import static com.sun.tools.sjavac.server.CompilationResult.ERROR_FATAL;

import static java.nio.charset.StandardCharsets.UTF_8;

import java.io.ByteArrayOutputStream;

import java.io.PrintStream;

import java.nio.file.Files;

import java.nio.file.Path;

import java.util.ArrayList;

import java.util.Collections;

import java.util.HashMap;

import java.util.HashSet;

import java.util.Map;

import com.sun.tools.sjavac.JavacState;

import com.sun.tools.sjavac.Module;

import com.sun.tools.sjavac.ProblemException;

import com.sun.tools.sjavac.Source;

import com.sun.tools.sjavac.Transformer;

import com.sun.tools.sjavac.options.Options;

import com.sun.tools.sjavac.options.SourceLocation;

    public CompilationResult compile(String[] args) {

        ByteArrayOutputStream outBaos = new ByteArrayOutputStream();

        ByteArrayOutputStream errBaos = new ByteArrayOutputStream();

        PrintStream out = new PrintStream(outBaos);

        PrintStream err = new PrintStream(errBaos);

        Options options;

        try {

            options = Options.parseArgs(args);

        } catch (IllegalArgumentException e) {

            Log.error(e.getMessage());

            return new CompilationResult(ERROR_FATAL);

        }

        Log.setLogLevel(options.getLogLevel());

        if (!validateOptions(options))

            return new CompilationResult(ERROR_FATAL);

        if (!createIfMissing(options.getDestDir()))

            return new CompilationResult(ERROR_FATAL);

        if (!createIfMissing(options.getStateDir()))

            return new CompilationResult(ERROR_FATAL);

        Path gensrc = options.getGenSrcDir();

        if (gensrc != null && !createIfMissing(gensrc))

            return new CompilationResult(ERROR_FATAL);

        Path hdrdir = options.getHeaderDir();

        if (hdrdir != null && !createIfMissing(hdrdir))

            return new CompilationResult(ERROR_FATAL);

        // Load the prev build state database.

        JavacState javac_state = JavacState.load(options, out, err);

        // Setup the suffix rules from the command line.

        Map<String, Transformer> suffixRules = new HashMap<>();

        // Handling of .java-compilation

        suffixRules.putAll(javac_state.getJavaSuffixRule());

        // Handling of -copy and -tr

        suffixRules.putAll(options.getTranslationRules());

        // All found modules are put here.

        Map<String,Module> modules = new HashMap<>();

        // We start out in the legacy empty no-name module.

        // As soon as we stumble on a module-info.java file we change to that module.

        Module current_module = new Module("", "");

        modules.put("", current_module);

        // Find all sources, use the suffix rules to know which files are sources.

        Map<String,Source> sources = new HashMap<>();

        // Find the files, this will automatically populate the found modules

        // with found packages where the sources are found!

        findSourceFiles(options.getSources(),

                        suffixRules.keySet(),

                        sources,

                        modules,

                        current_module,

                        options.isDefaultPackagePermitted(),

                        false);

        if (sources.isEmpty()) {

            Log.error("Found nothing to compile!");

            return new CompilationResult(CompilationResult.ERROR_FATAL,

                                          new String(outBaos.toByteArray(), UTF_8),

                                          new String(errBaos.toByteArray(), UTF_8));

        }

        // Create a map of all source files that are available for linking. Both -src and

        // -sourcepath point to such files. It is possible to specify multiple

        // -sourcepath options to enable different filtering rules. If the

        // filters are the same for multiple sourcepaths, they may be concatenated

        // using :(;). Before sending the list of sourcepaths to javac, they are

        // all concatenated. The list created here is used by the SmartFileWrapper to

        // make sure only the correct sources are actually available.

        // We might find more modules here as well.

        Map<String,Source> sources_to_link_to = new HashMap<>();

        List<SourceLocation> sourceResolutionLocations = new ArrayList<>();

        sourceResolutionLocations.addAll(options.getSources());

        sourceResolutionLocations.addAll(options.getSourceSearchPaths());

        findSourceFiles(sourceResolutionLocations,

                        Collections.singleton(".java"),

                        sources_to_link_to,

                        modules,

                        current_module,

                        options.isDefaultPackagePermitted(),

                        true);

        // Add the set of sources to the build database.

        javac_state.now().flattenPackagesSourcesAndArtifacts(modules);

        javac_state.now().checkInternalState("checking sources", false, sources);

        javac_state.now().checkInternalState("checking linked sources", true, sources_to_link_to);

        javac_state.setVisibleSources(sources_to_link_to);

        int round = 0;

        printRound(round);

        // If there is any change in the source files, taint packages

        // and mark the database in need of saving.

        javac_state.checkSourceStatus(false);

        // Find all existing artifacts. Their timestamp will match the last modified timestamps stored

        // in javac_state, simply because loading of the JavacState will clean out all artifacts

        // that do not match the javac_state database.

        javac_state.findAllArtifacts();

        // Remove unidentified artifacts from the bin, gensrc and header dirs.

        // (Unless we allow them to be there.)

        // I.e. artifacts that are not known according to the build database (javac_state).

        // For examples, files that have been manually copied into these dirs.

        // Artifacts with bad timestamps (ie the on disk timestamp does not match the timestamp

        // in javac_state) have already been removed when the javac_state was loaded.

        if (!options.areUnidentifiedArtifactsPermitted()) {

            javac_state.removeUnidentifiedArtifacts();

        }

        // Go through all sources and taint all packages that miss artifacts.

        javac_state.taintPackagesThatMissArtifacts();

        // Check recorded classpath public apis. Taint packages that depend on

        // classpath classes whose public apis have changed.

        javac_state.taintPackagesDependingOnChangedClasspathPackages();

        // Now clean out all known artifacts belonging to tainted packages.

        javac_state.deleteClassArtifactsInTaintedPackages();

        // Copy files, for example property files, images files, xml files etc etc.

        javac_state.performCopying(Util.pathToFile(options.getDestDir()), suffixRules);

        // Translate files, for example compile properties or compile idls.

        javac_state.performTranslation(Util.pathToFile(gensrc), suffixRules);

        // Add any potentially generated java sources to the tobe compiled list.

        // (Generated sources must always have a package.)

        Map<String,Source> generated_sources = new HashMap<>();

        try {

            Source.scanRoot(Util.pathToFile(options.getGenSrcDir()), Util.set(".java"), null, null, null, null,

                    generated_sources, modules, current_module, false, true, false);

            javac_state.now().flattenPackagesSourcesAndArtifacts(modules);

            // Recheck the the source files and their timestamps again.

            javac_state.checkSourceStatus(true);

            // Now do a safety check that the list of source files is identical

            // to the list Make believes we are compiling. If we do not get this

            // right, then incremental builds will fail with subtility.

            // If any difference is detected, then we will fail hard here.

            // This is an important safety net.

            javac_state.compareWithMakefileList(Util.pathToFile(options.getSourceReferenceList()));

            // Do the compilations, repeatedly until no tainted packages exist.

            boolean again;

            // Collect the name of all compiled packages.

            Set<String> recently_compiled = new HashSet<>();

            boolean[] rc = new boolean[1];

            CompilationService compilationService = new CompilationService();

            do {

                if (round > 0)

                    printRound(round);

                // Clean out artifacts in tainted packages.

                javac_state.deleteClassArtifactsInTaintedPackages();

                again = javac_state.performJavaCompilations(compilationService, options, recently_compiled, rc);

                if (!rc[0]) {

                    Log.debug("Compilation failed.");

                    break;

                if (!again) {

                    Log.debug("Nothing left to do.");

                }

                round++;

            } while (again);

            Log.debug("No need to do another round.");

            // Only update the state if the compile went well.

            if (rc[0]) {

                javac_state.save();

                // Reflatten only the artifacts.

                javac_state.now().flattenArtifacts(modules);

                // Remove artifacts that were generated during the last compile, but not this one.

                javac_state.removeSuperfluousArtifacts(recently_compiled);

            return new CompilationResult(rc[0] ? 0 : ERROR_FATAL,

                                          new String(outBaos.toByteArray(), UTF_8),

                                          new String(errBaos.toByteArray(), UTF_8));

        } catch (ProblemException e) {

            Log.error(e.getMessage());

            return new CompilationResult(ERROR_FATAL,

                                          new String(outBaos.toByteArray(), UTF_8),

                                          new String(errBaos.toByteArray(), UTF_8));

        } catch (Exception e) {

            e.printStackTrace(err);

            return new CompilationResult(ERROR_FATAL,

                                          new String(outBaos.toByteArray(), UTF_8),

                                          new String(errBaos.toByteArray(), UTF_8));

    private static boolean validateOptions(Options options) {

        String err = null;

        if (options.getDestDir() == null) {

            err = "Please specify output directory.";

        } else if (options.isJavaFilesAmongJavacArgs()) {

            err = "Sjavac does not handle explicit compilation of single .java files.";

        } else if (options.getServerConf() == null) {

            err = "No server configuration provided.";

        } else if (!options.getImplicitPolicy().equals("none")) {

            err = "The only allowed setting for sjavac is -implicit:none";

        } else if (options.getSources().isEmpty()) {

            err = "You have to specify -src.";

        } else if (options.getTranslationRules().size() > 1

                && options.getGenSrcDir() == null) {

            err = "You have translators but no gensrc dir (-s) specified!";

        }

        if (err != null)

            Log.error(err);

        return err == null;

    private static boolean createIfMissing(Path dir) {

        if (Files.isDirectory(dir))

            return true;

        if (Files.exists(dir)) {

            Log.error(dir + " is not a directory.");

            return false;

        }

        try {

            Files.createDirectories(dir);

        } catch (IOException e) {

            Log.error("Could not create directory: " + e.getMessage());

            return false;

        }

        return true;

    }

    /** Find source files in the given source locations. */

    public static void findSourceFiles(List<SourceLocation> sourceLocations,

                                       Set<String> sourceTypes,

                                       Map<String,Source> foundFiles,

                                       Map<String, Module> foundModules,

                                       Module currentModule,

                                       boolean permitSourcesInDefaultPackage,

                                       boolean inLinksrc) {

        for (SourceLocation source : sourceLocations) {

            source.findSourceFiles(sourceTypes,

                                   foundFiles,

                                   foundModules,

                                   currentModule,

                                   permitSourcesInDefaultPackage,

                                   inLinksrc);

    private static void printRound(int round) {

        Log.debug("****************************************");

        Log.debug("* Round " + round + "                              *");

        Log.debug("****************************************");

    }