/*

 * Copyright (c) 2013, 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.core.test;

import java.lang.annotation.RetentionPolicy;

import java.lang.reflect.Field;

import java.lang.reflect.Modifier;

import java.lang.reflect.ParameterizedType;

import java.lang.reflect.Type;

import java.util.Iterator;

import java.util.Map;

import java.util.Properties;

import org.graalvm.compiler.options.Option;

import org.graalvm.compiler.options.OptionDescriptor;

import org.graalvm.compiler.options.OptionDescriptors;

import org.graalvm.compiler.options.OptionKey;

import org.graalvm.compiler.options.OptionValues;

/**

 * An implementation of {@link OptionDescriptor} that uses reflection to create descriptors from a

 * list of field name and help text pairs. We cannot use the {@link Option} annotation as it has a

 * {@link RetentionPolicy#SOURCE} retention policy.

 *

 * This class is useful for working with {@link OptionKey} and {@link OptionValues} but without

 * having to rely on {@link Option} and its associated annotation processor.

 */

public class ReflectionOptionDescriptors implements OptionDescriptors {

    /**

     * Extracts name/value entries from a set of properties based on a given name prefix.

     *

     * @param properties the properties set to extract from

     * @param prefix entries whose names start with this prefix are extracted

     * @param stripPrefix specifies whether to remove the prefix from the names in the returned map

     */

    public static EconomicMap<String, String> extractEntries(Properties properties, String prefix, boolean stripPrefix) {

        EconomicMap<String, String> matches = EconomicMap.create();

        for (Map.Entry<Object, Object> e : properties.entrySet()) {

            String name = (String) e.getKey();

            if (name.startsWith(prefix)) {

                String value = (String) e.getValue();

                if (stripPrefix) {

                    name = name.substring(prefix.length());

                }

                matches.put(name, value);

            }

        }

        return matches;

    }

    private final EconomicMap<String, OptionDescriptor> descriptors = EconomicMap.create();

    public ReflectionOptionDescriptors(Class<?> declaringClass, String... fieldsAndHelp) {

        assert fieldsAndHelp.length % 2 == 0;

        for (int i = 0; i < fieldsAndHelp.length; i += 2) {

            String fieldName = fieldsAndHelp[i];

            String help = fieldsAndHelp[i + 1];

            addOption(declaringClass, fieldName, help);

        }

    }

    public ReflectionOptionDescriptors(Class<?> declaringClass, EconomicMap<String, String> fieldsAndHelp) {

        MapCursor<String, String> cursor = fieldsAndHelp.getEntries();

        while (cursor.advance()) {

            String fieldName = cursor.getKey();

            String help = cursor.getValue();

            addOption(declaringClass, fieldName, help);

        }

    }

    private void addOption(Class<?> declaringClass, String fieldName, String help) {

        try {

            Field f = declaringClass.getDeclaredField(fieldName);

            if (!OptionKey.class.isAssignableFrom(f.getType())) {

                throw new IllegalArgumentException(String.format("Option field must be of type %s: %s", OptionKey.class.getName(), f));

            }

            if (!Modifier.isStatic(f.getModifiers())) {

                throw new IllegalArgumentException(String.format("Option field must be static: %s", f));

            }

            f.setAccessible(true);

            Type declaredType = f.getAnnotatedType().getType();

            if (!(declaredType instanceof ParameterizedType)) {

                throw new IllegalArgumentException(String.format("Option field must have a parameterized type: %s", f));

            }

            ParameterizedType pt = (ParameterizedType) declaredType;

            Type[] actualTypeArguments = pt.getActualTypeArguments();

            assert actualTypeArguments.length == 1;

            Class<?> optionType = (Class<?>) actualTypeArguments[0];

            descriptors.put(fieldName, OptionDescriptor.create(fieldName, optionType, help, declaringClass, fieldName, (OptionKey<?>) f.get(null)));

        } catch (IllegalAccessException | NoSuchFieldException e) {

            throw new IllegalArgumentException(e);

        }

    }

    @Override

    public Iterator<OptionDescriptor> iterator() {

        return descriptors.getValues().iterator();

    }

    @Override

    public OptionDescriptor get(String value) {

        return descriptors.get(value);

    }

}