/*
 * 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.sling.jcr.jackrabbit.accessmanager.post;

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import javax.jcr.RepositoryException;
import javax.jcr.Session;
import javax.jcr.security.AccessControlList;
import javax.jcr.security.AccessControlManager;
import javax.jcr.security.AccessControlPolicy;
import javax.jcr.security.AccessControlPolicyIterator;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.request.header.MediaRangeList;
import org.apache.sling.api.resource.ResourceNotFoundException;
import org.apache.sling.api.resource.ResourceUtil;
import org.apache.sling.api.servlets.SlingAllMethodsServlet;
import org.apache.sling.api.wrappers.SlingRequestPaths;
import org.apache.sling.jcr.jackrabbit.accessmanager.impl.PrincipalAceHelper;
import org.apache.sling.servlets.post.AbstractPostResponse;
import org.apache.sling.servlets.post.HtmlResponse;
import org.apache.sling.servlets.post.JSONResponse;
import org.apache.sling.servlets.post.Modification;
import org.apache.sling.servlets.post.PostResponse;
import org.apache.sling.servlets.post.PostResponseCreator;
import org.apache.sling.servlets.post.SlingPostConstants;
import org.jetbrains.annotations.Nullable;
import org.osgi.framework.Constants;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Base class for all the POST servlets for the AccessManager operations
 */
public abstract class AbstractAccessPostServlet extends SlingAllMethodsServlet {
    private static final long serialVersionUID = -5918670409789895333L;

    /**
     * default log
     */
    private final transient Logger log = LoggerFactory.getLogger(getClass());

    /** Sorted list of post response creator holders. */
    private final List<PostResponseCreatorHolder> postResponseCreators = new ArrayList<>();

    /** Cached array of post response creators used during request processing. */
    private transient PostResponseCreator[] cachedPostResponseCreators = new PostResponseCreator[0];


    /* (non-Javadoc)
     * @see org.apache.sling.api.servlets.SlingAllMethodsServlet#doPost(org.apache.sling.api.SlingHttpServletRequest, org.apache.sling.api.SlingHttpServletResponse)
     */
    @Override
    protected void doPost(SlingHttpServletRequest request,
            SlingHttpServletResponse httpResponse) throws ServletException,
            IOException {
        // prepare the response
        PostResponse response = createPostResponse(request);
        response.setReferer(request.getHeader("referer"));

        // calculate the paths
        String path = getItemPath(request);
        response.setPath(path);

        // location
        response.setLocation(externalizePath(request, path));

        // parent location
        path = getParentPath(path);
        if (path != null) {
            response.setParentLocation(externalizePath(request, path));
        }

        Session session = request.getResourceResolver().adaptTo(Session.class);

        final List<Modification> changes = new ArrayList<>();

        try {
            handleOperation(request, response, changes);

            // set changes on html response
            for(Modification change : changes) {
                switch ( change.getType() ) {
                    case MODIFY : response.onModified(change.getSource()); break;
                    case DELETE : response.onDeleted(change.getSource()); break;
                    case MOVE :   response.onMoved(change.getSource(), change.getDestination()); break;
                    case COPY :   response.onCopied(change.getSource(), change.getDestination()); break;
                    case CREATE : response.onCreated(change.getSource()); break;
                    case ORDER : response.onChange("ordered", change.getSource(), change.getDestination()); break;
                default:
                    break;
                }
            }

            if (session.hasPendingChanges()) {
                session.save();
            }
        } catch (ResourceNotFoundException rnfe) {
            response.setStatus(HttpServletResponse.SC_NOT_FOUND,
                rnfe.getMessage());
        } catch (Exception throwable) {
            log.debug(String.format("Exception while handling POST %s with %s",
                    request.getResource().getPath(), getClass().getName()), throwable);
            response.setError(throwable);
        } finally {
            try {
                if (session.hasPendingChanges()) {
                    session.refresh(false);
                }
            } catch (RepositoryException e) {
                log.warn("RepositoryException in finally block: {}",
                    e.getMessage(), e);
            }
        }

        // check for redirect URL if processing succeeded
        if (response.isSuccessful()) {
            String redirect = null;
            try {
                redirect = getRedirectUrl(request, response);
            } catch (IOException e) {
                if (log.isDebugEnabled()) {
                    log.debug(String.format("Exception while handling redirect for POST %s with %s",
                            request.getResource().getPath(), getClass().getName()), e);
                }
                // http status code for 422 Unprocessable Entity
                response.setStatus(422, "invalid redirect");
                response.setError(e);
            }
            if (redirect != null) {
                httpResponse.sendRedirect(redirect); // NOSONAR
                return;
            }
        }

        // create a html response and send if unsuccessful or no redirect
        response.send(httpResponse, isSetStatus(request));
    }

    /**
     * Override if the path does not need to exist
     */
    protected void validateResourcePath(Session jcrSession, String resourcePath) throws RepositoryException {
        if (!allowNonExistingPaths()) {
            if (resourcePath == null) {
                throw new ResourceNotFoundException("Resource path was not supplied.");
            }

            if (!jcrSession.nodeExists(resourcePath)) {
                throw new ResourceNotFoundException("Resource is not a JCR Node");
            }
        }
    }

    /**
     * Creates an instance of a HtmlResponse.
     * @param req The request being serviced
     * @return a {@link org.apache.sling.servlets.post.JSONResponse} if any of these conditions are true:
     * <ul>
     *   <li>the response content type is application/json
     * </ul>
     * or a {@link org.apache.sling.servlets.post.HtmlResponse} otherwise
     * @deprecated use {@link #createPostResponse(SlingHttpServletRequest)} instead
     */
    @Deprecated
    protected AbstractPostResponse createHtmlResponse(SlingHttpServletRequest req) {
        return (AbstractPostResponse)createPostResponse(req);
    }

    /**
     * Creates an instance of a PostResponse.
     * @param req The request being serviced
     * @return a {@link org.apache.sling.servlets.post.JSONResponse} if any of these conditions are true:
     * <ul>
     *   <li> the request has an <code>Accept</code> header of <code>application/json</code></li>
     *   <li>the request is a JSON POST request (see SLING-1172)</li>
     *   <li>the request has a request parameter <code>:accept=application/json</code></li>
     * </ul>
     * or a {@link org.apache.sling.api.servlets.PostResponse} otherwise
     */
    PostResponse createPostResponse(final SlingHttpServletRequest req) {
        for (final PostResponseCreator creator : cachedPostResponseCreators) {
            final PostResponse response = creator.createPostResponse(req);
            if (response != null) {
                return response;
            }
        }

        //for backward compatibility, if no "accept" request param or header is supplied
        // then prefer the SlingHttpServletRequest#getResponseContentType value
        MediaRangeList mediaRangeList = null;
        String queryParam = req.getParameter(MediaRangeList.PARAM_ACCEPT);
        if (queryParam == null || queryParam.trim().length() == 0) {
            String headerValue = req.getHeader(MediaRangeList.HEADER_ACCEPT);
            if (headerValue == null || headerValue.trim().length() == 0) {
                //no param or header supplied, so try the response content type
                mediaRangeList = new MediaRangeList(req.getResponseContentType());
            }
        }

        // Fall through to default behavior
        if (mediaRangeList == null) {
            mediaRangeList = new MediaRangeList(req);
        }
        if (JSONResponse.RESPONSE_CONTENT_TYPE.equals(mediaRangeList.prefer("text/html", JSONResponse.RESPONSE_CONTENT_TYPE))) {
            return new JSONResponse();
        } else {
            return new HtmlResponse();
        }
    }

    /**
     * Extending Servlet should implement this operation to do the work
     *
     * @param request the sling http request to process
     * @param response the response
     * @param changes the changes to report
     * @throws RepositoryException if any errors applying the changes 
     * 
     * @deprecated use {@link #handleOperation(SlingHttpServletRequest, PostResponse, List)} instead
     */
    @Deprecated
    protected void handleOperation(SlingHttpServletRequest request,
            AbstractPostResponse response, List<Modification> changes) throws RepositoryException {
        handleOperation(request, (PostResponse)response, changes);
    }
    
    /**
     * Extending Servlet should implement this operation to do the work
     *
     * @param request the sling http request to process
     * @param response the response
     * @param changes the changes to report
     * @throws RepositoryException if any errors applying the changes 
     */
    protected abstract void handleOperation(SlingHttpServletRequest request,
            PostResponse response, List<Modification> changes) throws RepositoryException;


    /**
     * compute redirect URL (SLING-126)
     *
     * @param request the sling http request to process
     * @param ctx the post processor
     * @return the redirect location or <code>null</code>
     * @throws IOException if there is something invalid with the :redirect value
     * @deprecated use {@link #getRedirectUrl(HttpServletRequest, PostResponse)} instead
     */
    @Deprecated
    protected String getRedirectUrl(HttpServletRequest request, AbstractPostResponse ctx) throws IOException {
        return getRedirectUrl(request, (PostResponse)ctx);
    }
    
    /**
     * compute redirect URL (SLING-126)
     *
     * @param request the sling http request to process
     * @param ctx the post processor
     * @return the redirect location or <code>null</code>
     * @throws IOException if there is something invalid with the :redirect value
     */
    protected String getRedirectUrl(HttpServletRequest request, PostResponse ctx) throws IOException {
        // redirect param has priority (but see below, magic star)
        String result = request.getParameter(SlingPostConstants.RP_REDIRECT_TO);
        if (result != null) {
            try {
                URI redirectUri = new URI(result);
                if (redirectUri.getAuthority() != null) {
                    // if it has a host information
                    throw new IOException("The redirect target included host information. This is not allowed for security reasons!");
                }
            } catch (URISyntaxException e) {
                throw new IOException("The redirect target was not a valid uri");
            }

            if (ctx.getPath() != null) {
                // redirect to created/modified Resource
                int star = result.indexOf('*');
                if (star >= 0) {
                    StringBuilder buf = new StringBuilder();

                    // anything before the star
                    if (star > 0) {
                        buf.append(result.substring(0, star));
                    }

                    // append the name of the manipulated node
                    buf.append(ResourceUtil.getName(ctx.getPath()));

                    // anything after the star
                    if (star < result.length() - 1) {
                        buf.append(result.substring(star + 1));
                    }

                    // use the created path as the redirect result
                    result = buf.toString();

                } else if (result.endsWith(SlingPostConstants.DEFAULT_CREATE_SUFFIX)) {
                    // if the redirect has a trailing slash, append modified node
                    // name
                    result = result.concat(ResourceUtil.getName(ctx.getPath()));
                }
            }
        }
        return result;
    }

    protected boolean isSetStatus(SlingHttpServletRequest request) {
        String statusParam = request.getParameter(SlingPostConstants.RP_STATUS);
        if (statusParam == null) {
            log.debug(
                "getStatusMode: Parameter {} not set, assuming standard status code",
                SlingPostConstants.RP_STATUS);
            return true;
        }

        if (SlingPostConstants.STATUS_VALUE_BROWSER.equals(statusParam)) {
            log.debug(
                "getStatusMode: Parameter {} asks for user-friendly status code",
                SlingPostConstants.RP_STATUS);
            return false;
        }

        if (SlingPostConstants.STATUS_VALUE_STANDARD.equals(statusParam)) {
            log.debug(
                "getStatusMode: Parameter {} asks for standard status code",
                SlingPostConstants.RP_STATUS);
            return true;
        }

        log.debug("getStatusMode: Parameter {} set to unknown value {}, assuming standard status code",
            SlingPostConstants.RP_STATUS, statusParam);
        return true;
    }

    // ------ These methods were copied from AbstractSlingPostOperation ------

    /**
     * Returns the path of the resource of the request as the item path.
     * <p>
     * This method may be overwritten by extension if the operation has
     * different requirements on path processing.
     * </p>
     * @param request the sling http request to process
     * @return the resolved path of the found item
     */
    protected String getItemPath(SlingHttpServletRequest request) {
        if (allowNonExistingPaths()) {
            return PrincipalAceHelper.getEffectivePath(request);
        } else {
            return request.getResource().getPath();
        }
    }

    /**
     * Returns an external form of the given path prepending the context path
     * and appending a display extension.
     *
     * @param request the sling http request to process
     * @param path the path to externalize
     * @return the url
     */
    protected String externalizePath(SlingHttpServletRequest request,
            String path) {
        if (path == null) {
            if (allowNonExistingPaths()) {
                path = PrincipalAceHelper.RESOURCE_PATH_REPOSITORY;
            } else {
                return null;
            }
        }
        StringBuilder ret = new StringBuilder();
        ret.append(SlingRequestPaths.getContextPath(request));
        ret.append(request.getResourceResolver().map(path));

        // append optional extension
        String ext = request.getParameter(SlingPostConstants.RP_DISPLAY_EXTENSION);
        if (ext != null && ext.length() > 0) {
            if (ext.charAt(0) != '.') {
                ret.append('.');
            }
            ret.append(ext);
        }

        return ret.toString();
    }

    /**
     * Returns whether this operation can operate on paths that do
     * not exist yet
     * 
     * @return true if the resourcePath must exist, false otherwise
     */
    protected boolean allowNonExistingPaths() {
        return false;
    }

    /**
     * Returns an external form of the parent path
     * @param path the resource path
     * @return parent path
     */
    protected @Nullable String getParentPath(String path) {
        if (path == null) {
            // null path is ok for repository level privileges
            return null;
        }

        return ResourceUtil.getParent(path);
    }

    /**
     * Returns an <code>AccessControlList</code> to edit for the node at the
     * given <code>resourcePath</code>.
     *
     * @param accessControlManager The manager providing access control lists
     * @param resourcePath The node path for which to return an access control
     *            list
     * @param mayCreate <code>true</code> if an access control list should be
     *            created if the node does not have one yet.
     * @return The <code>AccessControlList</code> to modify to control access to
     *         the node.
     * @throws RepositoryException If the access control manager does not
     *             provide a <code>AccessControlPolicy</code> which is an
     *             <code>AccessControlList</code>.
     */
    protected AccessControlList getAccessControlList(
            final AccessControlManager accessControlManager,
            final String resourcePath, final boolean mayCreate)
            throws RepositoryException {

        // check for an existing access control list to edit
        AccessControlPolicy[] policies = accessControlManager.getPolicies(resourcePath);
        for (AccessControlPolicy policy : policies) {
            if (policy instanceof AccessControlList) {
                return (AccessControlList) policy;
            }
        }

        // no existing access control list, try to create if allowed
        if (mayCreate) {
            AccessControlPolicyIterator applicablePolicies = accessControlManager.getApplicablePolicies(resourcePath);
            while (applicablePolicies.hasNext()) {
                AccessControlPolicy policy = applicablePolicies.nextAccessControlPolicy();
                if (policy instanceof AccessControlList) {
                    return (AccessControlList) policy;
                }
            }
        }

        // neither an existing nor a create AccessControlList is available, fail
        throw new RepositoryException(
            "Unable to find or create an access control policy to update for "
                + resourcePath);

    }

    /**
     * Returns an <code>AccessControlList</code> to edit for the node at the
     * given <code>resourcePath</code>.
     *
     * @param accessControlManager The manager providing access control lists
     * @param resourcePath The node path for which to return an access control
     *            list
     * @param mayCreate <code>true</code> if an access control list should be
     *            created if the node does not have one yet.
     * @return The <code>AccessControlList</code> to modify to control access to
     *         the node or null if one could not be located or created
     * @throws RepositoryException if any errors reading the information
     */
    protected AccessControlList getAccessControlListOrNull(
            final AccessControlManager accessControlManager,
            final String resourcePath, final boolean mayCreate)
            throws RepositoryException {
        AccessControlList acl = null;
        // check for an existing access control list to edit
        AccessControlPolicy[] policies = accessControlManager.getPolicies(resourcePath);
        for (AccessControlPolicy policy : policies) {
            if (policy instanceof AccessControlList) {
                acl = (AccessControlList) policy;
            }
        }

        if (acl == null && mayCreate) {
            // no existing access control list, try to create if allowed
            AccessControlPolicyIterator applicablePolicies = accessControlManager.getApplicablePolicies(resourcePath);
            while (applicablePolicies.hasNext()) {
                AccessControlPolicy policy = applicablePolicies.nextAccessControlPolicy();
                if (policy instanceof AccessControlList) {
                    acl = (AccessControlList) policy;
                }
            }
        }
        return acl;
    }

    /**
     * Bind a new post response creator
     * 
     * @param creator the response creator service reference
     * @param properties the component properties for the service reference
     */
    // NOTE: the @Reference annotation is not inherited, so subclasses will need to override the #bindPostResponseCreator
    // and #unbindPostResponseCreator methods to provide the @Reference annotation.
    //
    // @Reference(service = PostResponseCreator.class,
    //         cardinality = ReferenceCardinality.MULTIPLE,
    //         policy = ReferencePolicy.DYNAMIC)
    protected void bindPostResponseCreator(final PostResponseCreator creator, final Map<String, Object> properties) {
        final PostResponseCreatorHolder nngh = new PostResponseCreatorHolder(creator, getRanking(properties));

        synchronized ( this.postResponseCreators ) {
            int index = 0;
            while ( index < this.postResponseCreators.size() &&
                    nngh.getRanking() < this.postResponseCreators.get(index).getRanking() ) {
                index++;
            }
            if ( index == this.postResponseCreators.size() ) {
                this.postResponseCreators.add(nngh);
            } else {
                this.postResponseCreators.add(index, nngh);
            }
            this.updatePostResponseCreatorCache();
        }
    }

    /**
     * Unbind a post response creator
     * 
     * @param creator the response creator service reference
     * @param properties the component properties for the service reference
     */
    protected void unbindPostResponseCreator(final PostResponseCreator creator, final Map<String, Object> properties) {
        synchronized ( this.postResponseCreators ) {
            final Iterator<PostResponseCreatorHolder> i = this.postResponseCreators.iterator();
            while ( i.hasNext() ) {
                final PostResponseCreatorHolder current = i.next();
                if ( current.getCreator() == creator ) {
                    i.remove();
                }
            }
            this.updatePostResponseCreatorCache();
        }
    }

    /**
     * Update the post response creator cache
     * This method is called by sync'ed methods, no need to add additional syncing.
     */
    private void updatePostResponseCreatorCache() {
        final PostResponseCreator[] localCache = new PostResponseCreator[this.postResponseCreators.size()];
        int index = 0;
        for(final PostResponseCreatorHolder current : this.postResponseCreators) {
            localCache[index] = current.getCreator();
            index++;
        }
        this.cachedPostResponseCreators = localCache;
    }
    
    private int getRanking(final Map<String, Object> properties) {
        final Object val = properties.get(Constants.SERVICE_RANKING);
        return val instanceof Integer ? (Integer)val : 0;
    }
    
    private static final class PostResponseCreatorHolder {
        private final PostResponseCreator creator;
        private final int ranking;

        public PostResponseCreatorHolder(PostResponseCreator creator, int ranking) {
            this.creator = creator;
            this.ranking = ranking;
        }

        public PostResponseCreator getCreator() {
            return creator;
        }

        public int getRanking() {
            return ranking;
        }

    }    
}