package org.marketcetera.core.position.impl;
import org.hamcrest.Description;
import org.hamcrest.Factory;
import org.hamcrest.Matcher;
import org.hamcrest.TypeSafeMatcher;

/**
 * Borrowed from Hamcrest 1.2RC3
 */
public class OrderingComparison<T extends Comparable<T>> extends TypeSafeMatcher<T> {
    private final T value;
    private final int minCompare, maxCompare;

    private OrderingComparison(T value, int minCompare, int maxCompare) {
        this.value = value;
        this.minCompare = minCompare;
        this.maxCompare = maxCompare;
    }

    @Override
    public boolean matchesSafely(T other) {
        int compare = Integer.signum(value.compareTo(other));
        return minCompare <= compare && compare <= maxCompare;
    }

    public void describeMismatchSafely(T item, Description mismatchDescription) {
      mismatchDescription.appendValue(value) .appendText(" was ")
                         .appendText(comparison(value.compareTo(item))).appendText(" ").appendValue(item);
    };
    
    public void describeTo(Description description) {
        description.appendText("a value ").appendText(comparison(minCompare));
        if (minCompare != maxCompare) {
            description.appendText(" or ").appendText(comparison(maxCompare));
        }
        description.appendText(" ").appendValue(value);
    }

    private String comparison(int compare) {
        if (compare > 0) {
            return "less than";
        }
        else if (compare == 0) {
            return "equal to ";
        }
        else {
            return "greater than";
        }
    }

    /**
     * Is value = expected?
     */
    @Factory
    public static <T extends Comparable<T>> Matcher<? super T> comparesEqualTo(T value) {
        return new OrderingComparison<T>(value, 0, 0);
    }

    /**
     * Is value > expected?
     */
    @Factory
    public static <T extends Comparable<T>> Matcher<? super T> greaterThan(T value) {
        return new OrderingComparison<T>(value, -1, -1);
    }

    /**
     * Is value >= expected?
     */
    @Factory
    public static <T extends Comparable<T>> Matcher<? super T> greaterThanOrEqualTo(T value) {
        return new OrderingComparison<T>(value, -1, 0);
    }

    /**
     * Is value < expected?
     */
    @Factory
    public static <T extends Comparable<T>> Matcher<? super T> lessThan(T value) {
        return new OrderingComparison<T>(value, 1, 1);
    }

    /**
     * Is value <= expected?
     */
    @Factory
    public static <T extends Comparable<T>> Matcher<? super T> lessThanOrEqualTo(T value) {
        return new OrderingComparison<T>(value, 0, 1);
    }
}