/*
 * Copyright 2022 DeNA Co., Ltd.
 *
 * 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 packetproxy.quic.value;

import lombok.AccessLevel;
import lombok.Getter;
import lombok.SneakyThrows;
import lombok.Value;

@Value
public class PacketNumber {

    static public final PacketNumber Infinite = new PacketNumber();

    static public PacketNumber of(long number) {
        return new PacketNumber(number);
    }

    static public PacketNumber max(PacketNumber a, PacketNumber b) {
        return a.getNumber() > b.getNumber() ? a : b;
    }

    @Getter(AccessLevel.NONE)
    boolean infinite;
    long number;

    private PacketNumber() {
        this.number = -1;
        this.infinite = true;
    }

    private PacketNumber(long number) {
        assert(number >= 0);
        this.number = number;
        this.infinite = false;
    }

    public boolean isInfinite() {
        return infinite;
    }

    public TruncatedPacketNumber getTruncatedPacketNumber(PacketNumber largestAckedPn) {
        if (!this.infinite) {
            return new TruncatedPacketNumber(this, largestAckedPn);
        }
        return null;
    }

    @SneakyThrows
    public PacketNumber plus(long num) {
        return new PacketNumber(this.number + num);
    }

    @SneakyThrows
    public PacketNumber minus(long num) {
        return new PacketNumber(this.number - num);
    }

    public long minus(PacketNumber packetPn) {
        return this.number - packetPn.number;
    }

    public boolean isLargerThan(PacketNumber packetPn) {
        return this.number > packetPn.getNumber();
    }

    public boolean isLargerThanOrEquals(PacketNumber packetPn) {
        return this.number >= packetPn.getNumber();
    }

    public String toString() {
        return "PacketNumber(" + (this.infinite ? "INF": this.number) + ")";
    }

}
