/*

 * Copyright (c) 2001, 2014, 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.javac.comp;

import java.util.AbstractQueue;

import java.util.Collection;

import java.util.HashMap;

import java.util.Iterator;

import java.util.LinkedList;

import java.util.Map;

import java.util.Queue;

import javax.tools.JavaFileObject;

import com.sun.tools.javac.util.Context;

/** A queue of all as yet unattributed classes.

 *

 *  <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>

 */

public class Todo extends AbstractQueue<Env<AttrContext>> {

    /** The context key for the todo list. */

    protected static final Context.Key<Todo> todoKey = new Context.Key<>();

    /** Get the Todo instance for this context. */

    public static Todo instance(Context context) {

        Todo instance = context.get(todoKey);

        if (instance == null)

            instance = new Todo(context);

        return instance;

    }

    /** Create a new todo list. */

    protected Todo(Context context) {

        context.put(todoKey, this);

    }

    public void append(Env<AttrContext> env) {

        add(env);

    }

    @Override

    public Iterator<Env<AttrContext>> iterator() {

        return contents.iterator();

    }

    @Override

    public int size() {

        return contents.size();

    }

    public boolean offer(Env<AttrContext> e) {

        if (contents.add(e)) {

            if (contentsByFile != null)

                addByFile(e);

            return true;

        } else {

            return false;

        }

    }

    /**

     * Removes all unattributed classes except those belonging to the given

     * collection of files.

     *

     * @param sourceFiles The source files of the classes to keep.

     */

    public void retainFiles(Collection<? extends JavaFileObject> sourceFiles) {

        for (Iterator<Env<AttrContext>> it = contents.iterator(); it.hasNext(); ) {

            Env<AttrContext> env = it.next();

            if (!sourceFiles.contains(env.toplevel.sourcefile)) {

                if (contentsByFile != null) removeByFile(env);

                it.remove();

            }

        }

    }

    public Env<AttrContext> poll() {

        if (size() == 0)

            return null;

        Env<AttrContext> env = contents.remove(0);

        if (contentsByFile != null)

            removeByFile(env);

        return env;

    }

    public Env<AttrContext> peek() {

        return (size() == 0 ? null : contents.get(0));

    }

    public Queue<Queue<Env<AttrContext>>> groupByFile() {

        if (contentsByFile == null) {

            contentsByFile = new LinkedList<>();

            for (Env<AttrContext> env: contents) {

                addByFile(env);

            }

        }

        return contentsByFile;

    }

    private void addByFile(Env<AttrContext> env) {

        JavaFileObject file = env.toplevel.sourcefile;

        if (fileMap == null)

            fileMap = new HashMap<>();

        FileQueue fq = fileMap.get(file);

        if (fq == null) {

            fq = new FileQueue();

            fileMap.put(file, fq);

            contentsByFile.add(fq);

        }

        fq.fileContents.add(env);

    }

    private void removeByFile(Env<AttrContext> env) {

        JavaFileObject file = env.toplevel.sourcefile;

        FileQueue fq = fileMap.get(file);

        if (fq == null)

            return;

        if (fq.fileContents.remove(env)) {

            if (fq.isEmpty()) {

                fileMap.remove(file);

                contentsByFile.remove(fq);

            }

        }

    }

    LinkedList<Env<AttrContext>> contents = new LinkedList<>();

    LinkedList<Queue<Env<AttrContext>>> contentsByFile;

    Map<JavaFileObject, FileQueue> fileMap;

    class FileQueue extends AbstractQueue<Env<AttrContext>> {

        @Override

        public Iterator<Env<AttrContext>> iterator() {

            return fileContents.iterator();

        }

        @Override

        public int size() {

            return fileContents.size();

        }

        public boolean offer(Env<AttrContext> e) {

            if (fileContents.offer(e)) {

                contents.add(e);

                return true;

            }

            return false;

        }

        public Env<AttrContext> poll() {

            if (fileContents.size() == 0)

                return null;

            Env<AttrContext> env = fileContents.remove(0);

            contents.remove(env);

            return env;

        }

        public Env<AttrContext> peek() {

            return (fileContents.size() == 0 ? null : fileContents.get(0));

        }

        LinkedList<Env<AttrContext>> fileContents = new LinkedList<>();

    }

}