// SPDX-FileCopyrightText: 2018 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0

package org.pgpainless.algorithm;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.bouncycastle.bcpg.sig.Features;

/**
 * An enumeration of features that may be set in the {@link Features} subpacket.
 *
 * @see <a href="https://tools.ietf.org/html/rfc4880#section-5.2.3.24">RFC4880: Features</a>
 */
public enum Feature {

    /**
     * Add modification detection package.
     *
     * @see <a href="https://tools.ietf.org/html/rfc4880#section-5.14">
     *     RFC-4880 §5.14: Modification Detection Code Packet</a>
     */
    MODIFICATION_DETECTION(Features.FEATURE_MODIFICATION_DETECTION),
    AEAD_ENCRYPTED_DATA(Features.FEATURE_AEAD_ENCRYPTED_DATA),
    VERSION_5_PUBLIC_KEY(Features.FEATURE_VERSION_5_PUBLIC_KEY)
    ;

    private static final Map<Byte, Feature> MAP = new ConcurrentHashMap<>();

    static {
        for (Feature f : Feature.values()) {
            MAP.put(f.featureId, f);
        }
    }

    public static Feature fromId(byte id) {
        return MAP.get(id);
    }

    private final byte featureId;

    Feature(byte featureId) {
        this.featureId = featureId;
    }

    public byte getFeatureId() {
        return featureId;
    }

    /**
     * Convert a bitmask into a list of {@link KeyFlag KeyFlags}.
     *
     * @param bitmask bitmask
     * @return list of key flags encoded by the bitmask
     */
    public static List<Feature> fromBitmask(int bitmask) {
        List<Feature> features = new ArrayList<>();
        for (Feature f : Feature.values()) {
            if ((bitmask & f.featureId) != 0) {
                features.add(f);
            }
        }
        return features;
    }

    /**
     * Encode a list of {@link KeyFlag KeyFlags} into a bitmask.
     *
     * @param features list of flags
     * @return bitmask
     */
    public static byte toBitmask(Feature... features) {
        byte mask = 0;
        for (Feature f : features) {
            mask |= f.featureId;
        }
        return mask;
    }
}