/*
 * 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.springboot.maven;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.HashSet;
import java.util.Properties;
import java.util.Set;
import java.util.TreeSet;

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 org.apache.commons.io.IOUtils;
import org.apache.maven.ProjectDependenciesResolver;
import org.apache.maven.artifact.Artifact;
import org.apache.maven.execution.MavenSession;
import org.apache.maven.plugin.MojoExecutionException;
import org.apache.maven.plugin.MojoFailureException;
import org.apache.maven.plugins.annotations.Component;
import org.apache.maven.plugins.annotations.LifecyclePhase;
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;
import org.apache.maven.project.ProjectBuilder;
import org.apache.maven.project.ProjectBuildingResult;

/**
 * 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,
        defaultPhase = LifecyclePhase.GENERATE_RESOURCES)
public class SpringBootStarterMojo extends AbstractSpringBootGenerator {

    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 session.
     */
    @Parameter(defaultValue = "${session}", readonly = true)
    private MavenSession session;

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

    @Component
    private ProjectDependenciesResolver projectDependenciesResolver;

    @Component
    private ProjectBuilder projectBuilder;

    @Override
    protected void executeAll() throws MojoExecutionException, MojoFailureException {
        try {
            // create the starter directory
            File starterDir = baseDir;

            // 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 and USAGE files
            writeStaticFiles();

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

    }

    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<>(csvToSet(properties.getProperty(getMainDepArtifactId())));


        Set<String> globalProps = csvToSet(properties.getProperty("global"));
        boolean inGlobal = false;
        for (String gp : globalProps) {
            String camelGav = getMainDepGroupId() + ":" + getMainDepArtifactId();
            String camelSpringBootGav = project.getGroupId() + ":" + project.getArtifactId();
            if (gp.equals(camelGav) || gp.equals(camelSpringBootGav)) {
                inGlobal = true;
                break;
            }
        }

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

        if (!deps.isEmpty()) {
            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);

            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().isEmpty()) {
            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-slf4j2-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_" + getMainDepArtifactId());
        getLog().debug("Configured exclusions: " + artExcl);
        if (artExcl != null && !artExcl.trim().isEmpty()) {
            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.isEmpty()) {
            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() = '" + getMainDepArtifactId() + "']").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<Artifact> dependencies;
        try {
            Artifact artifact = project.getArtifactMap().get(getMainDepGroupId() + ":" + getMainDepArtifactId());
            ProjectBuildingResult result = projectBuilder.build(artifact, project.getProjectBuildingRequest());
            MavenProject prj = result.getProject();
            prj.setRemoteArtifactRepositories(project.getRemoteArtifactRepositories());
            dependencies = projectDependenciesResolver.resolve(prj, Collections.singleton(Artifact.SCOPE_COMPILE), session);
        } catch (Exception e) {
            throw new RuntimeException("Unable to build project dependency tree", e);
        }

        Set<String> included = new TreeSet<>();
        dependencies.stream()
                .filter(a -> !Artifact.SCOPE_TEST.equals(a.getScope()))
                .map(a -> a.getGroupId() + ":" + a.getArtifactId())
                .forEach(included::add);
        included.retainAll(artifacts);

        return included;
    }

    private Document createBasePom() {
        try {
            File pomFile = new File(baseDir, "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);
                        DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
                        documentBuilderFactory.setFeature("http://apache.org/xml/features/disallow-doctype-decl",true);
                        documentBuilderFactory.setFeature("http://xml.org/sax/features/external-general-entities",false);
                        documentBuilderFactory.setFeature("http://xml.org/sax/features/external-parameter-entities",false);

                        DocumentBuilder builder = documentBuilderFactory.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 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(baseDir, "src/main/resources/META-INF/NOTICE.txt"));
        writeIfChanged(license, new File(baseDir, "src/main/resources/META-INF/LICENSE.txt"));
    }

    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);
    }

}
