/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.ike.ikev2;

import android.annotation.IntDef;
import android.util.ArraySet;

import com.android.ike.ikev2.exceptions.AuthenticationFailedException;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.net.Inet4Address;
import java.net.Inet6Address;
import java.net.UnknownHostException;
import java.util.Objects;
import java.util.Set;

/**
 * IkeIdentification is abstract base class that represents the common information for all types of
 * IKE entity identification.
 *
 * <p>IkeIdentification can be user configured or be constructed from an inbound packet.
 *
 * @see <a href="https://tools.ietf.org/html/rfc7296#section-3.5">RFC 7296, Internet Key Exchange
 *     Protocol Version 2 (IKEv2)</a>
 */
public abstract class IkeIdentification {
    // Set of supported ID types.
    private static final Set<Integer> SUPPORTED_ID_TYPES;

    @Retention(RetentionPolicy.SOURCE)
    @IntDef({
        ID_TYPE_IPV4_ADDR,
        ID_TYPE_FQDN,
        ID_TYPE_RFC822_ADDR,
        ID_TYPE_IPV6_ADDR,
        ID_TYPE_DER_ASN1_DN,
        ID_TYPE_DER_ASN1_GN,
        ID_TYPE_KEY_ID
    })
    public @interface IdType {}

    public static final int ID_TYPE_IPV4_ADDR = 1;
    public static final int ID_TYPE_FQDN = 2;
    public static final int ID_TYPE_RFC822_ADDR = 3;
    public static final int ID_TYPE_IPV6_ADDR = 5;
    public static final int ID_TYPE_DER_ASN1_DN = 9;
    public static final int ID_TYPE_DER_ASN1_GN = 10;
    public static final int ID_TYPE_KEY_ID = 11;

    static {
        SUPPORTED_ID_TYPES = new ArraySet();
        SUPPORTED_ID_TYPES.add(ID_TYPE_IPV4_ADDR);
        SUPPORTED_ID_TYPES.add(ID_TYPE_FQDN);
        SUPPORTED_ID_TYPES.add(ID_TYPE_RFC822_ADDR);
        SUPPORTED_ID_TYPES.add(ID_TYPE_IPV6_ADDR);
        SUPPORTED_ID_TYPES.add(ID_TYPE_DER_ASN1_DN);
        SUPPORTED_ID_TYPES.add(ID_TYPE_DER_ASN1_GN);
        SUPPORTED_ID_TYPES.add(ID_TYPE_KEY_ID);
    }

    public final int idType;

    protected IkeIdentification(@IdType int type) {
        idType = type;
    }

    /**
     * Return the encoded identification data in a byte array.
     *
     * @return the encoded identification data.
     */
    public abstract byte[] getEncodedIdData();

    /** IkeIpv4AddrIdentification represents ID information in IPv4 address ID type. */
    public static class IkeIpv4AddrIdentification extends IkeIdentification {
        public final Inet4Address ipv4Address;

        /**
         * Construct an instance of IkeIpv4AddrIdentification from decoding an inbound packet.
         *
         * @param ipv4AddrBytes IPv4 address in byte array.
         * @throws AuthenticationFailedException for decoding bytes error.
         */
        public IkeIpv4AddrIdentification(byte[] ipv4AddrBytes)
                throws AuthenticationFailedException {
            super(ID_TYPE_IPV4_ADDR);
            try {
                ipv4Address = (Inet4Address) (Inet4Address.getByAddress(ipv4AddrBytes));
            } catch (ClassCastException | UnknownHostException e) {
                throw new AuthenticationFailedException(e);
            }
        }

        /**
         * Construct an instance of IkeIpv4AddrIdentification with user provided IPv4 address for
         * building outbound packet.
         *
         * @param address user provided IPv4 address
         */
        public IkeIpv4AddrIdentification(Inet4Address address) {
            super(ID_TYPE_IPV4_ADDR);
            ipv4Address = address;
        }

        @Override
        public int hashCode() {
            return Objects.hash(idType, ipv4Address);
        }

        @Override
        public boolean equals(Object o) {
            if (!(o instanceof IkeIpv4AddrIdentification)) return false;

            return ipv4Address.equals(((IkeIpv4AddrIdentification) o).ipv4Address);
        }

        /**
         * Retrieve the byte-representation of the IPv4 address.
         *
         * @return the byte-representation of the IPv4 address.
         */
        @Override
        public byte[] getEncodedIdData() {
            return ipv4Address.getAddress();
        }
    }

    /** IkeIpv6AddrIdentification represents ID information in IPv6 address ID type. */
    public static class IkeIpv6AddrIdentification extends IkeIdentification {
        public final Inet6Address ipv6Address;

        /**
         * Construct an instance of IkeIpv6AddrIdentification from decoding an inbound packet.
         *
         * @param ipv6AddrBytes IPv6 address in byte array.
         * @throws AuthenticationFailedException for decoding bytes error.
         */
        public IkeIpv6AddrIdentification(byte[] ipv6AddrBytes)
                throws AuthenticationFailedException {
            super(ID_TYPE_IPV6_ADDR);
            try {
                ipv6Address = (Inet6Address) (Inet6Address.getByAddress(ipv6AddrBytes));
            } catch (ClassCastException | UnknownHostException e) {
                throw new AuthenticationFailedException(e);
            }
        }

        /**
         * Construct an instance of IkeIpv6AddrIdentification with user provided IPv6 address for
         * building outbound packet.
         *
         * @param address user provided IPv6 address
         */
        public IkeIpv6AddrIdentification(Inet6Address address) {
            super(ID_TYPE_IPV6_ADDR);
            ipv6Address = address;
        }

        @Override
        public int hashCode() {
            return Objects.hash(idType, ipv6Address);
        }

        @Override
        public boolean equals(Object o) {
            if (!(o instanceof IkeIpv6AddrIdentification)) return false;

            return ipv6Address.equals(((IkeIpv6AddrIdentification) o).ipv6Address);
        }

        /**
         * Retrieve the byte-representation of the IPv6 address.
         *
         * @return the byte-representation of the IPv6 address.
         */
        @Override
        public byte[] getEncodedIdData() {
            return ipv6Address.getAddress();
        }
    }
}