/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.lang3;

import java.io.Serializable;
import java.util.Comparator;

An immutable range of objects from a minimum to maximum point inclusive.
The objects need to either be implementations of Comparable or you need to supply a Comparator. 
#ThreadSafe# if the objects and comparator are thread-safe
Since:
3.0/**
 * <p>An immutable range of objects from a minimum to maximum point inclusive.</p>
 *
 * <p>The objects need to either be implementations of {@code Comparable}
 * or you need to supply a {@code Comparator}. </p>
 *
 * <p>#ThreadSafe# if the objects and comparator are thread-safe</p>
 *
 * @since 3.0
 */
public final class Range<T> implements Serializable {

    
Serialization version.
See Also:
Serializable/**
     * Serialization version.
     * @see java.io.Serializable
     */
    private static final long serialVersionUID = 1L;

    
The ordering scheme used in this range.
/**
     * The ordering scheme used in this range.
     */
    private final Comparator<T> comparator;
    
The minimum value in this range (inclusive).
/**
     * The minimum value in this range (inclusive).
     */
    private final T minimum;
    
The maximum value in this range (inclusive).
/**
     * The maximum value in this range (inclusive).
     */
    private final T maximum;
    
Cached output hashCode (class is immutable).
/**
     * Cached output hashCode (class is immutable).
     */
    private transient int hashCode;
    
Cached output toString (class is immutable).
/**
     * Cached output toString (class is immutable).
     */
    private transient String toString;

    
Obtains a range using the specified element as both the minimum
and maximum in this range.
The range uses the natural ordering of the elements to determine where
values lie in the range.
Params:
element –  the value to use for this range, not null
Type parameters:
<T> – the type of the elements in this range
Throws:
IllegalArgumentException – if the element is null
ClassCastException – if the element is not Comparable
Returns:
the range object, not null/**
     * <p>Obtains a range using the specified element as both the minimum
     * and maximum in this range.</p>
     *
     * <p>The range uses the natural ordering of the elements to determine where
     * values lie in the range.</p>
     *
     * @param <T> the type of the elements in this range
     * @param element  the value to use for this range, not null
     * @return the range object, not null
     * @throws IllegalArgumentException if the element is null
     * @throws ClassCastException if the element is not {@code Comparable}
     */
    public static <T extends Comparable<T>> Range<T> is(final T element) {
        return between(element, element, null);
    }

    
Obtains a range using the specified element as both the minimum
and maximum in this range.
The range uses the specified Comparator to determine where values lie in the range.
Params:
element –  the value to use for this range, must not be null
comparator –  the comparator to be used, null for natural ordering
Type parameters:
<T> – the type of the elements in this range
Throws:
IllegalArgumentException – if the element is null
ClassCastException – if using natural ordering and the elements are not Comparable
Returns:
the range object, not null/**
     * <p>Obtains a range using the specified element as both the minimum
     * and maximum in this range.</p>
     *
     * <p>The range uses the specified {@code Comparator} to determine where
     * values lie in the range.</p>
     *
     * @param <T> the type of the elements in this range
     * @param element  the value to use for this range, must not be {@code null}
     * @param comparator  the comparator to be used, null for natural ordering
     * @return the range object, not null
     * @throws IllegalArgumentException if the element is null
     * @throws ClassCastException if using natural ordering and the elements are not {@code Comparable}
     */
    public static <T> Range<T> is(final T element, final Comparator<T> comparator) {
        return between(element, element, comparator);
    }

    
Obtains a range with the specified minimum and maximum values (both inclusive).
The range uses the natural ordering of the elements to determine where
values lie in the range.
The arguments may be passed in the order (min,max) or (max,min).
The getMinimum and getMaximum methods will return the correct values.
Params:
fromInclusive –  the first value that defines the edge of the range, inclusive
toInclusive –  the second value that defines the edge of the range, inclusive
Type parameters:
<T> – the type of the elements in this range
Throws:
IllegalArgumentException – if either element is null
ClassCastException – if the elements are not Comparable
Returns:
the range object, not null/**
     * <p>Obtains a range with the specified minimum and maximum values (both inclusive).</p>
     *
     * <p>The range uses the natural ordering of the elements to determine where
     * values lie in the range.</p>
     *
     * <p>The arguments may be passed in the order (min,max) or (max,min).
     * The getMinimum and getMaximum methods will return the correct values.</p>
     *
     * @param <T> the type of the elements in this range
     * @param fromInclusive  the first value that defines the edge of the range, inclusive
     * @param toInclusive  the second value that defines the edge of the range, inclusive
     * @return the range object, not null
     * @throws IllegalArgumentException if either element is null
     * @throws ClassCastException if the elements are not {@code Comparable}
     */
    public static <T extends Comparable<T>> Range<T> between(final T fromInclusive, final T toInclusive) {
        return between(fromInclusive, toInclusive, null);
    }

    
Obtains a range with the specified minimum and maximum values (both inclusive).
The range uses the specified Comparator to determine where values lie in the range.
The arguments may be passed in the order (min,max) or (max,min).
The getMinimum and getMaximum methods will return the correct values.
Params:
fromInclusive –  the first value that defines the edge of the range, inclusive
toInclusive –  the second value that defines the edge of the range, inclusive
comparator –  the comparator to be used, null for natural ordering
Type parameters:
<T> – the type of the elements in this range
Throws:
IllegalArgumentException – if either element is null
ClassCastException – if using natural ordering and the elements are not Comparable
Returns:
the range object, not null/**
     * <p>Obtains a range with the specified minimum and maximum values (both inclusive).</p>
     *
     * <p>The range uses the specified {@code Comparator} to determine where
     * values lie in the range.</p>
     *
     * <p>The arguments may be passed in the order (min,max) or (max,min).
     * The getMinimum and getMaximum methods will return the correct values.</p>
     *
     * @param <T> the type of the elements in this range
     * @param fromInclusive  the first value that defines the edge of the range, inclusive
     * @param toInclusive  the second value that defines the edge of the range, inclusive
     * @param comparator  the comparator to be used, null for natural ordering
     * @return the range object, not null
     * @throws IllegalArgumentException if either element is null
     * @throws ClassCastException if using natural ordering and the elements are not {@code Comparable}
     */
    public static <T> Range<T> between(final T fromInclusive, final T toInclusive, final Comparator<T> comparator) {
        return new Range<>(fromInclusive, toInclusive, comparator);
    }

    
Creates an instance.
Params:
element1 –  the first element, not null
element2 –  the second element, not null
comp –  the comparator to be used, null for natural ordering/**
     * Creates an instance.
     *
     * @param element1  the first element, not null
     * @param element2  the second element, not null
     * @param comp  the comparator to be used, null for natural ordering
     */
    @SuppressWarnings("unchecked")
    private Range(final T element1, final T element2, final Comparator<T> comp) {
        if (element1 == null || element2 == null) {
            throw new IllegalArgumentException("Elements in a range must not be null: element1=" +
                                               element1 + ", element2=" + element2);
        }
        if (comp == null) {
            this.comparator = ComparableComparator.INSTANCE;
        } else {
            this.comparator = comp;
        }
        if (this.comparator.compare(element1, element2) < 1) {
            this.minimum = element1;
            this.maximum = element2;
        } else {
            this.minimum = element2;
            this.maximum = element1;
        }
    }

    // Accessors
    //--------------------------------------------------------------------

    
Gets the minimum value in this range.
Returns:
the minimum value in this range, not null/**
     * <p>Gets the minimum value in this range.</p>
     *
     * @return the minimum value in this range, not null
     */
    public T getMinimum() {
        return minimum;
    }

    
Gets the maximum value in this range.
Returns:
the maximum value in this range, not null/**
     * <p>Gets the maximum value in this range.</p>
     *
     * @return the maximum value in this range, not null
     */
    public T getMaximum() {
        return maximum;
    }

    
Gets the comparator being used to determine if objects are within the range.
Natural ordering uses an internal comparator implementation, thus this method never returns null. See isNaturalOrdering().
Returns:
the comparator being used, not null/**
     * <p>Gets the comparator being used to determine if objects are within the range.</p>
     *
     * <p>Natural ordering uses an internal comparator implementation, thus this
     * method never returns null. See {@link #isNaturalOrdering()}.</p>
     *
     * @return the comparator being used, not null
     */
    public Comparator<T> getComparator() {
        return comparator;
    }

    
Whether or not the Range is using the natural ordering of the elements.
Natural ordering uses an internal comparator implementation, thus this
method is the only way to check if a null comparator was specified.
Returns:
true if using natural ordering/**
     * <p>Whether or not the Range is using the natural ordering of the elements.</p>
     *
     * <p>Natural ordering uses an internal comparator implementation, thus this
     * method is the only way to check if a null comparator was specified.</p>
     *
     * @return true if using natural ordering
     */
    public boolean isNaturalOrdering() {
        return comparator == ComparableComparator.INSTANCE;
    }

    // Element tests
    //--------------------------------------------------------------------

    
Checks whether the specified element occurs within this range.
Params:
element –  the element to check for, null returns false
Returns:
true if the specified element occurs within this range/**
     * <p>Checks whether the specified element occurs within this range.</p>
     *
     * @param element  the element to check for, null returns false
     * @return true if the specified element occurs within this range
     */
    public boolean contains(final T element) {
        if (element == null) {
            return false;
        }
        return comparator.compare(element, minimum) > -1 && comparator.compare(element, maximum) < 1;
    }

    
Checks whether this range is after the specified element.
Params:
element –  the element to check for, null returns false
Returns:
true if this range is entirely after the specified element/**
     * <p>Checks whether this range is after the specified element.</p>
     *
     * @param element  the element to check for, null returns false
     * @return true if this range is entirely after the specified element
     */
    public boolean isAfter(final T element) {
        if (element == null) {
            return false;
        }
        return comparator.compare(element, minimum) < 0;
    }

    
Checks whether this range starts with the specified element.
Params:
element –  the element to check for, null returns false
Returns:
true if the specified element occurs within this range/**
     * <p>Checks whether this range starts with the specified element.</p>
     *
     * @param element  the element to check for, null returns false
     * @return true if the specified element occurs within this range
     */
    public boolean isStartedBy(final T element) {
        if (element == null) {
            return false;
        }
        return comparator.compare(element, minimum) == 0;
    }

    
Checks whether this range ends with the specified element.
Params:
element –  the element to check for, null returns false
Returns:
true if the specified element occurs within this range/**
     * <p>Checks whether this range ends with the specified element.</p>
     *
     * @param element  the element to check for, null returns false
     * @return true if the specified element occurs within this range
     */
    public boolean isEndedBy(final T element) {
        if (element == null) {
            return false;
        }
        return comparator.compare(element, maximum) == 0;
    }

    
Checks whether this range is before the specified element.
Params:
element –  the element to check for, null returns false
Returns:
true if this range is entirely before the specified element/**
     * <p>Checks whether this range is before the specified element.</p>
     *
     * @param element  the element to check for, null returns false
     * @return true if this range is entirely before the specified element
     */
    public boolean isBefore(final T element) {
        if (element == null) {
            return false;
        }
        return comparator.compare(element, maximum) > 0;
    }

    
Checks where the specified element occurs relative to this range.
The API is reminiscent of the Comparable interface returning -1 if the element is before the range, 0 if contained within the range and 1 if the element is after the range. 
Params:
element –  the element to check for, not null
Returns:
-1, 0 or +1 depending on the element's location relative to the range/**
     * <p>Checks where the specified element occurs relative to this range.</p>
     *
     * <p>The API is reminiscent of the Comparable interface returning {@code -1} if
     * the element is before the range, {@code 0} if contained within the range and
     * {@code 1} if the element is after the range. </p>
     *
     * @param element  the element to check for, not null
     * @return -1, 0 or +1 depending on the element's location relative to the range
     */
    public int elementCompareTo(final T element) {
        // Comparable API says throw NPE on null
        Validate.notNull(element, "Element is null");
        if (isAfter(element)) {
            return -1;
        } else if (isBefore(element)) {
            return 1;
        } else {
            return 0;
        }
    }

    // Range tests
    //--------------------------------------------------------------------

    
Checks whether this range contains all the elements of the specified range.
This method may fail if the ranges have two different comparators or element types.
Params:
otherRange –  the range to check, null returns false
Throws:
RuntimeException – if ranges cannot be compared
Returns:
true if this range contains the specified range/**
     * <p>Checks whether this range contains all the elements of the specified range.</p>
     *
     * <p>This method may fail if the ranges have two different comparators or element types.</p>
     *
     * @param otherRange  the range to check, null returns false
     * @return true if this range contains the specified range
     * @throws RuntimeException if ranges cannot be compared
     */
    public boolean containsRange(final Range<T> otherRange) {
        if (otherRange == null) {
            return false;
        }
        return contains(otherRange.minimum)
            && contains(otherRange.maximum);
    }

    
Checks whether this range is completely after the specified range.
This method may fail if the ranges have two different comparators or element types.
Params:
otherRange –  the range to check, null returns false
Throws:
RuntimeException – if ranges cannot be compared
Returns:
true if this range is completely after the specified range/**
     * <p>Checks whether this range is completely after the specified range.</p>
     *
     * <p>This method may fail if the ranges have two different comparators or element types.</p>
     *
     * @param otherRange  the range to check, null returns false
     * @return true if this range is completely after the specified range
     * @throws RuntimeException if ranges cannot be compared
     */
    public boolean isAfterRange(final Range<T> otherRange) {
        if (otherRange == null) {
            return false;
        }
        return isAfter(otherRange.maximum);
    }

    
Checks whether this range is overlapped by the specified range.
Two ranges overlap if there is at least one element in common.
This method may fail if the ranges have two different comparators or element types.
Params:
otherRange –  the range to test, null returns false
Throws:
RuntimeException – if ranges cannot be compared
Returns:
true if the specified range overlaps with this range; otherwise, false/**
     * <p>Checks whether this range is overlapped by the specified range.</p>
     *
     * <p>Two ranges overlap if there is at least one element in common.</p>
     *
     * <p>This method may fail if the ranges have two different comparators or element types.</p>
     *
     * @param otherRange  the range to test, null returns false
     * @return true if the specified range overlaps with this
     *  range; otherwise, {@code false}
     * @throws RuntimeException if ranges cannot be compared
     */
    public boolean isOverlappedBy(final Range<T> otherRange) {
        if (otherRange == null) {
            return false;
        }
        return otherRange.contains(minimum)
            || otherRange.contains(maximum)
            || contains(otherRange.minimum);
    }

    
Checks whether this range is completely before the specified range.
This method may fail if the ranges have two different comparators or element types.
Params:
otherRange –  the range to check, null returns false
Throws:
RuntimeException – if ranges cannot be compared
Returns:
true if this range is completely before the specified range/**
     * <p>Checks whether this range is completely before the specified range.</p>
     *
     * <p>This method may fail if the ranges have two different comparators or element types.</p>
     *
     * @param otherRange  the range to check, null returns false
     * @return true if this range is completely before the specified range
     * @throws RuntimeException if ranges cannot be compared
     */
    public boolean isBeforeRange(final Range<T> otherRange) {
        if (otherRange == null) {
            return false;
        }
        return isBefore(otherRange.minimum);
    }

    
Calculate the intersection of this and an overlapping Range. 
Params:
other – overlapping Range
Throws:
IllegalArgumentException – if other does not overlap this
Returns:
range representing the intersection of this and other (this if equal)
Since:
3.0.1/**
     * Calculate the intersection of {@code this} and an overlapping Range.
     * @param other overlapping Range
     * @return range representing the intersection of {@code this} and {@code other} ({@code this} if equal)
     * @throws IllegalArgumentException if {@code other} does not overlap {@code this}
     * @since 3.0.1
     */
    public Range<T> intersectionWith(final Range<T> other) {
        if (!this.isOverlappedBy(other)) {
            throw new IllegalArgumentException(String.format(
                "Cannot calculate intersection with non-overlapping range %s", other));
        }
        if (this.equals(other)) {
            return this;
        }
        final T min = getComparator().compare(minimum, other.minimum) < 0 ? other.minimum : minimum;
        final T max = getComparator().compare(maximum, other.maximum) < 0 ? maximum : other.maximum;
        return between(min, max, getComparator());
    }

    // Basics
    //--------------------------------------------------------------------

    
Compares this range to another object to test if they are equal.
.
To be equal, the minimum and maximum values must be equal, which
ignores any differences in the comparator.
Params:
obj – the reference object with which to compare
Returns:
true if this object is equal/**
     * <p>Compares this range to another object to test if they are equal.</p>.
     *
     * <p>To be equal, the minimum and maximum values must be equal, which
     * ignores any differences in the comparator.</p>
     *
     * @param obj the reference object with which to compare
     * @return true if this object is equal
     */
    @Override
    public boolean equals(final Object obj) {
        if (obj == this) {
            return true;
        } else if (obj == null || obj.getClass() != getClass()) {
            return false;
        } else {
            @SuppressWarnings("unchecked") // OK because we checked the class above
            final
            Range<T> range = (Range<T>) obj;
            return minimum.equals(range.minimum) &&
                   maximum.equals(range.maximum);
        }
    }

    
Gets a suitable hash code for the range.
Returns:
a hash code value for this object/**
     * <p>Gets a suitable hash code for the range.</p>
     *
     * @return a hash code value for this object
     */
    @Override
    public int hashCode() {
        int result = hashCode;
        if (hashCode == 0) {
            result = 17;
            result = 37 * result + getClass().hashCode();
            result = 37 * result + minimum.hashCode();
            result = 37 * result + maximum.hashCode();
            hashCode = result;
        }
        return result;
    }

    
Gets the range as a String.
The format of the String is '[min..max]'.
Returns:
the String representation of this range/**
     * <p>Gets the range as a {@code String}.</p>
     *
     * <p>The format of the String is '[<i>min</i>..<i>max</i>]'.</p>
     *
     * @return the {@code String} representation of this range
     */
    @Override
    public String toString() {
        if (toString == null) {
            toString = "[" + minimum + ".." + maximum + "]";
        }
        return toString;
    }

    
Formats the receiver using the given format.
This uses Formattable to perform the formatting. Three variables may be used to embed the minimum, maximum and comparator. Use %1$s for the minimum element, %2$s for the maximum element and %3$s for the comparator. The default format used by toString() is [%1$s..%2$s].
Params:
format –  the format string, optionally containing %1$s, %2$s and %3$s, not null
Returns:
the formatted string, not null/**
     * <p>Formats the receiver using the given format.</p>
     *
     * <p>This uses {@link java.util.Formattable} to perform the formatting. Three variables may
     * be used to embed the minimum, maximum and comparator.
     * Use {@code %1$s} for the minimum element, {@code %2$s} for the maximum element
     * and {@code %3$s} for the comparator.
     * The default format used by {@code toString()} is {@code [%1$s..%2$s]}.</p>
     *
     * @param format  the format string, optionally containing {@code %1$s}, {@code %2$s} and  {@code %3$s}, not null
     * @return the formatted string, not null
     */
    public String toString(final String format) {
        return String.format(format, minimum, maximum, comparator);
    }

    //-----------------------------------------------------------------------
    @SuppressWarnings({"rawtypes", "unchecked"})
    private enum ComparableComparator implements Comparator {
        INSTANCE;
        
Comparable based compare implementation.
Params:
obj1 – left hand side of comparison
obj2 – right hand side of comparison
Returns:
negative, 0, positive comparison value/**
         * Comparable based compare implementation.
         *
         * @param obj1 left hand side of comparison
         * @param obj2 right hand side of comparison
         * @return negative, 0, positive comparison value
         */
        @Override
        public int compare(final Object obj1, final Object obj2) {
            return ((Comparable) obj1).compareTo(obj2);
        }
    }

}