/*
    * 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.apache.commons.lang3.StringUtils;
  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.utils.Checksum;
  import org.owasp.dependencycheck.utils.FileFilterBuilder;
  import org.owasp.dependencycheck.utils.Settings;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.File;
  import java.io.FileFilter;
  import java.io.IOException;
  import java.io.UnsupportedEncodingException;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * <p>
   * Used to analyze CMake build files, and collect information that can be used to determine the associated CPE.</p>
   * <p>
   * Note: This analyzer catches straightforward invocations of the project command, plus some other observed patterns of version
   * inclusion in real CMake projects. Many projects make use of older versions of CMake and/or use custom "homebrew" ways to insert
   * version information. Hopefully as the newer CMake call pattern grows in usage, this analyzer allow more CPEs to be
   * identified.</p>
   *
   * @author Dale Visser
   */
  public class CMakeAnalyzer extends AbstractFileTypeAnalyzer {
  
      /**
       * The logger.
       */
      private static final Logger LOGGER = LoggerFactory.getLogger(CMakeAnalyzer.class);
  
      /**
       * Used when compiling file scanning regex patterns.
       */
      private static final int REGEX_OPTIONS = Pattern.DOTALL
              | Pattern.CASE_INSENSITIVE | Pattern.MULTILINE;
  
      /**
       * Regex to extract the product information.
       */
      private static final Pattern PROJECT = Pattern.compile(
              "^ *project *\\([ \\n]*(\\w+)[ \\n]*.*?\\)", REGEX_OPTIONS);
  
      /**
       * Regex to extract product and version information.
       *
       * Group 1: Product
       *
       * Group 2: Version
       */
      private static final Pattern SET_VERSION = Pattern
              .compile(
                      "^ *set\\s*\\(\\s*(\\w+)_version\\s+\"?(\\d+(?:\\.\\d+)+)[\\s\"]?\\)",
                      REGEX_OPTIONS);
  
      /**
       * Detects files that can be analyzed.
       */
      private static final FileFilter FILTER = FileFilterBuilder.newInstance().addExtensions(".cmake")
              .addFilenames("CMakeLists.txt").build();
  
      /**
       * A reference to SHA1 message digest.
       */
      private static MessageDigest sha1 = null;
  
      static {
          try {
              sha1 = MessageDigest.getInstance("SHA1");
          } catch (NoSuchAlgorithmException e) {
              LOGGER.error(e.getMessage());
          }
     }
 
     /**
      * Returns the name of the CMake analyzer.
      *
      * @return the name of the analyzer
      *
      */
     @Override
     public String getName() {
         return "CMake Analyzer";
     }
 
     /**
      * Tell that we are used for information collection.
      *
      * @return INFORMATION_COLLECTION
      */
     @Override
     public AnalysisPhase getAnalysisPhase() {
         return AnalysisPhase.INFORMATION_COLLECTION;
     }
 
     /**
      * Returns the set of supported file extensions.
      *
      * @return the set of supported file extensions
      */
     @Override
     protected FileFilter getFileFilter() {
         return FILTER;
     }
 
     /**
      * No-op initializer implementation.
      *
      * @throws Exception never thrown
      */
     @Override
     protected void initializeFileTypeAnalyzer() throws Exception {
         // Nothing to do here.
     }
 
     /**
      * Analyzes python packages and adds evidence to the dependency.
      *
      * @param dependency the dependency being analyzed
      * @param engine the engine being used to perform the scan
      * @throws AnalysisException thrown if there is an unrecoverable error analyzing the dependency
      */
     @Override
     protected void analyzeFileType(Dependency dependency, Engine engine)
             throws AnalysisException {
         final File file = dependency.getActualFile();
         final String parentName = file.getParentFile().getName();
         final String name = file.getName();
         dependency.setDisplayFileName(String.format("%s%c%s", parentName, File.separatorChar, name));
         String contents;
         try {
             contents = FileUtils.readFileToString(file).trim();
         } catch (IOException e) {
             throw new AnalysisException(
                     "Problem occurred while reading dependency file.", e);
         }
 
         if (StringUtils.isNotBlank(contents)) {
             final Matcher m = PROJECT.matcher(contents);
             int count = 0;
             while (m.find()) {
                 count++;
                 LOGGER.debug(String.format(
                         "Found project command match with %d groups: %s",
                         m.groupCount(), m.group(0)));
                 final String group = m.group(1);
                 LOGGER.debug("Group 1: " + group);
                 dependency.getProductEvidence().addEvidence(name, "Project",
                         group, Confidence.HIGH);
             }
             LOGGER.debug("Found {} matches.", count);
             analyzeSetVersionCommand(dependency, engine, contents);
         }
     }
 
     /**
      * Extracts the version information from the contents. If more then one version is found additional dependencies are added to
      * the dependency list.
      *
      * @param dependency the dependency being analyzed
      * @param engine the dependency-check engine
      * @param contents the version information
      */
     private void analyzeSetVersionCommand(Dependency dependency, Engine engine, String contents) {
         Dependency currentDep = dependency;
 
         final Matcher m = SET_VERSION.matcher(contents);
         int count = 0;
         while (m.find()) {
             count++;
             LOGGER.debug("Found project command match with {} groups: {}",
                     m.groupCount(), m.group(0));
             String product = m.group(1);
             final String version = m.group(2);
             LOGGER.debug("Group 1: " + product);
             LOGGER.debug("Group 2: " + version);
             final String aliasPrefix = "ALIASOF_";
             if (product.startsWith(aliasPrefix)) {
                 product = product.replaceFirst(aliasPrefix, "");
             }
             if (count > 1) {
                 //TODO - refactor so we do not assign to the parameter (checkstyle)
                 currentDep = new Dependency(dependency.getActualFile());
                 currentDep.setDisplayFileName(String.format("%s:%s", dependency.getDisplayFileName(), product));
                 final String filePath = String.format("%s:%s", dependency.getFilePath(), product);
                 currentDep.setFilePath(filePath);
 
                 byte[] path;
                 try {
                     path = filePath.getBytes("UTF-8");
                 } catch (UnsupportedEncodingException ex) {
                     path = filePath.getBytes();
                 }
                 currentDep.setSha1sum(Checksum.getHex(sha1.digest(path)));
                 engine.getDependencies().add(currentDep);
             }
             final String source = currentDep.getDisplayFileName();
             currentDep.getProductEvidence().addEvidence(source, "Product",
                     product, Confidence.MEDIUM);
             currentDep.getVersionEvidence().addEvidence(source, "Version",
                     version, Confidence.MEDIUM);
         }
         LOGGER.debug(String.format("Found %d matches.", count));
     }
 
     @Override
     protected String getAnalyzerEnabledSettingKey() {
         return Settings.KEYS.ANALYZER_CMAKE_ENABLED;
     }
 }