/*
 * Copyright 2017-present Open Networking Laboratory
 *
 * 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 org.onosproject.lisp.msg.protocols;

import com.google.common.base.Objects;
import io.netty.buffer.ByteBuf;
import org.onlab.util.ByteOperator;
import org.onosproject.lisp.msg.exceptions.LispParseError;
import org.onosproject.lisp.msg.exceptions.LispReaderException;
import org.onosproject.lisp.msg.exceptions.LispWriterException;
import org.onosproject.lisp.msg.types.LispAfiAddress;
import org.onosproject.lisp.msg.types.LispAfiAddress.AfiAddressWriter;

import static com.google.common.base.MoreObjects.toStringHelper;

/**
 * A default implementation class of LISP generic locator interface.
 */
public class DefaultLispGenericLocator implements LispGenericLocator {

    private final byte priority;
    private final byte weight;
    private final byte multicastPriority;
    private final byte multicastWeight;
    private final boolean localLocator;
    private final boolean rlocProbed;
    private final boolean routed;
    private final LispAfiAddress locatorAfi;

    private static final int LOCAL_LOCATOR_SHIFT_BIT = 2;
    private static final int PROBED_SHIFT_BIT = 1;

    private static final int ENABLE_BIT = 1;
    private static final int DISABLE_BIT = 0;

    private static final int SKIP_UNUSED_FLAG_LENGTH = 1;
    private static final int LOCAL_LOCATOR_INDEX = 2;
    private static final int RLOC_PROBED_INDEX = 1;
    private static final int ROUTED_INDEX = 0;

    /**
     * A private constructor that protects object instantiation from external.
     *
     * @param priority          uni-cast priority
     * @param weight            uni-cast weight
     * @param multicastPriority multi-cast priority
     * @param multicastWeight   multi-cast weight
     * @param localLocator      local locator flag
     * @param rlocProbed        RLOC probed flag
     * @param routed            routed flag
     * @param locatorAfi        locator AFI
     */
    DefaultLispGenericLocator(byte priority, byte weight, byte multicastPriority,
                              byte multicastWeight, boolean localLocator,
                              boolean rlocProbed, boolean routed,
                              LispAfiAddress locatorAfi) {
        this.priority = priority;
        this.weight = weight;
        this.multicastPriority = multicastPriority;
        this.multicastWeight = multicastWeight;
        this.localLocator = localLocator;
        this.rlocProbed = rlocProbed;
        this.routed = routed;
        this.locatorAfi = locatorAfi;
    }

    @Override
    public byte getPriority() {
        return priority;
    }

    @Override
    public byte getWeight() {
        return weight;
    }

    @Override
    public byte getMulticastPriority() {
        return multicastPriority;
    }

    @Override
    public byte getMulticastWeight() {
        return multicastWeight;
    }

    @Override
    public boolean isLocalLocator() {
        return localLocator;
    }

    @Override
    public boolean isRlocProbed() {
        return rlocProbed;
    }

    @Override
    public boolean isRouted() {
        return routed;
    }

    @Override
    public LispAfiAddress getLocatorAfi() {
        return locatorAfi;
    }

    @Override
    public void writeTo(ByteBuf byteBuf) throws LispWriterException {
    }

    @Override
    public String toString() {
        return toStringHelper(this)
                .add("priority", priority)
                .add("weight", weight)
                .add("multi-cast priority", multicastPriority)
                .add("multi-cast weight", multicastWeight)
                .add("local locator", localLocator)
                .add("RLOC probed", rlocProbed)
                .add("routed", routed)
                .add("locator AFI", locatorAfi).toString();
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        DefaultLispGenericLocator that = (DefaultLispGenericLocator) o;
        return Objects.equal(priority, that.priority) &&
                Objects.equal(weight, that.weight) &&
                Objects.equal(multicastPriority, that.multicastPriority) &&
                Objects.equal(multicastWeight, that.multicastWeight) &&
                Objects.equal(localLocator, that.localLocator) &&
                Objects.equal(rlocProbed, that.rlocProbed) &&
                Objects.equal(routed, that.routed) &&
                Objects.equal(locatorAfi, that.locatorAfi);
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(priority, weight, multicastPriority,
                multicastWeight, localLocator, rlocProbed, routed, locatorAfi);
    }

    public abstract static class AbstractGenericLocatorBuilder<T>
            implements GenericLocatorBuilder<T> {
        byte priority;
        byte weight;
        byte multicastPriority;
        byte multicastWeight;
        boolean localLocator;
        boolean rlocProbed;
        boolean routed;
        LispAfiAddress locatorAfi;

        @Override
        public T withPriority(byte priority) {
            this.priority = priority;
            return (T) this;
        }

        @Override
        public T withWeight(byte weight) {
            this.weight = weight;
            return (T) this;
        }

        @Override
        public T withMulticastPriority(byte priority) {
            this.multicastPriority = priority;
            return (T) this;
        }

        @Override
        public T withMulticastWeight(byte weight) {
            this.multicastWeight = weight;
            return (T) this;
        }

        @Override
        public T withLocalLocator(boolean localLocator) {
            this.localLocator = localLocator;
            return (T) this;
        }

        @Override
        public T withRlocProbed(boolean rlocProbed) {
            this.rlocProbed = rlocProbed;
            return (T) this;
        }

        @Override
        public T withRouted(boolean routed) {
            this.routed = routed;
            return (T) this;
        }

        @Override
        public T withLocatorAfi(LispAfiAddress locatorAfi) {
            this.locatorAfi = locatorAfi;
            return (T) this;
        }
    }

    /**
     * Deserializes LispGenericLocator message portion.
     *
     * @param byteBuf byte buffer
     * @return LispGenericLocator
     * @throws LispParseError      LISP message parse error
     * @throws LispReaderException LISP message reader exception
     */
    public static LispGenericLocator deserialize(ByteBuf byteBuf)
            throws LispParseError,
            LispReaderException {
        // priority -> 8 bits
        byte priority = (byte) byteBuf.readUnsignedByte();

        // weight -> 8 bits
        byte weight = (byte) byteBuf.readUnsignedByte();

        // multi-cast priority -> 8 bits
        byte multicastPriority = (byte) byteBuf.readUnsignedByte();

        // multi-cast weight -> 8 bits
        byte multicastWeight = (byte) byteBuf.readUnsignedByte();

        // let's skip unused flags
        byteBuf.skipBytes(SKIP_UNUSED_FLAG_LENGTH);

        byte flags = byteBuf.readByte();

        // local locator flag -> 1 bit
        boolean localLocator = ByteOperator.getBit(flags, LOCAL_LOCATOR_INDEX);

        // rloc probe flag -> 1 bit
        boolean rlocProbed = ByteOperator.getBit(flags, RLOC_PROBED_INDEX);

        // routed flag -> 1 bit
        boolean routed = ByteOperator.getBit(flags, ROUTED_INDEX);

        LispAfiAddress address = new LispAfiAddress.AfiAddressReader().readFrom(byteBuf);

        return new DefaultLispGenericLocator(priority, weight, multicastPriority,
                multicastWeight, localLocator, rlocProbed, routed, address);
    }

    /**
     * Serializes LispGenericLocator message portion.
     *
     * @param byteBuf        byte buffer
     * @param genericLocator generic locator
     * @throws LispWriterException LISP message writer exception
     */
    public static void serialize(ByteBuf byteBuf, LispGenericLocator genericLocator)
            throws LispWriterException {
        // priority
        byteBuf.writeByte(genericLocator.getPriority());

        // weight
        byteBuf.writeByte(genericLocator.getWeight());

        // multicast priority
        byteBuf.writeByte(genericLocator.getMulticastPriority());

        // multicast weight
        byteBuf.writeByte(genericLocator.getMulticastWeight());

        // unused flags
        byteBuf.writeByte((short) 0);

        // localLocator flag
        short localLocator = DISABLE_BIT;
        if (genericLocator.isLocalLocator()) {
            localLocator = (byte) (ENABLE_BIT << LOCAL_LOCATOR_SHIFT_BIT);
        }

        // rlocProbed flag
        short probed = DISABLE_BIT;
        if (genericLocator.isRlocProbed()) {
            probed = (byte) (ENABLE_BIT << PROBED_SHIFT_BIT);
        }

        // routed flag
        short routed = DISABLE_BIT;
        if (genericLocator.isRouted()) {
            routed = (byte) ENABLE_BIT;
        }

        byteBuf.writeByte((byte) (localLocator + probed + routed));

        // EID prefix AFI with EID prefix
        AfiAddressWriter afiAddressWriter = new AfiAddressWriter();
        afiAddressWriter.writeTo(byteBuf, genericLocator.getLocatorAfi());
    }
}