/*
 * Copyright (c) 2012, 2019, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.tools.sjavac.comp;

import java.io.IOException;
import java.io.PrintWriter;
import java.net.URI;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import javax.tools.*;
import javax.tools.JavaFileObject.Kind;

import com.sun.tools.javac.file.JavacFileManager;
import com.sun.tools.javac.util.DefinedBy;
import com.sun.tools.javac.util.DefinedBy.Api;
import com.sun.tools.javac.util.ListBuffer;

Intercepts reads and writes to the file system to gather
information about what artifacts are generated.
Traps writes to certain files, if the content written is identical
to the existing file.
Can also blind out the file manager from seeing certain files in the file system.
Necessary to prevent javac from seeing some sources where the source path points.
 
This is NOT part of any supported API.
 If you write code that depends on this, you do so at your own risk.
 This code and its internal interfaces are subject to change or
 deletion without notice.
/**
 * Intercepts reads and writes to the file system to gather
 * information about what artifacts are generated.
 *
 * Traps writes to certain files, if the content written is identical
 * to the existing file.
 *
 * Can also blind out the file manager from seeing certain files in the file system.
 * Necessary to prevent javac from seeing some sources where the source path points.
 *
 *  <p><b>This is NOT part of any supported API.
 *  If you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 */
@com.sun.tools.javac.api.ClientCodeWrapper.Trusted
public class SmartFileManager extends ForwardingJavaFileManager<JavaFileManager> {

    // Set of sources that can be seen by javac.
    Set<URI> visibleSources = new HashSet<>();
    // Map from modulename:packagename to artifacts.
    Map<String,Set<URI>> packageArtifacts = new HashMap<>();

    public SmartFileManager(JavaFileManager fileManager) {
        super(fileManager);
    }

    public void setVisibleSources(Set<URI> s) {
        visibleSources = s;
    }

    public void cleanArtifacts() {
        packageArtifacts = new HashMap<>();
    }

    
Set whether or not to use ct.sym as an alternate to rt.jar.
/**
     * Set whether or not to use ct.sym as an alternate to rt.jar.
     */
    public void setSymbolFileEnabled(boolean b) {
        if (!(fileManager instanceof JavacFileManager))
            throw new IllegalStateException();
        ((JavacFileManager) fileManager).setSymbolFileEnabled(b);
    }

    @DefinedBy(Api.COMPILER)
    public String inferBinaryName(Location location, JavaFileObject file) {
        return super.inferBinaryName(location, locUnwrap(file));
    }


    public Map<String,Set<URI>> getPackageArtifacts() {
        return packageArtifacts;
    }

    @Override @DefinedBy(Api.COMPILER)
    public Iterable<JavaFileObject> list(Location location,
                                         String packageName,
                                         Set<Kind> kinds,
                                         boolean recurse) throws IOException {
        // TODO: Do this lazily by returning an iterable with a filtering Iterator
        // Acquire the list of files.
        Iterable<JavaFileObject> files = super.list(location, packageName, kinds, recurse);
        if (visibleSources.isEmpty()) {
            return locWrapMany(files, location);
        }
        // Now filter!
        ListBuffer<JavaFileObject> filteredFiles = new ListBuffer<>();
        for (JavaFileObject f : files) {
            URI uri = f.toUri();
            String t = uri.toString();
            if (t.startsWith("jar:")
                || t.endsWith(".class")
                || visibleSources.contains(uri)) {
                filteredFiles.add(f);
            }
        }

        return locWrapMany(filteredFiles, location);
    }

    @Override @DefinedBy(Api.COMPILER)
    public JavaFileObject getJavaFileForInput(Location location,
                                              String className,
                                              Kind kind) throws IOException {
        JavaFileObject file = super.getJavaFileForInput(location, className, kind);
        file = locWrap(file, location);
        if (file == null || visibleSources.isEmpty()) {
            return file;
        }

        if (visibleSources.contains(file.toUri()) || isModuleInfo(file)) {
            return file;
        }
        return null;
    }

    @Override @DefinedBy(Api.COMPILER)
    public JavaFileObject getJavaFileForOutput(Location location,
                                               String className,
                                               Kind kind,
                                               FileObject sibling) throws IOException {
        JavaFileObject file = super.getJavaFileForOutput(location, className, kind, sibling);
        file = locWrap(file, location);
        if (file == null) return file;
        int dp = className.lastIndexOf('.');
        String pkg_name = "";
        if (dp != -1) {
            pkg_name = className.substring(0, dp);
        }
        // When modules are in use, then the mod_name might be something like "jdk_base"
        String mod_name = "";
        addArtifact(mod_name+":"+pkg_name, file.toUri());
        return file;
    }

    @Override @DefinedBy(Api.COMPILER)
    public FileObject getFileForInput(Location location,
                                      String packageName,
                                      String relativeName) throws IOException {
        FileObject file =  super.getFileForInput(location, packageName, relativeName);
        file = locWrap(file, location);
        if (file == null || visibleSources.isEmpty()) {
            return file;
        }

        if (visibleSources.contains(file.toUri()) || isModuleInfo(file)) {
            return file;
        }
        return null;
    }

    private boolean isModuleInfo(FileObject fo) {
        if (fo instanceof JavaFileObject) {
            JavaFileObject jfo = (JavaFileObject) fo;
            return jfo.isNameCompatible("module-info", Kind.SOURCE)
                || jfo.isNameCompatible("module-info", Kind.CLASS);
        }
        return false;
    }

    @Override @DefinedBy(Api.COMPILER)
    public FileObject getFileForOutput(Location location,
                                       String packageName,
                                       String relativeName,
                                       FileObject sibling) throws IOException {
        FileObject superFile = super.getFileForOutput(location, packageName, relativeName, sibling);
        FileObject file = locWrap(superFile, location);
        if (file == null) return file;

        if (location.equals(StandardLocation.NATIVE_HEADER_OUTPUT) && superFile instanceof JavaFileObject) {
           file = new SmartFileObject((JavaFileObject) file);
           packageName = ":" + packageNameFromFileName(relativeName);
        }
        if (packageName.equals("")) {
            packageName = ":";
        }
        addArtifact(packageName, file.toUri());
        return file;
    }

    @Override @DefinedBy(Api.COMPILER)
    public Location getLocationForModule(Location location, JavaFileObject fo) throws IOException {
        return super.getLocationForModule(location, locUnwrap(fo));
    }

    private static String packageNameFromFileName(String fn) {
        StringBuilder sb = new StringBuilder();
        int p = fn.indexOf('_'), pp = 0;
        while (p != -1) {
            if (sb.length() > 0) sb.append('.');
            sb.append(fn.substring(pp,p));
            if (p == fn.length()-1) break;
            pp = p+1;
            p = fn.indexOf('_',pp);
        }
        return sb.toString();
    }

    void addArtifact(String pkgName, URI art) {
        Set<URI> s = packageArtifacts.get(pkgName);
        if (s == null) {
            s = new HashSet<>();
            packageArtifacts.put(pkgName, s);
        }
        s.add(art);
    }

    public static JavaFileObject locWrap(JavaFileObject jfo, Location loc) {

        // From sjavac's perspective platform classes are not interesting and
        // there is no need to track the location for these file objects.
        // Also, there exists some jfo instanceof checks which breaks if
        // the jfos for platform classes are wrapped.
        if (loc == StandardLocation.PLATFORM_CLASS_PATH)
            return jfo;

        return jfo == null ? null : new JavaFileObjectWithLocation<>(jfo, loc);
    }

    private static FileObject locWrap(FileObject fo, Location loc) {
        if (fo instanceof JavaFileObject)
            return locWrap((JavaFileObject) fo, loc);
        return fo == null ? null : new FileObjectWithLocation<>(fo, loc);
    }

    @DefinedBy(Api.COMPILER)
    @Override
    public boolean isSameFile(FileObject a, FileObject b) {
        return super.isSameFile(locUnwrap(a), locUnwrap(b));
    }

    private static ListBuffer<JavaFileObject> locWrapMany(Iterable<JavaFileObject> jfos,
                                                          Location loc) {
        ListBuffer<JavaFileObject> locWrapped = new ListBuffer<>();
        for (JavaFileObject f : jfos)
            locWrapped.add(locWrap(f, loc));
        return locWrapped;
    }

    private static FileObject locUnwrap(FileObject fo) {
        if (fo instanceof FileObjectWithLocation<?>)
            return ((FileObjectWithLocation<?>) fo).getDelegate();
        if (fo instanceof JavaFileObjectWithLocation<?>)
            return ((JavaFileObjectWithLocation<?>) fo).getDelegate();
        return fo;
    }

    private static JavaFileObject locUnwrap(JavaFileObject fo) {
        if (fo instanceof JavaFileObjectWithLocation<?>)
            return ((JavaFileObjectWithLocation<?>) fo).getDelegate();
        return fo;
    }
}