//   Copyright 2012 Georg-August-Universität Göttingen, Germany
//
//   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 de.ugoe.cs.autoquest.plugin.html;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.xml.sax.SAXException;

import de.ugoe.cs.autoquest.eventcore.Event;
import de.ugoe.cs.autoquest.eventcore.IEventType;
import de.ugoe.cs.autoquest.eventcore.guimodel.GUIModel;
import de.ugoe.cs.autoquest.eventcore.guimodel.GUIModelException;
import de.ugoe.cs.autoquest.eventcore.guimodel.IGUIElement;
import de.ugoe.cs.autoquest.plugin.html.eventcore.HTMLEventTypeFactory;
import de.ugoe.cs.autoquest.plugin.html.guimodel.HTMLDocumentSpec;
import de.ugoe.cs.autoquest.plugin.html.guimodel.HTMLGUIElement;
import de.ugoe.cs.autoquest.plugin.html.guimodel.HTMLGUIElementSpec;
import de.ugoe.cs.autoquest.plugin.html.guimodel.HTMLPageElement;
import de.ugoe.cs.autoquest.plugin.html.guimodel.HTMLPageElementSpec;
import de.ugoe.cs.autoquest.plugin.html.guimodel.HTMLServerSpec;

/**
 * <p>
 * This class provides the functionality to parse XML log files generated by the HTMLMonitor of
 * AutoQUEST. The result of parsing a file is a collection of event sequences and a GUI model.
 * </p>
 * <p>
 * The parser can be configured with parsing parameters to ignore, e.g., ids or indexes of
 * parsed GUI elements. Details can be found in the manual pages of the respective parsing commands.
 * </p>
 * 
 * @author Fabian Glaser, Patrick Harms
 * @version 1.0
 * 
 */
public class HTMLLogParser extends AbstractDefaultLogParser {
    
    /**
     * <p>
     * the pattern used for parsing HTML GUI element paths
     * </p>
     */
    private Pattern htmlElementPattern =
        Pattern.compile("(\\w+)(\\[(\\d+)\\]|\\(htmlId=([\\w-]+)\\))");
    
    /**
     * <p>
     * the pattern used for parsing parsing parameters
     * </p>
     */
    private Pattern htmlElementSpecPattern =
        Pattern.compile("(\\w+)(\\[(\\d+)\\]|\\(htmlId=([\\w-#]+)\\))?");
    
    /**
     * <p>
     * parameters to influence parsing
     * </p>
     */
    private Map<String, List<String>> parseParams;

    /**
     * <p>
     * a map containing replacement specifications for ids of GUI elements
     * </p>
     */
    private Map<String, String> idReplacements;

    /**
     * <p>
     * initializes the parser with the parsing parameters to be considered
     * </p>
     *
     * @param parseParams the parsing parameters to be considered
     */
    public HTMLLogParser(Map<String, List<String>> parseParams) {
        this.parseParams = parseParams;
        
        for (String paramKey : parseParams.keySet()) {
            if (!"clearId".equals(paramKey) && !"clearIndex".equals(paramKey) &&
                !"idReplacements".equals(paramKey))
            {
                throw new IllegalArgumentException("unknown parse parameter key " + paramKey);
            }
        }
    }

    /* (non-Javadoc)
     * @see de.ugoe.cs.autoquest.plugin.html.AbstractDefaultLogParser#handleGUIElement(String, Map)
     */
    @Override
    protected boolean handleGUIElement(String id, Map<String, String> parameters)
        throws SAXException
    {
        HTMLGUIElementSpec specification = null;
        
        String parentId = parameters.get("parent");
        HTMLGUIElement parent = (HTMLGUIElement) super.getGUIElementTree().find(parentId);

        if (parameters.containsKey("host")) {
            // this is a server specification
            int port = 80;
            String portStr = parameters.get("port");
            
            if (portStr != null) {
                port = Integer.parseInt(portStr);
            }
            
            specification = new HTMLServerSpec(parameters.get("host"), port);
        }
        else if (parameters.containsKey("path")) {
            // this is a document specification
            
            if (parent != null) {
                if (!(parent.getSpecification() instanceof HTMLServerSpec)) {
                    throw new SAXException
                        ("invalid log: parent GUI element of a document is not of type server");
                }
                
                specification = new HTMLDocumentSpec
                    ((HTMLServerSpec) parent.getSpecification(), parameters.get("path"),
                     parameters.get("query"), parameters.get("title"));
            }
            else if (parentId == null) {
                throw new SAXException("invalid log: a document has no parent id");
            }
        }
        else if (parameters.containsKey("tagname")) {
            String tagName = parameters.get("tagname");
            
            if (!tagNameMustBeConsidered(tagName)) {
                return true;
            }

            if (parent != null) {
                if (!childrenMustBeConsidered(parent)) {
                    return true;
                }
                
                IGUIElement document = parent;
                
                while ((document != null) &&
                       (!(document.getSpecification() instanceof HTMLDocumentSpec)))
                {
                    document = document.getParent();
                }
                
                if (document == null) {
                    throw new SAXException
                        ("invalid log: parent hierarchy of a page element does not contain a " +
                         "document");
                }
                
                int index = -1;
                String indexStr = parameters.get("index");

                if ((indexStr != null) && (!"".equals(indexStr))) {
                    index = Integer.parseInt(indexStr);
                }
                
                String htmlId = parameters.get("htmlid");
                
                if (clearIndex(tagName, index, htmlId, parent)) {
                    index = -1;
                }
                
                String idReplacement = replaceHTMLId(tagName, index, htmlId, parent);
                if (idReplacement != null) {
                    htmlId = idReplacement;
                }
                else if (clearHTMLId(tagName, index, htmlId, parent)) {
                    htmlId = null;
                }
                
                if ((htmlId == null) && (index == -1)) {
                    // set at least a default index, if all is to be ignored.
                    index = 0;
                }

                specification = new HTMLPageElementSpec
                    ((HTMLDocumentSpec) document.getSpecification(),
                     tagName.intern(), htmlId == null ? null : htmlId.intern(), index);
                
            }
            else if (parentId == null) {
                throw new SAXException("invalid log: a page element has no parent id");
            }
        }
        else {
            throw new SAXException("invalid log: unknown GUI element");
        }

        if (specification != null) {
            try {
                super.getGUIElementTree().add(id, parentId, specification);
            }
            catch (GUIModelException e) {
                throw new SAXException("could not handle GUI element with id " +
                                       id + ": " + e.getMessage(), e);
            }
            return true;
        }
        else {
            return false;
        }
    }

    /**
     * <p>
     * checks if for a specific GUI element the index shall be ignored or not by considering the
     * parsing parameters.
     * </p>
     *
     * @param tagName the tag of the considered GUI element
     * @param index   the index of the GUI element
     * @param id      the id of the GUI element
     * @param parent  the parent GUI element of the considered GUI element
     * 
     * @return true if the index shall be ignored, false else.
     */
    private boolean clearIndex(String tagName, int index, String id, HTMLGUIElement parent) {
        return clearSomething("clearIndex", tagName, index, id, parent);
    }

    /**
     * <p>
     * checks if the parsing parameters define a replacement for the id of the given GUI element
     * and if so returns this replacement
     * </p>
     *
     * @param tagName the tag of the considered GUI element
     * @param index   the index of the GUI element
     * @param id      the id of the GUI element
     * @param parent  the parent GUI element of the considered GUI element
     * 
     * @return the identified replacement
     */
    private String replaceHTMLId(String tagName, int index, String htmlId, HTMLGUIElement parent)
        throws SAXException
    {
        if ((idReplacements == null) && (parseParams.containsKey("idReplacements"))) {
            idReplacements = new HashMap<String, String>();
            for (String fileName : parseParams.get("idReplacements")) {
                Properties props = new Properties();
                FileInputStream stream = null;
                try {
                    stream = new FileInputStream(new File(fileName));
                    props.load(stream);
                }
                catch (FileNotFoundException e) {
                    throw new SAXException("could not find file " + fileName, e);
                }
                catch (IOException e) {
                    throw new SAXException("error reading file " + fileName, e);
                }
                finally {
                    if (stream != null) {
                        try {
                            stream.close();
                        }
                        catch (IOException e) {
                            // ignore
                        }
                    }
                }
                
                for (Map.Entry<Object, Object> entry : props.entrySet()) {
                    idReplacements.put((String) entry.getKey(), (String) entry.getValue());
                }
            }
        }
        
        if (idReplacements != null) {
            for (Map.Entry<String, String> replacementSpec : idReplacements.entrySet()) {
                String tagSpec = replacementSpec.getKey();

                if (tagSpec.startsWith("/")) {
                    throw new IllegalArgumentException("can not handle absolute specifications");
                }
                else if (tagSpec.endsWith("/")) {
                    throw new IllegalArgumentException("specifications may not end with a /");
                }

                String[] tagSpecs = tagSpec.split("/");

                if (tagMatchesTagSpec(tagName, index, htmlId, parent, tagSpecs)) {
                    return replacementSpec.getValue();
                }
            }
        }
        
        return null;
    }

    /**
     * <p>
     * checks if for a specific GUI element the id shall be ignored or not by considering the
     * parsing parameters.
     * </p>
     *
     * @param tagName the tag of the considered GUI element
     * @param index   the index of the GUI element
     * @param id      the id of the GUI element
     * @param parent  the parent GUI element of the considered GUI element
     * 
     * @return true if the id shall be ignored, false else.
     */
    private boolean clearHTMLId(String tagName, int index, String id, HTMLGUIElement parent) {
        return clearSomething("clearId", tagName, index, id, parent);
    }
    
    /**
     * <p>
     * convenience method to check for the existence for specific parsing parameters for clearing
     * ids or indexes of GUI elements.
     * </p>
     *
     * @param parseParamId the id of the parsing parameter to be checked for the GUI element
     * @param tagName      the tag of the considered GUI element
     * @param index        the index of the GUI element
     * @param id           the id of the GUI element
     * @param parent       the parent GUI element of the considered GUI element
     * 
     * @return true if the denoted parse parameter is set to ignore, false else.
     */
    private boolean clearSomething(String         parseParamId,
                                   String         tagName,
                                   int            index,
                                   String         id,
                                   HTMLGUIElement parent)
    {
        if (parseParams.containsKey(parseParamId)) {
            for (String spec : parseParams.get(parseParamId)) {
                // determine the specification parts
                if (spec.startsWith("/")) {
                    throw new IllegalArgumentException("can not handle absolute specifications");
                }
                else if (spec.endsWith("/")) {
                    throw new IllegalArgumentException("specifications may not end with a /");
                }
                
                String[] tagSpecs = spec.split("/");
                
                if (tagMatchesTagSpec(tagName, index, id, parent, tagSpecs)) {
                    return true;
                }
            }
        }
        
        return false;
    }

    /**
     * <p>
     * convenience method to check if a given GUI element matches a specification tags provided
     * through the parsing parameters.
     * </p>
     *
     * @param tagName  the tag of the considered GUI element
     * @param index    the index of the GUI element
     * @param id       the id of the GUI element
     * @param parent   the parent GUI element of the considered GUI element
     * @param tagSpecs the specification of a GUI element to match against the given GUI element
     * 
     * @return true if the denoted parse parameter is set to ignore, false else.
     */
    private boolean tagMatchesTagSpec(String         tagName,
                                      int            index,
                                      String         id,
                                      HTMLGUIElement parent,
                                      String[]       tagSpecs)
    {
        
        if (tagSpecs.length > 0) {
            Matcher matcher = htmlElementSpecPattern.matcher(tagSpecs[tagSpecs.length - 1]);
            
            if (!matcher.matches()) {
                throw new IllegalArgumentException
                    ("illegal tag specification " + tagSpecs[tagSpecs.length - 1]);
            }
            
            if (!tagName.equals(matcher.group(1))) {
                return false;
            }
            
            String idCondition = matcher.group(4);
            
            if (idCondition != null) {
                if (!idCondition.equals(id)) {
                    // check if the id condition would match with ignoring specific characters
                    if ((id != null) && (idCondition.indexOf('#') > -1)) {
                        // first of all, the length must match
                        if (idCondition.length() != id.length()) {
                            return false;
                        }
                        
                        for (int i = 0; i < idCondition.length(); i++) {
                            if ((idCondition.charAt(i) != '#') &&
                                (idCondition.charAt(i) != id.charAt(i)))
                            {
                                // if there is a character that is neither ignored not matches
                                // the condition at a specific position, return "no match"
                                return false;
                            }
                        }
                        
                    }
                    else {
                        // no condition ignoring specific characters
                        return false;
                    }
                }
            }
            
            String indexCondition = matcher.group(3);
            
            if (indexCondition != null) {
                try {
                    if (index != Integer.parseInt(indexCondition)) {
                        return false;
                    }
                }
                catch (NumberFormatException e) {
                    throw new IllegalArgumentException
                        ("illegal tag index specification " + indexCondition, e);
                }
            }
            
            if (tagSpecs.length > 1) {
                if (parent instanceof HTMLPageElement) {
                    return tagMatchesTagSpec(((HTMLPageElement) parent).getTagName(),
                                             ((HTMLPageElement) parent).getIndex(),
                                             ((HTMLPageElement) parent).getHtmlId(),
                                             (HTMLGUIElement) parent.getParent(),
                                             Arrays.copyOfRange(tagSpecs, 0, tagSpecs.length - 1));
                }
                else {
                    throw new IllegalArgumentException
                        ("specification matches documents or servers. This is not supported yet.");
                }
            }
            else {
                return true;
            }
        }
        else {
            return true;
        }
    }

    /* (non-Javadoc)
     * @see de.ugoe.cs.autoquest.plugin.html.AbstractDefaultLogParser#handleEvent(String, Map)
     */
    @Override
    protected boolean handleEvent(String type, Map<String, String> parameters) throws SAXException {
        String targetId = parameters.get("target");
        
        if (targetId == null) {
            if (parseParams.size() != 0) {
                throw new SAXException
                    ("old log file versions can not be parsed with parse parameters");
            }
            
            String targetDocument = parameters.get("targetDocument");
            String targetDOMPath = parameters.get("targetDOMPath");
            
            if ((targetDocument == null) || (targetDOMPath == null)) {
                throw new SAXException("event has no target defined");
            }
            
            targetId = determineTargetId(targetDocument, targetDOMPath);
            
            if (targetId == null) {
                // the target id can not be determined yet
                return false;
            }
        }
        
        IGUIElement target = super.getGUIElementTree().find(targetId);
        
        if (target == null) {
            // event not processible yet
            return false;
        }

        IEventType eventType =
            HTMLEventTypeFactory.getInstance().getEventType(type, parameters, target);
        
        if (eventType != null) {
            Event event = new Event(eventType, target);

            String timestampStr = parameters.get("timestamp");
        
            if (timestampStr != null) {
                event.setTimestamp(Long.parseLong(timestampStr));
            }

            ((HTMLGUIElement) event.getTarget()).markUsed();
        
            super.addToSequence(event);
        }
        // else ignore unknown event type

        return true;
    }

    /**
     * <p>
     * used to determine the id of a target denoted by an event. This is only required for older
     * document formats. The new formats use concrete ids.
     * </p>
     */
    private String determineTargetId(String targetDocument, String targetDOMPath)
        throws SAXException
    {
        IGUIElement document = super.getGUIElementTree().find(targetDocument);
        
        if (document == null) {
            return null;
        }
        
        if (!(document.getSpecification() instanceof HTMLDocumentSpec)) {
            throw new SAXException("an id that should refer to an HTML document refers to" +
                                   "something else");
        }
        
        GUIModel model = super.getGUIElementTree().getGUIModel();
        IGUIElement child = document;
        String[] pathElements = targetDOMPath.split("/");
        int pathIndex = 0;
        
        HTMLPageElementSpec compareSpec;
        String tagName;
        int index;
        String htmlId;
        
        while ((pathIndex < pathElements.length) && (child != null)) {
            if ((pathElements[pathIndex] != null) && (!"".equals(pathElements[pathIndex]))) {           
                Matcher matcher = htmlElementPattern.matcher(pathElements[pathIndex]);
                if (!matcher.matches()) {
                    throw new SAXException
                        ("could not parse target DOM path element " + pathElements[pathIndex]);
                }

                tagName = matcher.group(1);
                String indexStr = matcher.group(3);
                htmlId = matcher.group(4);

                index = -1;
                if ((indexStr != null) && (!"".equals(indexStr))) {
                    index = Integer.parseInt(indexStr);
                }

                compareSpec = new HTMLPageElementSpec
                    ((HTMLDocumentSpec) document.getSpecification(), tagName, htmlId, index);

                List<IGUIElement> children = model.getChildren(child);
                child = null;

                for (IGUIElement candidate : children) {
                    if (compareSpec.getSimilarity(candidate.getSpecification())) {
                        child = candidate;
                        break;
                    }
                }
            }
            
            pathIndex++;
        }
        
        if (child != null) {
            return super.getGUIElementTree().find(child);
        }
        else {
            return null;
        }
    }

    /**
     * <p>
     * checks if tags with the provided name must be handled in the GUI model. As an example,
     * it is not necessary to handle "head" tags and anything included in them. 
     * </p>
     *
     * @param tagName the tag name to check
     * 
     * @return true, if the tag must be considered, false else
     */
    private boolean tagNameMustBeConsidered(String tagName) {
        if (!tagName.startsWith("input_")) {
            for (int i = 0; i < tagName.length(); i++) {
                // all known HTML tags are either letters or digits, but nothing else. Any GUI model
                // containing something different is proprietary and, therefore, ignored.
                if (!Character.isLetterOrDigit(tagName.charAt(i))) {
                    return false;
                }
            }
        }
        
        return
            !"head".equals(tagName) && !"title".equals(tagName) && !"script".equals(tagName) &&
            !"style".equals(tagName) && !"link".equals(tagName) && !"meta".equals(tagName) &&
            !"iframe".equals(tagName) && !"input_hidden".equals(tagName) &&
            !"option".equals(tagName) && !"tt".equals(tagName) && !"br".equals(tagName) &&
            !"colgroup".equals(tagName) && !"col".equals(tagName) && !"hr".equals(tagName) &&
            !"param".equals(tagName) && !"sfmsg".equals(tagName);

    }

    /**
     * <p>
     * checks if the children of a specified parent must be added to the GUI model or not.
     * </p>
     *
     * @param parent the parent tag to check
     * 
     * @return true, if the child of the tag must be considered, false else
     */
    private boolean childrenMustBeConsidered(HTMLGUIElement parent) {
        if (parent instanceof HTMLPageElement) {
            return !"svg".equals(((HTMLPageElement) parent).getTagName());
        }
        else {
            return true;
        }
    }

}