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package jnlp.sample.util;

import java.util.ArrayList;
import java.util.Arrays;

/**
 *   VersionID contains a JNLP version ID.
 *
 *  The VersionID also contains a prefix indicator that can
 *  be used when stored with a VersionString
 *
 */
public class VersionID implements Comparable {
    private String[] _tuple;   // Array of Integer or String objects
    private boolean  _usePrefixMatch;   // star (*) prefix
    private boolean  _useGreaterThan;  // plus (+) greather-than
    private boolean  _isCompound;       // and (&) operator
    private VersionID _rest;            // remaining part after the &

    /** Creates a VersionID object */
    public VersionID(String str) {
        _usePrefixMatch  = false;
        _useGreaterThan = false;
        _isCompound = false;
        if (str == null && str.length() == 0) {
            _tuple = new String[0];
            return;
        }

        // Check for compound
        int amp = str.indexOf("&");
        if (amp >= 0) {
            _isCompound = true;
            VersionID firstPart = new VersionID(str.substring(0, amp));
            _rest = new VersionID(str.substring(amp+1));
            _tuple = firstPart._tuple;
            _usePrefixMatch = firstPart._usePrefixMatch;
            _useGreaterThan = firstPart._useGreaterThan;
        } else {
            // Check for postfix
            if (str.endsWith("+")) {
                _useGreaterThan = true;
                str = str.substring(0, str.length() - 1);
            } else if (str.endsWith("*")) {
                _usePrefixMatch = true;
                str = str.substring(0, str.length() - 1);
            }

            ArrayList list = new ArrayList();
            int start = 0;
            for(int i = 0; i < str.length(); i++) {
                // Split at each separator character
                if (".-_".indexOf(str.charAt(i)) != -1) {
                    if (start < i) {
                        String value = str.substring(start, i);
                        list.add(value);
                    }
                    start = i + 1;
                }
            }
            if (start < str.length()) {
                list.add(str.substring(start, str.length()));
            }
            _tuple = new String[list.size()];
            _tuple = (String[])list.toArray(_tuple);
        }
    }

    /** Returns true if no flags are set */
    public boolean isSimpleVersion() {
        return !_useGreaterThan && !_usePrefixMatch && !_isCompound;
    }

    /** Match 'this' versionID against vid.
     *  The _usePrefixMatch/_useGreaterThan flag is used to determine if a
     *  prefix match of an exact match should be performed
     *  if _isCompound, must match _rest also.
     */
    public boolean match(VersionID vid) {
        if (_isCompound) {
            if (!_rest.match(vid)) {
                return false;
            }
        }
        return (_usePrefixMatch) ? this.isPrefixMatch(vid) :
            (_useGreaterThan) ? vid.isGreaterThanOrEqual(this) :
                matchTuple(vid);
    }

    /** Compares if two version IDs are equal */
    public boolean equals(Object o) {
        if (matchTuple(o)) {
             VersionID ov = (VersionID) o;
             if (_rest == null || _rest.equals(ov._rest)) {
                if ((_useGreaterThan == ov._useGreaterThan) &&
                    (_usePrefixMatch == ov._usePrefixMatch)) {
                        return true;
                }
            }
        }
        return false;
    }

    /** Compares if two version IDs are equal */
    private boolean matchTuple(Object o) {
        // Check for null and type
        if (o == null || !(o instanceof VersionID)) return false;
        VersionID vid = (VersionID)o;

        // Normalize arrays
        String[] t1 = normalize(_tuple, vid._tuple.length);
        String[] t2 = normalize(vid._tuple, _tuple.length);

        // Check contents
        for(int i = 0; i < t1.length; i++) {
            Object o1 = getValueAsObject(t1[i]);
            Object o2 = getValueAsObject(t2[i]);
            if (!o1.equals(o2)) return false;
        }
        return true;
    }

    private Object getValueAsObject(String value) {
        if (value.length() > 0 && value.charAt(0) != '-') {
            try { return Integer.valueOf(value);
            } catch(NumberFormatException nfe) { /* fall through */ }
        }
        return value;
    }

    public boolean isGreaterThan(VersionID vid) {
        return isGreaterThanOrEqualHelper(vid, false);
    }

    public boolean isGreaterThanOrEqual(VersionID vid) {
        return isGreaterThanOrEqualHelper(vid, true);
    }

    /** Compares if 'this' is greater than vid */
    private boolean isGreaterThanOrEqualHelper(VersionID vid,
        boolean allowEqual) {

        if (_isCompound) {
            if (!_rest.isGreaterThanOrEqualHelper(vid, allowEqual)) {
                return false;
            }
        }
        // Normalize the two strings
        String[] t1 = normalize(_tuple, vid._tuple.length);
        String[] t2 = normalize(vid._tuple, _tuple.length);

        for(int i = 0; i < t1.length; i++) {
            // Compare current element
            Object e1 = getValueAsObject(t1[i]);
            Object e2 = getValueAsObject(t2[i]);
            if (e1.equals(e2)) {
                // So far so good
            } else {
                if (e1 instanceof Integer && e2 instanceof Integer) {
                    return ((Integer)e1).intValue() > ((Integer)e2).intValue();
                } else {
                    String s1 = t1[i].toString();
                    String s2 = t2[i].toString();
                    return s1.compareTo(s2) > 0;
                }

            }
        }
        // If we get here, they are equal
        return allowEqual;
    }

    /** Checks if 'this' is a prefix of vid */
    public boolean isPrefixMatch(VersionID vid) {

        if (_isCompound) {
            if (!_rest.isPrefixMatch(vid)) {
                return false;
            }
        }
        // Make sure that vid is at least as long as the prefix
        String[] t2 = normalize(vid._tuple, _tuple.length);

        for(int i = 0; i < _tuple.length; i++) {
            Object e1 = _tuple[i];
            Object e2 = t2[i];
            if (e1.equals(e2)) {
                // So far so good
            } else {
                // Not a prefix
                return false;
            }
        }
        return true;
    }

    /** Normalize an array to a certain lengh */
    private String[] normalize(String[] list, int minlength) {
        if (list.length < minlength) {
            // Need to do padding
            String[] newlist = new String[minlength];
            System.arraycopy(list, 0, newlist, 0, list.length);
            Arrays.fill(newlist, list.length, newlist.length, "0");
            return newlist;
        } else {
            return list;
        }
    }

    public int compareTo(Object o) {
        if (o == null || !(o instanceof VersionID)) return -1;
        VersionID vid = (VersionID)o;
        return equals(vid) ? 0 : (isGreaterThanOrEqual(vid) ? 1 : -1);
    }
    /** Show it as a string */
    public String toString() {
        StringBuffer sb = new StringBuffer();
        for(int i = 0; i < _tuple.length -1; i++) {
            sb.append(_tuple[i]);
            sb.append('.');
        }
        if (_tuple.length > 0 ) sb.append(_tuple[_tuple.length - 1]);
        if (_usePrefixMatch) sb.append('+');
        return sb.toString();
    }
}
