package org.junit.internal.runners;

import java.lang.annotation.Annotation;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

import java.util.ArrayList;

import java.util.List;

import org.junit.After;

import org.junit.AfterClass;

import org.junit.Before;

import org.junit.BeforeClass;

import org.junit.Test;

public class MethodValidator {

	private final TestIntrospector fIntrospector;

	private final List<Throwable> fErrors= new ArrayList<Throwable>();

	private final Class<?> fTestClass;

	public MethodValidator(Class<?> testClass) {

		fTestClass= testClass;

		fIntrospector= new TestIntrospector(testClass);

	}

	public void validateInstanceMethods() {

		validateTestMethods(After.class, false);

		validateTestMethods(Before.class, false);

		validateTestMethods(Test.class, false);

	}

	public void validateStaticMethods() {

		validateTestMethods(BeforeClass.class, true);

		validateTestMethods(AfterClass.class, true);

	}

	public List<Throwable> validateMethodsForDefaultRunner() {

		validateNoArgConstructor();

		validateStaticMethods();

		validateInstanceMethods();

		return fErrors;

	}

	public void assertValid() throws InitializationError {

		if (!fErrors.isEmpty())

			throw new InitializationError(fErrors);

	}

	public void validateNoArgConstructor() {

		try {

			fTestClass.getConstructor();

		} catch (Exception e) {

			fErrors.add(new Exception("Test class should have public zero-argument constructor", e));

		}

	}

	private void validateTestMethods(Class<? extends Annotation> annotation,

			boolean isStatic) {

		List<Method> methods= fIntrospector.getTestMethods(annotation);

		for (Method each : methods) {

			if (Modifier.isStatic(each.getModifiers()) != isStatic) {

				String state= isStatic ? "should" : "should not";

				fErrors.add(new Exception("Method " + each.getName() + "() "

						+ state + " be static"));

			}

			if (!Modifier.isPublic(each.getDeclaringClass().getModifiers()))

				fErrors.add(new Exception("Class " + each.getDeclaringClass().getName()

						+ " should be public"));

			if (!Modifier.isPublic(each.getModifiers()))

				fErrors.add(new Exception("Method " + each.getName()

						+ " should be public"));

			if (each.getReturnType() != Void.TYPE)

				fErrors.add(new Exception("Method " + each.getName()

						+ " should be void"));

			if (each.getParameterTypes().length != 0)

				fErrors.add(new Exception("Method " + each.getName()

						+ " should have no parameters"));

		}

	}

}