/*  Copyright (c) 2000-2006 hamcrest.org
 */
package org.hamcrest.core;

import org.hamcrest.BaseMatcher;
import org.hamcrest.Description;
import org.hamcrest.Factory;
import org.hamcrest.Matcher;

import java.lang.reflect.Array;


Is the value equal to another value, as tested by the Object.equals invokedMethod? /**
 * Is the value equal to another value, as tested by the
 * {@link java.lang.Object#equals} invokedMethod?
 */
public class IsEqual<T> extends BaseMatcher<T> {
    private final Object expectedValue;

    public IsEqual(T equalArg) {
        expectedValue = equalArg;
    }

    @Override
    public boolean matches(Object actualValue) {
        return areEqual(actualValue, expectedValue);
    }

    @Override
    public void describeTo(Description description) {
        description.appendValue(expectedValue);
    }

    private static boolean areEqual(Object actual, Object expected) {
        if (actual == null) {
            return expected == null;
        }
        
        if (expected != null && isArray(actual)) {
            return isArray(expected) && areArraysEqual(actual, expected);
        }
        
        return actual.equals(expected);
    }

    private static boolean areArraysEqual(Object actualArray, Object expectedArray) {
        return areArrayLengthsEqual(actualArray, expectedArray) && areArrayElementsEqual(actualArray, expectedArray);
    }

    private static boolean areArrayLengthsEqual(Object actualArray, Object expectedArray) {
        return Array.getLength(actualArray) == Array.getLength(expectedArray);
    }

    private static boolean areArrayElementsEqual(Object actualArray, Object expectedArray) {
        for (int i = 0; i < Array.getLength(actualArray); i++) {
            if (!areEqual(Array.get(actualArray, i), Array.get(expectedArray, i))) {
                return false;
            }
        }
        return true;
    }

    private static boolean isArray(Object o) {
        return o.getClass().isArray();
    }

    
Creates a matcher that matches when the examined object is logically equal to the specified
operand, as determined by calling the Object.equals method on the examined object.
If the specified operand is null then the created matcher will only match if
the examined object's equals method returns true when passed a
null (which would be a violation of the equals contract), unless the
examined object itself is null, in which case the matcher will return a positive
match.
The created matcher provides a special behaviour when examining Arrays, whereby
it will match if both the operand and the examined object are arrays of the same length and
contain items that are equal to each other (according to the above rules) in the same
indexes.
 

For example:
assertThat("foo", equalTo("foo"));
assertThat(new String[] {"foo", "bar"}, equalTo(new String[] {"foo", "bar"}));

/**
     * Creates a matcher that matches when the examined object is logically equal to the specified
     * <code>operand</code>, as determined by calling the {@link java.lang.Object#equals} method on
     * the <b>examined</b> object.
     * 
     * <p>If the specified operand is <code>null</code> then the created matcher will only match if
     * the examined object's <code>equals</code> method returns <code>true</code> when passed a
     * <code>null</code> (which would be a violation of the <code>equals</code> contract), unless the
     * examined object itself is <code>null</code>, in which case the matcher will return a positive
     * match.</p>
     * 
     * <p>The created matcher provides a special behaviour when examining <code>Array</code>s, whereby
     * it will match if both the operand and the examined object are arrays of the same length and
     * contain items that are equal to each other (according to the above rules) <b>in the same
     * indexes</b>.</p> 
     * <p/>
     * For example:
     * <pre>
     * assertThat("foo", equalTo("foo"));
     * assertThat(new String[] {"foo", "bar"}, equalTo(new String[] {"foo", "bar"}));
     * </pre>
     * 
     */
    @Factory
    public static <T> Matcher<T> equalTo(T operand) {
        return new IsEqual<T>(operand);
    }
}