/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.clerezza.platform.content;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.locks.Lock;
import javax.ws.rs.HttpMethod;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.Response;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.TransformerFactoryConfigurationError;
import javax.xml.transform.dom.DOMResult;
import org.apache.clerezza.rdf.core.Literal;
import org.apache.clerezza.rdf.core.LiteralFactory;
import org.apache.clerezza.rdf.core.Resource;
import org.apache.clerezza.rdf.core.Triple;
import org.apache.clerezza.rdf.core.TripleCollection;
import org.apache.clerezza.rdf.core.UriRef;
import org.apache.clerezza.rdf.core.impl.TripleImpl;
import org.apache.clerezza.rdf.ontologies.DCTERMS;
import org.apache.clerezza.rdf.ontologies.HIERARCHY;
import org.apache.clerezza.rdf.ontologies.RDF;
import org.apache.clerezza.rdf.utils.GraphNode;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 *
 * @author agron
 */
class WebDavUtils {

    static final String infinite = "infinite";
    static final String prop = "prop";
    static final String allprop = "allprop";
    static final String propname = "propname";
    static final String propfind = "propfind";
    static final String proppatch = "propertyupdate";
    static final String set = "set";
    static final String remove = "remove";
    private static final String davUri = "DAV:";
    private static final String multistat = "multistatus";
    private static final String response = "response";
    private static final String href = "href";
    private static final String propstat = "propstat";
    private static final String status = "status";

    //WebDAV properties
    private static final String creationdate = "creationdate";
    private static final String displayname = "displayname";
    private static final String getcontentlanguage = "getcontentlanguage";
    private static final String getcontentlength = "getcontentlength";
    private static final String getcontenttype = "getcontenttype";
    private static final String getetag = "getetag";
    private static final String getlastmodified = "getlastmodified";
    private static final String lockdiscovery = "lockdiscovery";
    private static final String resourcetype = "resourcetype";
    private static final String supportedlock = "supportedlock";

    private static final List<String> davProps = new ArrayList<String>(Arrays.asList(
            creationdate, displayname, getcontentlanguage, getcontentlength,
            getcontenttype, getetag, getlastmodified, lockdiscovery,
            resourcetype, supportedlock));
    
    private static final List<String> protectedProps = new ArrayList<String>(Arrays.asList(
            creationdate, getcontentlength, getetag, getlastmodified,
            lockdiscovery, resourcetype, supportedlock));


    /**
     * Returns the {@link Node} from a given {@link Document}
     * @param doc
     * @param nodeName
     * @return null if Node wasen't found
     */
    static Node getNode(Document doc, String nodeName){
        NodeList nodes = doc.getElementsByTagNameNS(davUri, nodeName);
        if(nodes.getLength() == 1){
            return nodes.item(0);
        }
        return null;
    }

    /**
     * @param node
     * @return returns the first non Text node or null
     */
    static Node getFirstChild(Node node){
        NodeList nodeList = node.getChildNodes();
        for (int i = 0; i < nodeList.getLength(); i++) {
            if(nodeList.item(i).getLocalName() != null){
                return nodeList.item(i);
            }
        }
        return null;
    }

    /**
     * Converts a {@link Source} to a {@link Document}
     *
     * @throws ParserConfigurationException
     * @throws TransformerFactoryConfigurationError
     * @throws TransformerException
     */
    static Document sourceToDocument(Source body)
            throws ParserConfigurationException,
            TransformerFactoryConfigurationError, TransformerException {
        Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder()
                .newDocument();
        Transformer transformer = TransformerFactory.newInstance().newTransformer();
        DOMResult result = new DOMResult(doc);
        transformer.transform(body, result);
        return (Document) result.getNode();
    }

    /**
     * Returns the content of a requested header as a {@link String}
     *
     * @param headers
     * @param header
     *            header to be returned
     * @return returns <code>null</code> if the requested header is empty
     */
    static String getHeaderAsString(HttpHeaders headers, String header) {
        List<String> requestedHeader = headers.getRequestHeader(header);
        if(requestedHeader == null){
            return null;
        }
        Iterator<String> headerIterator = requestedHeader.iterator();
        if (headerIterator.hasNext()) {
            return headerIterator.next();
        } else {
            return null;
        }
    }

    /**
     * @param clazz
     * @return returns an ok Response with a DAV: and an ALLOW: header
     */
    static Response options(Class<?> clazz){
        Response.ResponseBuilder builder = Response.ok();
        builder.header("Dav", "1");
        Set<String> allow = new HashSet<String>();
        Method[] methods = clazz.getMethods();
        for (Method method : methods){
            for (Annotation annotation : method.getAnnotations()){
                HttpMethod httpMethod = annotation.annotationType()
                        .getAnnotation(HttpMethod.class);
                if(httpMethod != null){
                    allow.add(httpMethod.value());
                }
            }
        }
        if (allow.isEmpty()) {
            builder.header("Allow", "");
        } else {
            final Iterator<String> iterator = allow.iterator();
            final StringBuffer buffer = new StringBuffer(iterator.next());
            while (iterator.hasNext()) {
                buffer.append(", ");
                buffer.append(iterator.next());
            }
            builder.header("Allow", buffer.toString());
        }
        return builder.build();
    }

    /*------------------------------------------*
     * Putting the properties in a DOM Document *
     *------------------------------------------*/

    static Document createResponseDoc(Map<UriRef, PropertyMap> resultMap)
            throws ParserConfigurationException {
        Document responseDoc = DocumentBuilderFactory.newInstance().
                newDocumentBuilder().newDocument();
        Set<UriRef> nodeNameSet = resultMap.keySet();

        Element multistatElement = responseDoc.createElementNS(davUri,"D:" + multistat);
        // add multistat element to response
        responseDoc.appendChild(multistatElement);
        for (UriRef nodeName : nodeNameSet) {
            Element responseElement = responseDoc.createElementNS(davUri, "D:" + response);
            // add response element to response Document
            multistatElement.appendChild(responseElement);
            PropertyMap propertyMap = resultMap.get(nodeName);
            addElementsToResponse(propertyMap, responseElement, responseDoc, nodeName);
        }
        return responseDoc;
    }

    private static void addElementsToResponse(PropertyMap propertyMap,
            Element responseElement, Document responseDoc, UriRef nodeName) {
        Element hrefElement = responseDoc.createElementNS(davUri, "D:" + href);
        hrefElement.setTextContent(nodeName.getUnicodeString());
        // add hrefElement element to responseElement
        responseElement.appendChild(hrefElement);
        addPropsToPropstat(responseElement, propertyMap, responseDoc);

    }

    private static void addPropsToPropstat(Element responseElement, PropertyMap propertyMap,
            Document responseDoc) {
        Set<Property> props = propertyMap.keySet();
        Element propFoundElement = responseDoc.createElementNS(davUri, "D:" + prop);
        Element propNotFoundElement = responseDoc.createElementNS(davUri, "D:" + prop);
        for(Property propVal : props){
            String propName = propVal.prop;
            String ns = propVal.ns;
            String prf = ns.equalsIgnoreCase(davUri) ? "D:":"R:";
            String value = propertyMap.get(propVal);
            Element resultElement = responseDoc.createElementNS(ns, prf + propName);
            if(value != null){
                if (!(value.isEmpty())){
                    if (value.equals("collection")) {
                        resultElement.appendChild(responseDoc.createElementNS(
                                davUri, "D:collection"));
                    } else {
                        resultElement.setTextContent(value);
                    }
                }
                propFoundElement.appendChild(resultElement);
            } else {
                propNotFoundElement.appendChild(resultElement);
            }
        }
        Element propstatFoundElement = responseDoc.createElementNS(davUri,
                "D:" + propstat);
        Element statusFoundElement = responseDoc.createElementNS(davUri,
                "D:" + status);
        propstatFoundElement.appendChild(propFoundElement);
        statusFoundElement.setTextContent("HTTP/1.1 200 OK");
        propstatFoundElement.appendChild(statusFoundElement);
        responseElement.appendChild(propstatFoundElement);
        if(propNotFoundElement.hasChildNodes()){
            Element propstatNotFoundElement = responseDoc.createElementNS(davUri,
                    "D:" + propstat);
            Element statusNotFoundElement = responseDoc.createElementNS(davUri,
                    "D:" + status);
            propstatNotFoundElement.appendChild(propNotFoundElement);
            statusNotFoundElement.setTextContent("HTTP/1.1 404 Not Found");
            propstatNotFoundElement.appendChild(statusNotFoundElement);
            responseElement.appendChild(propstatNotFoundElement);
        }

    }

    /*------------------------------------------------------------*
     * Get the properties from the CollectionNode and its members *
     *------------------------------------------------------------*/

    static Map<UriRef, PropertyMap> getPropsByName(NodeList children,
            GraphNode node, String depthHeader, boolean includeValues) {
        List<Property> requestedUserProps = new ArrayList<Property>();
        List<Property> requestedDavProps = new ArrayList<Property>();

        for (int i = 0; i < children.getLength(); i++) {
            Node child = children.item(i);
            String localName = child.getLocalName();
            if(localName == null){
                continue;
            }
            String nsUri = child.getNamespaceURI();
            if (nsUri.equals(davUri)) {
                requestedDavProps.add(new Property(nsUri, localName));
            } else {
                requestedUserProps.add(new Property(nsUri, localName));
            }
        }
        Map<UriRef, PropertyMap> allprops = new HashMap<UriRef, PropertyMap>();

        if (node.hasProperty(RDF.type, HIERARCHY.Collection)) {
            return getCollectionProps(allprops, requestedUserProps, requestedDavProps,
                    node, depthHeader, includeValues);
        }else{
            addNodeProperties(allprops, requestedUserProps, requestedDavProps,
                    node, includeValues);
            return allprops;
        }

    }
    
    static Map<UriRef, PropertyMap> getCollectionProps(Map<UriRef, PropertyMap> allprops,
            List<Property> requestedUserProps, List<Property> requestedDavProps,
            GraphNode collection, String depthHeader, boolean includeValues) {
        if(allprops == null){
            allprops = new HashMap<UriRef, PropertyMap>();
        }
        addNodeProperties(allprops, requestedUserProps, requestedDavProps, collection,
                includeValues);
        if (depthHeader.equals("1") || depthHeader.equals(infinite)) {
            Iterator<GraphNode> membersIter = collection.getSubjectNodes(HIERARCHY.parent);
            List<GraphNode> members = new ArrayList<GraphNode>();
            while (membersIter.hasNext()) {
                members.add(membersIter.next());
            }
            addMemberProps(allprops, requestedUserProps, requestedDavProps, members,
                    depthHeader, includeValues);
        }
        return allprops;
    }

    private static void addMemberProps(Map<UriRef, PropertyMap> allprops,
            List<Property> requestedUserProps, List<Property> requestedDavProps,
            List<GraphNode> members, String depthHeader, boolean includeValues) {
        for (GraphNode member : members) {
            if (depthHeader.equals(infinite) && member.hasProperty(RDF.type, HIERARCHY.Collection)) {
                getCollectionProps(allprops, requestedUserProps, requestedDavProps,
                        member, depthHeader, includeValues);
            } else {
                addNodeProperties(allprops, requestedUserProps, requestedDavProps,
                        member,    includeValues);
            }
        }
    }

    static void addNodeProperties(Map<UriRef, PropertyMap> allprops,
            List<Property> requestedUserProps, List<Property> requestedDavProps,
            GraphNode node,    boolean includeValues) {

        if (requestedDavProps == null) {
            requestedDavProps = new ArrayList<Property>();
            for(String st : davProps){
                requestedDavProps.add(new Property(davUri, st));
            }
        }
        PropertyMap propertyMap = new PropertyMap();
        if (includeValues) {
            addDavProps(node, propertyMap, requestedDavProps);
            addUserProps(node, propertyMap, requestedUserProps);
        } else {
            addDavPropsWithoutValues(propertyMap);
            addUserPropsWithoutValues(node, propertyMap);
        }
        allprops.put((UriRef) node.getNode(), propertyMap);

    }

    private static void addUserProps(GraphNode node, PropertyMap propertyMap,
            List<Property> requestedProps) {
        Iterator<UriRef> userPropsIter;
        Lock readLock = node.readLock();
        readLock.lock(); 
        try {
            userPropsIter = node.getProperties();
        } finally {
            readLock.unlock();
        }
        Set<UriRef> userProps = new HashSet<UriRef>();
        while (userPropsIter.hasNext()) {
            userProps.add(userPropsIter.next());
        }
        userProps.remove(HIERARCHY.members);
        if (requestedProps != null) {
            for (Property requestedProp : requestedProps) {
                UriRef predicate = new UriRef(requestedProp.value());
                if (userProps.contains(predicate)) {
                    readLock.lock();
                    try {
                        Iterator<Resource> value = node.getObjects(predicate);
                        if (value.hasNext()) {
                            propertyMap.put(requestedProp, getValue(value.next()));
                        } else {
                            propertyMap.put(requestedProp, "");
                        }
                    } finally {
                        readLock.unlock();
                    }
                } else {
                    propertyMap.put(requestedProp, null);
                }
            }
        } else {
            for (UriRef uri : userProps) {
                String userProp = uri.getUnicodeString();
                int index = userProp.lastIndexOf("#");
                if (index == -1) {
                    index = userProp.lastIndexOf("/");
                }
                Property property = new Property(userProp.substring(0, index + 1),
                        userProp.substring(index + 1));

                Iterator<Resource> value = node.getObjects(uri);
                readLock.lock();
                try {
                    if (value.hasNext()) {
                        propertyMap.put(property, getValue(value.next()));
                    } else {
                        propertyMap.put(property, "");
                    }
                } finally {
                    readLock.unlock();
                }
            }
        }
    }

    private static void addUserPropsWithoutValues(GraphNode node,
            PropertyMap propertyMap) {
        Iterator<UriRef> userPropsIter;
        Lock readLock = node.readLock();
        readLock.lock();
        try {
            userPropsIter = node.getProperties();
        } finally {
            readLock.unlock();
        }
        Set<UriRef> userProps = new HashSet<UriRef>();
        while (userPropsIter.hasNext()) {
            userProps.add(userPropsIter.next());
        }
        userProps.remove(HIERARCHY.members);
        for (UriRef uri : userProps) {
            String userProp = uri.getUnicodeString();
            int index = userProp.lastIndexOf("#");
            if (index == -1) {
                index = userProp.lastIndexOf("/");
            }
            Property property = new Property(userProp.substring(0, index + 1),
                    userProp.substring(index + 1));
            propertyMap.put(property, "");
        }
    }

    /**
     * @param resource
     * @return returns the unicode string of an UriRef or the lexical form of a
     * Literal or the return value of a toString() on a BNode
     */
    private static String getValue(Resource resource){
        if(resource instanceof UriRef){
            return ((UriRef)resource).getUnicodeString();
        }else if(resource instanceof Literal){
            return ((Literal)resource).getLexicalForm();
        }else {
            return resource.toString();
        }
    }

    /**
     * FIXME find better implementation
     * @param node
     * @param propertyMap
     * @param includeValues
     * @param requestedProps
     */
    private static void addDavProps(GraphNode node, PropertyMap propertyMap,
            List<Property> requestedProps) {
        for (Property property : requestedProps) {
            if (davProps.contains(property.prop)) {
                if (property.prop.equalsIgnoreCase(displayname)) {
                    propertyMap.put(property, getLastSection(((UriRef)node.getNode()).getUnicodeString()));
                } else if (property.prop.equalsIgnoreCase(resourcetype)) {
                    if (node.hasProperty(RDF.type, HIERARCHY.Collection)) {
                        propertyMap.put(property, "collection");
                    } else {
                        propertyMap.put(property, "");
                    }
                } else if(property.prop.equalsIgnoreCase(creationdate)){
                    Lock readLock = node.readLock();
                    readLock.lock();
                    try {
                        Iterator<Resource> date = node.getObjects(DCTERMS.dateSubmitted);
                        if (date.hasNext()) {
                            String st = getValue(date.next());
                            propertyMap.put(property, st);
                        } else {
                            propertyMap.put(property, "");
                        }
                    } finally {
                        readLock.unlock();
                    }
                } else if(property.prop.equalsIgnoreCase(getlastmodified)){
                    Lock readLock = node.readLock();
                    readLock.lock();
                    try {
                        Iterator<Resource> date = node.getObjects(DCTERMS.modified);
                        if (date.hasNext()) {
                            String st = getValue(date.next());
                            propertyMap.put(property, st);
                        } else {
                            propertyMap.put(property, "");
                        }
                    } finally {
                        readLock.unlock();
                    }
                } else if(property.prop.equalsIgnoreCase(getcontenttype)){
                    Lock readLock = node.readLock();
                    readLock.lock();
                    try {
                        Iterator<Resource> mediaType = node.getObjects(DCTERMS.MediaType);
                        if (mediaType.hasNext()) {
                            String st = getValue(mediaType.next());
                            propertyMap.put(property, st);
                        } else {
                            propertyMap.put(property, "");
                        }
                    } finally {
                        readLock.unlock();
                    }
                } else {
                    propertyMap.put(property, "");
                }
            } else {
                propertyMap.put(property, null);
            }
        }
    }

    private static void addDavPropsWithoutValues(PropertyMap propertyMap) {
        for (String property : davProps) {
                propertyMap.put(new Property(davUri, property), "");
        }
    }

    /*-------------------*
     * Proppatch methods *
     *-------------------*/

    static Document modifyProperties(GraphNode hierarchyNode, NodeList propsToSet,
            NodeList propsToRemove) throws ParserConfigurationException {
        Document responseDoc = DocumentBuilderFactory.newInstance()
                    .newDocumentBuilder().newDocument();
        UriRef subject = (UriRef) hierarchyNode.getNode();
        Element hrefElement = responseDoc.createElementNS(davUri, href);
        hrefElement.setTextContent(subject.getUnicodeString());
        Element multistatus = responseDoc.createElementNS(davUri, multistat);
        Element responseElement = responseDoc.createElementNS(davUri, response);
        Element propOk = responseDoc.createElementNS(davUri, prop);
        Element propForbidden = responseDoc.createElementNS(davUri, prop);

        responseDoc.appendChild(multistatus);
        multistatus.appendChild(responseElement);
        responseElement.appendChild(hrefElement);

        Map<Property, String> setMap = getNodeListAsMap(propsToSet);
        Map<Property, String> removeMap = getNodeListAsMap(propsToRemove);
        TripleCollection contentGraph = hierarchyNode.getGraph();
        for(Map.Entry<Property, String> entry : setMap.entrySet()){
            Property property = entry.getKey();
            if(property.ns.equalsIgnoreCase(davUri)){
                if(protectedProps.contains(property.prop)){
                    propForbidden.appendChild(responseDoc
                            .createElementNS(davUri, property.prop));
                } else {
                    UriRef predicate = new UriRef(property.value());
                    Lock writeLock = hierarchyNode.writeLock();
                    writeLock.lock();
                    try {
                        Iterator<Resource> valIter = hierarchyNode.getObjects(predicate);
                        replaceProp(subject, predicate, valIter, contentGraph, entry);
                    } finally {
                        writeLock.unlock();
                    }
                    propOk.appendChild(responseDoc.createElementNS(davUri, property.prop));
                }
            } else {
                UriRef predicate = new UriRef(property.value());
                Lock writeLock = hierarchyNode.writeLock();
                writeLock.lock();
                try {
                    Iterator<Resource> valIter = hierarchyNode.getObjects(predicate);
                    replaceProp(subject, predicate, valIter, contentGraph, entry);
                } finally {
                    writeLock.unlock();
                }
                propOk.appendChild(responseDoc.createElementNS(property.ns, "R:" + property.prop));
            }
        }

        for(Map.Entry<Property, String> entry : removeMap.entrySet()){
            Property property = entry.getKey();
            if(davProps.contains(property.prop)){
                propForbidden.appendChild(responseDoc
                            .createElementNS(davUri, property.prop));
            } else {
                UriRef predicate = new UriRef(property.value());
                Lock writeLock = hierarchyNode.writeLock();
                writeLock.lock();
                try {
                    Iterator<Resource> valIter = hierarchyNode.getObjects(predicate);
                    Set<Triple> triplesToBeRemoved = new HashSet<Triple>();
                    while (valIter.hasNext()) {
                        triplesToBeRemoved.add(new TripleImpl(subject, predicate, valIter.next()));
                    }
                    contentGraph.removeAll(triplesToBeRemoved);
                } finally {
                    writeLock.unlock();
                }
                propOk.appendChild(responseDoc.createElementNS(property.ns, property.prop));

            }
        }

        if(propOk.hasChildNodes()){
            Element propstatOk = responseDoc.createElementNS(davUri, propstat);
            Element statusOk = responseDoc.createElementNS(davUri, status);
            responseElement.appendChild(propstatOk);
            propstatOk.appendChild(propOk);
            propstatOk.appendChild(statusOk);
            statusOk.setTextContent("HTTP/1.1 200 OK");
        }
        if(propForbidden.hasChildNodes()){
            Element propstatForbidden = responseDoc.createElementNS(davUri, propstat);
            Element statusForbidden = responseDoc.createElementNS(davUri, status);
            responseElement.appendChild(propstatForbidden);
            propstatForbidden.appendChild(propForbidden);
            propstatForbidden.appendChild(statusForbidden);
            statusForbidden.setTextContent("HTTP/1.1 403 Forbidden");
        }

        return responseDoc;
    }

    private static Map<Property, String> getNodeListAsMap(NodeList nodeList) {
        if (nodeList == null) {
            return new HashMap<Property, String>();
        }
        Map<Property, String> result = new HashMap<Property, String>();
        for (int i = 0; i < nodeList.getLength(); i++) {
            Node node = nodeList.item(i);
            String propName = node.getLocalName();
            if (propName != null) {
                String nsUri = node.getNamespaceURI();
                result.put(new Property(nsUri, propName), node.getTextContent());
            }
        }
        return result;
    }

    private static void replaceProp(UriRef subject, UriRef predicate,
            Iterator<Resource> valIter, TripleCollection contentGraph,
            Map.Entry<Property, String> entry) {
        LiteralFactory fac = LiteralFactory.getInstance();
        Set<Triple> triplesToBeRemoved = new HashSet<Triple>();
        if (valIter.hasNext()) {
            triplesToBeRemoved.add(new TripleImpl(subject, predicate, valIter.next()));
        }
        contentGraph.removeAll(triplesToBeRemoved);
        contentGraph.add(new TripleImpl(subject, predicate,
                fac.createTypedLiteral(entry.getValue())));
    }

    private static String getLastSection(String s) {
        return s.substring(s.lastIndexOf('/', s.length()-2));
    }

    /**
     * Helper class whicht is a {@link HashMap} that maps {@link Property} to a {@link String}
     * @author ali
     */
    @SuppressWarnings("serial")
    static class PropertyMap extends HashMap<Property, String> {
    }

    static class Property {
        final String ns;
        final String prop;

        public Property(String ns, String prop) {
            this.ns = ns;
            this.prop = prop;
        }

        public String value(){
            return ns+prop;
        }
    }

}
