ServiceCatalogBuilder.java

/*
 * Copyright (c) 2013 EMC Corporation
 * All Rights Reserved
 */

package com.emc.storageos.apidiff.model;

import com.emc.storageos.apidiff.Constants;
import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.input.SAXBuilder;

import java.io.File;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Helper class to parse XML File into data structure ServiceCatalog.
 * Prepare data for further comparison
 */
public class ServiceCatalogBuilder {

    private ServiceCatalogBuilder() {
    }

    public static ServiceCatalog build(final String filePath) {
        return build(new File(filePath));
    }

    /**
     * Parses xml file to ServiceCatalog with Jdom
     * 
     * @param xmlFile
     *            The instance of xml file
     * @return instance of ServiceCatalog
     */
    public static ServiceCatalog build(final File xmlFile) {

        String fileName = xmlFile.getName().trim().toLowerCase();
        // remove suffix
        if (fileName.endsWith(Constants.XML_FILE_SUFFIX)) {
            fileName = fileName.substring(0, fileName.length() - Constants.XML_FILE_SUFFIX.length() - 1);
        } else {
            throw new IllegalArgumentException("API file is not xml format: " + fileName);
        }

        // filter name
        int separatorIndex = fileName.indexOf(Constants.NAME_STRING_SEPARATOR);
        if (separatorIndex == -1) {
            throw new IllegalArgumentException("API file name should split with "
                    + Constants.NAME_STRING_SEPARATOR + " actually: " + fileName);
        }
        String serviceName = fileName.substring(0, separatorIndex);
        String version = fileName.substring(separatorIndex + 1, fileName.length());

        Document document;
        try {
            document = new SAXBuilder().build(xmlFile);
        } catch (Exception ex) {
            throw new IllegalArgumentException("Invalid XML file:\n " + xmlFile.getAbsolutePath(), ex);
        }

        if (document == null) {
            return null;
        }

        // Navigates to resource tag, it's a little tricky here, depends on structure of xml file completely.
        List<Element> resourceList = document.getRootElement()
                .getChild(Constants.REST_NODE)
                .getChild(Constants.RESOURCES_NODE)
                .getChildren();

        // Navigates to element tag, it's a little tricky here, depends on structure of xml file completely.
        List<Element> elementList = document.getRootElement()
                .getChild(Constants.DATA_NODE)
                .getChild(Constants.DATA_SCHEMA_NODE)
                .getChild(Constants.ELEMENTS_NODE)
                .getChildren();

        return new ServiceCatalog(parseResource(resourceList), parseElement(elementList), serviceName, version);
    }

    /**
     * Parses tag list <resource> to get REST API details
     * 
     * @param resourceList
     *            The list of resource tag
     * @return details of api resource
     */
    public static Map<ApiIdentifier, ApiDescriptor> parseResource(List<Element> resourceList) {
        if (resourceList == null) {
            throw new NullPointerException("Please navigate to right resource tag before parse it");
        }
        Map<ApiIdentifier, ApiDescriptor> resourceMap = new HashMap<ApiIdentifier, ApiDescriptor>();

        for (Element element : resourceList) {
            String path = element.getAttributeValue(Constants.ATTRIBUTE_NAME).trim();
            Element opElement = element.getChild(Constants.OPERATION_NODE);
            String method = opElement.getAttributeValue(Constants.ATTRIBUTE_NAME).trim();
            ApiIdentifier apiIdentifier = new ApiIdentifier(method, path);

            ApiDescriptor apiResource = new ApiDescriptor();

            Element opInValue = opElement.getChild(Constants.OPERATION_INVALUE_NODE);
            if (opInValue != null) {
                Element xmlElement = opInValue.getChild(Constants.XML_ELEMENT_NODE);
                if (xmlElement != null && xmlElement.getAttributeValue(Constants.ATTRIBUTE_ELEMENT_NAME) != null) {
                    apiResource.setRequestElement(xmlElement.getAttributeValue(Constants.ATTRIBUTE_ELEMENT_NAME).trim());
                }
            }

            Element opOutValue = opElement.getChild(Constants.OPERATION_OUTVALUE_NODE);
            if (opOutValue != null) {
                Element xmlElement = opOutValue.getChild(Constants.XML_ELEMENT_NODE);
                if (xmlElement != null && xmlElement.getAttributeValue(Constants.ATTRIBUTE_ELEMENT_NAME) != null) {
                    apiResource.setResponseElement(xmlElement.getAttributeValue(Constants.ATTRIBUTE_ELEMENT_NAME).trim());
                }
            }

            for (Element paramElement : opElement.getChildren(Constants.OPERATION_PARAMETER_NODE)) {
                if (paramElement.getAttributeValue(Constants.ATTRIBUTE_NAME) != null) {
                    apiResource.getParameters().add(paramElement.getAttributeValue(Constants.ATTRIBUTE_NAME).trim());
                }
            }

            resourceMap.put(apiIdentifier, apiResource);
        }

        return resourceMap;
    }

    /**
     * Parses tag list <element> to get REST API details
     * 
     * @param elementList
     *            The list of element tag
     * @return details of API element
     */
    public static Map<String, String> parseElement(List<Element> elementList) {
        if (elementList == null) {
            throw new NullPointerException("Please navigate to right element tag before parse it");
        }
        Map<String, String> elmentMap = new HashMap<String, String>();
        for (Element element : elementList) {
            String exampleXml = filterExampleXml(element.getChildText(Constants.ELEMENT_EXAMPLE_XML_NODE).trim());
            elmentMap.put(element.getAttributeValue(Constants.ATTRIBUTE_NAME).trim(), exampleXml);
        }
        return elmentMap;
    }

    /**
     * Helper method to filter example xml
     * 
     * @param examplXml
     *            The content of example xml
     * @return the filtered example xml
     */
    private static String filterExampleXml(String examplXml) {
        int begin = 0;
        int end = examplXml.length();
        if (examplXml.startsWith(Constants.EXAMLE_XML_HEADER)) {
            begin = Constants.EXAMLE_XML_HEADER.length() - 1;
        }
        if (examplXml.endsWith(Constants.EXAMLE_XML_TAILER)) {
            end = end - Constants.EXAMLE_XML_TAILER.length();
        }

        return examplXml.substring(begin, end);
    }

}