed_page = transformPage(page);
		
		return transformed_page;
    }
    
    /** overwrite this to add any extra info that might be needed in the page before transformation */
    protected void addExtraInfo(Element page) {}

    /** transform the page using xslt
	     * we need to get any format element out of the page and add it to the xslt
	     * before transforming */
    protected Node transformPage(Element page) {

		logger.debug("page before transfomring:");
		logger.debug(this.converter.getPrettyString(page));

		Element request = (Element)GSXML.getChildByTagName(page, GSXML.PAGE_REQUEST_ELEM);
		String action = request.getAttribute(GSXML.ACTION_ATT);
		String subaction = request.getAttribute(GSXML.SUBACTION_ATT);
		
		String output = request.getAttribute(GSXML.OUTPUT_ATT);
		// we should choose how to transform the data based on output, eg diff
		// choice for html, and wml??
		// for now, if output=xml, we don't transform the page, we just return 
		// the page xml
		if (output.equals("xml")) {
		    return page;
		}
		

		Element cgi_param_list = (Element)GSXML.getChildByTagName(request, GSXML.PARAM_ELEM+GSXML.LIST_MODIFIER);
		String collection = "";
		if (cgi_param_list != null) {
		    HashMap params = GSXML.extractParams(cgi_param_list, false);
		    collection = (String)params.get(GSParams.COLLECTION);
		    if (collection == null) collection = "";
		}
		
		String xslt_file = getXSLTFileName(action, subaction, collection);
		if (xslt_file==null) {
			// returning file not found error page to indicate which file is missing
			return fileNotFoundErrorPage(xslt_file);
		}
		
		Document style_doc = this.converter.getDOM(new File(xslt_file), "UTF-8");
		String errorPage = this.converter.getParseErrorMessage();
		if(errorPage != null) {
			return XMLTransformer.constructErrorXHTMLPage(
				"Cannot parse the xslt file: " + xslt_file + "\n" + errorPage);
		}
		if (style_doc == null) {
		    logger.error(" cant parse the xslt file needed, so returning the original page!");
		    return page;
		}
		
		// put the page into a document - this is necessary for xslt to get
		// the paths right if you have paths relative to the document root
		// eg /page.
		Document doc = this.converter.newDOM();
		doc.appendChild(doc.importNode(page, true));
		Element page_response = (Element)GSXML.getChildByTagName(page, GSXML.PAGE_RESPONSE_ELEM);
		Element format_elem = (Element)GSXML.getChildByTagName(page_response, GSXML.FORMAT_ELEM);
		if (output.equals("formatelem")) {
			return format_elem;
		}
		if (format_elem != null) {
			//page_response.removeChild(format_elem);
			logger.debug("format elem="+this.converter.getPrettyString(format_elem));
			// need to transform the format info
			String configStylesheet_file = GSFile.stylesheetFile(GlobalProperties.getGSDL3Home(), (String)this.config_params.get(GSConstants.SITE_NAME), collection, (String)this.config_params.get(GSConstants.INTERFACE_NAME), base_interfaces,   "config_format.xsl");
			Document configStylesheet_doc = this.converter.getDOM(new File(configStylesheet_file));
			if (configStylesheet_doc != null) {
				Document format_doc = this.converter.newDOM();
				format_doc.appendChild(format_doc.importNode(format_elem, true));
				Node result = this.transformer.transform(configStylesheet_doc, format_doc);
				
				// Since we started creating documents with DocTypes, we can end up with 
				// Document objects here. But we will be working with an Element instead, 
				// so we grab the DocumentElement() of the Document object in such a case.
				Element new_format;
				if(result.getNodeType() == Node.DOCUMENT_NODE) {
					new_format = ((Document)result).getDocumentElement();
				} else {
					new_format = (Element)result;
				}
				logger.debug("new format elem="+this.converter.getPrettyString(new_format));
				if (output.equals("newformat")) {
					return new_format;
				}
				
				// add extracted GSF statements in to the main stylesheet
				GSXSLT.mergeStylesheets(style_doc, new_format);
				//System.out.println("added extracted GSF statements into the main stylesheet") ;
				
				// add extracted GSF statements in to the debug test stylesheet
				//GSXSLT.mergeStylesheets(oldStyle_doc, new_format);
			} else {
				logger.error(" couldn't parse the config_format stylesheet, adding the format info as is");
				GSXSLT.mergeStylesheets(style_doc, format_elem);
			//	GSXSLT.mergeStylesheets(oldStyle_doc, format_elem);
			}
			logger.debug("the converted stylesheet is:");
			logger.debug(this.converter.getPrettyString(style_doc.getDocumentElement()));
		}
		//for debug purposes only
		Document oldStyle_doc = style_doc;


		Document preprocessingXsl  ;
		try {
			preprocessingXsl = getPreprocessDoc();
			String errMsg = ((XMLConverter.ParseErrorHandler)parser.getErrorHandler()).getErrorMessage();
			if(errMsg != null) {
				return XMLTransformer.constructErrorXHTMLPage("error loading preprocess xslt file: " 
				+ preprocess_xsl_filename + "\n" + errMsg);
			} 
		} catch (java.io.FileNotFoundException e) {
			return fileNotFoundErrorPage(e.getMessage());
		} catch (Exception e) {
			e.printStackTrace() ;
			System.out.println("error loading preprocess xslt") ;
			return XMLTransformer.constructErrorXHTMLPage("error loading preprocess xslt\n" + e.getMessage());
		}

		Document libraryXsl = null;
		try {
			libraryXsl = getLibraryDoc() ;
			String errMsg = ((XMLConverter.ParseErrorHandler)parser.getErrorHandler()).getErrorMessage();
			if(errMsg != null) {
				return XMLTransformer.constructErrorXHTMLPage("Error loading xslt file: " 
				+ this.getLibraryXSLFilename() + "\n" + errMsg);
			} 
		} catch (java.io.FileNotFoundException e) {
			return fileNotFoundErrorPage(e.getMessage());
		} catch (Exception e) {
			e.printStackTrace() ;
			System.out.println("error loading library xslt") ;
			return XMLTransformer.constructErrorXHTMLPage("error loading library xslt\n" + e.getMessage()) ;
		}
		
		//   Combine the skin file and library variables/templates into one document. 
		//   Please note: We dont just use xsl:import because the preprocessing stage  
		//   needs to know what's available in the library.

		Document skinAndLibraryXsl = null ;
		Document skinAndLibraryDoc = converter.newDOM();
		try {
			
			skinAndLibraryXsl = converter.newDOM();
			Element root = skinAndLibraryXsl.createElement("skinAndLibraryXsl") ;
			skinAndLibraryXsl.appendChild(root) ;
			
			Element s = skinAndLibraryXsl.createElement("skinXsl") ;
			s.appendChild(skinAndLibraryXsl.importNode(style_doc.getDocumentElement(), true)) ;
			root.appendChild(s) ;
			
			Element l = skinAndLibraryXsl.createElement("libraryXsl") ;
			Element libraryXsl_el = libraryXsl.getDocumentElement();
			l.appendChild(skinAndLibraryXsl.importNode(libraryXsl_el, true)) ;
			root.appendChild(l) ;
			//System.out.println("Skin and Library XSL are now together") ;
			
			
			//System.out.println("Pre-processing the skin file...") ;
			
			//pre-process the skin style sheet
			//In other words, apply the preProcess.xsl to 'skinAndLibraryXsl' in order to
			//expand all GS-Lib statements into complete XSL statements and also to create
			//a valid  xsl style sheet document.

			Transformer preProcessor = transformerFactory.newTransformer(new DOMSource(preprocessingXsl));
			preProcessor.setErrorListener(new XMLTransformer.TransformErrorListener());
			DOMResult result = new DOMResult();
			result.setNode(skinAndLibraryDoc);
			preProcessor.transform(new DOMSource(skinAndLibraryXsl), result);
			//System.out.println("GS-Lib statements are now expanded") ;		
			
		}	
		catch (TransformerException e) {
			e.printStackTrace() ;
			System.out.println("TransformerException while preprocessing the skin xslt") ;
			return XMLTransformer.constructErrorXHTMLPage(e.getMessage()) ;
		}
		catch (Exception e) {
			e.printStackTrace() ;
			System.out.println("Error while preprocessing the skin xslt") ;
			return XMLTransformer.constructErrorXHTMLPage(e.getMessage()) ;
		}
	
	// there is a thing called a URIResolver which you can set for a
	// transformer or transformer factory. may be able to use this
	// instead of this absoluteIncludepaths hack

		GSXSLT.absoluteIncludePaths(skinAndLibraryDoc, GlobalProperties.getGSDL3Home(), 
				(String)this.config_params.get(GSConstants.SITE_NAME), 
				collection, (String)this.config_params.get(GSConstants.INTERFACE_NAME), 
				base_interfaces);


		//Same but for the debug version when we want the do the transformation like we use to do
		//without any gslib elements.
		GSXSLT.absoluteIncludePaths(oldStyle_doc, GlobalProperties.getGSDL3Home(), 
				(String)this.config_params.get(GSConstants.SITE_NAME), 
				collection, (String)this.config_params.get(GSConstants.INTERFACE_NAME), 
				base_interfaces);
				
		//Send different stages of the skin xslt to the browser for debug purposes only
		//using &o=skindoc or &o=skinandlib etc...
		if (output.equals("skindoc")) {
			return converter.getDOM(getStringFromDocument(style_doc));
		}
		if (output.equals("skinandlib")) {
			return converter.getDOM(getStringFromDocument(skinAndLibraryXsl));
		}
		if (output.equals("skinandlibdoc")) {
			return converter.getDOM(getStringFromDocument(skinAndLibraryDoc));
		}
		if (output.equals("oldskindoc")) {
			return converter.getDOM(getStringFromDocument(oldStyle_doc));
		}

		// DocType defaults in case the skin doesn't have an "xsl:output" element
		String qualifiedName = "html";
		String publicID = "-//W3C//DTD HTML 4.01 Transitional//EN";
		String systemID = "http://www.w3.org/TR/html4/loose.dtd";
		
		// Try to get the system and public ID from the current skin xsl document
		// otherwise keep the default values.
		Element root = skinAndLibraryDoc.getDocumentElement();
		NodeList nodes = root.getElementsByTagName("xsl:output");
		// If there is at least one "xsl:output" command in the final xsl then...
		if(nodes.getLength() != 0) {
			// There should be only one element called xsl:output, 
			// but if this is not the case get the last one
			Element xsl_output = (Element)nodes.item(nodes.getLength()-1);
			if (xsl_output != null) {
				// Qualified name will always be html even for xhtml pages
				//String attrValue = xsl_output.getAttribute("method");
				//qualifiedName = attrValue.equals("") ? qualifiedName : attrValue;
				
				String attrValue = xsl_output.getAttribute("doctype-system");
				systemID = attrValue.equals("") ? systemID : attrValue;
				
				attrValue = xsl_output.getAttribute("doctype-public");
				publicID = attrValue.equals("") ? publicID : attrValue;
			}
		}
		
		// We need to create an empty document with a predefined DocType,
		// that will then be used for the transformation by the DOMResult
		Document docWithDoctype = converter.newDOM(qualifiedName, publicID, systemID);
		
		//System.out.println(converter.getPrettyString(docWithDoctype));
		//System.out.println("Doctype vals: " + qualifiedName + " " + publicID + " " + systemID) ;
		
		//System.out.println("Generate final HTML from current skin") ;
		//Transformation of the XML message from the receptionist to HTML with doctype
		return this.transformer.transform(skinAndLibraryDoc, doc, config_params, docWithDoctype);
		
		
		// The line below will do the transformation like we use to do before having Skin++ implemented,
		// it will not contain any GS-Lib statements expanded, and the result will not contain any doctype.

		//return (Element)this.transformer.transform(style_doc, doc, config_params);  

	}
	
	
	// method to convert Document to a proper XML string for debug purposes only
	protected String getStringFromDocument(Document doc)
	{
		String content = "";
	    try
	    {
	       DOMSource domSource = new DOMSource(doc);
	       StringWriter writer = new StringWriter();
	       StreamResult result = new StreamResult(writer);
	       TransformerFactory tf = TransformerFactory.newInstance();
	       Transformer transformer = tf.newTransformer();
	       transformer.transform(domSource, result);
	       content = writer.toString();
	       System.out.println("Change the & to &Amp; for proper debug dispay") ;
	       content = content.replaceAll("&", "&amp;");
	       writer.flush();
	    }
	    catch(TransformerException ex)
	    {
	       ex.printStackTrace();
	       return null;
	    }
	    return content;
	} 


	protected Document getPreprocessDoc() throws Exception {

		File xslt_file = new File(preprocess_xsl_filename) ;

		FileReader reader = new FileReader(xslt_file);
		InputSource xml_source = new InputSource(reader);
		this.parser.parse(xml_source);
		Document doc = this.parser.getDocument();

		return doc ;		
	}

	protected Document getLibraryDoc() throws Exception {
		Document doc = null;
		File xslt_file = new File(this.getLibraryXSLFilename()) ;

		FileReader reader = new FileReader(xslt_file);
		InputSource xml_source = new InputSource(reader);
		this.parser.parse(xml_source);
		
		doc = this.parser.getDocument();
		return doc ;		
	}   

	protected String getXSLTFileName(String action, String subaction,
				    String collection) {

	String name = null;
	if (!subaction.equals("")) {
	    String key = action+":"+subaction;
	    name = (String) this.xslt_map.get(key);
	}
	// try the action by itself
	if (name==null) {
	    name = (String) this.xslt_map.get(action);
	}
	// now find the absolute path
	String stylesheet = GSFile.stylesheetFile(GlobalProperties.getGSDL3Home(), (String)this.config_params.get(GSConstants.SITE_NAME), collection, (String)this.config_params.get(GSConstants.INTERFACE_NAME), base_interfaces, name);
	if (stylesheet==null) {
	    logger.info(" cant find stylesheet for "+name);
	}
	return stylesheet;
    }

	// returns the library.xsl path of the library file that is applicable for the current interface
	protected String getLibraryXSLFilename() {
		return GSFile.xmlTransformDir(GSFile.interfaceHome(
			GlobalProperties.getGSDL3Home(), (String)this.config_params.get(GSConstants.INTERFACE_NAME)))
			+ File.separatorChar + "library.xsl";
	}
	
	// Call this when a FileNotFoundException could be thrown when loading an xsl (xml) file.
	// Returns an error xhtml page indicating which xsl (or other xml) file is missing.
	protected Document fileNotFoundErrorPage(String filenameMessage) {
		String errorMessage = "ERROR missing file: " + filenameMessage;
		Element errPage = XMLTransformer.constructErrorXHTMLPage(errorMessage);
		logger.error(errorMessage);
		System.err.println("****" + errorMessage);
		return errPage.getOwnerDocument();
	}
}