/*
 * 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.pipes.internal;

import org.apache.commons.collections.IteratorUtils;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.resource.ValueMap;
import org.apache.sling.pipes.BasePipe;
import org.apache.sling.pipes.PipeBindings;
import org.apache.sling.pipes.Plumber;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.jcr.Node;
import javax.jcr.NodeIterator;
import javax.jcr.RepositoryException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.regex.Pattern;

/**
 * intends to output the input only if configured conditions are fulfilled
 */
public class FilterPipe extends BasePipe {
    private static Logger logger = LoggerFactory.getLogger(FilterPipe.class);
    public static final String RESOURCE_TYPE = RT_PREFIX + "filter";
    public static final String PREFIX_FILTER = "slingPipesFilter_";
    public static final String PN_NOT = PREFIX_FILTER + "not";
    public static final String PN_NOCHILDREN = PREFIX_FILTER + "noChildren";
    public static final String PN_TEST = PREFIX_FILTER + "test";
    public static final String PN_INJECTCHILDRENCOUNT = PREFIX_FILTER + "injectChildrenCount";
    public static final String BINDING_CHILDREN_COUNT = "childrenCount";
    Map<String, Pattern> propertiesPatterns;

    public FilterPipe(Plumber plumber, Resource resource, PipeBindings upperBindings) {
        super(plumber, resource, upperBindings);
    }

    Pattern getPattern(Resource filterResource, final String propertyKey) {
        if (propertiesPatterns == null) {
            propertiesPatterns = new HashMap<>();
        }
        String key = filterResource.getPath() + SLASH + propertyKey;
        return propertiesPatterns.computeIfAbsent(key, x -> {
            String value = getBindings().instantiateExpression(filterResource.getValueMap().get(propertyKey, String.class));
            return value != null ? Pattern.compile(value)  : null;
        });//en.wikipedia.org
    }

    boolean propertiesPass(ValueMap current, Resource filterResource) {
        ValueMap filter = filterResource.getValueMap();
        if (filter.containsKey(PN_TEST)){
            Object test = bindings.instantiateObject(filter.get(PN_TEST, PipeBindings.FALSE_BINDING));
            if (! (test instanceof Boolean)){
                logger.error("instantiated test {} is not a boolean, filtering out", test);
                return false;
            }
            return (Boolean) test;
        }
        for (String key : filter.keySet()){
            if (! IGNORED_PROPERTIES.contains(key) && !key.startsWith(PREFIX_FILTER)){
                Pattern pattern = getPattern(filterResource, key);
                if (!current.containsKey(key) || !pattern.matcher(current.get(key, String.class)).matches()){
                    return false;
                }
            }
        }
        return true;
    }

    boolean hasNoChildrenFilter(ValueMap filter) {
        return (Boolean) bindings.instantiateObject(filter.get(PN_NOCHILDREN, PipeBindings.FALSE_BINDING));
    }

    boolean iterateOverChildren(Resource currentResource, Resource filterResource) throws RepositoryException {
        Node filterNode = filterResource.adaptTo(Node.class);
        Node currentNode = currentResource.adaptTo(Node.class);
        if (filterNode != null) {
            boolean returnValue = true;
            for (NodeIterator children = filterNode.getNodes(); returnValue && children.hasNext(); ) {
                String childName = children.nextNode().getName();
                if (currentNode != null && !currentNode.hasNode(childName)) {
                    return false;
                } else {
                    returnValue &= filterPasses(currentResource.getChild(childName), filterResource.getChild(childName));
                }
            }
            return returnValue;
        }
        return false;
    }

    boolean childrenPass(Resource currentResource, Resource filterResource) throws RepositoryException {
        Node currentNode = currentResource.adaptTo(Node.class);
        if (currentNode != null) {
            if (hasNoChildrenFilter(filterResource.getValueMap())) {
                return !currentNode.hasNodes();
            } else {
                return iterateOverChildren(currentResource, filterResource);
            }
        }
        return false;
    }

    boolean filterPasses(Resource currentResource, Resource filterResource) throws RepositoryException {
        if (currentResource != null && filterResource != null) {
            ValueMap current = currentResource.getValueMap();
            ValueMap filter = filterResource.getValueMap();
            boolean injectChildrenCount = (Boolean) bindings.instantiateObject(filter.get(PN_INJECTCHILDRENCOUNT, PipeBindings.FALSE_BINDING));
            if (injectChildrenCount) {
                Node currentNode = currentResource.adaptTo(Node.class);
                if (currentNode != null) {
                    int childrenCount = IteratorUtils.toList(currentNode.getNodes()).size();
                    bindings.addBinding(BINDING_CHILDREN_COUNT, childrenCount);
                }
            }
            if (propertiesPass(current, filterResource)) {
                return childrenPass(currentResource, filterResource);
            }
        }
        return false;
    }

    @Override
    protected Iterator<Resource> computeOutput() {
        Resource resource = getInput();
        if (resource != null) {
            try {
                boolean not = getBindings().instantiateExpression(properties.get(PN_NOT, "false")).equals(Boolean.TRUE.toString());
                //the not does a exclusive or with the filter:
                // - true filter with "true" not is false,
                // - false filter with false not is false,
                // - all the other combinations should pass
                if (filterPasses(resource, getConfiguration()) ^ not) {
                    logger.debug("filter passes for {}", resource.getPath());
                    return super.computeOutput();
                } else {
                    logger.debug("{} got filtered out", resource.getPath());
                }
            } catch (RepositoryException e) {
                logger.error("unable to filter the input", e);
            }
        }
        return EMPTY_ITERATOR;
    }
}