/*

 * Copyright (c) 2016, 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.hotspot;

import static jdk.vm.ci.common.InitTimer.timer;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import java.util.stream.Collectors;

import org.graalvm.compiler.debug.Assertions;

import org.graalvm.compiler.debug.GraalError;

import org.graalvm.compiler.options.Option;

import org.graalvm.compiler.options.OptionKey;

import org.graalvm.compiler.options.OptionType;

import org.graalvm.compiler.options.OptionValues;

import org.graalvm.compiler.phases.tiers.CompilerConfiguration;

import org.graalvm.compiler.serviceprovider.GraalServices;

import org.graalvm.util.EconomicMap;

import jdk.vm.ci.code.Architecture;

import jdk.vm.ci.common.InitTimer;

/**

 * A factory that creates the {@link CompilerConfiguration} the Graal compiler will use. Each

 * factory must have a unique {@link #name} and {@link #autoSelectionPriority}. The latter imposes a

 * total ordering between factories for the purpose of auto-selecting the factory to use.

 */

public abstract class CompilerConfigurationFactory implements Comparable<CompilerConfigurationFactory> {

    static class Options {

        // @formatter:off

        @Option(help = "Names the Graal compiler configuration to use. If ommitted, the compiler configuration " +

                       "with the highest auto-selection priority is used. To see the set of available configurations, " +

                       "supply the value 'help' to this option.", type = OptionType.Expert)

        public static final OptionKey<String> CompilerConfiguration = new OptionKey<>(null);

        // @formatter:on

    }

    /**

     * The name of this factory. This must be unique across all factory instances and is used when

     * selecting a factory based on the value of {@link Options#CompilerConfiguration}.

     */

    private final String name;

    /**

     * The priority of this factory. This must be unique across all factory instances and is used

     * when selecting a factory when {@link Options#CompilerConfiguration} is omitted

     */

    private final int autoSelectionPriority;

    protected CompilerConfigurationFactory(String name, int autoSelectionPriority) {

        this.name = name;

        this.autoSelectionPriority = autoSelectionPriority;

        assert checkAndAddNewFactory(this);

    }

    public abstract CompilerConfiguration createCompilerConfiguration();

    /**

     * Collect the set of available {@linkplain HotSpotBackendFactory backends} for this compiler

     * configuration.

     */

    public BackendMap createBackendMap() {

        // default to backend with the same name as the compiler configuration

        return new DefaultBackendMap(name);

    }

    public interface BackendMap {

        HotSpotBackendFactory getBackendFactory(Architecture arch);

    }

    public static class DefaultBackendMap implements BackendMap {

        private final EconomicMap<Class<? extends Architecture>, HotSpotBackendFactory> backends = EconomicMap.create();

        @SuppressWarnings("try")

        public DefaultBackendMap(String backendName) {

            try (InitTimer t = timer("HotSpotBackendFactory.register")) {

                for (HotSpotBackendFactory backend : GraalServices.load(HotSpotBackendFactory.class)) {

                    if (backend.getName().equals(backendName)) {

                        Class<? extends Architecture> arch = backend.getArchitecture();

                        HotSpotBackendFactory oldEntry = backends.put(arch, backend);

                        assert oldEntry == null || oldEntry == backend : "duplicate Graal backend";

                    }

                }

            }

        }

        @Override

        public final HotSpotBackendFactory getBackendFactory(Architecture arch) {

            return backends.get(arch.getClass());

        }

    }

    @Override

    public int compareTo(CompilerConfigurationFactory o) {

        if (autoSelectionPriority > o.autoSelectionPriority) {

            return -1;

        }

        if (autoSelectionPriority < o.autoSelectionPriority) {

            return 1;

        }

        assert this == o : "distinct compiler configurations cannot have the same auto selection priority";

        return 0;

    }

    /**

     * List used to assert uniqueness of {@link #name} and {@link #autoSelectionPriority} across all

     * {@link CompilerConfigurationFactory} instances.

     */

    private static final List<CompilerConfigurationFactory> factories = Assertions.assertionsEnabled() ? new ArrayList<>() : null;

    private static boolean checkAndAddNewFactory(CompilerConfigurationFactory factory) {

        for (CompilerConfigurationFactory other : factories) {

            assert !other.name.equals(factory.name) : factory.getClass().getName() + " cannot have the same selector as " + other.getClass().getName() + ": " + factory.name;

            assert other.autoSelectionPriority != factory.autoSelectionPriority : factory.getClass().getName() + " cannot have the same auto-selection priority as " + other.getClass().getName() +

                            ": " + factory.autoSelectionPriority;

        }

        factories.add(factory);

        return true;

    }

    /**

     * @return sorted list of {@link CompilerConfigurationFactory}s

     */

    private static List<CompilerConfigurationFactory> getAllCandidates() {

        List<CompilerConfigurationFactory> candidates = new ArrayList<>();

        for (CompilerConfigurationFactory candidate : GraalServices.load(CompilerConfigurationFactory.class)) {

            candidates.add(candidate);

        }

        Collections.sort(candidates);

        return candidates;

    }

    /**

     * Selects and instantiates a {@link CompilerConfigurationFactory}. The selection algorithm is

     * as follows: if {@code name} is non-null, then select the factory with the same name else if

     * {@code Options.CompilerConfiguration.getValue()} is non-null then select the factory whose

     * name matches the value else select the factory with the highest

     * {@link #autoSelectionPriority} value.

     *

     * @param name the name of the compiler configuration to select (optional)

     */

    @SuppressWarnings("try")

    public static CompilerConfigurationFactory selectFactory(String name, OptionValues options) {

        CompilerConfigurationFactory factory = null;

        try (InitTimer t = timer("CompilerConfigurationFactory.selectFactory")) {

            String value = name == null ? Options.CompilerConfiguration.getValue(options) : name;

            if ("help".equals(value)) {

                System.out.println("The available Graal compiler configurations are:");

                for (CompilerConfigurationFactory candidate : getAllCandidates()) {

                    System.out.println("    " + candidate.name);

                }

                System.exit(0);

            } else if (value != null) {

                for (CompilerConfigurationFactory candidate : GraalServices.load(CompilerConfigurationFactory.class)) {

                    if (candidate.name.equals(value)) {

                        factory = candidate;

                        break;

                    }

                }

                if (factory == null) {

                    throw new GraalError("Graal compiler configuration '%s' not found. Available configurations are: %s", value,

                                    getAllCandidates().stream().map(c -> c.name).collect(Collectors.joining(", ")));

                }

            } else {

                List<CompilerConfigurationFactory> candidates = getAllCandidates();

                if (candidates.isEmpty()) {

                    throw new GraalError("No %s providers found", CompilerConfigurationFactory.class.getName());

                }

                factory = candidates.get(0);

            }

        }

        return factory;

    }

}