/*
 * Copyright 2010 the original author or authors.
 *
 * 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 org.gradle.api.plugins;

import com.google.common.collect.ImmutableSet;
import org.gradle.api.Action;
import org.gradle.api.Incubating;
import org.gradle.api.NamedDomainObjectContainer;
import org.gradle.api.Nullable;
import org.gradle.api.Plugin;
import org.gradle.api.Project;
import org.gradle.api.Task;
import org.gradle.api.artifacts.Configuration;
import org.gradle.api.artifacts.ConfigurationContainer;
import org.gradle.api.artifacts.ConfigurationPublications;
import org.gradle.api.artifacts.ConfigurationVariant;
import org.gradle.api.artifacts.Dependency;
import org.gradle.api.artifacts.PublishArtifact;
import org.gradle.api.attributes.AttributeMatchingStrategy;
import org.gradle.api.attributes.MultipleCandidatesDetails;
import org.gradle.api.attributes.Usage;
import org.gradle.api.file.FileCollection;
import org.gradle.api.internal.artifacts.ArtifactAttributes;
import org.gradle.api.internal.artifacts.publish.AbstractPublishArtifact;
import org.gradle.api.internal.artifacts.publish.ArchivePublishArtifact;
import org.gradle.api.internal.component.BuildableJavaComponent;
import org.gradle.api.internal.component.ComponentRegistry;
import org.gradle.api.internal.java.JavaLibrary;
import org.gradle.api.internal.plugins.DefaultArtifactPublicationSet;
import org.gradle.api.internal.project.ProjectInternal;
import org.gradle.api.tasks.SourceSet;
import org.gradle.api.tasks.bundling.Jar;
import org.gradle.api.tasks.compile.JavaCompile;
import org.gradle.api.tasks.javadoc.Javadoc;
import org.gradle.api.tasks.testing.Test;
import org.gradle.internal.cleanup.BuildOutputCleanupRegistry;
import org.gradle.language.jvm.tasks.ProcessResources;

import java.io.File;
import java.util.Arrays;
import java.util.Collection;
import java.util.Date;
import java.util.Set;
import java.util.concurrent.Callable;

import static org.gradle.api.attributes.Usage.FOR_RUNTIME;
import static org.gradle.api.attributes.Usage.USAGE_ATTRIBUTE;

/**
 * <p>A {@link Plugin} which compiles and tests Java source, and assembles it into a JAR file.</p>
 */
public class JavaPlugin implements Plugin<ProjectInternal> {
    /**
     * The name of the task that processes resources.
     */
    public static final String PROCESS_RESOURCES_TASK_NAME = "processResources";

    /**
     * The name of the lifecycle task which outcome is that all the classes of a component are generated.
     */
    public static final String CLASSES_TASK_NAME = "classes";

    /**
     * The name of the task which compiles Java sources.
     */
    public static final String COMPILE_JAVA_TASK_NAME = "compileJava";

    /**
     * The name of the task which processes the test resources.
     */
    public static final String PROCESS_TEST_RESOURCES_TASK_NAME = "processTestResources";

    /**
     * The name of the lifecycle task which outcome is that all test classes of a component are generated.
     */
    public static final String TEST_CLASSES_TASK_NAME = "testClasses";

    /**
     * The name of the task which compiles the test Java sources.
     */
    public static final String COMPILE_TEST_JAVA_TASK_NAME = "compileTestJava";

    /**
     * The name of the task which triggers execution of tests.
     */
    public static final String TEST_TASK_NAME = "test";

    /**
     * The name of the task which generates the component main jar.
     */
    public static final String JAR_TASK_NAME = "jar";

    /**
     * The name of the task which generates the component javadoc.
     */
    public static final String JAVADOC_TASK_NAME = "javadoc";

    /**
     * The name of the API configuration, where dependencies exported by a component at compile time should
     * be declared.
     * @since 3.4
     */
    @Incubating
    public static final String API_CONFIGURATION_NAME = "api";

    /**
     * The name of the implementation configuration, where dependencies that are only used internally by
     * a component should be declared.
     * @since 3.4
     */
    @Incubating
    public static final String IMPLEMENTATION_CONFIGURATION_NAME = "implementation";

    /**
     * The name of the configuration used by consumers to get the API elements of a component, that is to say
     * the dependencies which are required to compile against that component.
     *
     * @since 3.4
     */
    @Incubating
    public static final String API_ELEMENTS_CONFIGURATION_NAME = "apiElements";

    /**
     * The name of the configuration that is used to declare API or implementation dependencies. This configuration
     * is deprecated.
     *
     * @deprecated Users should prefer {@link #API_CONFIGURATION_NAME} or {@link #IMPLEMENTATION_CONFIGURATION_NAME}.
     */
    public static final String COMPILE_CONFIGURATION_NAME = "compile";

    /**
     * The name of the configuration that is used to declare dependencies which are only required to compile a component,
     * but not at runtime.
     */
    public static final String COMPILE_ONLY_CONFIGURATION_NAME = "compileOnly";

    /**
     * The name of the "runtime" configuration. This configuration is deprecated and doesn't represent a correct view of
     * the runtime dependencies of a component.
     *
     * @deprecated Consumers should use {@link #RUNTIME_ELEMENTS_CONFIGURATION_NAME} instead.
     */
    public static final String RUNTIME_CONFIGURATION_NAME = "runtime";

    /**
     * The name of the runtime only dependencies configuration, used to declare dependencies
     * that should only be found at runtime.
     * @since 3.4
     */
    @Incubating
    public static final String RUNTIME_ONLY_CONFIGURATION_NAME = "runtimeOnly";

    /**
     * The name of the runtime classpath configuration, used by a component to query its own runtime classpath.
     * @since 3.4
     */
    @Incubating
    public static final String RUNTIME_CLASSPATH_CONFIGURATION_NAME = "runtimeClasspath";

    /**
     * The name of the runtime elements configuration, that should be used by consumers
     * to query the runtime dependencies of a component.
     * @since 3.4
     */
    @Incubating
    public static final String RUNTIME_ELEMENTS_CONFIGURATION_NAME = "runtimeElements";

    /**
     * The name of the compile classpath configuration.
     * @since 3.4
     */
    @Incubating
    public static final String COMPILE_CLASSPATH_CONFIGURATION_NAME = "compileClasspath";

    public static final String TEST_COMPILE_CONFIGURATION_NAME = "testCompile";

    /**
     * The name of the test implementation dependencies configuration.
     * @since 3.4
     */
    @Incubating
    public static final String TEST_IMPLEMENTATION_CONFIGURATION_NAME = "testImplementation";

    /**
     * The name of the configuration that should be used to declare dependencies which are only required
     * to compile the tests, but not when running them.
     */
    public static final String TEST_COMPILE_ONLY_CONFIGURATION_NAME = "testCompileOnly";

    /**
     * The name of the configuration that represents the component runtime classpath. This configuration doesn't
     * represent the exact runtime dependencies and therefore is deprecated.
     *
     * @deprecated Use {@link #TEST_RUNTIME_CLASSPATH_CONFIGURATION_NAME} instead.
     */
    public static final String TEST_RUNTIME_CONFIGURATION_NAME = "testRuntime";

    /**
     * The name of the test runtime only dependencies configuration.
     * @since 3.4
     */
    @Incubating
    public static final String TEST_RUNTIME_ONLY_CONFIGURATION_NAME = "testRuntimeOnly";

    /**
     * The name of the test compile classpath configuration.
     * @since 3.4
     */
    @Incubating
    public static final String TEST_COMPILE_CLASSPATH_CONFIGURATION_NAME = "testCompileClasspath";

    /**
     * The name of the test runtime classpath configuration.
     * @since 3.4
     */
    @Incubating
    public static final String TEST_RUNTIME_CLASSPATH_CONFIGURATION_NAME = "testRuntimeClasspath";

    /**
     * Represents the "classes directory" format of a variant of a Java component. This can be used
     * when querying artifacts to only get the class directories, instead of, typically, a jar dependency.
     *
     * @since 3.4
     */
    @Incubating
    public static final String CLASS_DIRECTORY = "org.gradle.java.classes.directory";

    /**
     * Represents the "resources directory" format of a variant of a Java component. This can be used
     * when querying artifacts to only get the resources directories, instead of, typically, a jar dependency.
     *
     * @since 3.4
     */
    @Incubating
    public static final String RESOURCES_DIRECTORY = "org.gradle.java.resources.directory";

    /**
     * Represents the "jar" format of a variant of a Java component.
     * @since 3.5
     */
    @Incubating
    public static final String JAR_TYPE = "jar";

    // this is a workaround to force the classes variant to be used at compile time when using the Java library
    static final String NON_DEFAULT_JAR_TYPE = "org.gradle.java.implicit";

    private static final Set<String> VARIANT_TYPES = ImmutableSet.of(JAR_TYPE, CLASS_DIRECTORY, RESOURCES_DIRECTORY);
    private static final Set<String> DIR_VARIANT_TYPES = ImmutableSet.of(NON_DEFAULT_JAR_TYPE, CLASS_DIRECTORY, RESOURCES_DIRECTORY);

    public void apply(ProjectInternal project) {
        project.getPluginManager().apply(JavaBasePlugin.class);

        JavaPluginConvention javaConvention = project.getConvention().getPlugin(JavaPluginConvention.class);
        project.getServices().get(ComponentRegistry.class).setMainComponent(new BuildableJavaComponentImpl(javaConvention));
        BuildOutputCleanupRegistry buildOutputCleanupRegistry = project.getServices().get(BuildOutputCleanupRegistry.class);

        configureSourceSets(javaConvention, buildOutputCleanupRegistry);
        configureCompatibilityRules(project);
        configureConfigurations(project);

        configureJavaDoc(javaConvention);
        configureTest(project, javaConvention);
        configureArchivesAndComponent(project, javaConvention);
        configureBuild(project);
    }

    private void configureCompatibilityRules(ProjectInternal project) {
        AttributeMatchingStrategy<String> matchingStrategy = project.getDependencies().getAttributesSchema().getMatchingStrategy(ArtifactAttributes.ARTIFACT_FORMAT);
        matchingStrategy.getDisambiguationRules().add(new Action<MultipleCandidatesDetails<String>>() {
            @Override
            public void execute(MultipleCandidatesDetails<String> details) {
                // Use Jar if all are selected
                if (details.getCandidateValues().equals(VARIANT_TYPES)) {
                    details.closestMatch(JAR_TYPE);
                    return;
                }
                // Use classes if dir variants are selected
                if (details.getCandidateValues().equals(DIR_VARIANT_TYPES)) {
                    details.closestMatch(CLASS_DIRECTORY);
                }
            }
        });
    }

    private void configureSourceSets(JavaPluginConvention pluginConvention, final BuildOutputCleanupRegistry buildOutputCleanupRegistry) {
        Project project = pluginConvention.getProject();

        SourceSet main = pluginConvention.getSourceSets().create(SourceSet.MAIN_SOURCE_SET_NAME);

        SourceSet test = pluginConvention.getSourceSets().create(SourceSet.TEST_SOURCE_SET_NAME);
        test.setCompileClasspath(project.files(main.getOutput(), project.getConfigurations().getByName(TEST_COMPILE_CLASSPATH_CONFIGURATION_NAME)));
        test.setRuntimeClasspath(project.files(test.getOutput(), main.getOutput(), project.getConfigurations().getByName(TEST_RUNTIME_CLASSPATH_CONFIGURATION_NAME)));

        // Register the project's source set output directories
        pluginConvention.getSourceSets().all(new Action<SourceSet>() {
            @Override
            public void execute(SourceSet sourceSet) {
                buildOutputCleanupRegistry.registerOutputs(sourceSet.getOutput());
            }
        });
    }

    private void configureJavaDoc(JavaPluginConvention pluginConvention) {
        Project project = pluginConvention.getProject();

        SourceSet mainSourceSet = pluginConvention.getSourceSets().getByName(SourceSet.MAIN_SOURCE_SET_NAME);
        Javadoc javadoc = project.getTasks().create(JAVADOC_TASK_NAME, Javadoc.class);
        javadoc.setDescription("Generates Javadoc API documentation for the main source code.");
        javadoc.setGroup(JavaBasePlugin.DOCUMENTATION_GROUP);
        javadoc.setClasspath(mainSourceSet.getOutput().plus(mainSourceSet.getCompileClasspath()));
        javadoc.setSource(mainSourceSet.getAllJava());
        addDependsOnTaskInOtherProjects(javadoc, true, JAVADOC_TASK_NAME, COMPILE_CONFIGURATION_NAME);
    }

    private void configureArchivesAndComponent(Project project, JavaPluginConvention pluginConvention) {
        Jar jar = project.getTasks().create(JAR_TASK_NAME, Jar.class);
        jar.setDescription("Assembles a jar archive containing the main classes.");
        jar.setGroup(BasePlugin.BUILD_GROUP);
        jar.from(pluginConvention.getSourceSets().getByName(SourceSet.MAIN_SOURCE_SET_NAME).getOutput());

        ArchivePublishArtifact jarArtifact = new ArchivePublishArtifact(jar);
        Configuration apiElementConfiguration = project.getConfigurations().getByName(API_ELEMENTS_CONFIGURATION_NAME);
        Configuration runtimeConfiguration = project.getConfigurations().getByName(RUNTIME_CONFIGURATION_NAME);
        Configuration runtimeElementsConfiguration = project.getConfigurations().getByName(RUNTIME_ELEMENTS_CONFIGURATION_NAME);

        project.getExtensions().getByType(DefaultArtifactPublicationSet.class).addCandidate(jarArtifact);

        JavaCompile javaCompile = (JavaCompile) project.getTasks().getByPath(COMPILE_JAVA_TASK_NAME);
        ProcessResources processResources = (ProcessResources) project.getTasks().getByPath(PROCESS_RESOURCES_TASK_NAME);

        addVariants(apiElementConfiguration, jarArtifact, javaCompile, processResources);
        addVariants(runtimeConfiguration, jarArtifact, javaCompile, processResources);
        addVariants(runtimeElementsConfiguration, jarArtifact, javaCompile, processResources);

        project.getComponents().add(new JavaLibrary(project.getConfigurations(), jarArtifact));
    }

    private void addVariants(Configuration configuration, ArchivePublishArtifact jarArtifact, final JavaCompile javaCompile, final ProcessResources processResources) {
        ConfigurationPublications publications = configuration.getOutgoing();

        // Configure an implicit variant
        publications.getArtifacts().add(jarArtifact);
        publications.getAttributes().attribute(ArtifactAttributes.ARTIFACT_FORMAT, JavaPlugin.JAR_TYPE);

        // Define some additional variants
        NamedDomainObjectContainer<ConfigurationVariant> runtimeVariants = publications.getVariants();
        createVariant(runtimeVariants, "classes", JavaPlugin.CLASS_DIRECTORY, new IntermediateJavaArtifact(JavaPlugin.CLASS_DIRECTORY, javaCompile) {
            @Override
            public File getFile() {
                return javaCompile.getDestinationDir();
            }
        });
        createVariant(runtimeVariants, "resources", JavaPlugin.RESOURCES_DIRECTORY, new IntermediateJavaArtifact(JavaPlugin.RESOURCES_DIRECTORY, processResources) {
            @Override
            public File getFile() {
                return processResources.getDestinationDir();
            }
        });
    }

    private void createVariant(NamedDomainObjectContainer<ConfigurationVariant> variants, String name, String artifactType, PublishArtifact artifact) {
        ConfigurationVariant variant = variants.create(name);
        variant.getAttributes().attribute(ArtifactAttributes.ARTIFACT_FORMAT, artifactType);
        variant.artifact(artifact);
    }

    private void configureBuild(Project project) {
        addDependsOnTaskInOtherProjects(project.getTasks().getByName(JavaBasePlugin.BUILD_NEEDED_TASK_NAME), true,
            JavaBasePlugin.BUILD_NEEDED_TASK_NAME, TEST_RUNTIME_CONFIGURATION_NAME);
        addDependsOnTaskInOtherProjects(project.getTasks().getByName(JavaBasePlugin.BUILD_DEPENDENTS_TASK_NAME), false,
            JavaBasePlugin.BUILD_DEPENDENTS_TASK_NAME, TEST_RUNTIME_CONFIGURATION_NAME);
    }

    private void configureTest(final Project project, final JavaPluginConvention pluginConvention) {
        project.getTasks().withType(Test.class, new Action<Test>() {
            public void execute(final Test test) {
                test.getConventionMapping().map("testClassesDir", new Callable<Object>() {
                    public Object call() throws Exception {
                        return pluginConvention.getSourceSets().getByName(SourceSet.TEST_SOURCE_SET_NAME).getOutput().getClassesDir();
                    }
                });
                test.getConventionMapping().map("classpath", new Callable<Object>() {
                    public Object call() throws Exception {
                        return pluginConvention.getSourceSets().getByName(SourceSet.TEST_SOURCE_SET_NAME).getRuntimeClasspath();
                    }
                });
            }
        });
        Test test = project.getTasks().create(TEST_TASK_NAME, Test.class);
        project.getTasks().getByName(JavaBasePlugin.CHECK_TASK_NAME).dependsOn(test);
        test.setDescription("Runs the unit tests.");
        test.setGroup(JavaBasePlugin.VERIFICATION_GROUP);
    }

    private void configureConfigurations(Project project) {
        ConfigurationContainer configurations = project.getConfigurations();

        Configuration defaultConfiguration = configurations.getByName(Dependency.DEFAULT_CONFIGURATION);
        Configuration compileConfiguration = configurations.getByName(COMPILE_CONFIGURATION_NAME);
        Configuration implementationConfiguration = configurations.getByName(IMPLEMENTATION_CONFIGURATION_NAME);
        Configuration runtimeConfiguration = configurations.getByName(RUNTIME_CONFIGURATION_NAME);
        Configuration runtimeOnlyConfiguration = configurations.getByName(RUNTIME_ONLY_CONFIGURATION_NAME);
        Configuration compileTestsConfiguration = configurations.getByName(TEST_COMPILE_CONFIGURATION_NAME);
        Configuration testImplementationConfiguration = configurations.getByName(TEST_IMPLEMENTATION_CONFIGURATION_NAME);
        Configuration testRuntimeConfiguration = configurations.getByName(TEST_RUNTIME_CONFIGURATION_NAME);
        Configuration testRuntimeOnlyConfiguration = configurations.getByName(TEST_RUNTIME_ONLY_CONFIGURATION_NAME);

        compileTestsConfiguration.extendsFrom(compileConfiguration);
        testImplementationConfiguration.extendsFrom(implementationConfiguration);
        testRuntimeConfiguration.extendsFrom(runtimeConfiguration);
        testRuntimeOnlyConfiguration.extendsFrom(runtimeOnlyConfiguration);

        Configuration apiElementsConfiguration = configurations.maybeCreate(API_ELEMENTS_CONFIGURATION_NAME);
        apiElementsConfiguration.setVisible(false);
        apiElementsConfiguration.setDescription("API elements for main.");
        apiElementsConfiguration.setCanBeResolved(false);
        apiElementsConfiguration.setCanBeConsumed(true);
        apiElementsConfiguration.getAttributes().attribute(Usage.USAGE_ATTRIBUTE, Usage.FOR_COMPILE);
        apiElementsConfiguration.extendsFrom(compileConfiguration, runtimeConfiguration);

        Configuration runtimeElementsConfiguration = configurations.maybeCreate(RUNTIME_ELEMENTS_CONFIGURATION_NAME);
        runtimeElementsConfiguration.setVisible(false);
        runtimeElementsConfiguration.setCanBeConsumed(true);
        runtimeElementsConfiguration.setCanBeResolved(false);
        runtimeElementsConfiguration.setDescription("Elements of runtime for main.");
        runtimeElementsConfiguration.getAttributes().attribute(USAGE_ATTRIBUTE, FOR_RUNTIME);
        runtimeElementsConfiguration.extendsFrom(implementationConfiguration, runtimeOnlyConfiguration, runtimeConfiguration);

        defaultConfiguration.extendsFrom(runtimeElementsConfiguration);
    }

    /**
     * Adds a dependency on tasks with the specified name in other projects.  The other projects are determined from
     * project lib dependencies using the specified configuration name. These may be projects this project depends on or
     * projects that depend on this project based on the useDependOn argument.
     *
     * @param task Task to add dependencies to
     * @param useDependedOn if true, add tasks from projects this project depends on, otherwise use projects that depend on this one.
     * @param otherProjectTaskName name of task in other projects
     * @param configurationName name of configuration to use to find the other projects
     */
    private void addDependsOnTaskInOtherProjects(final Task task, boolean useDependedOn, String otherProjectTaskName,
                                                 String configurationName) {
        Project project = task.getProject();
        final Configuration configuration = project.getConfigurations().getByName(configurationName);
        task.dependsOn(configuration.getTaskDependencyFromProjectDependency(useDependedOn, otherProjectTaskName));
    }

    /**
     * This is only used by buildSrc to add to the buildscript classpath.
     */
    private static class BuildableJavaComponentImpl implements BuildableJavaComponent {
        private final JavaPluginConvention convention;

        public BuildableJavaComponentImpl(JavaPluginConvention convention) {
            this.convention = convention;
        }

        public Collection<String> getRebuildTasks() {
            return Arrays.asList(BasePlugin.CLEAN_TASK_NAME, JavaBasePlugin.BUILD_TASK_NAME);
        }

        public Collection<String> getBuildTasks() {
            return Arrays.asList(JavaBasePlugin.BUILD_TASK_NAME);
        }

        public FileCollection getRuntimeClasspath() {
            ProjectInternal project = convention.getProject();
            SourceSet mainSourceSet = convention.getSourceSets().getByName(SourceSet.MAIN_SOURCE_SET_NAME);
            FileCollection runtimeClasspath = mainSourceSet.getRuntimeClasspath();
            FileCollection gradleApi = project.getConfigurations().detachedConfiguration(project.getDependencies().gradleApi(), project.getDependencies().localGroovy());
            Configuration runtimeElements = project.getConfigurations().getByName(mainSourceSet.getRuntimeElementsConfigurationName());
            FileCollection mainSourceSetArtifact = runtimeElements.getOutgoing().getArtifacts().getFiles();
            return mainSourceSetArtifact.plus(runtimeClasspath.minus(mainSourceSet.getOutput()).minus(gradleApi));
        }

        public Configuration getCompileDependencies() {
            return convention.getProject().getConfigurations().getByName(JavaPlugin.COMPILE_CONFIGURATION_NAME);
        }
    }

    /**
     * A custom artifact type which allows the getFile call to be done lazily only when the
     * artifact is actually needed.
     */
    private abstract static class IntermediateJavaArtifact extends AbstractPublishArtifact {
        private final String type;

        IntermediateJavaArtifact(String type, Task task) {
            super(task);
            this.type = type;
        }

        @Override
        public String getName() {
            return getFile().getName();
        }

        @Override
        public String getExtension() {
            return "";
        }

        @Override
        public String getType() {
            return type;
        }

        @Nullable
        @Override
        public String getClassifier() {
            return null;
        }

        @Override
        public Date getDate() {
            return null;
        }
    }
}
