/*
 * 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.karaf.tooling.tracker;

import java.io.File;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import java.util.Set;
import java.util.TreeSet;

import org.apache.karaf.shell.api.action.lifecycle.Service;
import org.apache.karaf.util.tracker.annotation.Managed;
import org.apache.karaf.util.tracker.annotation.ProvideService;
import org.apache.karaf.util.tracker.annotation.RequireService;
import org.apache.karaf.util.tracker.annotation.Services;
import org.apache.maven.artifact.Artifact;
import org.apache.maven.model.Resource;
import org.apache.maven.plugin.AbstractMojo;
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.xbean.finder.ClassFinder;
import org.osgi.framework.BundleActivator;
import org.sonatype.plexus.build.incremental.BuildContext;

/**
 * Generates service requirement and capabilities for activators
 */
@Mojo(name = "service-metadata-generate", defaultPhase = LifecyclePhase.PROCESS_CLASSES, requiresDependencyResolution = ResolutionScope.COMPILE_PLUS_RUNTIME, inheritByDefault = false)
public class GenerateServiceMetadata extends AbstractMojo {

    /**
     * The maven project.
     */
    @Parameter(defaultValue = "${project}")
    protected MavenProject project;

    @Parameter(defaultValue="BNDExtension-Bundle-Activator")
    protected String activatorProperty;

    @Parameter(defaultValue="BNDExtension-Require-Capability")
    protected String requirementsProperty;

    @Parameter(defaultValue="BNDExtension-Provide-Capability")
    protected String capabilitiesProperty;

    @Parameter(defaultValue = "${project.build.directory}/generated/karaf-tracker")
    protected String outputDirectory;

    /**
     * The classloader to use for loading the commands.
     * Can be "project" or "plugin"
     */
    @Parameter(defaultValue = "project")
    protected String classLoader;
    
    @Parameter(defaultValue=".*")
    protected String artifactInclude;

    @Component
    private BuildContext buildContext;

    public void execute() throws MojoExecutionException, MojoFailureException {
        try {
            boolean addSourceDirectory = false;

            List<String> requirements = new ArrayList<>();
            List<String> capabilities = new ArrayList<>();

            ClassFinder finder = createFinder(classLoader);
            List<Class<?>> classes = finder.findAnnotatedClasses(Services.class);

            List<Class<?>> activators = new ArrayList<>();
            for (Class<?> clazz : classes) {
                URL classUrl = clazz.getClassLoader().getResource(clazz.getName().replace('.', '/') + ".class");
                URL outputDirectoryUrl = new File(project.getBuild().getOutputDirectory()).toURI().toURL();
                if (classUrl == null || !classUrl.getPath().startsWith(outputDirectoryUrl.getPath())) {
                    getLog().info("Ignoring " + classUrl);
                    continue;
                }

                if (BundleActivator.class.isAssignableFrom(clazz)) {
                    activators.add(clazz);
                }

                writeServiceProperties(clazz);

                Services services = clazz.getAnnotation(Services.class);
                if (services != null) {
                    for (RequireService req : services.requires()) {
                        requirements.add(getRequirement(req));
                    }
                    for (ProvideService cap : services.provides()) {
                        capabilities.add(getCapability(cap));
                    }
                }
                
                addSourceDirectory = true;
            }

            if (addSourceDirectory) {
                Resource resource = new Resource();
                resource.setDirectory(outputDirectory);
                project.addResource(resource);
            }

            project.getProperties().setProperty(requirementsProperty, String.join(",", requirements));
            project.getProperties().setProperty(capabilitiesProperty, String.join(",", capabilities));
            if (activators.size() == 1) {
                getLog().info("Activator " + activators.get(0).getName());
                project.getProperties().setProperty(activatorProperty, activators.get(0).getName());
            }
            project.getProperties().setProperty("BNDExtension-Private-Package", "org.apache.karaf.util.tracker");
            project.getProperties().setProperty("BNDPrependExtension-Import-Package", "!org.apache.karaf.util.tracker.annotation");

            List<Class<?>> services = finder.findAnnotatedClasses(Service.class);
            Set<String> packages = new TreeSet<>();
            for (Class<?> clazz : services) {
                getLog().info("Service " + clazz.getPackage().getName());
                packages.add(clazz.getPackage().getName());
            }
            if (!packages.isEmpty()) {
                project.getProperties().setProperty("BNDExtension-Karaf-Commands", String.join(",", packages));
            }

        } catch (Exception e) {
            throw new MojoExecutionException("Error building commands help", e);
        }
    }

    private String getRequirement(RequireService req) {
        String fltWithClass = combine(req.filter(), "(objectClass=" + req.value().getName() + ")");
        return "osgi.service;effective:=active;filter:=\"" + fltWithClass + "\"";
    }
    
    private String getCapability(ProvideService cap) {
        return "osgi.service;effective:=active;objectClass=" + cap.value().getName();
    }

    private void writeServiceProperties(Class<?> serviceClazz) throws IOException {
        Properties props = new Properties();
        Services services = serviceClazz.getAnnotation(Services.class);
        if (services != null) {
            for (RequireService req : services.requires()) {
                props.setProperty(req.value().getName(), req.filter());
            }
        }
        Managed managed = serviceClazz.getAnnotation(Managed.class);
        if (managed != null) {
            props.setProperty("pid", managed.value());
        }

        File file = new File(outputDirectory, "OSGI-INF/karaf-tracker/" + serviceClazz.getName());
        file.getParentFile().mkdirs();
        try (OutputStream os = buildContext.newFileOutputStream(file)) {
            props.store(os, null);
        }
    }

    private String combine(String filter1, String filter2) {
        if (filter1!=null && !filter1.isEmpty()) {
            return "(&" + filter2 + filter1 + ")";
        } else {
            return filter2;
        }
    }

    private ClassFinder createFinder(String classloaderType) throws Exception {
        ClassFinder finder;
        if ("project".equals(classloaderType)) {
            List<URL> urls = new ArrayList<>();

            urls.add(new File(project.getBuild().getOutputDirectory()).toURI().toURL());
            for (Artifact artifact : project.getArtifacts()) {
                if (artifactInclude != null && artifactInclude.length() > 0 && artifact.getArtifactId().matches(artifactInclude)) {
                    File file = artifact.getFile();
                    if (file != null) {
                        getLog().debug("Use artifact " + artifact.getArtifactId() + ": " + file);
                        urls.add(file.toURI().toURL());
                    }
                } else {
                    getLog().debug("Ignore artifact " + artifact.getArtifactId());
                }
            }
            ClassLoader loader = new URLClassLoader(urls.toArray(new URL[urls.size()]), getClass().getClassLoader());
            finder = new ClassFinder(loader, urls);
        } else if ("plugin".equals(classLoader)) {
            finder = new ClassFinder(getClass().getClassLoader());
        } else {
            throw new MojoFailureException("classLoader attribute must be 'project' or 'plugin'");
        }
        return finder;
    }

}