/*
 * Copyright (C) 2017-2019 Ignite Realtime Foundation. All rights reserved.
 *
 * 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.jivesoftware.util;

import java.util.Objects;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Holds version information for Java specification (a major and minor version, eg: 1.8,
 * or just a number, eg: 11).
 *
 * For comparison purposes, only the minor version number is used.
 *
 * @author Guus der Kinderen, guus.der.kinderen@gmail.com
 */
public final class JavaSpecVersion implements Comparable<JavaSpecVersion> {

    private static final Pattern PATTERN_SINGLE = Pattern.compile( "(\\d+)");
    private static final Pattern PATTERN_DOUBLE = Pattern.compile( "(\\d+)\\.(\\d+)");

    /**
     * The major number (ie 1.x).
     */
    private final int major;

    /**
     * The minor version number (ie x.8).
     */
    private final int minor;

    /**
     * Create a new version information object.
     *
     * @param major the major release number.
     * @param minor the minor release number.
     */
    public JavaSpecVersion( int major, int minor ) {
        this.major = major;
        this.minor = minor;
    }

    /**
     * Create a new version from a simple version string (e.g. "1.8")
     *
     * @param source the version string
     */
    public JavaSpecVersion( CharSequence source ) {
        if (source != null) {
            Matcher matcherSingle = PATTERN_SINGLE.matcher( source);
            Matcher matcherDouble = PATTERN_DOUBLE.matcher( source);
            if (matcherDouble.matches()) {
                major = Integer.parseInt(matcherDouble.group(1));
                minor = Integer.parseInt(matcherDouble.group(2));
            } else if (matcherSingle.matches()) {
                major = 0;
                minor = Integer.parseInt(matcherSingle.group(1));
            } else {
                this.major = this.minor = 0;
            }
        } else {
            this.major = this.minor = 0;
        }
    }

    /**
     * Returns the version number of this instance of Openfire as a
     * String (ie major.minor.revision).
     *
     * @return The version as a string
     */
    public String getVersionString() {
        if ( major > 0 ) {
            return major + "." + minor;
        } else {
            return String.valueOf( minor );
        }
    }

    /**
     * Convenience method for comparing versions
     * 
     * @param otherVersion a version to compare against
     * @return {@code true} if this version is newer, otherwise {@code false}
     */
    public boolean isNewerThan(JavaSpecVersion otherVersion) {
        return this.compareTo(otherVersion) > 0;
    }

    @Override
    public int compareTo(JavaSpecVersion that) {
        if (that == null) {
            return 1;
        }
        return Integer.compare(minor, that.minor);
    }

    @Override
    public boolean equals(Object o) {
        if (o == this) {
            return true;
        }
        if (!(o instanceof JavaSpecVersion )) {
            return false;
        }
        JavaSpecVersion other = (JavaSpecVersion) o;

        return Objects.equals(minor, other.minor);
    }

    @Override
    public int hashCode() {
        return minor;
    }

    @Override
    public String toString() {
        return getVersionString();
    }
}