package org.testng.internal.junit;

import org.testng.AssertJUnit;

import java.lang.reflect.Array;

/**
 * Defines criteria for finding two items "equal enough". Concrete subclasses
 * may demand exact equality, or, for example, equality within a given delta.
 */
public abstract class ComparisonCriteria {
    /**
     * Asserts that two arrays are equal, according to the criteria defined by
     * the concrete subclass. If they are not, an {@link AssertionError} is
     * thrown with the given message. If <code>expecteds</code> and
     * <code>actuals</code> are <code>null</code>, they are considered equal.
     * 
     * @param message
     *            the identifying message for the {@link AssertionError} (
     *            <code>null</code> okay)
     * @param expecteds
     *            Object array or array of arrays (multi-dimensional array) with
     *            expected values.
     * @param actuals
     *            Object array or array of arrays (multi-dimensional array) with
     *            actual values
     */
    public void arrayEquals(String message, Object expecteds, Object actuals)
            throws ArrayComparisonFailure {
        if (expecteds == actuals)
            return;
        String header= message == null ? "" : message + ": ";

        int expectedsLength= assertArraysAreSameLength(expecteds,
                actuals, header);

        for (int i= 0; i < expectedsLength; i++) {
            Object expected= Array.get(expecteds, i);
            Object actual= Array.get(actuals, i);

            if (isArray(expected) && isArray(actual)) {
                try {
                    arrayEquals(message, expected, actual);
                } catch (ArrayComparisonFailure e) {
                    e.addDimension(i);
                    throw e;
                }
            } else
                try {
                    assertElementsEqual(expected, actual);
                } catch (AssertionError e) {
                    throw new ArrayComparisonFailure(header, e, i);
                }
        }
    }

    private boolean isArray(Object expected) {
        return expected != null && expected.getClass().isArray();
    }

    private int assertArraysAreSameLength(Object expecteds,
            Object actuals, String header) {
        if (expecteds == null)
            AssertJUnit.fail(header + "expected array was null");
        if (actuals == null)
            AssertJUnit.fail(header + "actual array was null");
        int actualsLength= Array.getLength(actuals);
        int expectedsLength= Array.getLength(expecteds);
        if (actualsLength != expectedsLength)
            AssertJUnit.fail(header + "array lengths differed, expected.length="
                    + expectedsLength + " actual.length=" + actualsLength);
        return expectedsLength;
    }

    protected abstract void assertElementsEqual(Object expected, Object actual);
}
