/**
    * This file Copyright (c) 2015 Magnolia International
    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
    *
    *
    * This file is dual-licensed under both the Magnolia
    * Network Agreement and the GNU General Public License.
    * You may elect to use one or the other of these licenses.
    *
   * This file is distributed in the hope that it will be
   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
   * implied warranty of MERCHANTABILITY or FITNESS FOR A
   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
   * Redistribution, except as permitted by whichever of the GPL
   * or MNA you select, is prohibited.
   *
   * 1. For the GPL license (GPL), you can redistribute and/or
   * modify this file under the terms of the GNU General
   * Public License, Version 3, as published by the Free Software
   * Foundation.  You should have received a copy of the GNU
   * General Public License, Version 3 along with this program;
   * if not, write to the Free Software Foundation, Inc., 51
   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * 2. For the Magnolia Network Agreement (MNA), this file
   * and the accompanying materials are made available under the
   * terms of the MNA which accompanies this distribution, and
   * is available at http://www.magnolia-cms.com/mna.html
   *
   * Any modifications to this file must keep this entire header
   * intact.
   *
   */
  package info.magnolia.config.source.yaml;
  
  import info.magnolia.config.registry.DefinitionMetadataBuilder;
  import info.magnolia.resourceloader.Resource;
  
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.apache.commons.io.FilenameUtils;
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Parse the config path for the metadata attributes, according to a regex pattern.
   * <p>
   * Relies preferably on named groups, e.g. <code>{@value #GROUP_MODULE}</code>, <code>{@value #GROUP_NAME}</code> or <code>{@value #GROUP_RELATIVE_PATH}</code>,
   * otherwise will interpret first group as module name, and last group as definition name.
   */
  public class RegexBasedPathToMetadataInferrer implements PathToMetadataInferrer {
  
      private static final Logger log = LoggerFactory.getLogger(RegexBasedPathToMetadataInferrer.class);
  
      public static final String GROUP_MODULE = "module";
      public static final String GROUP_NAME = "name";
      public static final String GROUP_RELATIVE_PATH = "relPath";
  
      private final Pattern pathPattern;
  
      public RegexBasedPathToMetadataInferrer(Pattern pathPattern) {
          this.pathPattern = pathPattern;
      }
  
      @Override
      public DefinitionMetadataBuilder populateFrom(DefinitionMetadataBuilder metadataBuilder, Resource resource) {
          final String relativePath = resource.getPath();
          final Matcher matcher = matcherFor(relativePath);
          final String fallbackDefinitionName = fallbackDefinitionName(matcher, relativePath);
          final String moduleName = moduleName(matcher, relativePath);
          final String relativeLocation = relativeLocation(matcher, relativePath);
          return metadataBuilder
                  .name(fallbackDefinitionName)
                  .module(moduleName)
                  .relativeLocation(relativeLocation);
      }
  
      protected String fallbackDefinitionName(Matcher matcher, String path) {
          if (matcher.groupCount() < 1) {
              // If we're here, matcher should match, unless it's an invalid pattern
              final String nameWithoutExtension = FilenameUtils.getBaseName(path);
              log.debug("Pattern {} does not have a capturing group to infer definition name from path {}; falling back to filename without extension: {}", pathPattern, path, nameWithoutExtension);
              return nameWithoutExtension;
          }
  
          try {
              // We want to optionally support named groups in patterns. However, since
              // Pattern.namedGroups() is not a part of public API - we cannot reliably tell
              // whether the named group is present, the following logic - is a workaround
              // (alternatively reflection could be used).
              return matcher.group(GROUP_NAME);
          } catch (IllegalArgumentException e) {
              if (matcher.groupCount() > 1) {
                  // pick last group
                  return matcher.group(matcher.groupCount());
              } else {
                  return matcher.group(1);
             }
         }
     }
 
     protected String moduleName(Matcher matcher, String path) {
         if (matcher.groupCount() < 2) {
             log.debug("Pattern {} does not have a capturing group to infer module name from path {}; falling back to default: {}", pathPattern, path, "yaml");
             return "yaml";
         }
 
         try {
             // We want to optionally support named groups in patterns. However, since
             // Pattern.namedGroups() is not a part of public API - we cannot reliably tell
             // whether the named group is present, the following logic - is a workaround
             // (alternatively reflection could be used).. Meh.
             return matcher.group(GROUP_MODULE);
         } catch (IllegalArgumentException e) {
             // pick first group
             return matcher.group(1);
         }
     }
 
     protected String relativeLocation(Matcher matcher, String path) {
         // Just assemble a matcher group named <relPath> and the name (from the matcher as well, we don't want it to be overridden by def)
         try {
             // Using named groups in the pattern should be optional, but ....
             // Yuck. Pattern.namedGroups() is not public... so it's this or reflection. Meh.
             String group = matcher.group(GROUP_RELATIVE_PATH);
             return StringUtils.isNotBlank(group) ? group + matcher.group(GROUP_NAME) : matcher.group(GROUP_NAME);
         } catch (IllegalArgumentException e) {
             if (matcher.groupCount() > 1) {
                 // first group is module and last group is name, pick whatever's in between (name included, leading slash excluded if any)
                 String subPath = path.substring(matcher.end(1), matcher.end(matcher.groupCount()));
                 return StringUtils.strip(subPath, "/");
             }
             return FilenameUtils.removeExtension(StringUtils.removeStart(path, "/"));
         }
     }
 
     protected Matcher matcherFor(String relativePath) {
         final Matcher matcher = pathPattern.matcher(relativePath);
         if (!matcher.matches()) {
             // FileResourceLoader should have rejected this file if it didn't match the pattern, so we shouldn't be here unless someone tried to force-register a file through code?
             throw new IllegalStateException(String.format("%s doesn't match pattern %s, rejecting.", relativePath, pathPattern));
         }
         return matcher;
     }
 
 }