/*
 * Copyright 2002-2018 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
 *
 *      https://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.springframework.test.web;

import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.springframework.util.ObjectUtils;
import org.springframework.web.servlet.ModelAndView;

import static org.springframework.test.util.AssertionErrors.*;

/**
 * A collection of assertions intended to simplify testing scenarios dealing
 * with Spring Web MVC {@link org.springframework.web.servlet.ModelAndView
 * ModelAndView} objects.
 *
 * <p>Intended for use with JUnit 4 and TestNG. All {@code assert*()} methods
 * throw {@link AssertionError}s.
 *
 * @author Sam Brannen
 * @author Alef Arendsen
 * @author Bram Smeets
 * @since 2.5
 * @see org.springframework.web.servlet.ModelAndView
 */
public abstract class ModelAndViewAssert {

        /**
         * Checks whether the model value under the given {@code modelName}
         * exists and checks it type, based on the {@code expectedType}. If the
         * model entry exists and the type matches, the model value is returned.
         * @param mav ModelAndView to test against (never {@code null})
         * @param modelName name of the object to add to the model (never {@code null})
         * @param expectedType expected type of the model value
         * @return the model value
         */
        @SuppressWarnings("unchecked")
        public static <T> T assertAndReturnModelAttributeOfType(ModelAndView mav, String modelName, Class<T> expectedType) {
                assertTrue("ModelAndView is null", mav != null);
                Object obj = mav.getModel().get(modelName);
                assertTrue("Model attribute with name '" + modelName + "' is null", obj != null);
                assertTrue("Model attribute is not of expected type '" + expectedType.getName() + "' but rather of type '" +
                                obj.getClass().getName() + "'", expectedType.isAssignableFrom(obj.getClass()));
                return (T) obj;
        }

        /**
         * Compare each individual entry in a list, without first sorting the lists.
         * @param mav ModelAndView to test against (never {@code null})
         * @param modelName name of the object to add to the model (never {@code null})
         * @param expectedList the expected list
         */
        @SuppressWarnings("rawtypes")
        public static void assertCompareListModelAttribute(ModelAndView mav, String modelName, List expectedList) {
                assertTrue("ModelAndView is null", mav != null);
                List modelList = assertAndReturnModelAttributeOfType(mav, modelName, List.class);
                assertTrue("Size of model list is '" + modelList.size() + "' while size of expected list is '" +
                                expectedList.size() + "'", expectedList.size() == modelList.size());
                assertTrue("List in model under name '" + modelName + "' is not equal to the expected list.",
                                expectedList.equals(modelList));
        }

        /**
         * Assert whether or not a model attribute is available.
         * @param mav ModelAndView to test against (never {@code null})
         * @param modelName name of the object to add to the model (never {@code null})
         */
        public static void assertModelAttributeAvailable(ModelAndView mav, String modelName) {
                assertTrue("ModelAndView is null", mav != null);
                assertTrue("Model attribute with name '" + modelName + "' is not available",
                                mav.getModel().containsKey(modelName));
        }

        /**
         * Compare a given {@code expectedValue} to the value from the model
         * bound under the given {@code modelName}.
         * @param mav ModelAndView to test against (never {@code null})
         * @param modelName name of the object to add to the model (never {@code null})
         * @param expectedValue the model value
         */
        public static void assertModelAttributeValue(ModelAndView mav, String modelName, Object expectedValue) {
                assertTrue("ModelAndView is null", mav != null);
                Object modelValue = assertAndReturnModelAttributeOfType(mav, modelName, Object.class);
                assertTrue("Model value with name '" + modelName + "' is not the same as the expected value which was '" +
                                expectedValue + "'", modelValue.equals(expectedValue));
        }

        /**
         * Inspect the {@code expectedModel} to see if all elements in the
         * model appear and are equal.
         * @param mav ModelAndView to test against (never {@code null})
         * @param expectedModel the expected model
         */
        public static void assertModelAttributeValues(ModelAndView mav, Map<String, Object> expectedModel) {
                assertTrue("ModelAndView is null", mav != null);
                Map<String, Object> model = mav.getModel();

                if (!model.keySet().equals(expectedModel.keySet())) {
                        StringBuilder sb = new StringBuilder("Keyset of expected model does not match.\n");
                        appendNonMatchingSetsErrorMessage(expectedModel.keySet(), model.keySet(), sb);
                        fail(sb.toString());
                }

                StringBuilder sb = new StringBuilder();
                for (String modelName : model.keySet()) {
                        Object assertionValue = expectedModel.get(modelName);
                        Object mavValue = model.get(modelName);
                        if (!assertionValue.equals(mavValue)) {
                                sb.append("Value under name '").append(modelName).append("' differs, should have been '").append(
                                        assertionValue).append("' but was '").append(mavValue).append("'\n");
                        }
                }

                if (sb.length() != 0) {
                        sb.insert(0, "Values of expected model do not match.\n");
                        fail(sb.toString());
                }
        }

        /**
         * Compare each individual entry in a list after having sorted both lists
         * (optionally using a comparator).
         * @param mav ModelAndView to test against (never {@code null})
         * @param modelName name of the object to add to the model (never {@code null})
         * @param expectedList the expected list
         * @param comparator the comparator to use (may be {@code null}). If not
         * specifying the comparator, both lists will be sorted not using any comparator.
         */
        @SuppressWarnings({"unchecked", "rawtypes"})
        public static void assertSortAndCompareListModelAttribute(
                        ModelAndView mav, String modelName, List expectedList, Comparator comparator) {

                assertTrue("ModelAndView is null", mav != null);
                List modelList = assertAndReturnModelAttributeOfType(mav, modelName, List.class);
                assertTrue("Size of model list is '" + modelList.size() + "' while size of expected list is '" +
                                expectedList.size() + "'", expectedList.size() == modelList.size());

                if (comparator != null) {
                        Collections.sort(modelList, comparator);
                        Collections.sort(expectedList, comparator);
                }
                else {
                        Collections.sort(modelList);
                        Collections.sort(expectedList);
                }

                assertTrue("List in model under name '" + modelName + "' is not equal to the expected list.",
                                expectedList.equals(modelList));
        }

        /**
         * Check to see if the view name in the ModelAndView matches the given
         * {@code expectedName}.
         * @param mav ModelAndView to test against (never {@code null})
         * @param expectedName the name of the model value
         */
        public static void assertViewName(ModelAndView mav, String expectedName) {
                assertTrue("ModelAndView is null", mav != null);
                assertTrue("View name is not equal to '" + expectedName + "' but was '" + mav.getViewName() + "'",
                                ObjectUtils.nullSafeEquals(expectedName, mav.getViewName()));
        }


        private static void appendNonMatchingSetsErrorMessage(
                        Set<String> assertionSet, Set<String> incorrectSet, StringBuilder sb) {

                Set<String> tempSet = new HashSet<String>(incorrectSet);
                tempSet.removeAll(assertionSet);

                if (!tempSet.isEmpty()) {
                        sb.append("Set has too many elements:\n");
                        for (Object element : tempSet) {
                                sb.append('-');
                                sb.append(element);
                                sb.append('\n');
                        }
                }

                tempSet = new HashSet<String>(assertionSet);
                tempSet.removeAll(incorrectSet);

                if (!tempSet.isEmpty()) {
                        sb.append("Set is missing elements:\n");
                        for (Object element : tempSet) {
                                sb.append('-');
                                sb.append(element);
                                sb.append('\n');
                        }
                }
        }

}