/*

 * Copyright (c) 2013, 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.

 *

 * 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 org.graalvm.compiler.phases;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import java.util.ListIterator;

import org.graalvm.compiler.nodes.StructuredGraph;

/**

 * A compiler phase that can apply an ordered collection of phases to a graph.

 */

public class PhaseSuite<C> extends BasePhase<C> {

    private List<BasePhase<? super C>> phases;

    private boolean immutable;

    public PhaseSuite() {

        this.phases = new ArrayList<>();

    }

    @Override

    public boolean checkContract() {

        return false;

    }

    public boolean isImmutable() {

        return immutable;

    }

    public synchronized void setImmutable() {

        if (!immutable) {

            phases = Collections.unmodifiableList(phases);

            immutable = true;

        }

    }

    /**

     * Add a new phase at the beginning of this suite.

     */

    public final void prependPhase(BasePhase<? super C> phase) {

        phases.add(0, phase);

    }

    /**

     * Add a new phase at the end of this suite.

     */

    public final void appendPhase(BasePhase<? super C> phase) {

        phases.add(phase);

    }

    /**

     * Inserts a phase before the last phase in the suite. If the suite contains no phases the new

     * phase will be inserted as the first phase.

     */

    public final void addBeforeLast(BasePhase<? super C> phase) {

        ListIterator<BasePhase<? super C>> last = findLastPhase();

        if (last.hasPrevious()) {

            last.previous();

        }

        last.add(phase);

    }

    /**

     * Returns a {@link ListIterator} at the position of the last phase in the suite. If the suite

     * has no phases then it will return an empty iterator.

     */

    public ListIterator<BasePhase<? super C>> findLastPhase() {

        ListIterator<BasePhase<? super C>> it = phases.listIterator();

        while (it.hasNext()) {

            it.next();

        }

        return it;

    }

    /**

     * Gets an unmodifiable view on the phases in this suite.

     */

    public List<BasePhase<? super C>> getPhases() {

        return Collections.unmodifiableList(phases);

    }

    /**

     * Returns a {@link ListIterator} at the position of the first phase which is an instance of

     * {@code phaseClass} or null if no such phase can be found.

     *

     * Calling {@link ListIterator#previous()} would return the phase that was found.

     *

     * @param phaseClass the type of phase to look for.

     */

    public final ListIterator<BasePhase<? super C>> findPhase(Class<? extends BasePhase<? super C>> phaseClass) {

        return findPhase(phaseClass, false);

    }

    /**

     * Returns a {@link ListIterator} at the position of the first phase which is an instance of

     * {@code phaseClass} or, if {@code recursive} is true, is a {@link PhaseSuite} containing a

     * phase which is an instance of {@code phaseClass}. This method returns null if no such phase

     * can be found.

     *

     * Calling {@link ListIterator#previous()} would return the phase or phase suite that was found.

     *

     * @param phaseClass the type of phase to look for

     * @param recursive whether to recursively look into phase suites.

     */

    public final ListIterator<BasePhase<? super C>> findPhase(Class<? extends BasePhase<? super C>> phaseClass, boolean recursive) {

        ListIterator<BasePhase<? super C>> it = phases.listIterator();

        if (findNextPhase(it, phaseClass, recursive)) {

            return it;

        } else {

            return null;

        }

    }

    public static <C> boolean findNextPhase(ListIterator<BasePhase<? super C>> it, Class<? extends BasePhase<? super C>> phaseClass) {

        return findNextPhase(it, phaseClass, false);

    }

    @SuppressWarnings("unchecked")

    public static <C> boolean findNextPhase(ListIterator<BasePhase<? super C>> it, Class<? extends BasePhase<? super C>> phaseClass, boolean recursive) {

        while (it.hasNext()) {

            BasePhase<? super C> phase = it.next();

            if (phaseClass.isInstance(phase)) {

                return true;

            } else if (recursive && phase instanceof PhaseSuite) {

                PhaseSuite<C> suite = (PhaseSuite<C>) phase;

                if (suite.findPhase(phaseClass, true) != null) {

                    return true;

                }

            }

        }

        return false;

    }

    /**

     * Removes the first instance of the given phase class, looking recursively into inner phase

     * suites.

     */

    @SuppressWarnings("unchecked")

    public boolean removePhase(Class<? extends BasePhase<? super C>> phaseClass) {

        ListIterator<BasePhase<? super C>> it = phases.listIterator();

        while (it.hasNext()) {

            BasePhase<? super C> phase = it.next();

            if (phaseClass.isInstance(phase)) {

                it.remove();

                return true;

            } else if (phase instanceof PhaseSuite) {

                PhaseSuite<C> innerSuite = (PhaseSuite<C>) phase;

                if (innerSuite.removePhase(phaseClass)) {

                    if (innerSuite.phases.isEmpty()) {

                        it.remove();

                    }

                    return true;

                }

            }

        }

        return false;

    }

    /**

     * Removes the first instance of the given phase class, looking recursively into inner phase

     * suites.

     */

    @SuppressWarnings("unchecked")

    public boolean replacePhase(Class<? extends BasePhase<? super C>> phaseClass, BasePhase<? super C> newPhase) {

        ListIterator<BasePhase<? super C>> it = phases.listIterator();

        while (it.hasNext()) {

            BasePhase<? super C> phase = it.next();

            if (phaseClass.isInstance(phase)) {

                it.set(newPhase);

                return true;

            } else if (phase instanceof PhaseSuite) {

                PhaseSuite<C> innerSuite = (PhaseSuite<C>) phase;

                if (innerSuite.replacePhase(phaseClass, newPhase)) {

                    return true;

                }

            }

        }

        return false;

    }

    @Override

    protected void run(StructuredGraph graph, C context) {

        for (BasePhase<? super C> phase : phases) {

            phase.apply(graph, context);

        }

    }

    public PhaseSuite<C> copy() {

        PhaseSuite<C> suite = new PhaseSuite<>();

        suite.phases.addAll(phases);

        return suite;

    }

}