/*
 * Copyright 2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.gradle.api.internal.tasks.testing.junit;

import org.gradle.api.GradleException;
import org.gradle.api.InvalidUserDataException;
import org.gradle.api.Transformer;
import org.gradle.api.internal.tasks.testing.filter.TestSelectionMatcher;
import org.gradle.internal.concurrent.ThreadSafe;
import org.gradle.util.CollectionUtils;
import org.junit.runner.Description;
import org.junit.runner.Request;
import org.junit.runner.Runner;
import org.junit.runner.manipulation.Filter;
import org.junit.runner.manipulation.Filterable;
import org.junit.runner.manipulation.NoTestsRemainException;
import org.junit.runner.notification.RunListener;
import org.junit.runner.notification.RunNotifier;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

public class JUnitTestClassExecuter {
    private final ClassLoader applicationClassLoader;
    private final RunListener listener;
    private final JUnitSpec options;
    private final TestClassExecutionListener executionListener;

    public JUnitTestClassExecuter(ClassLoader applicationClassLoader, JUnitSpec spec, RunListener listener, TestClassExecutionListener executionListener) {
        assert executionListener instanceof ThreadSafe;
        this.applicationClassLoader = applicationClassLoader;
        this.listener = listener;
        this.options = spec;
        this.executionListener = executionListener;
    }

    public void execute(String testClassName) {
        executionListener.testClassStarted(testClassName);

        Throwable failure = null;
        try {
            runTestClass(testClassName);
        } catch (Throwable throwable) {
            failure = throwable;
        }

        executionListener.testClassFinished(failure);
    }

    private void runTestClass(String testClassName) throws ClassNotFoundException {
        final Class<?> testClass = Class.forName(testClassName, false, applicationClassLoader);
        List<Filter> filters = new ArrayList<Filter>();
        if (options.hasCategoryConfiguration()) {
            verifyJUnitCategorySupport();
            Transformer<Class<?>, String> transformer = new Transformer<Class<?>, String>() {
                public Class<?> transform(final String original) {
                    try {
                        return applicationClassLoader.loadClass(original);
                    } catch (ClassNotFoundException e) {
                        throw new InvalidUserDataException(String.format("Can't load category class [%s].", original), e);
                    }
                }
            };
            filters.add(new CategoryFilter(
                    CollectionUtils.collect(options.getIncludeCategories(), transformer),
                    CollectionUtils.collect(options.getExcludeCategories(), transformer)
            ));
        }

        Request request = Request.aClass(testClass);
        Runner runner = request.getRunner();

        if (!options.getIncludedTests().isEmpty()) {
            TestSelectionMatcher matcher = new TestSelectionMatcher(options.getIncludedTests());

            // For test suites (including suite-like custom Runners), if the test suite class
            // matches the filter, run the entire suite instead of filtering away its contents.
            if (!runner.getDescription().isSuite() || !matcher.matchesTest(testClassName, null)) {
                filters.add(new MethodNameFilter(matcher));
            }
        }

        if (runner instanceof Filterable) {
            Filterable filterable = (Filterable) runner;
            for (Filter filter : filters) {
                try {
                    filterable.filter(filter);
                } catch (NoTestsRemainException e) {
                    // Ignore
                    return;
                }
            }
        } else if (allTestsFiltered(runner, filters)) {
            return;
        }

        RunNotifier notifier = new RunNotifier();
        notifier.addListener(listener);
        runner.run(notifier);
    }

    private void verifyJUnitCategorySupport() {
        try {
            applicationClassLoader.loadClass("org.junit.experimental.categories.Category");
        } catch (ClassNotFoundException e) {
            throw new GradleException("JUnit Categories defined but declared JUnit version does not support Categories.");
        }
    }

    private boolean allTestsFiltered(Runner runner, List<Filter> filters) {
        LinkedList<Description> queue = new LinkedList<Description>();
        queue.add(runner.getDescription());
        while (!queue.isEmpty()) {
            Description description = queue.removeFirst();
            queue.addAll(description.getChildren());
            boolean run = true;
            for (Filter filter : filters) {
                if (!filter.shouldRun(description)) {
                    run = false;
                    break;
                }
            }
            if (run) {
                return false;
            }
        }
        return true;
    }

    private static class MethodNameFilter extends org.junit.runner.manipulation.Filter {

        private final TestSelectionMatcher matcher;

        public MethodNameFilter(TestSelectionMatcher matcher) {
            this.matcher = matcher;
        }

        @Override
        public boolean shouldRun(Description description) {
            if (matcher.matchesTest(JUnitTestEventAdapter.className(description), JUnitTestEventAdapter.methodName(description))) {
                return true;
            }

            for (Description child : description.getChildren()) {
                if (shouldRun(child)) {
                    return true;
                }
            }

            return false;
        }

        @Override
        public String describe() {
            return "Includes matching test methods";
        }
    }
}
