/*
    * 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.rat.config.exclusion;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Objects;
  import java.util.Set;
  import java.util.TreeSet;
  import java.util.stream.Collectors;
  
  import org.apache.rat.document.DocumentName;
  import org.apache.rat.document.DocumentNameMatcher;
  import org.apache.rat.utils.DefaultLog;
  import org.apache.rat.utils.ExtendedIterator;
  
  import static java.lang.String.format;
  
  /**
   * Processes the include and exclude patterns and applies the result against a base directory
   * to return an IReportable that contains all the reportable objects.
   */
  public class ExclusionProcessor {
      /** Strings that identify the files/directories to exclude */
      private final Set<String> excludedPatterns;
      /** Path matchers that exclude files/directories */
      private final List<DocumentNameMatcher> excludedPaths;
      /** Strings that identify the files/directories to include (overrides exclude) */
      private final Set<String> includedPatterns;
      /** Path matchers that identify the files/directories to include (overrides exclude) */
      private final List<DocumentNameMatcher> includedPaths;
      /**
       * Collections of StandardCollections that have file processors that should be
       * used to add additional exclude files to the process
       */
      private final Set<StandardCollection> fileProcessors;
      /** Standard collections that contribute to the inclusion processing */
      private final Set<StandardCollection> includedCollections;
      /** Standard collections that contribute to the exclusion procession */
      private final Set<StandardCollection> excludedCollections;
      /** The last generated PathMatcher */
      private DocumentNameMatcher lastMatcher;
      /** The base dir for the last PathMatcher */
      private DocumentName lastMatcherBaseDir;
  
      /**
       * Constructs the processor.
       */
      public ExclusionProcessor() {
          excludedPatterns = new HashSet<>();
          excludedPaths = new ArrayList<>();
          includedPatterns = new HashSet<>();
          includedPaths = new ArrayList<>();
          fileProcessors = new HashSet<>();
          includedCollections = new HashSet<>();
          excludedCollections = new HashSet<>();
      }
  
      /** Reset the {@link #lastMatcher} and {@link #lastMatcherBaseDir} to start again */
      private void resetLastMatcher() {
          lastMatcher = null;
          lastMatcherBaseDir = null;
      }
  
      /**
       * Add the Iterable of strings to the collection of file/directory patters to ignore.
       * @param patterns the patterns to add
       * @return this
       */
      public ExclusionProcessor addIncludedPatterns(final Iterable<String> patterns) {
          DefaultLog.getInstance().debug(format("Including patterns: %s", String.join(", ", patterns)));
          patterns.forEach(includedPatterns::add);
          resetLastMatcher();
          return this;
      }
  
      /**
       * Add a DocumentNameMatcher to the collection of file/directory patterns to ignore.
       * @param matcher the DocumentNameMatcher to add. Will be ignored if {@code null}.
       * @return this
       */
     public ExclusionProcessor addIncludedMatcher(final DocumentNameMatcher matcher) {
         if (matcher != null) {
             includedPaths.add(matcher);
             resetLastMatcher();
         }
         return this;
     }
 
     /**
      * Add the file processor from a StandardCollection.
      * @param collection the collection to add the processor from.
      * @return this
      */
     public ExclusionProcessor addFileProcessor(final StandardCollection collection) {
         if (collection != null) {
             DefaultLog.getInstance().debug(format("Processing exclude file from %s.", collection));
             fileProcessors.add(collection);
             resetLastMatcher();
         }
         return this;
     }
 
     /**
      * Add the patterns from the StandardCollection as included patterns.
      * @param collection the standard collection to add the includes from.
      * @return this
      */
     public ExclusionProcessor addIncludedCollection(final StandardCollection collection) {
         if (collection != null) {
             DefaultLog.getInstance().debug(format("Including %s collection.", collection));
             includedCollections.add(collection);
             resetLastMatcher();
         }
         return this;
     }
 
     /**
      * Add the patterns from collections of patterns as excluded patterns.
      * @param patterns the strings to that define patterns to be excluded from processing.
      * @return this
      */
     public ExclusionProcessor addExcludedPatterns(final Iterable<String> patterns) {
         DefaultLog.getInstance().debug(format("Excluding patterns: %s", String.join(", ", patterns)));
         patterns.forEach(excludedPatterns::add);
         resetLastMatcher();
         return this;
     }
 
     /**
      * Add the DocumentNameMatcher as an excluded pattern.
      * @param matcher the DocumentNameMatcher to exclude.
      * @return this
      */
     public ExclusionProcessor addExcludedMatcher(final DocumentNameMatcher matcher) {
         if (matcher != null) {
             excludedPaths.add(matcher);
             resetLastMatcher();
         }
         return this;
     }
 
     /**
      * Report the excluded files to the appendable object.
      * @param appendable the appendable object to write to.
      */
     public void reportExclusions(final Appendable appendable) throws IOException {
         appendable.append(format("Excluding patterns: %s%n", String.join(", ", excludedPatterns)));
         appendable.append(format("Including patterns: %s%n", String.join(", ", includedPatterns)));
         for (StandardCollection sc : excludedCollections) {
             appendable.append(format("Excluding %s collection.%n", sc.name()));
         }
         for (StandardCollection sc : includedCollections) {
             appendable.append(format("Including %s collection.%n", sc.name()));
         }
         for (StandardCollection sc : fileProcessors) {
             appendable.append(format("Processing exclude file from %s.%n", sc.name()));
         }
         for (DocumentNameMatcher nameMatcher : excludedPaths) {
             appendable.append(format("Excluding %s.%n", nameMatcher.toString()));
         }
     }
 
 
     /**
      * Excludes the files/directories specified by a StandardCollection.
      * @param collection the StandardCollection that identifies the files to exclude.
      * @return this
      */
     public ExclusionProcessor addExcludedCollection(final StandardCollection collection) {
         if (collection != null) {
             DefaultLog.getInstance().debug(format("Excluding %s collection.", collection));
             excludedCollections.add(collection);
             resetLastMatcher();
         }
         return this;
     }
 
     /**
      * Creates a Document name matcher that will return {@code false} on any
      * document that is excluded.
      * @param basedir the base directory to make everything relative to.
      * @return A DocumentNameMatcher that will return {@code false} for any document that is to be excluded.
      */
     public DocumentNameMatcher getNameMatcher(final DocumentName basedir) {
         // if lastMatcher is not set or the basedir is not the same as the last one then
         // we have to regenerate the matching document.
         // Otherwise we can just return the lastMatcher since there is no change.
         if (lastMatcher == null || !basedir.equals(lastMatcherBaseDir)) {
             lastMatcherBaseDir = basedir;
 
             // add the file processors
             final List<MatcherSet> matchers = extractFileProcessors(basedir);
             final MatcherSet.Builder fromCommandLine = new MatcherSet.Builder();
             DocumentName.Builder nameBuilder = DocumentName.builder(basedir).setBaseName(basedir);
             extractPatterns(nameBuilder, fromCommandLine);
             extractCollectionPatterns(nameBuilder, fromCommandLine);
             extractCollectionMatchers(fromCommandLine);
             extractPaths(fromCommandLine);
             matchers.add(fromCommandLine.build());
 
             lastMatcher = MatcherSet.merge(matchers).createMatcher();
             DefaultLog.getInstance().debug(format("Created matcher set for %s%n%s", basedir.getName(),
                     lastMatcher));
         }
         return lastMatcher;
     }
 
     /**
      * Extracts the file processors from {@link #fileProcessors}.
      * @param basedir The directory to base the file processors on.
      * @return a list of MatcherSets that are created for each {@link #fileProcessors} entry.
      */
     private List<MatcherSet> extractFileProcessors(final DocumentName basedir) {
         final List<MatcherSet> fileProcessorList = new ArrayList<>();
         for (StandardCollection sc : fileProcessors) {
             ExtendedIterator<List<MatcherSet>> iter =  sc.fileProcessorBuilder().map(builder -> builder.build(basedir));
             if (iter.hasNext()) {
                 iter.forEachRemaining(fileProcessorList::addAll);
             } else {
                 DefaultLog.getInstance().debug(String.format("%s does not have a fileProcessor.", sc));
             }
         }
         return fileProcessorList;
     }
 
     /**
      * Converts the pattern to use the directory separator specified by the document name and localises it for
      * exclusion processing.
      * @param documentName The document name to adjust the pattern against.
      * @param pattern the pattern.
      * @return the prepared pattern.
      */
     private String preparePattern(final DocumentName documentName, final String pattern) {
         return ExclusionUtils.qualifyPattern(documentName,
                         ExclusionUtils.convertSeparator(pattern, "/", documentName.getDirectorySeparator()));
     }
 
     /**
      * Extracts {@link #includedPatterns} and {@link #excludedPatterns} into the specified matcherBuilder.
      * @param nameBuilder The name builder for the pattern. File names are resolved against the generated name.
      * @param matcherBuilder the MatcherSet.Builder to add the patterns to.
      */
     private void extractPatterns(final DocumentName.Builder nameBuilder, final MatcherSet.Builder matcherBuilder) {
         DocumentName name = nameBuilder.setName("Patterns").build();
         if (!excludedPatterns.isEmpty()) {
             matcherBuilder.addExcluded(name, excludedPatterns.stream()
                     .map(s -> preparePattern(name, s))
                     .collect(Collectors.toSet()));
         }
         if (!includedPatterns.isEmpty()) {
             matcherBuilder.addIncluded(name, includedPatterns.stream()
                     .map(s -> preparePattern(name, s)).collect(Collectors.toSet()));
         }
     }
 
     /**
      * Extracts {@link #includedCollections} and {@link #excludedCollections} patterns into the specified matcherBuilder.
      * @param nameBuilder the name builder for the pattern names.
      * @param matcherBuilder the MatcherSet.Builder to add the collections to.
      */
     private void extractCollectionPatterns(final DocumentName.Builder nameBuilder, final MatcherSet.Builder matcherBuilder) {
         final Set<String> incl = new TreeSet<>();
         final Set<String> excl = new TreeSet<>();
         for (StandardCollection sc : includedCollections) {
             Set<String> patterns = sc.patterns();
             if (patterns.isEmpty()) {
                 DefaultLog.getInstance().debug(String.format("%s does not have a defined collection for inclusion.", sc));
             } else {
                 MatcherSet.Builder.segregateList(incl, excl, sc.patterns());
             }
         }
         for (StandardCollection sc : excludedCollections) {
             Set<String> patterns = sc.patterns();
             if (patterns.isEmpty()) {
                 DefaultLog.getInstance().debug(String.format("%s does not have a defined collection for exclusion.", sc));
             } else {
                 MatcherSet.Builder.segregateList(excl, incl, sc.patterns());
             }
         }
         DocumentName name = nameBuilder.setName("Collections").build();
         matcherBuilder
                 .addExcluded(name, excl.stream().map(s -> preparePattern(name.getBaseDocumentName(), s)).collect(Collectors.toSet()))
                 .addIncluded(name, incl.stream().map(s -> preparePattern(name.getBaseDocumentName(), s)).collect(Collectors.toSet()));
     }
 
     /**
      * Extracts {@link #includedCollections} and {@link #excludedCollections} matchers into the specified matcherBuilder.
      * @param matcherBuilder the MatcherSet.Builder to add the collections to.
      */
     private void extractCollectionMatchers(final MatcherSet.Builder matcherBuilder) {
         ExtendedIterator.create(includedCollections.iterator())
                 .map(StandardCollection::staticDocumentNameMatcher)
                 .filter(Objects::nonNull)
                 .forEachRemaining(matcherBuilder::addIncluded);
 
         ExtendedIterator.create(excludedCollections.iterator())
                 .map(StandardCollection::staticDocumentNameMatcher)
                 .filter(Objects::nonNull)
                 .forEachRemaining(matcherBuilder::addExcluded);
     }
 
     /**
      * Extracts {@link #includedPaths} and {@link #excludedPaths} patterns into the specified matcherBuilder.
      * @param matcherBuilder the MatcherSet.Builder to add the collections to.
      */
     private void extractPaths(final MatcherSet.Builder matcherBuilder) {
         if (!includedPaths.isEmpty()) {
             for (DocumentNameMatcher matcher : includedPaths) {
                 DefaultLog.getInstance().debug(format("Including path matcher %s", matcher));
                 matcherBuilder.addIncluded(matcher);
             }
         }
         if (!excludedPaths.isEmpty()) {
             for (DocumentNameMatcher matcher : excludedPaths) {
                 DefaultLog.getInstance().debug(format("Excluding path matcher %s", matcher));
                 matcherBuilder.addExcluded(matcher);
             }
         }
     }
 
 }