tooling/maven/camel-package-maven-plugin/src/main/java/org/apache/camel/maven/packaging/SpringBootStarterMojo.java

/*
 * 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.camel.maven.packaging;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.TreeSet;
import java.util.stream.Collectors;

import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
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.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import freemarker.cache.URLTemplateLoader;
import freemarker.template.Configuration;
import freemarker.template.Template;
import freemarker.template.TemplateException;
import org.apache.commons.io.IOUtils;
import org.apache.maven.plugin.AbstractMojo;
import org.apache.maven.plugin.MojoExecutionException;
import org.apache.maven.plugin.MojoFailureException;
import org.apache.maven.plugins.annotations.Mojo;
import org.apache.maven.plugins.annotations.Parameter;
import org.apache.maven.plugins.annotations.ResolutionScope;
import org.apache.maven.project.MavenProject;

/**
 * Generate Spring Boot starter for the component
 */
@Mojo(name = "prepare-spring-boot-starter", threadSafe = true,
        requiresDependencyCollection = ResolutionScope.COMPILE_PLUS_RUNTIME,
        requiresDependencyResolution = ResolutionScope.COMPILE_PLUS_RUNTIME)
public class SpringBootStarterMojo extends AbstractMojo {

    private static final String[] IGNORE_MODULES = {
        /* OSGi -> */ "camel-blueprint", "camel-core-osgi", "camel-eventadmin", "camel-paxlogging",
        /* extended core */ "camel-attachments",
        /* Java EE -> */ "camel-cdi",
        /* MicroProfile -> */ "camel-microprofile-config",
        /* MicroProfile -> */ "camel-microprofile-health",
        /* MicroProfile -> */ "camel-microprofile-metrics",
        /* deprecated (and not working perfectly) -> */ "camel-swagger", "camel-ibatis",
        /* currently incompatible */ "camel-spark-rest",
        /* others (not managed) -> */ "camel-core-xml"};

    private static final boolean IGNORE_TEST_MODULES = true;

    private static final String GENERATED_SECTION_START = "START OF GENERATED CODE";
    private static final String GENERATED_SECTION_START_COMMENT = "<!--" + GENERATED_SECTION_START + "-->";
    private static final String GENERATED_SECTION_END = "END OF GENERATED CODE";
    private static final String GENERATED_SECTION_END_COMMENT = "<!--" + GENERATED_SECTION_END + "-->";

    /**
     * The maven project.
     */
    @Parameter(property = "project", required = true, readonly = true)
    protected MavenProject project;

    /**
     * Allows using the existing pom.xml file if present.
     */
    @Parameter(property = "reuseExistingPom", defaultValue = "true")
    protected boolean reuseExistingPom;

    /**
     * The project directory
     */
    @Parameter(defaultValue = "${basedir}")
    protected File baseDir;

    @Override
    public void execute() throws MojoExecutionException, MojoFailureException {

        if (!isStarterAllowed()) {
            getLog().info("Spring-Boot-Starter: starter not allowed for module " + project.getArtifactId() + ": skipping.");
            return;
        }

        try {
            // create the starter directory
            File starterDir = starterDir();
            getLog().info("Spring-Boot-Starter: starter dir for the component is: " + starterDir.getAbsolutePath());

            if (!starterDir.exists()) {
                starterDir.mkdirs();
            }



            // create the base pom.xml
            Document pom = createBasePom();

            // Apply changes to the starter pom
            fixExcludedDependencies(pom);
            fixAdditionalDependencies(pom);
            fixAdditionalRepositories(pom);

            // Write the starter pom
            File pomFile = new File(starterDir, "pom.xml");
            writeXmlFormatted(pom, pomFile);

            // write LICENSE, USAGE and spring.provides files
            writeStaticFiles();
            writeSpringProvides();

            // synchronized all starters with their parent pom 'modules' section
            synchronizeParentPom();

        } catch (Exception e) {
            throw new MojoFailureException("Unable to create starter", e);
        }

    }

    private File starterDir() {
        return SpringBootHelper.starterDir(baseDir, project.getArtifactId());
    }

    private File allStartersDir() {
        return SpringBootHelper.allStartersDir(baseDir);
    }

    private void fixAdditionalDependencies(Document pom) throws Exception {
        Properties properties = new Properties();
        properties.load(getClass().getResourceAsStream("/spring-boot-fix-dependencies.properties"));

        Set<String> deps = new TreeSet<>();
        deps.addAll(csvToSet(properties.getProperty(project.getArtifactId())));


        Set<String> globalProps = csvToSet(properties.getProperty("global"));
        boolean inGlobal = false;
        for (String gp : globalProps) {
            String[] comps = gp.split("\\:");
            String stdName = (comps[0] + ":" + comps[1]).replace("-starter", "");
            String camelGav = project.getGroupId() + ":" + project.getArtifactId();
            String camelSpringBootGav = project.getGroupId() + ".springboot:" + project.getArtifactId();
            if (stdName.equals(camelGav) || stdName.equals(camelSpringBootGav)) {
                inGlobal = true;
                break;
            }
        }

        if (!inGlobal) {
            // add global properties for all modules not in global properties
            deps.addAll(globalProps);
        }

        if (deps.size() > 0) {
            getLog().debug("The following dependencies will be added to the starter: " + deps);

            XPath xpath = XPathFactory.newInstance().newXPath();
            Node dependencies = ((NodeList) xpath.compile("/project/dependencies").evaluate(pom, XPathConstants.NODESET)).item(0);

            if (deps.size() > 0) {
                dependencies.appendChild(pom.createComment(GENERATED_SECTION_START));
                for (String dep : deps) {
                    Element dependency = pom.createElement("dependency");
                    dependencies.appendChild(dependency);

                    String[] comps = dep.split("\\:");
                    String groupIdStr = comps[0];
                    String artifactIdStr = comps[1];
                    String versionStr = comps.length > 2 ? comps[2] : null;

                    Element groupId = pom.createElement("groupId");
                    groupId.setTextContent(groupIdStr);
                    dependency.appendChild(groupId);

                    Element artifactId = pom.createElement("artifactId");
                    artifactId.setTextContent(artifactIdStr);
                    dependency.appendChild(artifactId);

                    if (versionStr != null) {
                        Element version = pom.createElement("version");
                        version.setTextContent(versionStr);
                        dependency.appendChild(version);
                    }

                }
                dependencies.appendChild(pom.createComment(GENERATED_SECTION_END));
            }
        }
    }

    private void fixAdditionalRepositories(Document pom) throws Exception {
        if (project.getFile() != null) {
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            dbf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, Boolean.TRUE);
            dbf.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true);
            DocumentBuilder builder = dbf.newDocumentBuilder();
            Document originalPom = builder.parse(project.getFile());

            XPath xpath = XPathFactory.newInstance().newXPath();
            Node repositories = (Node) xpath.compile("/project/repositories").evaluate(originalPom, XPathConstants.NODE);
            if (repositories != null) {
                pom.getDocumentElement().appendChild(pom.createComment(GENERATED_SECTION_START));
                pom.getDocumentElement().appendChild(pom.importNode(repositories, true));
                pom.getDocumentElement().appendChild(pom.createComment(GENERATED_SECTION_END));
            }
        } else {
            getLog().warn("Cannot access the project pom file to retrieve repositories");
        }
    }

    private Set<String> csvToSet(String csv) {
        if (csv == null || csv.trim().length() == 0) {
            return new TreeSet<>();
        }

        Set<String> set = new TreeSet<>();
        for (String s : csv.split(",")) {
            set.add(s.trim());
        }
        return set;
    }

    private void fixExcludedDependencies(Document pom) throws Exception {
        Set<String> loggingImpl = new HashSet<>();

        loggingImpl.add("commons-logging:commons-logging");

        loggingImpl.add("log4j:log4j");
        loggingImpl.add("log4j:apache-log4j-extras");

        // removing also the default implementation
        loggingImpl.add("ch.qos.logback:logback-core");
        loggingImpl.add("ch.qos.logback:logback-classic");

        loggingImpl.add("org.apache.logging.log4j:log4j");
        loggingImpl.add("org.apache.logging.log4j:log4j-jcl");
        loggingImpl.add("org.apache.logging.log4j:log4j-core");
        loggingImpl.add("org.apache.logging.log4j:log4j-slf4j-impl");

        loggingImpl.add("org.slf4j:slf4j-jcl");
        loggingImpl.add("org.slf4j:slf4j-jdk14");
        loggingImpl.add("org.slf4j:slf4j-log4j12");
        loggingImpl.add("org.slf4j:slf4j-log4j13");
        loggingImpl.add("org.slf4j:slf4j-nop");
        loggingImpl.add("org.slf4j:slf4j-simple");

        // excluded dependencies
        Set<String> configExclusions = new HashSet<>();
        Properties properties = new Properties();
        properties.load(getClass().getResourceAsStream("/spring-boot-fix-dependencies.properties"));
        String artExcl = properties.getProperty("exclude_" + project.getArtifactId());
        getLog().debug("Configured exclusions: " + artExcl);
        if (artExcl != null && artExcl.trim().length() > 0) {
            for (String dep : artExcl.split(",")) {
                getLog().debug("Adding configured exclusion: " + dep);
                configExclusions.add(dep);
            }
        }

        Set<String> libsToRemove = new TreeSet<>();
        libsToRemove.addAll(loggingImpl);
        libsToRemove.addAll(configExclusions);
        libsToRemove = filterIncludedArtifacts(libsToRemove);

        if (libsToRemove.size() > 0) {
            getLog().info("Spring-Boot-Starter: the following dependencies will be removed from the starter: " + libsToRemove);

            XPath xpath = XPathFactory.newInstance().newXPath();
            Node dependency = ((NodeList) xpath.compile("/project/dependencies/dependency[artifactId/text() = '" + project.getArtifactId() + "']").evaluate(pom, XPathConstants.NODESET)).item(0);

            Element exclusions = pom.createElement("exclusions");

            dependency.appendChild(pom.createComment(GENERATED_SECTION_START));
            dependency.appendChild(exclusions);
            dependency.appendChild(pom.createComment(GENERATED_SECTION_END));

            for (String lib : libsToRemove) {
                String groupIdStr = lib.split("\\:")[0];
                String artifactIdStr = lib.split("\\:")[1];

                Element exclusion = pom.createElement("exclusion");

                Element groupId = pom.createElement("groupId");
                groupId.setTextContent(groupIdStr);
                exclusion.appendChild(groupId);

                Element artifactId = pom.createElement("artifactId");
                artifactId.setTextContent(artifactIdStr);
                exclusion.appendChild(artifactId);

                exclusions.appendChild(exclusion);
            }
        }
    }

    private Set<String> filterIncludedArtifacts(Set<String> artifacts) {
        Set<String> included = new TreeSet<>();

        included.addAll(project.getArtifactMap().keySet());
        included.retainAll(artifacts);

        return included;
    }

    private void synchronizeParentPom() throws Exception {
        File pomFile = new File(allStartersDir(), "pom.xml");
        DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
        Document pom = builder.parse(pomFile);

        XPath xpath = XPathFactory.newInstance().newXPath();
        Node modules = ((NodeList) xpath.compile("/project/modules").evaluate(pom, XPathConstants.NODESET)).item(0);

        // cleanup current modules
        while (modules.hasChildNodes()) {
            modules.removeChild(modules.getFirstChild());
        }

        for (File starterDir : Arrays
                .asList(allStartersDir().listFiles((f, n) ->
                        (new File(f, n)).isDirectory() && n.endsWith(SpringBootHelper.STARTER_SUFFIX) && (new File(new File(f, n), "pom.xml").exists()))).stream().sorted()
                .collect(Collectors.toList())) {
            Node module = pom.createElement("module");
            module.setTextContent(starterDir.getName());
            modules.appendChild(module);
        }

        writeXmlFormatted(pom, pomFile);
    }

    private Document createBasePom() throws Exception {
        Document pom = null;
        if (reuseExistingPom) {
            pom = createBasePomFromExisting();
        }
        if (pom == null) {
            pom = createBasePomFromScratch();
        }

        return pom;
    }

    private Document createBasePomFromExisting() {
        try {
            File pomFile = new File(starterDir(), "pom.xml");
            if (pomFile.exists()) {
                try (InputStream in = new FileInputStream(pomFile)) {
                    String content = IOUtils.toString(in, StandardCharsets.UTF_8);
                    boolean editablePom = content.contains(GENERATED_SECTION_START_COMMENT);
                    if (editablePom) {
                        content = removeGeneratedSections(content, 10);
                        DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();

                        Document pom;
                        try (InputStream contentIn = new ByteArrayInputStream(content.getBytes(StandardCharsets.UTF_8))) {
                            pom = builder.parse(contentIn);
                        }

                        getLog().debug("Reusing the existing pom.xml for the starter");
                        return pom;
                    }
                }
            }
        } catch (Exception e) {
            getLog().warn("Cannot use the existing pom.xml file", e);
        }

        return null;
    }

    private String removeGeneratedSections(String pom, int maxNumber) {
        if (maxNumber > 0 && pom.contains(GENERATED_SECTION_START_COMMENT)) {
            int start = pom.indexOf(GENERATED_SECTION_START_COMMENT);
            int end = pom.indexOf(GENERATED_SECTION_END_COMMENT);
            if (end <= start) {
                throw new IllegalArgumentException("Generated sections inside the xml document are not well-formed");
            }

            String newPom = pom.substring(0, start) + pom.substring(end + GENERATED_SECTION_END_COMMENT.length());
            return removeGeneratedSections(newPom, maxNumber - 1);
        }

        return pom;
    }

    private Document createBasePomFromScratch() throws Exception {
        getLog().info("Creating a new pom.xml for the starter from scratch");

        Template pomTemplate = getTemplate("spring-boot-starter-template-pom.template");
        Map<String, String> props = new HashMap<>();
        props.put("version", project.getVersion());
        props.put("componentId", getComponentId());
        props.put("componentName", project.getName());
        props.put("componentDescription", project.getDescription());

        StringWriter sw = new StringWriter();
        pomTemplate.process(props, sw);

        String xml = sw.toString();
        ByteArrayInputStream bin = new ByteArrayInputStream(xml.getBytes(StandardCharsets.UTF_8));

        DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
        Document pom = builder.parse(bin);
        return pom;
    }

    private void writeStaticFiles() throws IOException {
        String notice;
        String license;
        try (InputStream isNotice = getClass().getResourceAsStream("/spring-boot-starter-NOTICE.txt");
             InputStream isLicense = getClass().getResourceAsStream("/spring-boot-starter-LICENSE.txt")) {
            notice = IOUtils.toString(isNotice, StandardCharsets.UTF_8);
            license = IOUtils.toString(isLicense, StandardCharsets.UTF_8);
        }

        writeIfChanged(notice, new File(starterDir(), "src/main/resources/META-INF/NOTICE.txt"));
        writeIfChanged(license, new File(starterDir(), "src/main/resources/META-INF/LICENSE.txt"));
    }

    private void writeSpringProvides() throws IOException, TemplateException {
        Template fileTemplate = getTemplate("spring-boot-starter-template-spring.provides");
        Map<String, String> props = new HashMap<>();
        props.put("artifactId", project.getArtifactId());

        File outDir = new File(starterDir(), "src/main/resources/META-INF");
        outDir.mkdirs();
        File outFile = new File(outDir, "spring.provides");

        StringWriter sw = new StringWriter();
        fileTemplate.process(props, sw);
        sw.close();

        writeIfChanged(sw.toString(), outFile);
    }


    private Template getTemplate(String name) throws IOException {
        Configuration cfg = new Configuration(Configuration.getVersion());

        cfg.setTemplateLoader(new URLTemplateLoader() {
            @Override
            protected URL getURL(String name) {
                return SpringBootStarterMojo.class.getResource("/" + name);
            }
        });

        cfg.setDefaultEncoding("UTF-8");
        Template template = cfg.getTemplate(name);
        return template;
    }


    private boolean isStarterAllowed() {

        for (String ignored : IGNORE_MODULES) {
            if (ignored.equals(project.getArtifactId())) {
                getLog().debug("Component inside ignore list");
                return false;
            }
        }

        if (IGNORE_TEST_MODULES && (project.getArtifactId().startsWith("camel-test")
            || project.getArtifactId().startsWith("camel-testcontainers"))) {
            getLog().debug("Test components are ignored");
            return false;
        }

        if (project.getPackaging() != null && !project.getPackaging().equals("jar")) {
            getLog().debug("Ignored for wrong packaging");
            return false;
        }

        // include 'camel-core'
        if (baseDir.getName().equals("camel-core")) {
            return true;
        }

        // Build a starter for all components under the 'components' dir and include submodules ending with '-component'
        if (baseDir.getParentFile().getName().equals("components") || baseDir.getName().endsWith("-component")) {
            return true;
        }

        if (baseDir.getName().equals("camel-jaxp")) {
            return true;
        }

        getLog().debug("Component directory mismatch");
        return false;
    }


    private String getComponentId() {
        String componentName = project.getArtifact().getArtifactId();
        String componentId = componentName.replace("camel-", "");
        return componentId;
    }

    private void writeXmlFormatted(Document pom, File destination) throws Exception {
        XPathExpression xpath = XPathFactory.newInstance().newXPath().compile("//text()[normalize-space(.) = '']");
        NodeList emptyNodes = (NodeList) xpath.evaluate(pom, XPathConstants.NODESET);

        // Remove empty text nodes
        for (int i = 0; i < emptyNodes.getLength(); i++) {
            Node emptyNode = emptyNodes.item(i);
            emptyNode.getParentNode().removeChild(emptyNode);
        }

        pom.setXmlStandalone(true);

        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        transformerFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, Boolean.TRUE);
        Transformer transformer = transformerFactory.newTransformer();
        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
        transformer.setOutputProperty(OutputKeys.METHOD, "xml");
        transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");

        DOMSource source = new DOMSource(pom);

        String content;
        try (StringWriter out = new StringWriter()) {
            StreamResult result = new StreamResult(out);
            transformer.transform(source, result);
            content = out.toString();
        }

        // Fix header formatting problem
        content = content.replaceFirst("-->", "-->\n").replaceFirst("\\?><!--", "\\?>\n<!--");

        writeIfChanged(content, destination);
    }

    private void writeIfChanged(String content, File file) throws IOException {
        boolean write = true;

        if (file.exists()) {
            try (FileReader fr = new FileReader(file)) {
                String oldContent = IOUtils.toString(fr);
                if (!content.equals(oldContent)) {
                    getLog().debug("Writing new file " + file.getAbsolutePath());
                    fr.close();
                } else {
                    getLog().debug("File " + file.getAbsolutePath() + " has been left unchanged");
                    write = false;
                }
            }
        } else {
            // Create the structure
            File parent = file.getParentFile();
            parent.mkdirs();
        }

        if (write) {
            try (FileWriter fw = new FileWriter(file)) {
                IOUtils.write(content, fw);
            }
        }
    }

}