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// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

package jodd.util;

/**
 * Abstract binary search. It is more abstract then {@link BinarySearch}.
 */
public abstract class BinarySearchBase {

    /**
     * Compares element at index position with the target.
     */
    protected abstract int compare(int index);

    // ---------------------------------------------------------------- find

    /**
     * Finds index of given element in inclusive index range. Returns negative
     * value if element is not found.
     */
    public int find(int low, int high) {
        while (low <= high) {
            int mid = (low + high) >>> 1;
            int delta = compare(mid);

            if (delta < 0) {
                low = mid + 1;
            } else if (delta > 0) {
                high = mid - 1;
            } else {
                return mid;
            }
        }
        // not found
        return -(low + 1);
    }

    // ---------------------------------------------------------------- first

    /**
     * Finds very first index of given element in inclusive index range. Returns negative
     * value if element is not found.
     */
    public int findFirst(int low, int high) {

        int ndx = -1;
        while (low <= high) {
            int mid = (low + high) >>> 1;
            int delta = compare(mid);

            if (delta < 0) {
                low = mid + 1;
            } else {
                if (delta == 0) {
                    ndx = mid;
                }
                high = mid - 1;
            }
        }

        if (ndx == -1) {
            return -(low + 1);
        }

        return ndx;
    }

    // ---------------------------------------------------------------- last

    /**
     * Finds very last index of given element in inclusive index range. Returns negative
     * value if element is not found.
     */
    public int findLast(int low, int high) {
        int ndx = -1;
        while (low <= high) {
            int mid = (low + high) >>> 1;
            int delta = compare(mid);

            if (delta > 0) {
                high = mid - 1;
            } else {
                if (delta == 0) {
                    ndx = mid;
                }
                low = mid + 1;
            }
        }

        if (ndx == -1) {
            return -(low + 1);
        }

        return ndx;
    }

}