/*
    * This file is part of dependency-check-core.
    *
    * 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
    *
    *     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.
   *
   * Copyright (c) 2015 Institute for Defense Analyses. All Rights Reserved.
   */
  package org.owasp.dependencycheck.analyzer;
  
  import org.apache.commons.io.FileUtils;
  import org.owasp.dependencycheck.Engine;
  import org.owasp.dependencycheck.analyzer.exception.AnalysisException;
  import org.owasp.dependencycheck.dependency.Confidence;
  import org.owasp.dependencycheck.dependency.Dependency;
  import org.owasp.dependencycheck.dependency.EvidenceCollection;
  import org.owasp.dependencycheck.utils.FileFilterBuilder;
  import org.owasp.dependencycheck.utils.Settings;
  import org.owasp.dependencycheck.utils.UrlStringUtils;
  
  import java.io.File;
  import java.io.FileFilter;
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * Used to analyze Autoconf input files named configure.ac or configure.in. Files simply named "configure" are also analyzed,
   * assuming they are generated by Autoconf, and contain certain special package descriptor variables.
   *
   * @author Dale Visser
   * @see <a href="https://www.gnu.org/software/autoconf/">Autoconf - GNU Project - Free Software Foundation (FSF)</a>
   */
  @Experimental
  public class AutoconfAnalyzer extends AbstractFileTypeAnalyzer {
  
      /**
       * Autoconf output filename.
       */
      private static final String CONFIGURE = "configure";
  
      /**
       * Autoconf input filename.
       */
      private static final String CONFIGURE_IN = "configure.in";
  
      /**
       * Autoconf input filename.
       */
      private static final String CONFIGURE_AC = "configure.ac";
  
      /**
       * The name of the analyzer.
       */
      private static final String ANALYZER_NAME = "Autoconf Analyzer";
  
      /**
       * The phase that this analyzer is intended to run in.
       */
      private static final AnalysisPhase ANALYSIS_PHASE = AnalysisPhase.INFORMATION_COLLECTION;
  
      /**
       * The set of file extensions supported by this analyzer.
       */
      private static final String[] EXTENSIONS = {"ac", "in"};
  
      /**
       * Matches AC_INIT variables in the output configure script.
       */
      private static final Pattern PACKAGE_VAR = Pattern.compile(
              "PACKAGE_(.+?)='(.*?)'", Pattern.DOTALL | Pattern.CASE_INSENSITIVE);
  
      /**
       * Matches AC_INIT statement in configure.ac file.
       */
      private static final Pattern AC_INIT_PATTERN;
  
      static {
          // each instance of param or sep_param has a capture group
          final String param = "\\[{0,2}(.+?)\\]{0,2}";
          final String sepParam = "\\s*,\\s*" + param;
          // Group 1: Package
          // Group 2: Version
          // Group 3: optional
          // Group 4: Bug report address (if it exists)
          // Group 5: optional
          // Group 6: Tarname (if it exists)
         // Group 7: optional
         // Group 8: URL (if it exists)
         AC_INIT_PATTERN = Pattern.compile(String.format(
                 "AC_INIT\\(%s%s(%s)?(%s)?(%s)?\\s*\\)", param, sepParam,
                 sepParam, sepParam, sepParam), Pattern.DOTALL
                 | Pattern.CASE_INSENSITIVE);
     }
 
     /**
      * The file filter used to determine which files this analyzer supports.
      */
     private static final FileFilter FILTER = FileFilterBuilder.newInstance().addFilenames(CONFIGURE).addExtensions(
             EXTENSIONS).build();
 
     /**
      * Returns the FileFilter
      *
      * @return the FileFilter
      */
     @Override
     protected FileFilter getFileFilter() {
         return FILTER;
     }
 
     /**
      * Returns the name of the analyzer.
      *
      * @return the name of the analyzer.
      */
     @Override
     public String getName() {
         return ANALYZER_NAME;
     }
 
     /**
      * Returns the phase that the analyzer is intended to run in.
      *
      * @return the phase that the analyzer is intended to run in.
      */
     @Override
     public AnalysisPhase getAnalysisPhase() {
         return ANALYSIS_PHASE;
     }
 
     /**
      * Returns the key used in the properties file to reference the analyzer's enabled property.
      *
      * @return the analyzer's enabled property setting key
      */
     @Override
     protected String getAnalyzerEnabledSettingKey() {
         return Settings.KEYS.ANALYZER_PYTHON_DISTRIBUTION_ENABLED;
     }
 
     @Override
     protected void analyzeFileType(Dependency dependency, Engine engine)
             throws AnalysisException {
         final File actualFile = dependency.getActualFile();
         final String name = actualFile.getName();
         if (name.startsWith(CONFIGURE)) {
             final File parent = actualFile.getParentFile();
             final String parentName = parent.getName();
             dependency.setDisplayFileName(parentName + "/" + name);
             final boolean isOutputScript = CONFIGURE.equals(name);
             if (isOutputScript || CONFIGURE_AC.equals(name)
                     || CONFIGURE_IN.equals(name)) {
                 final String contents = getFileContents(actualFile);
                 if (!contents.isEmpty()) {
                     if (isOutputScript) {
                         extractConfigureScriptEvidence(dependency, name,
                                 contents);
                     } else {
                         gatherEvidence(dependency, name, contents);
                     }
                 }
             }
         } else {
             // copy, alter and set in case some other thread is iterating over
             final List<Dependency> dependencies = new ArrayList<Dependency>(
                     engine.getDependencies());
             dependencies.remove(dependency);
             engine.setDependencies(dependencies);
         }
     }
 
     /**
      * Extracts evidence from the configuration.
      *
      * @param dependency the dependency being analyzed
      * @param name the name of the source of evidence
      * @param contents the contents to analyze for evidence
      */
     private void extractConfigureScriptEvidence(Dependency dependency,
             final String name, final String contents) {
         final Matcher matcher = PACKAGE_VAR.matcher(contents);
         while (matcher.find()) {
             final String variable = matcher.group(1);
             final String value = matcher.group(2);
             if (!value.isEmpty()) {
                 if (variable.endsWith("NAME")) {
                     dependency.getProductEvidence().addEvidence(name, variable,
                             value, Confidence.HIGHEST);
                 } else if ("VERSION".equals(variable)) {
                     dependency.getVersionEvidence().addEvidence(name, variable,
                             value, Confidence.HIGHEST);
                 } else if ("BUGREPORT".equals(variable)) {
                     dependency.getVendorEvidence().addEvidence(name, variable,
                             value, Confidence.HIGH);
                 } else if ("URL".equals(variable)) {
                     dependency.getVendorEvidence().addEvidence(name, variable,
                             value, Confidence.HIGH);
                 }
             }
         }
     }
 
     /**
      * Retrieves the contents of a given file.
      *
      * @param actualFile the file to read
      * @return the contents of the file
      * @throws AnalysisException thrown if there is an IO Exception
      */
     private String getFileContents(final File actualFile)
             throws AnalysisException {
         try {
             return FileUtils.readFileToString(actualFile, Charset.defaultCharset()).trim();
         } catch (IOException e) {
             throw new AnalysisException(
                     "Problem occurred while reading dependency file.", e);
         }
     }
 
     /**
      * Gathers evidence from a given file
      *
      * @param dependency the dependency to add evidence to
      * @param name the source of the evidence
      * @param contents the evidence to analyze
      */
     private void gatherEvidence(Dependency dependency, final String name,
             String contents) {
         final Matcher matcher = AC_INIT_PATTERN.matcher(contents);
         if (matcher.find()) {
             final EvidenceCollection productEvidence = dependency
                     .getProductEvidence();
             productEvidence.addEvidence(name, "Package", matcher.group(1),
                     Confidence.HIGHEST);
             dependency.getVersionEvidence().addEvidence(name,
                     "Package Version", matcher.group(2), Confidence.HIGHEST);
             final EvidenceCollection vendorEvidence = dependency
                     .getVendorEvidence();
             if (null != matcher.group(3)) {
                 vendorEvidence.addEvidence(name, "Bug report address",
                         matcher.group(4), Confidence.HIGH);
             }
             if (null != matcher.group(5)) {
                 productEvidence.addEvidence(name, "Tarname", matcher.group(6),
                         Confidence.HIGH);
             }
             if (null != matcher.group(7)) {
                 final String url = matcher.group(8);
                 if (UrlStringUtils.isUrl(url)) {
                     vendorEvidence.addEvidence(name, "URL", url,
                             Confidence.HIGH);
                 }
             }
         }
     }
 
     /**
      * Initializes the file type analyzer.
      *
      * @throws Exception thrown if there is an exception during initialization
      */
     @Override
     protected void initializeFileTypeAnalyzer() throws Exception {
         // No initialization needed.
     }
 }