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/*
 * Copyright (c) 1997, 2023 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.eclipse.angus.mail.imap.protocol;

import java.util.ArrayList;
import java.util.List;

/**
 * This class holds the 'start' and 'end' for a range of messages.
 */
public class MessageSet {

    public int start;
    public int end;

    public MessageSet() {
    }

    public MessageSet(int start, int end) {
        this.start = start;
        this.end = end;
    }

    /**
     * Count the total number of elements in a MessageSet
     *
     * @return how many messages in this MessageSet
     */
    public int size() {
        return end - start + 1;
    }

    /**
     * Convert an array of integers into an array of MessageSets
     *
     * @param    msgs    the messages
     * @return array of MessageSet objects
     */
    public static MessageSet[] createMessageSets(int[] msgs) {
        List v = new ArrayList<>();
        int i, j;

        for (i = 0; i < msgs.length; i++) {
            MessageSet ms = new MessageSet();
            ms.start = msgs[i];

            // Look for contiguous elements
            for (j = i + 1; j < msgs.length; j++) {
                if (msgs[j] != msgs[j - 1] + 1)
                    break;
            }
            ms.end = msgs[j - 1];
            v.add(ms);
            i = j - 1; // i gets incremented @ top of the loop
        }
        return v.toArray(new MessageSet[0]);
    }

    /**
     * Convert an array of MessageSets into an IMAP sequence range
     *
     * @param    msgsets    the MessageSets
     * @return IMAP sequence string
     */
    public static String toString(MessageSet[] msgsets) {
        if (msgsets == null || msgsets.length == 0) // Empty msgset
            return null;

        int i = 0;  // msgset index
        StringBuilder s = new StringBuilder();
        int size = msgsets.length;
        int start, end;

        for (; ; ) {
            start = msgsets[i].start;
            end = msgsets[i].end;

            if (end > start)
                s.append(start).append(':').append(end);
            else // end == start means only one element
                s.append(start);

            i++; // Next MessageSet
            if (i >= size) // No more MessageSets
                break;
            else
                s.append(',');
        }
        return s.toString();
    }


    /*
     * Count the total number of elements in an array of MessageSets
     */
    public static int size(MessageSet[] msgsets) {
        int count = 0;

        if (msgsets == null) // Null msgset
            return 0;

        for (int i = 0; i < msgsets.length; i++)
            count += msgsets[i].size();

        return count;
    }
}