/*
 * Copyright (c) 2014, 2021, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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
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 */
package org.openjdk.jmh.util;

import java.util.Collection;
import java.util.SortedMap;
import java.util.TreeMap;

public class IntervalMap<T>  {

    static final class Interval implements Comparable<Interval> {
        final long from, to;

        public Interval(long from, long to) {
            this.from = from;
            this.to = to;
        }

        @Override
        public int compareTo(Interval other) {
            return Long.compare(from, other.from);
        }

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + (int) (from ^ (from >>> 32));
            return result;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            Interval other = (Interval) obj;
            if (from != other.from) {
                return false;
            }
            return true;
        }
    }

    final SortedMap<Interval, T> from;

    public IntervalMap() {
        from = new TreeMap<>();
    }

    public void add(T val, long from, long to) {
        // TODO: Check for intersections
        this.from.put(new Interval(from, to), val);
    }

    public T get(long k) {
        Interval i = new Interval(k, k);
        T key = from.get(i);
        if (key != null) {
            return key;
        }
        SortedMap<Interval, T> head = from.headMap(i);
        if (head.isEmpty()) {
            return null;
        } else {
            Interval last = head.lastKey();
            if (k >= last.from && k < last.to) {
                return from.get(last);  // Interval from..to contains k
            } else {
                return null;
            }
        }
    }

    public Collection<T> allValues() {
        return from.values();
    }

    public void merge(IntervalMap<T> other) {
        from.putAll(other.from);
    }
}
