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package org.apidesign.bck2brwsr.dew;

import java.io.BufferedReader;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.net.URL;

import java.util.ArrayList;

import java.util.Collections;

import java.util.EnumSet;

import java.util.Enumeration;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import java.util.Set;

import java.util.zip.ZipEntry;

import java.util.zip.ZipFile;

import javax.tools.FileObject;

import javax.tools.JavaFileManager;

import javax.tools.JavaFileObject;

import javax.tools.StandardLocation;

/**

 *

 * @author Tomas Zezula

 */

public class ClassLoaderFileManager implements JavaFileManager {

    private static final Location[] READ_LOCATIONS = {

        StandardLocation.PLATFORM_CLASS_PATH,

        StandardLocation.CLASS_PATH,

        StandardLocation.SOURCE_PATH

    };

    private static final Location[] WRITE_LOCATIONS = {

        StandardLocation.CLASS_OUTPUT,

        StandardLocation.SOURCE_OUTPUT

    };

    private static final Location[] CLASS_LOADER_LOCATIONS = {

        StandardLocation.ANNOTATION_PROCESSOR_PATH

    };

    private Map<Location, Map<String,List<MemoryFileObject>>> generated;

    ClassLoaderFileManager() {

        generated = new HashMap<>();

        for (Location l : WRITE_LOCATIONS) {

            generated.put(l, new HashMap<String, List<MemoryFileObject>>());

        }

    }

    @Override

    public ClassLoader getClassLoader(Location location) {

        if (canClassLoad(location)) {

            return new SafeClassLoader(getClass().getClassLoader());

        } else {

            return null;

        }

    }

    @Override

    public Iterable<JavaFileObject> list(Location location, String packageName, Set<JavaFileObject.Kind> kinds, boolean recurse) throws IOException {

        if (canRead(location)) {

            final List<JavaFileObject> res = new ArrayList<JavaFileObject>();

            for (String resource : getResources(convertFQNToResource(packageName))) {

                final JavaFileObject jfo = new ClassLoaderJavaFileObject(resource);

                if (kinds.contains(jfo.getKind())) {

                    res.add(jfo);

                }

            }

            return res;

        } else if (canWrite(location)) {

            Map<String,List<MemoryFileObject>> folders = generated.get(location);

            List<MemoryFileObject> files = folders.get(convertFQNToResource(packageName));

            if (files != null) {

                final List<JavaFileObject> res = new ArrayList<JavaFileObject>();

                for (JavaFileObject file : files) {

                    if (kinds.contains(file.getKind()) && file.getLastModified() >= 0) {

                        res.add(file);

                    }

                }

                return res;

            }

        }

        return Collections.<JavaFileObject>emptyList();

    }

    @Override

    public String inferBinaryName(Location location, JavaFileObject file) {

        return ((InferableJavaFileObject)file).infer();

    }

    @Override

    public boolean isSameFile(FileObject a, FileObject b) {

        return a.toUri().equals(b.toUri());

    }

    @Override

    public boolean handleOption(String current, Iterator<String> remaining) {

        return false;

    }

    @Override

    public boolean hasLocation(Location location) {

        for (Location l : StandardLocation.values()) {

            if (l.equals(location)) {

                return true;

            }

        }

        return false;

    }

    @Override

    public JavaFileObject getJavaFileForInput(Location location, String className, JavaFileObject.Kind kind) throws IOException {

        if (canRead(location)) {

            return new ClassLoaderJavaFileObject(convertFQNToResource(className) + kind.extension);

        } else {

            throw new UnsupportedOperationException("Unsupported location for reading: " + location);   //NOI18N

        }

    }

    @Override

    public JavaFileObject getJavaFileForOutput(Location location, String className, JavaFileObject.Kind kind, FileObject sibling) throws IOException {

        if (canWrite(location)) {

            final String resource = convertFQNToResource(className) + kind.extension;

            final MemoryFileObject res = new MemoryFileObject(resource, null);

            register(location, resource, res);

            return res;

        } else {

            throw new UnsupportedOperationException("Unsupported location for reading: " + location);   //NOI18N

        }

    }

    @Override

    public FileObject getFileForInput(Location location, String packageName, String relativeName) throws IOException {

        if (canRead(location)) {

            return new ClassLoaderJavaFileObject(convertFQNToResource(packageName) + '/' + relativeName); //NOI18N

        } else {

            throw new UnsupportedOperationException("Unsupported location for reading: " + location);   //NOI18N

        }

    }

    @Override

    public FileObject getFileForOutput(Location location, String packageName, String relativeName, FileObject sibling) throws IOException {

        if (canWrite(location)) {

            final String resource = convertFQNToResource(packageName) + '/' + relativeName; //NOI18N

            final MemoryFileObject res = new MemoryFileObject(resource, null);

            register(location, resource, res);

            return res;

        } else {

            throw new UnsupportedOperationException("Unsupported location for reading: " + location);   //NOI18N

        }

    }

    @Override

    public void flush() throws IOException {

    }

    @Override

    public void close() throws IOException {        

    }

    @Override

    public int isSupportedOption(String option) {

        return -1;

    }

//    private List<String> getResources(String folder) throws IOException {

//        final List<String> result = new ArrayList<String>();

//        final BufferedReader in = new BufferedReader(new InputStreamReader(

//                this.getClass().getClassLoader().getResourceAsStream(String.format("%s/pkg-list", folder.substring(0))),    //NOI18N

//                "UTF-8"));  //NOI18N

//        try {

//            String line;

//            while ((line = in.readLine()) != null) {

//                result.add(line);

//            }

//        } finally {

//            in.close();

//        }

//        return result;

//    }

    //MOCK IMPL

    private List<String> getResources(String folder) throws IOException {

        if (classPathContent == null) {

            classPathContent = new HashMap<>();

//            final String boot = System.getProperty("sun.boot.class.path");  //NOI18N

            final String cp = System.getProperty("java.class.path");

            for (String entry : cp.split(File.pathSeparator)) {

                File f = new File (entry);

                if (f.canRead()) {

                    if (f.isFile()) {

                        ZipFile zf = new ZipFile(f);

                        try {

                            Enumeration<? extends ZipEntry> entries = zf.entries();

                            while (entries.hasMoreElements()) {

                                ZipEntry e = entries.nextElement();

                                if (e.isDirectory()) {

                                    continue;

                                }

                                final String name = String.format("/%s",e.getName());

                                final String owner = getOwner(name);

                                List<String> content = classPathContent.get(owner);

                                if (content == null) {

                                    content = new ArrayList<>();

                                    classPathContent.put(owner, content);

                                }

                                content.add(name);

                            }

                        } finally {

                            zf.close();

                        }

                    } else if (f.isDirectory()) {

                        addFiles(f,"/", classPathContent);

                    }

                }

            }                                    

        }

        List<String> content = classPathContent.get(folder);

        return content == null ? Collections.<String>emptyList() : content;

    }

    private void addFiles(File folder, String path, Map<String,List<String>> into) {

        for (File f : folder.listFiles()) {

            String fname = path + (path.length() == 1 ? "" : "/") +  f.getName();

            if (f.isDirectory()) {

                addFiles(f, fname, into);

            } else {

                List<String> content = into.get(path);

                if (content == null) {

                    content = new ArrayList<>();

                    classPathContent.put(path, content);

                }

                content.add(fname);

            }

        }

    }

    private Map<String,List<String>> classPathContent;

    private void register(Location loc, String resource, MemoryFileObject jfo) {

        Map<String,List<MemoryFileObject>> folders = generated.get(loc);

        final String folder = getOwner(resource);

        List<MemoryFileObject> content = folders.get(folder);

        if (content == null) {

            content = new ArrayList<>();

            folders.put(folder, content);

        }

        content.add(jfo);

    }

    private static String getOwner(String resource) {

        int lastSlash = resource.lastIndexOf('/');

        assert lastSlash >= 0;

        return resource.substring(0, lastSlash);

    }

    private static boolean canRead(Location loc) {

        for (Location rl : READ_LOCATIONS) {

            if (rl.equals(loc)) {

                return true;

            }

        }

        return false;

    }

    private static boolean canWrite(Location loc) {

        for (Location wl : WRITE_LOCATIONS) {

            if (wl.equals(loc)) {

                return true;

            }

        }

        return false;

    }

    private static boolean canClassLoad(Location loc) {

        for (Location cll : CLASS_LOADER_LOCATIONS) {

            if (cll.equals(loc)) {

                return true;

            }

        }

        return false;

    }

    static String convertFQNToResource(String fqn) {

        return '/' + fqn.replace('.', '/');   //NOI18N

    }

    static String convertResourceToFQN(String resource) {

        assert resource.startsWith("/");    //NOI18N

        int lastSlash = resource.lastIndexOf('/');  //NOI18N

        int lastDot = resource.lastIndexOf('.');    //NOI18N

        int stop = lastSlash < lastDot ?

            lastDot :

            resource.length();

        return resource.substring(1, stop).replace('/', '.');    //NOI18N

    }

    JavaFileObject createMemoryFileObject (String resourceName, JavaFileObject.Kind kind, byte[] content) {

        final InferableJavaFileObject jfo  = new MemoryFileObject(resourceName, kind, content);

        return jfo;

    }

    Iterable<? extends MemoryFileObject> getGeneratedFiles(JavaFileObject.Kind... kinds) {

        final Set<JavaFileObject.Kind> ks = EnumSet.noneOf(JavaFileObject.Kind.class);

        Collections.addAll(ks, kinds);

        final List<MemoryFileObject> res = new ArrayList<>();

        for (Map<String,List<MemoryFileObject>> folders : generated.values()) {

            for (List<MemoryFileObject> content : folders.values()) {

                for (MemoryFileObject fo : content) {

                    if (ks.contains(fo.getKind()) && fo.getLastModified() >= 0) {

                        res.add(fo);

                    }

                }

            }

        }

        return res;

    }

    private static final class SafeClassLoader extends ClassLoader {

        private final ClassLoader delegate;

        SafeClassLoader(final ClassLoader delegate) {

            this.delegate = delegate;

        }

        @Override

        public URL getResource(String name) {

            return delegate.getResource(name);

        }

        @Override

        public InputStream getResourceAsStream(String name) {

            return delegate.getResourceAsStream(name);

        }

        @Override

        public Enumeration<URL> getResources(String name) throws IOException {

            return delegate.getResources(name);

        }

        @Override

        public Class<?> loadClass(String name) throws ClassNotFoundException {

            return delegate.loadClass(name);

        }

    }

}