/*
 * Copyright (c) 2013 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.yangtools.yang2sources.plugin;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMap.Builder;
import com.google.common.collect.ImmutableSet;
import com.google.common.io.CharStreams;
import java.io.File;
import java.io.IOException;
import java.io.Reader;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.maven.plugin.MojoExecutionException;
import org.apache.maven.plugin.MojoFailureException;
import org.apache.maven.project.MavenProject;
import org.codehaus.plexus.util.FileUtils;
import org.opendaylight.yangtools.yang.common.QNameModule;
import org.opendaylight.yangtools.yang.common.SimpleDateFormatUtil;
import org.opendaylight.yangtools.yang.model.api.Module;
import org.opendaylight.yangtools.yang.model.api.SchemaContext;
import org.opendaylight.yangtools.yang.model.repo.api.RevisionSourceIdentifier;
import org.opendaylight.yangtools.yang.model.repo.api.SourceIdentifier;
import org.opendaylight.yangtools.yang.model.repo.api.YangTextSchemaSource;
import org.opendaylight.yangtools.yang.parser.repo.YangTextSchemaContextResolver;
import org.opendaylight.yangtools.yang.parser.repo.YangTextSchemaSourceRegistration;
import org.opendaylight.yangtools.yang2sources.plugin.ConfigArg.CodeGeneratorArg;
import org.opendaylight.yangtools.yang2sources.plugin.Util.ContextHolder;
import org.opendaylight.yangtools.yang2sources.spi.BasicCodeGenerator;
import org.opendaylight.yangtools.yang2sources.spi.BuildContextAware;
import org.opendaylight.yangtools.yang2sources.spi.MavenProjectAware;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.sonatype.plexus.build.incremental.BuildContext;
import org.sonatype.plexus.build.incremental.DefaultBuildContext;

class YangToSourcesProcessor {
    private static final Logger LOG = LoggerFactory.getLogger(YangToSourcesProcessor.class);

    static final String LOG_PREFIX = "yang-to-sources:";
    private static final String META_INF_STR = "META-INF";
    private static final String YANG_STR = "yang";

    static final String META_INF_YANG_STRING = META_INF_STR + File.separator + YANG_STR;
    static final String META_INF_YANG_STRING_JAR = META_INF_STR + "/" + YANG_STR;
    static final String META_INF_YANG_SERVICES_STRING_JAR = META_INF_STR + "/" + "services";

    private final File yangFilesRootDir;
    private final Set<File> excludedFiles;
    private final List<CodeGeneratorArg> codeGenerators;
    private final MavenProject project;
    private final boolean inspectDependencies;
    private final BuildContext buildContext;
    private final YangProvider yangProvider;

    @VisibleForTesting
    YangToSourcesProcessor(final File yangFilesRootDir, final Collection<File> excludedFiles,
            final List<CodeGeneratorArg> codeGenerators, final MavenProject project, final boolean inspectDependencies,
            final YangProvider yangProvider) {
        this(new DefaultBuildContext(), yangFilesRootDir, excludedFiles, codeGenerators, project,
                inspectDependencies, yangProvider);
    }

    private YangToSourcesProcessor(final BuildContext buildContext, final File yangFilesRootDir,
            final Collection<File> excludedFiles, final List<CodeGeneratorArg> codeGenerators,
            final MavenProject project, final boolean inspectDependencies, final YangProvider yangProvider) {
        this.buildContext = Preconditions.checkNotNull(buildContext, "buildContext");
        this.yangFilesRootDir = Preconditions.checkNotNull(yangFilesRootDir, "yangFilesRootDir");
        this.excludedFiles = ImmutableSet.copyOf(excludedFiles);
        this.codeGenerators = ImmutableList.copyOf(codeGenerators);
        this.project = Preconditions.checkNotNull(project);
        this.inspectDependencies = inspectDependencies;
        this.yangProvider = yangProvider;
    }

    YangToSourcesProcessor(final BuildContext buildContext, final File yangFilesRootDir,
                final Collection<File> excludedFiles, final List<CodeGeneratorArg> codeGenerators,
                final MavenProject project, final boolean inspectDependencies) {
        this(yangFilesRootDir, excludedFiles, codeGenerators, project, inspectDependencies, new YangProvider());
    }

    public void execute() throws MojoExecutionException, MojoFailureException {
        ContextHolder context = processYang();
        if (context != null) {
            generateSources(context);
            yangProvider.addYangsToMetaInf(project, yangFilesRootDir, excludedFiles);
        }
    }

    void conditionalExecute(final boolean skip) throws MojoExecutionException, MojoFailureException {
        if (skip) {
            LOG.info("Skipping YANG code generation because property yang.skip is true");

            // But manually add resources
            // add META_INF/yang
            yangProvider.addYangsToMetaInf(project, yangFilesRootDir, excludedFiles);

            // add META_INF/services
            File generatedServicesDir = new GeneratedDirectories(project).getYangServicesDir();
            YangProvider.setResource(generatedServicesDir, project);
            LOG.debug("{} Yang services files from: {} marked as resources: {}", LOG_PREFIX, generatedServicesDir,
                    META_INF_YANG_SERVICES_STRING_JAR);


        } else {
            execute();
        }
    }

    @SuppressWarnings("checkstyle:illegalCatch")
    private ContextHolder processYang() throws MojoExecutionException {
        LOG.info("{} Inspecting {}", LOG_PREFIX, yangFilesRootDir);
        try {
            /*
             * Collect all files which affect YANG context. This includes all
             * files in current project and optionally any jars/files in the
             * dependencies.
             */
            final Collection<File> yangFilesInProject = Util.listFiles(yangFilesRootDir, excludedFiles);

            final Collection<File> allFiles = new ArrayList<>(yangFilesInProject);
            if (inspectDependencies) {
                allFiles.addAll(Util.findYangFilesInDependencies(project));
            }

            if (allFiles.isEmpty()) {
                LOG.info("{} No input files found", LOG_PREFIX);
                return null;
            }

            /*
             * Check if any of the listed files changed. If no changes occurred,
             * simply return null, which indicates and of execution.
             */
            boolean noChange = true;
            for (final File f : allFiles) {
                if (buildContext.hasDelta(f)) {
                    LOG.debug("{} buildContext {} indicates {} changed, forcing regeneration", LOG_PREFIX,
                            buildContext, f);
                    noChange = false;
                }
            }

            if (noChange) {
                LOG.info("{} None of {} input files changed", LOG_PREFIX, allFiles.size());
                return null;
            }

            final Builder<SourceIdentifier, String> b = ImmutableMap.builder();
            final YangTextSchemaContextResolver resolver = YangTextSchemaContextResolver.create("maven-plugin");
            for (final File f : yangFilesInProject) {
                final YangTextSchemaSourceRegistration reg = resolver.registerSource(YangTextSchemaSource.forFile(f));
                // Registration has an accurate identifier
                b.put(reg.getInstance().getIdentifier(), f.getName());
            }

            final Map<SourceIdentifier, String> sourcesInProject = b.build();

            /**
             * Set contains all modules generated from input sources. Number of
             * modules may differ from number of sources due to submodules
             * (parsed submodule's data are added to its parent module). Set
             * cannot contains null values.
             */
            if (inspectDependencies) {
                final List<YangTextSchemaSource> sourcesInDependencies = Util.findYangFilesInDependenciesAsStream(
                    project);
                for (YangTextSchemaSource s : toUniqueSources(sourcesInDependencies)) {
                    resolver.registerSource(s);
                }
            }

            final SchemaContext schemaContext = resolver.trySchemaContext();
            final Set<Module> projectYangModules = new HashSet<>();
            final Map<Module, String> projectYangFiles = new HashMap<>();
            for (Module module : schemaContext.getModules()) {
                final SourceIdentifier modId = moduleToIdentifier(module);
                LOG.debug("Looking for source {}", modId);
                final String file = sourcesInProject.get(modId);
                if (file != null) {
                    LOG.debug("Module {} belongs to current project", module);
                    projectYangModules.add(module);
                    projectYangFiles.put(module, file);

                    for (Module sub : module.getSubmodules()) {
                        final SourceIdentifier subId = moduleToIdentifier(sub);
                        final String subFile = sourcesInProject.get(subId);
                        if (subFile != null) {
                            LOG.debug("Submodule {} belongs to current project", sub);
                            projectYangFiles.put(sub, subFile);
                        } else {
                            LOG.warn("Submodule {} not found in input files", sub);
                        }
                    }
                }
            }

            LOG.debug("Processed project files: {}", yangFilesInProject);
            LOG.info("{} Project model files parsed: {}", LOG_PREFIX, yangFilesInProject.size());
            return new ContextHolder(schemaContext, projectYangModules, projectYangFiles);
        } catch (Exception e) {
            // MojoExecutionException is thrown since execution cannot continue
            LOG.error("{} Unable to parse {} files from {}", LOG_PREFIX, Util.YANG_SUFFIX, yangFilesRootDir, e);
            Throwable rootCause = Throwables.getRootCause(e);
            throw new MojoExecutionException(LOG_PREFIX + " Unable to parse " + Util.YANG_SUFFIX + " files from "
                    + yangFilesRootDir, rootCause);
        }
    }

    private static SourceIdentifier moduleToIdentifier(final Module module) {
        final QNameModule mod = module.getQNameModule();
        final Date rev = mod.getRevision();
        final Optional<String> optRev;
        if (!SimpleDateFormatUtil.DEFAULT_DATE_REV.equals(rev)) {
            optRev = Optional.of(mod.getFormattedRevision());
        } else {
            optRev = Optional.absent();
        }

        return RevisionSourceIdentifier.create(module.getName(), optRev);
    }

    private static Collection<YangTextSchemaSource> toUniqueSources(final Collection<YangTextSchemaSource> sources)
            throws IOException {
        final Map<String, YangTextSchemaSource> byContent = new HashMap<>();
        for (YangTextSchemaSource s : sources) {
            try (Reader reader = s.asCharSource(StandardCharsets.UTF_8).openStream()) {
                final String contents = CharStreams.toString(reader);
                byContent.putIfAbsent(contents, s);
            }
        }
        return byContent.values();
    }

    /**
     * Call generate on every generator from plugin configuration.
     */
    @SuppressWarnings("checkstyle:illegalCatch")
    private void generateSources(final ContextHolder context) throws MojoFailureException {
        if (codeGenerators.size() == 0) {
            LOG.warn("{} No code generators provided", LOG_PREFIX);
            return;
        }

        final Map<String, String> thrown = new HashMap<>();
        for (CodeGeneratorArg codeGenerator : codeGenerators) {
            try {
                generateSourcesWithOneGenerator(context, codeGenerator);
            } catch (Exception e) {
                // try other generators, exception will be thrown after
                LOG.error("{} Unable to generate sources with {} generator", LOG_PREFIX, codeGenerator
                        .getCodeGeneratorClass(), e);
                thrown.put(codeGenerator.getCodeGeneratorClass(), e.getClass().getCanonicalName());
            }
        }

        if (!thrown.isEmpty()) {
            String message = " One or more code generators failed, including failed list(generatorClass=exception) ";
            LOG.error("{}" + message + "{}", LOG_PREFIX, thrown.toString());
            throw new MojoFailureException(LOG_PREFIX + message + thrown.toString());
        }
    }

    /**
     * Instantiate generator from class and call required method.
     */
    private void generateSourcesWithOneGenerator(final ContextHolder context, final CodeGeneratorArg codeGeneratorCfg)
            throws ClassNotFoundException, InstantiationException, IllegalAccessException, IOException {

        codeGeneratorCfg.check();

        final BasicCodeGenerator g = getInstance(codeGeneratorCfg.getCodeGeneratorClass(), BasicCodeGenerator.class);
        LOG.info("{} Code generator instantiated from {}", LOG_PREFIX, codeGeneratorCfg.getCodeGeneratorClass());

        final File outputDir = codeGeneratorCfg.getOutputBaseDir(project);

        if (outputDir == null) {
            throw new NullPointerException("outputBaseDir is null. Please provide a valid outputBaseDir value in the "
                    + "pom.xml");
        }

        project.addCompileSourceRoot(outputDir.getAbsolutePath());

        LOG.info("{} Sources will be generated to {}", LOG_PREFIX, outputDir);
        LOG.debug("{} Project root dir is {}", LOG_PREFIX, project.getBasedir());
        LOG.debug("{} Additional configuration picked up for : {}: {}", LOG_PREFIX, codeGeneratorCfg
                        .getCodeGeneratorClass(), codeGeneratorCfg.getAdditionalConfiguration());

        if (g instanceof BuildContextAware) {
            ((BuildContextAware)g).setBuildContext(buildContext);
        }
        if (g instanceof MavenProjectAware) {
            ((MavenProjectAware)g).setMavenProject(project);
        }
        g.setAdditionalConfig(codeGeneratorCfg.getAdditionalConfiguration());
        File resourceBaseDir = codeGeneratorCfg.getResourceBaseDir(project);

        YangProvider.setResource(resourceBaseDir, project);
        g.setResourceBaseDir(resourceBaseDir);
        LOG.debug("{} Folder: {} marked as resources for generator: {}", LOG_PREFIX, resourceBaseDir,
                codeGeneratorCfg.getCodeGeneratorClass());

        FileUtils.deleteDirectory(outputDir);
        LOG.info("{} Succesfully deleted output directory {}", LOG_PREFIX, outputDir);

        Collection<File> generated = g.generateSources(context.getContext(), outputDir, context.getYangModules(),
            context::moduleToResourcePath);

        LOG.info("{} Sources generated by {}: {}", LOG_PREFIX, codeGeneratorCfg.getCodeGeneratorClass(), generated);
    }

    /**
     * Instantiate object from fully qualified class name.
     */
    private static <T> T getInstance(final String codeGeneratorClass, final Class<T> baseType) throws
            ClassNotFoundException, InstantiationException, IllegalAccessException {
        final Class<?> clazz = Class.forName(codeGeneratorClass);

        Preconditions.checkArgument(baseType.isAssignableFrom(clazz), "Code generator %s has to implement %s", clazz,
            baseType);
        return baseType.cast(clazz.newInstance());
    }
}