/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.apache.maven.plugin.compiler;
  
  import javax.lang.model.element.Modifier;
  import javax.lang.model.element.NestingKind;
  import javax.tools.FileObject;
  import javax.tools.JavaFileObject;
  import javax.tools.StandardJavaFileManager;
  import javax.tools.StandardLocation;
  
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.io.Reader;
  import java.io.UncheckedIOException;
  import java.io.Writer;
  import java.net.URI;
  import java.nio.charset.Charset;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  import java.util.Set;
  import java.util.StringJoiner;
  import java.util.stream.Stream;
  import java.util.stream.StreamSupport;
  
  import org.apache.maven.api.JavaPathType;
  import org.apache.maven.api.PathType;
  
  /**
   * Source files for a call to {@code javac} or {@code javadoc} command to be executed as a separated process.
   *
   * @author Martin Desruisseaux
   *
   * @see ForkedCompiler
   */
  final class ForkedToolSources implements StandardJavaFileManager {
      /**
       * Option for source files. These options are not declared in
       * {@link JavaPathType} because they are not about dependencies.
       */
      private enum SourcePathType implements PathType {
          /**
           * The option for the directory of source files.
           */
          SOURCES("--source-path"),
  
          /**
           * The option for the directory of generated sources.
           */
          GENERATED_SOURCES("-s"),
  
          /**
           * The option for the directory of compiled class files.
           */
          OUTPUT("-d");
  
          /**
           * The Java option for this enumeration value.
           */
          private final String option;
  
          SourcePathType(String option) {
              this.option = option;
          }
  
          @Override
          public String id() {
              return name();
          }
  
          @Override
          public Optional<String> option() {
              return Optional.of(option);
          }
 
         @Override
         public String[] option(Iterable<? extends Path> paths) {
             var builder = new StringJoiner(File.pathSeparator);
             paths.forEach((path) -> builder.add(path.toString()));
             return new String[] {option, builder.toString()};
         }
     };
 
     /**
      * Search paths associated to locations.
      * This map only stores verbatim the collections provided by callers.
      *
      * @see #setLocationFromPaths(Location, Collection)
      * @see #getLocationAsPaths(Location)
      */
     private final Map<PathType, Collection<? extends Path>> locations;
 
     /**
      * The encoding of the files to read.
      */
     final Charset encoding;
 
     /**
      * Creates an initially empty collection of files.
      */
     ForkedToolSources(Charset encoding) {
         if (encoding == null) {
             encoding = Charset.defaultCharset();
         }
         this.encoding = encoding;
         locations = new HashMap<>();
     }
 
     /**
      * Unconditionally returns -1, meaning that the given option is unsupported.
      * Required by the interface, but not used by the Maven plugin.
      */
     @Override
     public int isSupportedOption(String option) {
         return -1;
     }
 
     /**
      * Nevers handle the given option.
      */
     @Override
     public boolean handleOption(String current, Iterator<String> remaining) {
         return false;
     }
 
     /**
      * Returns the path to the source file represented by the given object.
      */
     @Override
     public Path asPath(FileObject file) {
         return (file instanceof Item) ? ((Item) file).path : Path.of(file.toUri());
     }
 
     /**
      * Checks if the given objects represents the same canonical file.
      * Required by the interface, but not used by the Maven plugin.
      */
     @Override
     public boolean isSameFile(FileObject a, FileObject b) {
         return asPath(a).equals(asPath(b));
     }
 
     /**
      * Returns {@code JavaFileObject} instances representing the given filenames.
      */
     @Override
     public Iterable<? extends JavaFileObject> getJavaFileObjects(String... names) {
         return fromNames(Arrays.stream(names));
     }
 
     /**
      * Returns {@code JavaFileObject} instances representing the given {@code File} instances.
      */
     @Override
     public Iterable<? extends JavaFileObject> getJavaFileObjects(File... files) {
         return fromFiles(Arrays.stream(files));
     }
 
     /**
      * Returns {@code JavaFileObject} instances representing the given filenames.
      */
     @Override
     public Iterable<? extends JavaFileObject> getJavaFileObjectsFromStrings(Iterable<String> names) {
         return fromNames(StreamSupport.stream(names.spliterator(), false));
     }
 
     /**
      * Returns {@code JavaFileObject} instances representing the given {@code File} instances.
      */
     @Override
     public Iterable<? extends JavaFileObject> getJavaFileObjectsFromFiles(Iterable<? extends File> files) {
         return fromFiles(StreamSupport.stream(files.spliterator(), false));
     }
 
     /**
      * Returns {@code JavaFileObject} instances representing the given {@code Path} instances.
      */
     @Override
     public Iterable<? extends JavaFileObject> getJavaFileObjectsFromPaths(Collection<? extends Path> paths) {
         return paths.stream().map(Item::new).toList();
     }
 
     /**
      * Helper method for the construction of {@code JavaFileObject} instances from {@code File} instances.
      */
     private Iterable<? extends JavaFileObject> fromFiles(Stream<? extends File> files) {
         return files.map((file) -> new Item(file.toPath())).toList();
     }
 
     /**
      * Helper method for the construction of {@code JavaFileObject} instances from filenames.
      */
     private Iterable<? extends JavaFileObject> fromNames(Stream<? extends String> names) {
         return names.map((name) -> new Item(Path.of(name))).toList();
     }
 
     /**
      * A simple implementation of Java file as a wrapper around a path. This class implements some methods
      * as a matter of principle, but those methods should not be invoked because the file will not be opened
      * in this Java Virtual Machine. We only need a container for a {@link Path} instance.
      */
     private final class Item implements JavaFileObject {
         /**
          * Path to the source file.
          */
         final Path path;
 
         /**
          * Creates a new object for the given path to a Java source file.
          */
         Item(Path path) {
             this.path = path;
         }
 
         /**
          * Returns the path to the source file.
          */
         @Override
         public String getName() {
             return path.toString();
         }
 
         /**
          * Returns the path to the source file.
          */
         @Override
         public String toString() {
             return getName();
         }
 
         /**
          * Returns the path as an URI.
          */
         @Override
         public URI toUri() {
             return path.toUri();
         }
 
         /**
          * Returns whether the file is a source, a class or other kind of object.
          */
         @Override
         public Kind getKind() {
             String filename = path.getFileName().toString();
             for (Kind k : Kind.values()) {
                 if (filename.endsWith(k.extension)) {
                     return k;
                 }
             }
             return Kind.OTHER;
         }
 
         /**
          * Returns whether this object is compatible with the given non-qualified name and the given type.
          */
         @Override
         public boolean isNameCompatible(String simpleName, Kind kind) {
             return path.getFileName().toString().equals(simpleName.concat(kind.extension));
         }
 
         /**
          * Returns {@code null}, meaning that this object as no information about nesting kind.
          */
         @Override
         public NestingKind getNestingKind() {
             return null;
         }
 
         /**
          * Returns {@code null}, meaning that this object as no information about access level.
          */
         @Override
         public Modifier getAccessLevel() {
             return null;
         }
 
         /**
          * Returns the time this file object was last modified.
          */
         @Override
         public long getLastModified() {
             try {
                 return Files.getLastModifiedTime(path).toMillis();
             } catch (IOException e) {
                 throw new UncheckedIOException(e);
             }
         }
 
         /**
          * Deletes the source file if it exists.
          */
         @Override
         public boolean delete() {
             try {
                 return Files.deleteIfExists(path);
             } catch (IOException e) {
                 throw new UncheckedIOException(e);
             }
         }
 
         /**
          * Opens the file an an input stream.
          * Implemented as a matter of principle, but should not be invoked.
          */
         @Override
         public InputStream openInputStream() throws IOException {
             return Files.newInputStream(path);
         }
 
         /**
          * Opens the file an an output stream.
          * Implemented as a matter of principle, but should not be invoked.
          */
         @Override
         public OutputStream openOutputStream() throws IOException {
             return Files.newOutputStream(path);
         }
 
         /**
          * Opens the file a character reader.
          * Implemented as a matter of principle, but should not be invoked.
          */
         @Override
         public Reader openReader(boolean ignoreEncodingErrors) throws IOException {
             return Files.newBufferedReader(path, encoding);
         }
 
         /**
          * Returns the file content.
          * Implemented as a matter of principle, but should not be invoked.
          */
         @Override
         public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOException {
             return Files.readString(path, encoding);
         }
 
         /**
          * Opens the file a character writer.
          * Implemented as a matter of principle, but should not be invoked.
          */
         @Override
         public Writer openWriter() throws IOException {
             return Files.newBufferedWriter(path, encoding);
         }
     }
 
     /**
      * Converts the {@code File} instances to {@code Path} instances and delegate.
      * This is defined as a matter of principle but is not used by the Maven compiler plugin.
      *
      * @see #setLocationFromPaths(Location, Collection)
      */
     @Override
     public void setLocation(Location location, Iterable<? extends File> files) {
         List<Path> paths = null;
         if (files != null) {
             paths = StreamSupport.stream(files.spliterator(), false)
                     .map(File::toPath)
                     .toList();
         }
         setLocationFromPaths(location, paths);
     }
 
     /**
      * Converts the {@code Path} instances to {@code file} instances for the given location.
      * This is defined as a matter of principle but is not used by the Maven compiler plugin.
      *
      * @see #setLocationFromPaths(Location, Collection)
      */
     @Override
     public Iterable<? extends File> getLocation(Location location) {
         var paths = getLocationAsPaths(location);
         if (paths != null) {
             return paths.stream().map(Path::toFile).toList();
         }
         return null;
     }
 
     /**
      * Associates the given search paths with the given location.
      * The location may identify the class-path, module-path, doclet-path, etc.
      * Any previous value will be discarded.
      */
     @Override
     public void setLocationFromPaths(Location location, Collection<? extends Path> paths) {
         PathType type = JavaPathType.valueOf(location).orElse(null);
         if (type == null) {
             if (location == StandardLocation.SOURCE_OUTPUT) {
                 type = SourcePathType.GENERATED_SOURCES;
             } else if (location == StandardLocation.SOURCE_PATH) {
                 type = SourcePathType.SOURCES;
             } else if (location == StandardLocation.CLASS_OUTPUT) {
                 type = SourcePathType.OUTPUT;
             } else {
                 throw new IllegalArgumentException("Unsupported location: " + location);
             }
         }
         if (paths == null || paths.isEmpty()) {
             locations.remove(type);
         } else {
             locations.put(type, paths);
         }
     }
 
     /**
      * Returns the search path associated with the given location, or {@code null} if none.
      */
     @Override
     public Collection<? extends Path> getLocationAsPaths(Location location) {
         return locations.get(JavaPathType.valueOf(location).orElse(null));
     }
 
     /**
      * Returns whether a location is known to this file manager.
      * This is defined as a matter of principle but is not used by the Maven compiler plugin.
      */
     @Override
     public boolean hasLocation(Location location) {
         return getLocationAsPaths(location) != null;
     }
 
     /**
      * Adds class-path, module-path and other paths to the given command.
      *
      * @param command the list where to add the options
      */
     void addAllLocations(List<String> command) {
         for (Map.Entry<PathType, Collection<? extends Path>> entry : locations.entrySet()) {
             for (String element : entry.getKey().option(entry.getValue())) {
                 command.add(element);
             }
         }
     }
 
     /**
      * Not yet implemented (not needed for forked tools).
      */
     @Override
     public Iterable<JavaFileObject> list(
             Location location, String packageName, Set<JavaFileObject.Kind> kinds, boolean recurse) throws IOException {
         throw new UnsupportedOperationException("Not supported yet.");
     }
 
     /**
      * Not yet implemented (not needed for forked tools).
      */
     @Override
     public String inferBinaryName(Location location, JavaFileObject file) {
         throw new UnsupportedOperationException("Not supported yet.");
     }
 
     /**
      * Not yet implemented (not needed for forked tools).
      */
     @Override
     public JavaFileObject getJavaFileForInput(Location location, String className, JavaFileObject.Kind kind)
             throws IOException {
         throw new UnsupportedOperationException("Not supported yet.");
     }
 
     /**
      * Not yet implemented (not needed for forked tools).
      */
     @Override
     public JavaFileObject getJavaFileForOutput(
             Location location, String className, JavaFileObject.Kind kind, FileObject sibling) throws IOException {
         throw new UnsupportedOperationException("Not supported yet.");
     }
 
     /**
      * Not yet implemented (not needed for forked tools).
      */
     @Override
     public FileObject getFileForInput(Location location, String packageName, String relativeName) throws IOException {
         throw new UnsupportedOperationException("Not supported yet.");
     }
 
     /**
      * Not yet implemented (not needed for forked tools).
      */
     @Override
     public FileObject getFileForOutput(Location location, String packageName, String relativeName, FileObject sibling)
             throws IOException {
         throw new UnsupportedOperationException("Not supported yet.");
     }
 
     /**
      * Returns a class loader for loading plug-ins, or {@code null} if disabled.
      */
     @Override
     public ClassLoader getClassLoader(Location location) {
         return null;
     }
 
     /**
      * Flushes any resources opened for output by this file manager.
      */
     @Override
     public void flush() {}
 
     /**
      * Releases any resources opened by this file manager.
      */
     @Override
     public void close() {
         locations.clear();
     }
 }