package org.junit.runner;

import java.lang.annotation.Annotation;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collection;

/**

 * <p>A <code>Description</code> describes a test which is to be run or has been run. <code>Descriptions</code> 

 * can be atomic (a single test) or compound (containing children tests). <code>Descriptions</code> are used

 * to provide feedback about the tests that are about to run (for example, the tree view

 * visible in many IDEs) or tests that have been run (for example, the failures view).</p>

 * 

 * <p><code>Descriptions</code> are implemented as a single class rather than a Composite because

 * they are entirely informational. They contain no logic aside from counting their tests.</p>

 * 

 * <p>In the past, we used the raw {@link junit.framework.TestCase}s and {@link junit.framework.TestSuite}s

 * to display the tree of tests. This was no longer viable in JUnit 4 because atomic tests no longer have 

 * a superclass below {@link Object}. We needed a way to pass a class and name together. Description 

 * emerged from this.</p>

 * 

 * @see org.junit.runner.Request

 * @see org.junit.runner.Runner

 */

public class Description {

	/**

	 * Create a <code>Description</code> named <code>name</code>.

	 * Generally, you will add children to this <code>Description</code>.

	 * @param name the name of the <code>Description</code> 

	 * @param annotations 

	 * @return a <code>Description</code> named <code>name</code>

	 */

	public static Description createSuiteDescription(String name, Annotation... annotations) {

		return new Description(name, annotations);

	}

	/**

	 * Create a <code>Description</code> of a single test named <code>name</code> in the class <code>clazz</code>.

	 * Generally, this will be a leaf <code>Description</code>.

	 * @param clazz the class of the test

	 * @param name the name of the test (a method name for test annotated with {@link org.junit.Test})

	 * @param annotations meta-data about the test, for downstream interpreters

	 * @return a <code>Description</code> named <code>name</code>

	 */

	public static Description createTestDescription(Class<?> clazz, String name, Annotation... annotations) {

		return new Description(String.format("%s(%s)", name, clazz.getName()), annotations);

	}

	/**

	 * Create a <code>Description</code> of a single test named <code>name</code> in the class <code>clazz</code>.

	 * Generally, this will be a leaf <code>Description</code>.  

	 * (This remains for binary compatibility with clients of JUnit 4.3)

	 * @param clazz the class of the test

	 * @param name the name of the test (a method name for test annotated with {@link org.junit.Test})

	 * @return a <code>Description</code> named <code>name</code>

	 */

	public static Description createTestDescription(Class<?> clazz, String name) {

		return createTestDescription(clazz, name, new Annotation[0]);

	}

	/**

	 * Create a <code>Description</code> named after <code>testClass</code>

	 * @param testClass A {@link Class} containing tests 

	 * @return a <code>Description</code> of <code>testClass</code>

	 */

	public static Description createSuiteDescription(Class<?> testClass) {

		return new Description(testClass.getName(), testClass.getAnnotations());

	}

	/**

	 * Describes a Runner which runs no tests

	 */

	public static final Description EMPTY= new Description("No Tests");

	/**

	 * Describes a step in the test-running mechanism that goes so wrong no

	 * other description can be used (for example, an exception thrown from a Runner's

	 * constructor

	 */

	public static final Description TEST_MECHANISM= new Description("Test mechanism");

	private final ArrayList<Description> fChildren= new ArrayList<Description>();

	private final String fDisplayName;

	private final Annotation[] fAnnotations;

	private Description(final String displayName, Annotation... annotations) {

		fDisplayName= displayName;

		fAnnotations= annotations;

	}

	/**

	 * @return a user-understandable label

	 */

	public String getDisplayName() {

		return fDisplayName;

	}

	/**

	 * Add <code>Description</code> as a child of the receiver.

	 * @param description the soon-to-be child.

	 */

	public void addChild(Description description) {

		getChildren().add(description);

	}

	/**

	 * @return the receiver's children, if any

	 */

	public ArrayList<Description> getChildren() {

		return fChildren;

	}

	/**

	 * @return <code>true</code> if the receiver is a suite

	 */

	public boolean isSuite() {

		return !isTest();

	}

	/**

	 * @return <code>true</code> if the receiver is an atomic test

	 */

	public boolean isTest() {

		return getChildren().isEmpty();

	}

	/**

	 * @return the total number of atomic tests in the receiver

	 */

	public int testCount() {

		if (isTest())

			return 1;

		int result= 0;

		for (Description child : getChildren())

			result+= child.testCount();

		return result;

	}

	@Override

	public int hashCode() {

		return getDisplayName().hashCode();

	}

	@Override

	public boolean equals(Object obj) {

		if (!(obj instanceof Description))

			return false;

		Description d = (Description) obj;

		return getDisplayName().equals(d.getDisplayName())

				&& getChildren().equals(d.getChildren());

	}

	@Override

	public String toString() {

		return getDisplayName();

	}

	/**

	 * @return true if this is a description of a Runner that runs no tests

	 */

	public boolean isEmpty() {

		return equals(EMPTY);

	}

	/**

	 * @return a copy of this description, with no children (on the assumption that some of the

	 * children will be added back)

	 */

	public Description childlessCopy() {

		return new Description(fDisplayName, fAnnotations);

	}

	/**

	 * @return the annotation of type annotationType that is attached to this description node, 

	 * or null if none exists

	 */

	public <T extends Annotation> T getAnnotation(Class<T> annotationType) {

		for (Annotation each : fAnnotations)

			if (each.annotationType().equals(annotationType))

				return annotationType.cast(each);

		return null;

	}

	/**

	 * @return all of the annotations attached to this description node

	 */

	public Collection<Annotation> getAnnotations() {

		return Arrays.asList(fAnnotations);

	}

}