/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 ~ 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.scriptingbundle.plugin.processor.filevault;

import java.io.BufferedReader;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Objects;
import java.util.Optional;
import java.util.Set;

import javax.jcr.PropertyType;
import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.apache.commons.lang3.StringUtils;
import org.apache.jackrabbit.spi.commons.name.NameConstants;
import org.apache.jackrabbit.vault.util.DocViewProperty;
import org.apache.sling.jcr.resource.api.JcrResourceConstants;
import org.apache.sling.scriptingbundle.plugin.processor.Constants;
import org.jetbrains.annotations.NotNull;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

public class VaultContentXmlReader {

    private static final DocumentBuilderFactory documentBuilderFactory;

    static {
        try {
            documentBuilderFactory = DocumentBuilderFactory.newInstance();
            documentBuilderFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
            documentBuilderFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_SCHEMA, "");
            documentBuilderFactory.setAttribute(XMLConstants.FEATURE_SECURE_PROCESSING, Boolean.TRUE);
            documentBuilderFactory.setExpandEntityReferences(false);
            documentBuilderFactory.setNamespaceAware(true);
        } catch (IllegalArgumentException e) {
            throw new IllegalStateException("Cannot disable DTD features.", e);
        }
    }

    private final String resourceSuperType;
    private final Path path;
    private final Set<String> requiredResourceTypes;

    public VaultContentXmlReader(@NotNull Path path) throws IOException {
        this.path = path;
        this.requiredResourceTypes = new HashSet<>();
        try (BufferedReader reader = Files.newBufferedReader(path, StandardCharsets.UTF_8)) {
            DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
            Document document = documentBuilder.parse(new InputSource(reader));
            NodeList nodeList = document.getElementsByTagNameNS(NameConstants.JCR_ROOT.getNamespaceURI(),
                    NameConstants.JCR_ROOT.getLocalName());
            if (nodeList.getLength() == 1 && nodeList.item(0).equals(document.getDocumentElement())) {
                String resourceSuperTypeRawValue = document.getDocumentElement().getAttributeNS(JcrResourceConstants.SLING_NAMESPACE_URI,
                        Constants.SLING_RESOURCE_SUPER_TYPE_XML_LOCAL_NAME);
                if (StringUtils.isNotEmpty(resourceSuperTypeRawValue)) {
                    DocViewProperty resourceSuperTypeDocViewProperty =
                            DocViewProperty.parse(JcrResourceConstants.SLING_RESOURCE_SUPER_TYPE_PROPERTY, resourceSuperTypeRawValue);
                    if ((resourceSuperTypeDocViewProperty.type == PropertyType.STRING ||
                            resourceSuperTypeDocViewProperty.type == PropertyType.UNDEFINED) && !resourceSuperTypeDocViewProperty.isMulti) {
                        this.resourceSuperType = resourceSuperTypeDocViewProperty.values[0];
                    } else {
                        throw new IllegalArgumentException(String.format("Invalid %s property value (%s) in file %s.",
                                JcrResourceConstants.SLING_RESOURCE_SUPER_TYPE_PROPERTY, resourceSuperTypeRawValue, path));
                    }
                } else {
                    this.resourceSuperType = null;
                }

                String requiredResourceTypesRawValue =
                        document.getDocumentElement().getAttributeNS(JcrResourceConstants.SLING_NAMESPACE_URI
                                , Constants.SLING_REQUIRED_RESOURCE_TYPES_XML_LOCAL_NAME);
                if (StringUtils.isNotEmpty(requiredResourceTypesRawValue)) {
                    DocViewProperty requiredResourceTypesDocViewProperty =
                            DocViewProperty.parse(Constants.SLING_REQUIRED_RESOURCE_TYPES,
                                    requiredResourceTypesRawValue);
                    if (requiredResourceTypesDocViewProperty.isMulti &&
                            (requiredResourceTypesDocViewProperty.type == PropertyType.STRING ||
                                    requiredResourceTypesDocViewProperty.type == PropertyType.UNDEFINED)) {
                        requiredResourceTypes.addAll(Arrays.asList(requiredResourceTypesDocViewProperty.values));
                    } else {
                       throw new IllegalArgumentException(String.format("Invalid %s property value (%s) in file %s.",
                                Constants.SLING_REQUIRED_RESOURCE_TYPES, requiredResourceTypesRawValue, path));
                    }
                }


            } else {
                throw new IllegalArgumentException(String.format(
                        "Path %s does not seem to provide a Docview format - https://jackrabbit.apache.org/filevault/docview.html.",
                        path));
            }
        } catch (ParserConfigurationException | SAXException e) {
            throw new IOException(e);
        }


    }

    @NotNull
    public Path getPath() {
        return path;
    }

    @NotNull
    public Optional<String> getSlingResourceSuperType() {
        return Optional.ofNullable(resourceSuperType);
    }

    @NotNull
    public Set<String> getSlingRequiredResourceTypes() {
        return Collections.unmodifiableSet(requiredResourceTypes);
    }

    @Override
    public int hashCode() {
        return Objects.hash(path, resourceSuperType, requiredResourceTypes);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof VaultContentXmlReader) {
            VaultContentXmlReader other = (VaultContentXmlReader) obj;
            return Objects.equals(path, other.path) && Objects.equals(resourceSuperType, other.resourceSuperType) &&
                    Objects.equals(requiredResourceTypes, other.requiredResourceTypes);
        }
        return false;
    }
}