de.gematik.refv.valmodule.erpta7.helper.BundleReducer Maven / Gradle / Ivy

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/*
Copyright (c) 2022-2024 gematik GmbH

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.gematik.refv.valmodule.erpta7.helper;

import lombok.SneakyThrows;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;

public class BundleReducer {

    private final DocumentBuilder documentBuilder;
    private final XPathFactory xPathFactory;
    private final TransformerFactory transformerFactory;
    private final Document document;

    @SneakyThrows
    public BundleReducer(String resourceBody) {
        DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
        documentBuilder = documentBuilderFactory.newDocumentBuilder();
        xPathFactory = XPathFactory.newInstance();
        transformerFactory = TransformerFactory.newInstance();
        document = documentBuilder.parse(new InputSource(new StringReader(resourceBody)));
    }

    public List getAllRezeptBundlesAsString() throws XPathExpressionException, TransformerException {
        List allEntriesAsStrings = new ArrayList<>();
        XPath xpath = xPathFactory.newXPath();
        NodeList resources = (NodeList) xpath.compile("/Bundle/entry/resource/Bundle").evaluate(document, XPathConstants.NODESET);

        for (int i = 0; i < resources.getLength(); i++) {
            Node resource = resources.item(i);
            Element rootElement = (Element) resource;
            rootElement.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns", "http://hl7.org/fhir");
            allEntriesAsStrings.add(serializeToString(rootElement));
        }

        return allEntriesAsStrings;
    }

    public String getReducedResourceBody() throws XPathExpressionException, TransformerException {
        NodeList fixedChildren = getFixedChildren(document);
        NodeList entries = getEntries(document);

        Document newDoc = documentBuilder.newDocument();
        Element rootElement = newDoc.createElementNS("http://hl7.org/fhir", "Bundle");
        newDoc.appendChild(rootElement);

        copyFixedChildren(newDoc, rootElement, fixedChildren);
        copyFirstRezeptBundle(newDoc, rootElement, entries);

        return serializeToString(newDoc);
    }

    private NodeList getFixedChildren(Document doc) throws XPathExpressionException {
        XPath xpath = xPathFactory.newXPath();
        XPathExpression expr = xpath.compile("/Bundle/*[not(self::entry/resource/Bundle)]");
        return (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
    }

    private NodeList getEntries(Document doc) throws XPathExpressionException {
        XPath xpath = xPathFactory.newXPath();
        return (NodeList) xpath.compile("/Bundle/entry").evaluate(doc, XPathConstants.NODESET);
    }

    private void copyFixedChildren(Document newDoc, Element rootElement, NodeList fixedChildren) {
        for (int i = 0; i < fixedChildren.getLength(); i++) {
            Node fixedNode = fixedChildren.item(i);
            Node importedNode = newDoc.importNode(fixedNode, true);
            rootElement.appendChild(importedNode);
        }
    }

    private void copyFirstRezeptBundle(Document newDoc, Element rootElement, NodeList entries) throws XPathExpressionException {
        XPath xPath = xPathFactory.newXPath();
        XPathExpression bundleExpression = xPath.compile("resource/Bundle");

        for (int i = 0; i < entries.getLength(); i++) {
            Node entryNode = entries.item(i);
            NodeList bundleNodes = (NodeList) bundleExpression.evaluate(entryNode, XPathConstants.NODESET);
            if (bundleNodes.getLength() > 0) {
                Node importedNode = newDoc.importNode(entryNode, true);
                rootElement.appendChild(importedNode);
                break;
            }
        }
    }

    // This implementation produces different line endings in different environments (e.g. local vs jenkins).
    // But this doesn't affect the validation process and is faster than other implementations that set fix line endings (e.g. LSSerializer).
    private String serializeToString(Node newDoc) throws TransformerException {
        StringWriter sw = new StringWriter();
        Transformer transformer = transformerFactory.newTransformer();
        transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
        transformer.transform(new DOMSource(newDoc), new StreamResult(sw));
        return sw.toString();
    }
}