/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.wicket.util.tester;

import static org.junit.jupiter.api.Assertions.assertEquals;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.net.URISyntaxException;
import java.net.URL;

import org.apache.wicket.markup.MarkupParser;
import org.apache.wicket.markup.MarkupStream;
import org.apache.wicket.util.diff.Diff;
import org.apache.wicket.util.diff.DifferentiationFailedException;
import org.apache.wicket.util.io.Streams;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.resource.ResourceStreamNotFoundException;
import org.apache.wicket.util.string.StringList;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This is a utility class. It serves two purposes.
 * <p>
 * First: compare a string output generated by wicket with a file's content (expected result).
 * <p>
 * Second: Create/replace the expected result file with the new content, if a system property has be
 * made available like -Dwicket.replace.expected.results=true
 *
 * @author Juergen Donnerstag
 */
public final class DiffUtil
{
        private static final Logger log = LoggerFactory.getLogger(DiffUtil.class);
        private static final String ENCODING = "UTF-8";

        /**
         * Replace the expected result file with the current output.
         *
         * @param document
         *            How the expected result should look like
         * @param clazz
         *            Used to load the file (relative to clazz package)
         * @param file
         *            The name of the expected result file to be created
         * @throws IOException
         */
        public static void replaceExpectedResultFile(final String document, final Class<?> clazz,
                final String file) throws IOException
        {
                String filename = clazz.getPackage().getName();
                filename = filename.replace('.', '/');
                filename += "/" + file;

                try
                {
                        final URL url = clazz.getClassLoader().getResource(filename);
                        filename = new File(url.toURI()).getAbsolutePath();
                }
                catch (URISyntaxException ex)
                {
                        throw new IOException(ex);
                }

                filename = filename.replaceAll("([/\\\\])target\\1test-classes\\1", "$1src$1test$1java$1");
                PrintWriter out = new PrintWriter(new FileOutputStream(filename));
                out.print(document);
                out.close();
        }

        /**
         * Compare the output generated by Wicket ("document") with the a previously generated file
         * which contains the expected result.
         *
         * @param document
         *            Current output
         * @param file
         *            Expected output
         * @param clazz
         *            Used to load the file (relative to clazz package)
         * @param failWithAssert
         * @return true, if equal
         * @throws IOException
         */
        public static boolean validatePage(String document, final Class<?> clazz,
                final String file, boolean failWithAssert) throws IOException
        {
                Args.notNull(document, "document");

                String filename = clazz.getPackage().getName();
                filename = filename.replace('.', '/');
                filename += "/" + file;

                InputStream in = clazz.getClassLoader().getResourceAsStream(filename);
                if (in == null)
                {
                        throw new IOException("File not found: " + filename);
                }

                String reference = Streams.readString(in, ENCODING);

                // replace all line endings with unix style line ending
                reference = reference.replaceAll("\n\r", "\n");
                reference = reference.replaceAll("\r\n", "\n");

                // replace all line endings with unix style line ending
                document = document.replaceAll("\n\r", "\n");
                document = document.replaceAll("\r\n", "\n");

                boolean equals = compareMarkup(document, reference);
                if (equals == false)
                {
                        // Change the condition to true, if you want to make the new output
                        // the reference output for future tests. That is, it is regarded as
                        // correct. It'll replace the current reference files. Thus change
                        // it only for one test-run.
                        // -Dwicket.replace.expected.results=true
                        if (Boolean.getBoolean("wicket.replace.expected.results"))
                        {
                                in.close();
                                in = null;

                                replaceExpectedResultFile(document, clazz, file);
                                return true;
                        }

                        log.error("File name: " + file);
                        /*  */
                        log.error("===================");
                        log.error(reference);
                        log.error("===================");

                        log.error(document);
                        log.error("===================");
                        /* */

                        String[] test1 = StringList.tokenize(reference, "\n").toArray();
                        String[] test2 = StringList.tokenize(document, "\n").toArray();
                        Diff df = new Diff(test1);
                        try
                        {
                                df.diff(test2);
                        }
                        catch (DifferentiationFailedException e)
                        {
                                throw new RuntimeException(e);
                        }

                        // System.out.println(r.toString());

                        if (failWithAssert)
                        {
                                assertEquals(reference, document, filename);
                        }
                }

                return equals;
        }

        /**
         * @param a
         *            String a
         * @param b
         *            String b
         * @return True if the two strings have the same markup tags
         */
        private static boolean compareMarkup(final String a, final String b)
        {
                try
                {
                        // Parse a and b into markup and compare
                        final MarkupStream amarkup = new MarkupStream(new MarkupParser(a).parse());
                        final MarkupStream bmarkup = new MarkupStream(new MarkupParser(b).parse());
                        return amarkup.equalTo(bmarkup);
                }
                catch (IOException e)
                {
                        log.error(e.getMessage(), e);
                }
                catch (ResourceStreamNotFoundException e)
                {
                        log.error(e.getMessage(), e);
                }
                return false;
        }

}