package co.codewizards.cloudstore.core.updater;

import java.io.Serializable;
import java.util.Arrays;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * This class is used to <code>version</code> the client plugins of JFire and may be used to act
 * as a version identifier in any project.
 *
 * The pattern a version <code>String</code> is:
 * <code>major</code>{@value #DEFAULT_SEPARATOR}<code>minor</code>{@value #DEFAULT_SEPARATOR}
 * <code>release</code>[{@value #DEFAULT_SEPARATOR}<code>patchLevel</code>
 * [{@value #DEFAULT_SEPARATOR}<code>suffix</code>]] <br>
 * The suffix may consist of 'a-zA-Z0-9#$!_-'. Additionally the following version string is
 * also valid: '<pre>1.2.3.test</pre>'.
 *
 * <p>Examples of valid versions are:
 * <ul>
 *      <li><pre>1.2.3</pre></li>
 *      <li><pre>1.2.3.4</pre></li>
 *      <li><pre>1.2.3.4.test</pre></li>
 *      <li><pre>1.2.3.t_e!st</pre></li>
 * </ul>
 * </p>
 *
 *
 * <p>Note: This class is immutable!</p>
 *
 * @author Marius Heinzmann marius[AT]NightLabs[DOT]de
 * @author Marco Schulze marco@nightlabs.de
 * @author Niklas Schiffler <nick@nightlabs.de>
 */
public class Version implements Comparable<Version>, Serializable
{
        private static final String SNAPSHOT_SUFFIX = "SNAPSHOT";

        private static final long serialVersionUID = 1L;

        /**
         * The minimum Version that can exist.
         */
        public static final Version MIN_VERSION = new Version(0,0,0,0);

        /**
         * The maximum Version possible.
         */
        public static final Version MAX_VERSION = new Version(Integer.MAX_VALUE, Integer.MAX_VALUE,
                        Integer.MAX_VALUE, Integer.MAX_VALUE);

        private int major;
        private int minor;
        private int release;
        private int patchLevel;
        private String suffix;

        private static final String DEFAULT_SEPARATOR = ".";
        private static final String SUFFIX_SEPARATOR = "-";
        private static final String EMPTYSTRING = "";

        /**
         * Creates a new instance from the given {@code versionStr}.
         * @param versionStr the version encoded as a String.
         * @throws MalformedVersionException
         */
        public Version(String versionStr)
        throws MalformedVersionException
        {
                if (versionStr == null || versionStr.length() == 0)
                        throw new IllegalArgumentException("versionStr must NEITHER be null NOR empty!");

                parseVersion(versionStr);
                validate();
        }

        /**
         * @param major
         * @param minor
         * @param release
         * @param patchLevel
         */
        public Version(int major, int minor, int release, int patchLevel) {
                this(major, minor, release, patchLevel, null);
        }

        /**
         * @param major
         * @param minor
         * @param release
         * @param patchLevel
         * @param suffix
         */
        public Version(int major, int minor, int release, int patchLevel, String suffix) {
                this.major = major;
                this.minor = minor;
                this.release = release;
                this.patchLevel = patchLevel;
                if (suffix == null)
                        suffix = EMPTYSTRING;
//              TODO: should we limit the length of a suffix?? There is no need to, but it might become a
//                                      Problem when persisting in the DB.
//              else if (suffix.length() > MAX_STRING.length())
//                      throw new IllegalArgumentException("The given suffix is too long! It is allowed to have a " +
//                                      "maximum of "+MAX_STRING.length()+" characters!");

                this.suffix = suffix;
                validate();
        }

        /**
         * A regex that is used to check the suffix for valid characters.
         */
        public static Pattern validityCheck = null;

        private void validate() {
                if (major < 0)
                        throw new MalformedVersionException("Negative major versions are invalid!");
                if (minor < 0)
                        throw new MalformedVersionException("Negative minor versions are invalid!");
                if (release < 0)
                        throw new MalformedVersionException("Negative release versions are invalid!");
                if (patchLevel < 0)
                        throw new MalformedVersionException("Negative patchlevels are invalid!");

                if (suffix == null || suffix.length() == 0)
                        return;

                // This omits parsing problems of other classes which may as well be represented as strings
                // and have other separators which may be used inside this suffix.
                if (validityCheck == null)
                        validityCheck = Pattern.compile("[\\w#\\$!\\-]*");

                 if (! validityCheck.matcher(suffix).matches())
                         throw new MalformedVersionException("The suffix contains illegal characters! Suffix='"
                                         +suffix+"'. Legal characters ='a-zA-Z0-9#$!_-'.");
        }

        /**
         * @return Returns the major.
         */
        public int getMajor() {
                return major;
        }

        /**
         * @param major The major with which to create a new Version.
         * @return A copy of this Version except for the given new major.
         */
        public Version changeMajor(int major) {
                return new Version(major, minor, release, patchLevel, suffix);
        }

        /**
         * @return Returns the minor.
         */
        public int getMinor() {
                return minor;
        }

        /**
         * @param minor The minor with which to create a new Version.
         * @return A copy of this Version except for the given new minor.
         */
        public Version changeMinor(int minor) {
                return new Version(major, minor, release, patchLevel, suffix);
        }

        /**
         * @return Returns the patchLevel.
         */
        public int getPatchLevel() {
                return patchLevel;
        }

        /**
         * @param patchLevel The patchLevel with which to create a new Version.
         * @return A copy of this Version except for the given new patchLevel.
         */
        public Version changePatchLevel(int patchLevel) {
                return new Version(major, minor, release, patchLevel, suffix);
        }

        /**
         * @return Returns the release.
         */
        public int getRelease() {
                return release;
        }

        /**
         * @param release The <code>release</code> with which to create a new Version.
         * @return A copy of this Version except for the given new <code>release</code>.
         */
        public Version changeRelease(int release) {
                return new Version(major, minor, release, patchLevel, suffix);
        }

        /**
         * @return Returns the suffix.
         */
        public String getSuffix() {
                return suffix;
        }

        /**
         * @param suffix The <code>suffix</code> with which to create a new Version.
         * @return A copy of this Version except for the given new <code>suffix</code>.
         */
        public Version changeSuffix(String suffix) {
                return new Version(major, minor, release, patchLevel, suffix);
        }

        /**
         * Returns the String representation of this version, which is defined as:
         * <code>major</code>{@value #DEFAULT_SEPARATOR}<code>minor</code>{@value #DEFAULT_SEPARATOR}
         * <code>release</code>[{@value #DEFAULT_SEPARATOR}<code>patchLevel</code>
         * [{@value #DEFAULT_SEPARATOR}<code>suffix</code>]] <br>
         * The suffix may consist of 'a-zA-Z0-9#$!_-'. Additionally the following version string is
         * also valid: '<pre>1.2.3.test</pre>'.
         *
         * @return the <code>String</code> representation of this version.
         */
        @Override
        public String toString() {
                StringBuffer sb = new StringBuffer();
                sb.append(major);
                sb.append(DEFAULT_SEPARATOR);
                sb.append(minor);
                sb.append(DEFAULT_SEPARATOR);
                sb.append(release);
                if (patchLevel != 0) {
                        sb.append(DEFAULT_SEPARATOR);
                        sb.append(patchLevel);
                }
                if (suffix != null && !EMPTYSTRING.equals(suffix)) {
                        sb.append(SUFFIX_SEPARATOR);
                        sb.append(suffix);
                }
                return sb.toString();
        }

        /**
         * Creates a Version out of its String ({@link #toString()}) representation. The String should
         * conform to the following pattern:
         * <code>major</code>{@value #DEFAULT_SEPARATOR}<code>minor</code>{@value #DEFAULT_SEPARATOR}
         * <code>release</code>{@value #DEFAULT_SEPARATOR}<code>patchLevel</code>
         * {@value #DEFAULT_SEPARATOR}<code>suffix</code>.
         *
         * @param version the {@link #toString()} representation of a version.
         * @throws MalformedVersionException if the given <code>String</code> does not conform to the
         *      pattern described.
         */
        private void parseVersion(String version)
                throws MalformedVersionException
        {
                Pattern versionPattern = Pattern.compile(
//              The whole rexexp not escaped
//                      (\d+)\.(\d+)\.(\d+)(?:[-\.](?:(\d+)|([\w#\$!\-]+)|(?:(\d+)[-\.]([\w#\$!\-]+))))?\s*\z
                                "(\\d+)\\.(\\d+)\\.(\\d+)(?:[-\\.](?:(\\d+)|([\\w#\\$!\\-]+)|(?:(\\d+)[-\\.]([\\w#\\$!\\-]+))))?\\s*\\z");
//              EOI = end of input; OPT(..) = optional; | = or
//        major  . minor  . release OPT( ./- (patchLevel  | suffix | patchLevel ./- suffix)) whitespace* EOI
//              the endofinput prohibits the parsing of '1.7.0-9-asf.narf' which would otherwise be read as
//              '1.7.0-9-asf'.
                Matcher m = versionPattern.matcher(version);
                if(m.find())
                {
                        this.major = Integer.parseInt(m.group(1));
                        this.minor = Integer.parseInt(m.group(2));
                        this.release = Integer.parseInt(m.group(3));

                        // Assumption is that if the element in the 4th group is parseable as an int -> it is an int.
                        // So given the string '1.2.3.02' the '02' is interpreted as an int, not a string!
                        if (m.group(4) != null)
                        {
                                try
                                {
//                              assume we got a small JFire version without suffix.
                                        this.patchLevel = Integer.parseInt(m.group(4));
                                        this.suffix = "";
                                }
                                catch (NumberFormatException nfe)
                                {
//                              since the number is too big -> it must be a suffix consisting only of numbers
                                        this.patchLevel = 0;
                                        this.suffix = m.group(4);
                                }
                        }
                        else if (m.group(5) != null)
                        {
//                      assume that we are given an osgi-version -> group(5) = suffix
                                this.patchLevel = 0;
                                this.suffix = m.group(5);
                        }
                        else if (m.group(6) != null && m.group(7) != null)
                        {
//                              assume we have a full JFire version
                                try {
                                        this.patchLevel = Integer.parseInt(m.group(6));
                                        this.suffix = m.group(7);
                                } catch (NumberFormatException nfe2) {
                                        throw new MalformedVersionException("The patchlevel has to be a parseable number! " +
                                                        "given patchlevel: '"+m.group(6)+"' given encoded version: '"+version+"'");
                                }
                        }
                        else
                        {
                                // assume we have only major.minor.release
                                for (int i = 4; i < 8; i++)
                                {
                                        if (m.group(i) != null)
                                                throw new MalformedVersionException("Malformed version string: " + version);
                                }
                        }
                }
        }

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

                final Version otherVersion = (Version) other;

                return major == otherVersion.major
                                && minor == otherVersion.minor
                                && release == otherVersion.release
                                && patchLevel == otherVersion.patchLevel
                                && equals(suffix, otherVersion.suffix);
        }

        private static boolean equals(Object obj0, Object obj1)
        {
                if (obj0 instanceof Object[] && obj1 instanceof Object[])
                        return obj0 == obj1 || Arrays.equals((Object[])obj0, (Object[])obj1);
                return obj0 == obj1 || (obj0 != null && obj0.equals(obj1));
        }

        @Override
        public int hashCode() {
                final int PRIME = 31;
                int result = 1;
                result = result * PRIME + major;
                result = result * PRIME + minor;
                result = result * PRIME + release;
                result = result * PRIME + patchLevel;
                result = result * PRIME + (suffix == null ? 0 : suffix.hashCode());
                return result;
        }

        /**
         * Compares this <code>Version</code> object to another one.
         *
         * <p>
         * A version is considered to be <b>less than </b> another version if its major component is less
         * than the other version's major component, or the major components are equal and its minor
         * component is less than the other version's minor component, or the major and minor components
         * are equal and its release component is less than the other version's release component.
         * The suffix is not relevant for the natural ordering of Versions, though for equality.
         * <p>
         * Note: Given two version <code>v1,v2</code> and <code>v1.compareTo(Version v2) = 0</code>,
         * this does not imply that <code>v1</code> and <code>v2</code> are equal according to equals!
         * </p>
         *
         * <p>
         * A version is considered to be <b>equal to</b> another version if the
         * major, minor and micro components are equal and the qualifier component
         * is equal (see {@link #equals(Object)}).
         * </p>
         *
         * @param other The <code>Version</code> object to be compared.
         * @return A negative integer, zero, or a positive integer if this object is
         *         less than, equal to, or greater than the specified
         *         <code>Version</code> object.
         */
        @Override
        public int compareTo(Version other) {
                if (this == other)
                        return 0;

                int difference = major - other.major;
                if (difference != 0)
                        return difference;

                difference = minor - other.minor;
                if (difference != 0)
                        return difference;

                difference = release - other.release;
                if (difference != 0)
                        return difference;

                difference = patchLevel - other.patchLevel;
                if (difference != 0)
                        return difference;

                // We currently take only the "SNAPSHOT" suffix into account. Every other
                // suffix is ignored when it comes to comparing.
                if (suffix == null) {
                        if (other.suffix == null)
                                return 0;

                        if (other.suffix.equalsIgnoreCase(SNAPSHOT_SUFFIX))
                                return 1;

                        // TODO Maybe we'll later change this to compare the suffix as well.
                        return 0;
                }

                if (suffix.equalsIgnoreCase(other.suffix))
                        return 0;

                if (suffix.equalsIgnoreCase(SNAPSHOT_SUFFIX))
                        return -1;

                // TODO Maybe we'll later change this to compare the suffix as well.
                return 0;
        }

}