/*
 * Copyright (c) 2006, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package jnlp.converter.parser;

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<VersionID> {
    private final String[] _tuple;           // Array of Integer or String objects
    private final boolean  _usePrefixMatch;  // star (*) prefix
    private final boolean  _useGreaterThan;  // plus (+) greather-than
    private final boolean  _isCompound;      // and (&) operator
    private final VersionID _rest;           // remaining part after the &

    /**
     * Creates a VersionID object from a given <code>String</code>.
     * @param str version string to parse
     */
    public VersionID(String str) {
        if (str == null || str.length() == 0) {
            _tuple = new String[0];
            _useGreaterThan = false;
            _usePrefixMatch = false;
            _isCompound = false;
            _rest = null;
            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 {
            _isCompound = false;
            _rest = null;
            // Check for postfix
            if (str.endsWith("+")) {
                _useGreaterThan = true;
                _usePrefixMatch = false;
                str = str.substring(0, str.length() - 1);
            } else if (str.endsWith("*")) {
                _useGreaterThan = false;
                _usePrefixMatch = true;
                str = str.substring(0, str.length() - 1);
            } else {
                _useGreaterThan = false;
                _usePrefixMatch = false;
            }

            ArrayList<String> 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 = list.toArray(new String[0]);
        }
    }

    /** @return 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.isPrefixMatchTuple(vid) :
            (_useGreaterThan) ? vid.isGreaterThanOrEqualTuple(this) :
                matchTuple(vid);
    }

    /** Compares if two version IDs are equal */
    @Override
    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;
    }

    /** Computes a hash code for a VersionID */
    @Override
    public int hashCode() {
        boolean first = true;
        int hashCode = 0;
        for (String tuple : _tuple) {
            if (first) {
                first = false;
                hashCode = tuple.hashCode();
            } else {
                hashCode = hashCode ^ tuple.hashCode();
            }
        }
        return hashCode;
    }

    /** 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) {
        if (vid == null) {
            return false;
        }
        return isGreaterThanOrEqualHelper(vid, false, true);
    }

    public boolean isGreaterThanOrEqual(VersionID vid) {
        if (vid == null) {
            return false;
        }
        return isGreaterThanOrEqualHelper(vid, true, true);
    }

    boolean isGreaterThanOrEqualTuple(VersionID vid) {
        return isGreaterThanOrEqualHelper(vid, true, false);
    }

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

        if (useRest && _isCompound) {
            if (!_rest.isGreaterThanOrEqualHelper(vid, allowEqual, true)) {
                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) {
                    // if both can be parsed as ints, compare ints
                    return ((Integer)e1).intValue() > ((Integer)e2).intValue();
                } else {
                    if (e1 instanceof Integer)  {
                        return false; // e1 (numeric) < e2 (non-numeric)
                    } else if (e2 instanceof Integer) {
                        return true; // e1 (non-numeric) > e2 (numeric)
                    }

                    String s1 = t1[i];
                    String s2 = t2[i];

                    return s1.compareTo(s2) > 0;
                }

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

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

        // 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;
        }
    }

    @Override
    public int compareTo(VersionID o) {
        if (o == null || !(o instanceof VersionID)) {
            return -1;
        }
        VersionID vid = o;
        return equals(vid) ? 0 : (isGreaterThanOrEqual(vid) ? 1 : -1);
    }

    /** Show it as a string */
    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        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 (_useGreaterThan) {
            sb.append('+');
        }
        if (_usePrefixMatch) {
            sb.append('*');
        }
        if (_isCompound) {
            sb.append("&");
            sb.append(_rest);
        }
        return sb.toString();
    }
}