////////////////////////////////////////////////////////////////////////////////
   // checkstyle: Checks Java source code for adherence to a set of rules.
   // Copyright (C) 2001-2019 the original author or authors.
   //
   // This library is free software; you can redistribute it and/or
   // modify it under the terms of the GNU Lesser General Public
   // License as published by the Free Software Foundation; either
   // version 2.1 of the License, or (at your option) any later version.
   //
  // This library is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  // Lesser General Public License for more details.
  //
  // You should have received a copy of the GNU Lesser General Public
  // License along with this library; if not, write to the Free Software
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  ////////////////////////////////////////////////////////////////////////////////
  
  package com.puppycrawl.tools.checkstyle.checks;
  
  import java.io.File;
  import java.io.InputStream;
  import java.nio.file.Files;
  import java.nio.file.NoSuchFileException;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.Optional;
  import java.util.Properties;
  import java.util.Set;
  import java.util.SortedSet;
  import java.util.TreeSet;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  import java.util.stream.Collectors;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import com.puppycrawl.tools.checkstyle.Definitions;
  import com.puppycrawl.tools.checkstyle.GlobalStatefulCheck;
  import com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck;
  import com.puppycrawl.tools.checkstyle.api.FileText;
  import com.puppycrawl.tools.checkstyle.api.LocalizedMessage;
  import com.puppycrawl.tools.checkstyle.api.MessageDispatcher;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  /**
   * <p>
   * The TranslationCheck class helps to ensure the correct translation of code by
   * checking locale-specific resource files for consistency regarding their keys.
   * Two locale-specific resource files describing one and the same context are consistent if they
   * contain the same keys. TranslationCheck also can check an existence of required translations
   * which must exist in project, if 'requiredTranslations' option is used.
   * </p>
   * <p>
   * An example of how to configure the check is:
   * </p>
   * <pre>
   * &lt;module name="Translation"/&gt;
   * </pre>
   * Check has the following options:
   *
   * <p><b>baseName</b> - a base name regexp for resource bundles which contain message resources. It
   * helps the check to distinguish config and localization resources. Default value is
   * <b>^messages.*$</b>
   * <p>An example of how to configure the check to validate only bundles which base names start with
   * "ButtonLabels":
   * </p>
   * <pre>
   * &lt;module name="Translation"&gt;
   *     &lt;property name="baseName" value="^ButtonLabels.*$"/&gt;
   * &lt;/module&gt;
   * </pre>
   * <p>To configure the check to check only files which have '.properties' and '.translations'
   * extensions:
   * </p>
   * <pre>
   * &lt;module name="Translation"&gt;
   *     &lt;property name="fileExtensions" value="properties, translations"/&gt;
   * &lt;/module&gt;
   * </pre>
   *
   * <p><b>requiredTranslations</b> which allows to specify language codes of required translations
   * which must exist in project. Language code is composed of the lowercase, two-letter codes as
   * defined by <a href="https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes">ISO 639-1</a>.
   * Default value is <b>empty String Set</b> which means that only the existence of
   * default translation is checked. Note, if you specify language codes (or just one language
   * code) of required translations the check will also check for existence of default translation
   * files in project. ATTENTION: the check will perform the validation of ISO codes if the option
   * is used. So, if you specify, for example, "mm" for language code, TranslationCheck will rise
   * violation that the language code is incorrect.
   * <br>
  *
  */
 @GlobalStatefulCheck
 public class TranslationCheck extends AbstractFileSetCheck {
 
     /**
      * A key is pointing to the warning message text for missing key
      * in "messages.properties" file.
      */
     public static final String MSG_KEY = "translation.missingKey";
 
     /**
      * A key is pointing to the warning message text for missing translation file
      * in "messages.properties" file.
      */
     public static final String MSG_KEY_MISSING_TRANSLATION_FILE =
         "translation.missingTranslationFile";
 
     /** Resource bundle which contains messages for TranslationCheck. */
     private static final String TRANSLATION_BUNDLE =
         "com.puppycrawl.tools.checkstyle.checks.messages";
 
     /**
      * A key is pointing to the warning message text for wrong language code
      * in "messages.properties" file.
      */
     private static final String WRONG_LANGUAGE_CODE_KEY = "translation.wrongLanguageCode";
 
     /**
      * Regexp string for default translation files.
      * For example, messages.properties.
      */
     private static final String DEFAULT_TRANSLATION_REGEXP = "^.+\\..+$";
 
     /**
      * Regexp pattern for bundles names which end with language code, followed by country code and
      * variant suffix. For example, messages_es_ES_UNIX.properties.
      */
     private static final Pattern LANGUAGE_COUNTRY_VARIANT_PATTERN =
         CommonUtil.createPattern("^.+\\_[a-z]{2}\\_[A-Z]{2}\\_[A-Za-z]+\\..+$");
     /**
      * Regexp pattern for bundles names which end with language code, followed by country code
      * suffix. For example, messages_es_ES.properties.
      */
     private static final Pattern LANGUAGE_COUNTRY_PATTERN =
         CommonUtil.createPattern("^.+\\_[a-z]{2}\\_[A-Z]{2}\\..+$");
     /**
      * Regexp pattern for bundles names which end with language code suffix.
      * For example, messages_es.properties.
      */
     private static final Pattern LANGUAGE_PATTERN =
         CommonUtil.createPattern("^.+\\_[a-z]{2}\\..+$");
 
     /** File name format for default translation. */
     private static final String DEFAULT_TRANSLATION_FILE_NAME_FORMATTER = "%s.%s";
     /** File name format with language code. */
     private static final String FILE_NAME_WITH_LANGUAGE_CODE_FORMATTER = "%s_%s.%s";
 
     /** Formatting string to form regexp to validate required translations file names. */
     private static final String REGEXP_FORMAT_TO_CHECK_REQUIRED_TRANSLATIONS =
         "^%1$s\\_%2$s(\\_[A-Z]{2})?\\.%3$s$|^%1$s\\_%2$s\\_[A-Z]{2}\\_[A-Za-z]+\\.%3$s$";
     /** Formatting string to form regexp to validate default translations file names. */
     private static final String REGEXP_FORMAT_TO_CHECK_DEFAULT_TRANSLATIONS = "^%s\\.%s$";
 
     /** Logger for TranslationCheck. */
     private final Log log;
 
     /** The files to process. */
     private final Set<File> filesToProcess = ConcurrentHashMap.newKeySet();
 
     /** The base name regexp pattern. */
     private Pattern baseName;
 
     /**
      * Language codes of required translations for the check (de, pt, ja, etc).
      */
     private Set<String> requiredTranslations = new HashSet<>();
 
     /**
      * Creates a new {@code TranslationCheck} instance.
      */
     public TranslationCheck() {
         setFileExtensions("properties");
         baseName = CommonUtil.createPattern("^messages.*$");
         log = LogFactory.getLog(TranslationCheck.class);
     }
 
     /**
      * Sets the base name regexp pattern.
      * @param baseName base name regexp.
      */
     public void setBaseName(Pattern baseName) {
         this.baseName = baseName;
     }
 
     /**
      * Sets language codes of required translations for the check.
      * @param translationCodes a comma separated list of language codes.
      */
     public void setRequiredTranslations(String... translationCodes) {
         requiredTranslations = Arrays.stream(translationCodes).collect(Collectors.toSet());
         validateUserSpecifiedLanguageCodes(requiredTranslations);
     }
 
     /**
      * Validates the correctness of user specified language codes for the check.
      * @param languageCodes user specified language codes for the check.
      */
     private void validateUserSpecifiedLanguageCodes(Set<String> languageCodes) {
         for (String code : languageCodes) {
             if (!isValidLanguageCode(code)) {
                 final LocalizedMessage msg = new LocalizedMessage(1, TRANSLATION_BUNDLE,
                         WRONG_LANGUAGE_CODE_KEY, new Object[] {code}, getId(), getClass(), null);
                 final String exceptionMessage = String.format(Locale.ROOT,
                         "%s [%s]", msg.getMessage(), TranslationCheck.class.getSimpleName());
                 throw new IllegalArgumentException(exceptionMessage);
             }
         }
     }
 
     /**
      * Checks whether user specified language code is correct (is contained in available locales).
      * @param userSpecifiedLanguageCode user specified language code.
      * @return true if user specified language code is correct.
      */
     private static boolean isValidLanguageCode(final String userSpecifiedLanguageCode) {
         boolean valid = false;
         final Locale[] locales = Locale.getAvailableLocales();
         for (Locale locale : locales) {
             if (userSpecifiedLanguageCode.equals(locale.toString())) {
                 valid = true;
                 break;
             }
         }
         return valid;
     }
 
     @Override
     public void beginProcessing(String charset) {
         filesToProcess.clear();
     }
 
     @Override
     protected void processFiltered(File file, FileText fileText) {
         // We just collecting files for processing at finishProcessing()
         filesToProcess.add(file);
     }
 
     @Override
     public void finishProcessing() {
         final Set<ResourceBundle> bundles = groupFilesIntoBundles(filesToProcess, baseName);
         for (ResourceBundle currentBundle : bundles) {
             checkExistenceOfDefaultTranslation(currentBundle);
             checkExistenceOfRequiredTranslations(currentBundle);
             checkTranslationKeys(currentBundle);
         }
     }
 
     /**
      * Checks an existence of default translation file in the resource bundle.
      * @param bundle resource bundle.
      */
     private void checkExistenceOfDefaultTranslation(ResourceBundle bundle) {
         final Optional<String> fileName = getMissingFileName(bundle, null);
         if (fileName.isPresent()) {
             logMissingTranslation(bundle.getPath(), fileName.get());
         }
     }
 
     /**
      * Checks an existence of translation files in the resource bundle.
      * The name of translation file begins with the base name of resource bundle which is followed
      * by '_' and a language code (country and variant are optional), it ends with the extension
      * suffix.
      * @param bundle resource bundle.
      */
     private void checkExistenceOfRequiredTranslations(ResourceBundle bundle) {
         for (String languageCode : requiredTranslations) {
             final Optional<String> fileName = getMissingFileName(bundle, languageCode);
             if (fileName.isPresent()) {
                 logMissingTranslation(bundle.getPath(), fileName.get());
             }
         }
     }
 
     /**
      * Returns the name of translation file which is absent in resource bundle or Guava's Optional,
      * if there is not missing translation.
      * @param bundle resource bundle.
      * @param languageCode language code.
      * @return the name of translation file which is absent in resource bundle or Guava's Optional,
      *         if there is not missing translation.
      */
     private static Optional<String> getMissingFileName(ResourceBundle bundle, String languageCode) {
         final String fileNameRegexp;
         final boolean searchForDefaultTranslation;
         final String extension = bundle.getExtension();
         final String baseName = bundle.getBaseName();
         if (languageCode == null) {
             searchForDefaultTranslation = true;
             fileNameRegexp = String.format(Locale.ROOT, REGEXP_FORMAT_TO_CHECK_DEFAULT_TRANSLATIONS,
                     baseName, extension);
         }
         else {
             searchForDefaultTranslation = false;
             fileNameRegexp = String.format(Locale.ROOT,
                 REGEXP_FORMAT_TO_CHECK_REQUIRED_TRANSLATIONS, baseName, languageCode, extension);
         }
         Optional<String> missingFileName = Optional.empty();
         if (!bundle.containsFile(fileNameRegexp)) {
             if (searchForDefaultTranslation) {
                 missingFileName = Optional.of(String.format(Locale.ROOT,
                         DEFAULT_TRANSLATION_FILE_NAME_FORMATTER, baseName, extension));
             }
             else {
                 missingFileName = Optional.of(String.format(Locale.ROOT,
                         FILE_NAME_WITH_LANGUAGE_CODE_FORMATTER, baseName, languageCode, extension));
             }
         }
         return missingFileName;
     }
 
     /**
      * Logs that translation file is missing.
      * @param filePath file path.
      * @param fileName file name.
      */
     private void logMissingTranslation(String filePath, String fileName) {
         final MessageDispatcher dispatcher = getMessageDispatcher();
         dispatcher.fireFileStarted(filePath);
         log(1, MSG_KEY_MISSING_TRANSLATION_FILE, fileName);
         fireErrors(filePath);
         dispatcher.fireFileFinished(filePath);
     }
 
     /**
      * Groups a set of files into bundles.
      * Only files, which names match base name regexp pattern will be grouped.
      * @param files set of files.
      * @param baseNameRegexp base name regexp pattern.
      * @return set of ResourceBundles.
      */
     private static Set<ResourceBundle> groupFilesIntoBundles(Set<File> files,
                                                              Pattern baseNameRegexp) {
         final Set<ResourceBundle> resourceBundles = new HashSet<>();
         for (File currentFile : files) {
             final String fileName = currentFile.getName();
             final String baseName = extractBaseName(fileName);
             final Matcher baseNameMatcher = baseNameRegexp.matcher(baseName);
             if (baseNameMatcher.matches()) {
                 final String extension = CommonUtil.getFileExtension(fileName);
                 final String path = getPath(currentFile.getAbsolutePath());
                 final ResourceBundle newBundle = new ResourceBundle(baseName, path, extension);
                 final Optional<ResourceBundle> bundle = findBundle(resourceBundles, newBundle);
                 if (bundle.isPresent()) {
                     bundle.get().addFile(currentFile);
                 }
                 else {
                     newBundle.addFile(currentFile);
                     resourceBundles.add(newBundle);
                 }
             }
         }
         return resourceBundles;
     }
 
     /**
      * Searches for specific resource bundle in a set of resource bundles.
      * @param bundles set of resource bundles.
      * @param targetBundle target bundle to search for.
      * @return Guava's Optional of resource bundle (present if target bundle is found).
      */
     private static Optional<ResourceBundle> findBundle(Set<ResourceBundle> bundles,
                                                        ResourceBundle targetBundle) {
         Optional<ResourceBundle> result = Optional.empty();
         for (ResourceBundle currentBundle : bundles) {
             if (targetBundle.getBaseName().equals(currentBundle.getBaseName())
                     && targetBundle.getExtension().equals(currentBundle.getExtension())
                     && targetBundle.getPath().equals(currentBundle.getPath())) {
                 result = Optional.of(currentBundle);
                 break;
             }
         }
         return result;
     }
 
     /**
      * Extracts the base name (the unique prefix) of resource bundle from translation file name.
      * For example "messages" is the base name of "messages.properties",
      * "messages_de_AT.properties", "messages_en.properties", etc.
      * @param fileName the fully qualified name of the translation file.
      * @return the extracted base name.
      */
     private static String extractBaseName(String fileName) {
         final String regexp;
         final Matcher languageCountryVariantMatcher =
             LANGUAGE_COUNTRY_VARIANT_PATTERN.matcher(fileName);
         final Matcher languageCountryMatcher = LANGUAGE_COUNTRY_PATTERN.matcher(fileName);
         final Matcher languageMatcher = LANGUAGE_PATTERN.matcher(fileName);
         if (languageCountryVariantMatcher.matches()) {
             regexp = LANGUAGE_COUNTRY_VARIANT_PATTERN.pattern();
         }
         else if (languageCountryMatcher.matches()) {
             regexp = LANGUAGE_COUNTRY_PATTERN.pattern();
         }
         else if (languageMatcher.matches()) {
             regexp = LANGUAGE_PATTERN.pattern();
         }
         else {
             regexp = DEFAULT_TRANSLATION_REGEXP;
         }
         // We use substring(...) instead of replace(...), so that the regular expression does
         // not have to be compiled each time it is used inside 'replace' method.
         final String removePattern = regexp.substring("^.+".length());
         return fileName.replaceAll(removePattern, "");
     }
 
     /**
      * Extracts path from a file name which contains the path.
      * For example, if file nam is /xyz/messages.properties, then the method
      * will return /xyz/.
      * @param fileNameWithPath file name which contains the path.
      * @return file path.
      */
     private static String getPath(String fileNameWithPath) {
         return fileNameWithPath
             .substring(0, fileNameWithPath.lastIndexOf(File.separator));
     }
 
     /**
      * Checks resource files in bundle for consistency regarding their keys.
      * All files in bundle must have the same key set. If this is not the case
      * an error message is posted giving information which key misses in which file.
      * @param bundle resource bundle.
      */
     private void checkTranslationKeys(ResourceBundle bundle) {
         final Set<File> filesInBundle = bundle.getFiles();
         // build a map from files to the keys they contain
         final Set<String> allTranslationKeys = new HashSet<>();
         final Map<File, Set<String>> filesAssociatedWithKeys = new HashMap<>();
         for (File currentFile : filesInBundle) {
             final Set<String> keysInCurrentFile = getTranslationKeys(currentFile);
             allTranslationKeys.addAll(keysInCurrentFile);
             filesAssociatedWithKeys.put(currentFile, keysInCurrentFile);
         }
         checkFilesForConsistencyRegardingTheirKeys(filesAssociatedWithKeys, allTranslationKeys);
     }
 
     /**
      * Compares th the specified key set with the key sets of the given translation files (arranged
      * in a map). All missing keys are reported.
      * @param fileKeys a Map from translation files to their key sets.
      * @param keysThatMustExist the set of keys to compare with.
      */
     private void checkFilesForConsistencyRegardingTheirKeys(Map<File, Set<String>> fileKeys,
                                                             Set<String> keysThatMustExist) {
         for (Entry<File, Set<String>> fileKey : fileKeys.entrySet()) {
             final MessageDispatcher dispatcher = getMessageDispatcher();
             final String path = fileKey.getKey().getPath();
             dispatcher.fireFileStarted(path);
             final Set<String> currentFileKeys = fileKey.getValue();
             final Set<String> missingKeys = keysThatMustExist.stream()
                 .filter(key -> !currentFileKeys.contains(key)).collect(Collectors.toSet());
             for (Object key : missingKeys) {
                 log(1, MSG_KEY, key);
             }
             fireErrors(path);
             dispatcher.fireFileFinished(path);
         }
     }
 
     /**
      * Loads the keys from the specified translation file into a set.
      * @param file translation file.
      * @return a Set object which holds the loaded keys.
      */
     private Set<String> getTranslationKeys(File file) {
         Set<String> keys = new HashSet<>();
         try (InputStream inStream = Files.newInputStream(file.toPath())) {
             final Properties translations = new Properties();
             translations.load(inStream);
             keys = translations.stringPropertyNames();
         }
         // -@cs[IllegalCatch] It is better to catch all exceptions since it can throw
         // a runtime exception.
         catch (final Exception ex) {
             logException(ex, file);
         }
         return keys;
     }
 
     /**
      * Helper method to log an exception.
      * @param exception the exception that occurred
      * @param file the file that could not be processed
      */
     private void logException(Exception exception, File file) {
         final String[] args;
         final String key;
         if (exception instanceof NoSuchFileException) {
             args = null;
             key = "general.fileNotFound";
         }
         else {
             args = new String[] {exception.getMessage()};
             key = "general.exception";
         }
         final LocalizedMessage message =
             new LocalizedMessage(
                 0,
                 Definitions.CHECKSTYLE_BUNDLE,
                 key,
                 args,
                 getId(),
                 getClass(), null);
         final SortedSet<LocalizedMessage> messages = new TreeSet<>();
         messages.add(message);
         getMessageDispatcher().fireErrors(file.getPath(), messages);
         log.debug("Exception occurred.", exception);
     }
 
     /** Class which represents a resource bundle. */
     private static class ResourceBundle {
 
         /** Bundle base name. */
         private final String baseName;
         /** Common extension of files which are included in the resource bundle. */
         private final String extension;
         /** Common path of files which are included in the resource bundle. */
         private final String path;
         /** Set of files which are included in the resource bundle. */
         private final Set<File> files;
 
         /**
          * Creates a ResourceBundle object with specific base name, common files extension.
          * @param baseName bundle base name.
          * @param path common path of files which are included in the resource bundle.
          * @param extension common extension of files which are included in the resource bundle.
          */
         /* package */ ResourceBundle(String baseName, String path, String extension) {
             this.baseName = baseName;
             this.path = path;
             this.extension = extension;
             files = new HashSet<>();
         }
 
         public String getBaseName() {
             return baseName;
         }
 
         public String getPath() {
             return path;
         }
 
         public String getExtension() {
             return extension;
         }
 
         public Set<File> getFiles() {
             return Collections.unmodifiableSet(files);
         }
 
         /**
          * Adds a file into resource bundle.
          * @param file file which should be added into resource bundle.
          */
         public void addFile(File file) {
             files.add(file);
         }
 
         /**
          * Checks whether a resource bundle contains a file which name matches file name regexp.
          * @param fileNameRegexp file name regexp.
          * @return true if a resource bundle contains a file which name matches file name regexp.
          */
         public boolean containsFile(String fileNameRegexp) {
             boolean containsFile = false;
             for (File currentFile : files) {
                 if (Pattern.matches(fileNameRegexp, currentFile.getName())) {
                     containsFile = true;
                     break;
                 }
             }
             return containsFile;
         }
 
     }
 
 }