Issue #37: inject, invoke maven command, read file and clean up

src/main/java/com/github/checkstyle/regression/extract/CheckstyleInjector.java

@@ -0,0 +1,74 @@
+////////////////////////////////////////////////////////////////////////////////
+// checkstyle: Checks Java source code for adherence to a set of rules.
+// Copyright (C) 2001-2017 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.github.checkstyle.regression.extract;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
+
+/**
+ * @author LuoLiangchen
+ */
+final class CheckstyleInjector {
+    static File generateExtractInfoFile(String repoPath, String branch)
+            throws IOException, GitAPIException {
+        checkoutToPrBranch(repoPath, branch);
+        moveInjectFilesToCheckstyleRepo(repoPath);
+        invokeMavenCommand(repoPath);
+        return null;
+    }
+
+    static void clearInjections() {
+        // clear the injected files and the generated info file
+    }
+
+    private static void invokeMavenCommand(String repoPath) {
+        // invoke maven command to generate the extract info file
+    }
+
+    private static void moveInjectFilesToCheckstyleRepo(String repoPath) {
+        // move the injected files to checkstyle repo ...
+    }
+
+    private static void checkoutToPrBranch(String repoPath, String branch)
+            throws IOException, GitAPIException {
+        final File gitDir = new File(repoPath, ".git");
+        final Repository repository = new FileRepositoryBuilder().setGitDir(gitDir)
+                .readEnvironment().findGitDir().build();
+
+        try {
+            final Git git = new Git(repository);
+
+            try {
+                git.checkout().setName(branch).call();
+            }
+            finally {
+                git.close();
+            }
+        }
+        finally {
+            repository.close();
+        }
+    }
+}

src/main/java/com/github/checkstyle/regression/extract/ExtractInfoProcessor.java

@@ -19,13 +19,19 @@
 
 package com.github.checkstyle.regression.extract;
 
+import java.io.File;
+import java.io.FileInputStream;
 import java.io.IOException;
+import java.io.InputStreamReader;
 import java.io.Reader;
 import java.lang.reflect.Type;
+import java.nio.charset.Charset;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import org.eclipse.jgit.api.errors.GitAPIException;
+
 import com.github.checkstyle.regression.data.ModuleExtractInfo;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
@@ -57,6 +63,31 @@ private ExtractInfoProcessor() {
         GSON = gsonBuilder.create();
     }
 
+    /**
+     * Gets the module extract info map from the given branch of checkstyle repository.
+     * @param repoPath the path of checkstyle repository
+     * @param branch   the given branch on which to generate the extract info
+     * @return the full qualified name to module extract info map
+     * @throws IOException     failure when creating or reading the info file
+     * @throws GitAPIException failure when running Git command
+     */
+    public static Map<String, ModuleExtractInfo> getModuleExtractInfos(
+            String repoPath, String branch) throws IOException, GitAPIException {
+        final Map<String, ModuleExtractInfo> returnValue;
+
+        try {
+            final File file = CheckstyleInjector.generateExtractInfoFile(repoPath, branch);
+            final Reader reader = new InputStreamReader(
+                    new FileInputStream(file), Charset.forName("UTF-8"));
+            returnValue = getModuleExtractInfosFromReader(reader);
+        }
+        finally {
+            CheckstyleInjector.clearInjections();
+        }
+
+        return returnValue;
+    }
+
     /**
      * Gets the module extract info map from the given reader. Map key is the
      * fully qualified module name.