/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.onlab.onos.openflow.controller;

import org.projectfloodlight.openflow.util.HexString;

import java.net.URI;
import java.net.URISyntaxException;

import static com.google.common.base.Preconditions.checkArgument;
import static org.onlab.util.Tools.fromHex;
import static org.onlab.util.Tools.toHex;

/**
 * The class representing a network switch DPID.
 * This class is immutable.
 */
public final class Dpid {

    private static final String SCHEME = "of";
    private static final long UNKNOWN = 0;
    private final long value;

    /**
     * Default constructor.
     */
    public Dpid() {
        this.value = Dpid.UNKNOWN;
    }

    /**
     * Constructor from a long value.
     *
     * @param value the value to use.
     */
    public Dpid(long value) {
        this.value = value;
    }

    /**
     * Constructor from a string.
     *
     * @param value the value to use.
     */
    public Dpid(String value) {
        this.value = HexString.toLong(value);
    }

    /**
     * Get the value of the DPID.
     *
     * @return the value of the DPID.
     */
    public long value() {
        return value;
    }

    /**
     * Convert the DPID value to a ':' separated hexadecimal string.
     *
     * @return the DPID value as a ':' separated hexadecimal string.
     */
    @Override
    public String toString() {
        return HexString.toHexString(this.value);
    }

    @Override
    public boolean equals(Object other) {
        if (!(other instanceof Dpid)) {
            return false;
        }

        Dpid otherDpid = (Dpid) other;

        return value == otherDpid.value;
    }

    @Override
    public int hashCode() {
        int hash = 17;
        hash += 31 * hash + (int) (value ^ value >>> 32);
        return hash;
    }

    /**
     * Returns DPID created from the given device URI.
     *
     * @param uri device URI
     * @return dpid
     */
    public static Dpid dpid(URI uri) {
        checkArgument(uri.getScheme().equals(SCHEME), "Unsupported URI scheme");
        return new Dpid(fromHex(uri.getSchemeSpecificPart()));
    }

    /**
     * Produces device URI from the given DPID.
     *
     * @param dpid device dpid
     * @return device URI
     */
    public static URI uri(Dpid dpid) {
        return uri(dpid.value);
    }

    /**
     * Produces device URI from the given DPID long.
     *
     * @param value device dpid as long
     * @return device URI
     */
    public static URI uri(long value) {
        try {
            return new URI(SCHEME, toHex(value), null);
        } catch (URISyntaxException e) {
            return null;
        }
    }

}