diff --git a/src/main/scala/app/AccountController.scala b/src/main/scala/app/AccountController.scala
index d8e6362..4586186 100644
--- a/src/main/scala/app/AccountController.scala
+++ b/src/main/scala/app/AccountController.scala
@@ -76,7 +76,7 @@
 
       updateImage(userName, form.fileId, form.clearImage)
       flash += "info" -> "Account information has been updated."
-      redirect("/%s/_edit".format(userName))
+      redirect(s"/${userName}/_edit")
 
     } getOrElse NotFound
   })
diff --git a/src/main/scala/app/CreateRepositoryController.scala b/src/main/scala/app/CreateRepositoryController.scala
index 1e51caa..e10e5bb 100644
--- a/src/main/scala/app/CreateRepositoryController.scala
+++ b/src/main/scala/app/CreateRepositoryController.scala
@@ -1,7 +1,7 @@
 package app
 
 import util.Directory._
-import util.UsersAuthenticator
+import util.{JGitUtil, UsersAuthenticator}
 import service._
 import java.io.File
 import org.eclipse.jgit.api.Git
@@ -56,13 +56,7 @@
 
     // Create the actual repository
     val gitdir = getRepositoryDir(loginUserName, form.name)
-    val repository = new RepositoryBuilder().setGitDir(gitdir).setBare.build
-
-    repository.create
-
-    val config = repository.getConfig
-    config.setBoolean("http", null, "receivepack", true)
-    config.save
+    JGitUtil.initRepository(gitdir)
 
     if(form.createReadme){
       val tmpdir = getInitRepositoryDir(loginUserName, form.name)
@@ -73,9 +67,13 @@
         // Create README.md
         FileUtils.writeStringToFile(new File(tmpdir, "README.md"),
           if(form.description.nonEmpty){
-            form.name + "\n===============\n\n" + form.description.get
+            form.name + "\n" +
+            "===============\n" +
+            "\n" +
+            form.description.get
           } else {
-            form.name + "\n===============\n"
+            form.name + "\n" +
+            "===============\n"
           }, "UTF-8")
 
         val git = Git.open(tmpdir)
@@ -95,7 +93,7 @@
     recordCreateRepositoryActivity(loginUserName, form.name, loginUserName)
 
     // redirect to the repository
-    redirect("/%s/%s".format(loginUserName, form.name))
+    redirect(s"/${loginUserName}/${form.name}")
   })
   
   /**
diff --git a/src/main/scala/app/IndexController.scala b/src/main/scala/app/IndexController.scala
index 7eff0cd..c16873b 100644
--- a/src/main/scala/app/IndexController.scala
+++ b/src/main/scala/app/IndexController.scala
@@ -9,10 +9,13 @@
   with SystemSettingsService with ActivityService =>
   
   get("/"){
+    val loginAccount = context.loginAccount
+
     html.index(getRecentActivities(),
-      getAccessibleRepositories(context.loginAccount, baseUrl),
+      getAccessibleRepositories(loginAccount, baseUrl),
       loadSystemSettings(),
-      context.loginAccount.map{ account => getRepositoryNamesOfUser(account.userName) }.getOrElse(Nil))
+      loginAccount.map{ account => getRepositoryNamesOfUser(account.userName) }.getOrElse(Nil)
+    )
   }
 
 }
\ No newline at end of file
diff --git a/src/main/scala/app/LabelsController.scala b/src/main/scala/app/LabelsController.scala
index e01c63e..e666d67 100644
--- a/src/main/scala/app/LabelsController.scala
+++ b/src/main/scala/app/LabelsController.scala
@@ -24,7 +24,7 @@
 
   post("/:owner/:repository/issues/label/new", newForm)(collaboratorsOnly { (form, repository) =>
     createLabel(repository.owner, repository.name, form.labelName, form.color.substring(1))
-    redirect("/%s/%s/issues".format(repository.owner, repository.name))
+    redirect(s"/${repository.owner}/${repository.name}/issues")
   })
 
   ajaxGet("/:owner/:repository/issues/label/edit")(collaboratorsOnly { repository =>
@@ -53,9 +53,9 @@
   private def labelName: Constraint = new Constraint(){
     def validate(name: String, value: String): Option[String] =
       if(!value.matches("^[^,]+$")){
-        Some("%s contains invalid character.".format(name))
+        Some(s"${name} contains invalid character.")
       } else if(value.startsWith("_") || value.startsWith("-")){
-        Some("%s starts with invalid character.".format(name))
+        Some(s"${name} starts with invalid character.")
       } else {
         None
       }
diff --git a/src/main/scala/app/MilestonesController.scala b/src/main/scala/app/MilestonesController.scala
index 480b8bc..55c60d0 100644
--- a/src/main/scala/app/MilestonesController.scala
+++ b/src/main/scala/app/MilestonesController.scala
@@ -35,7 +35,7 @@
 
   post("/:owner/:repository/issues/milestones/new", milestoneForm)(collaboratorsOnly { (form, repository) =>
     createMilestone(repository.owner, repository.name, form.title, form.description, form.dueDate)
-    redirect("/%s/%s/issues/milestones".format(repository.owner, repository.name))
+    redirect(s"/${repository.owner}/${repository.name}/issues/milestones")
   })
 
   get("/:owner/:repository/issues/milestones/:milestoneId/edit")(collaboratorsOnly { repository =>
@@ -45,28 +45,28 @@
   post("/:owner/:repository/issues/milestones/:milestoneId/edit", milestoneForm)(collaboratorsOnly { (form, repository) =>
     getMilestone(repository.owner, repository.name, params("milestoneId").toInt).map { milestone =>
       updateMilestone(milestone.copy(title = form.title, description = form.description, dueDate = form.dueDate))
-      redirect("/%s/%s/issues/milestones".format(repository.owner, repository.name))
+      redirect(s"/${repository.owner}/${repository.name}/issues/milestones")
     } getOrElse NotFound
   })
 
   get("/:owner/:repository/issues/milestones/:milestoneId/close")(collaboratorsOnly { repository =>
     getMilestone(repository.owner, repository.name, params("milestoneId").toInt).map { milestone =>
       closeMilestone(milestone)
-      redirect("/%s/%s/issues/milestones".format(repository.owner, repository.name))
+      redirect(s"/${repository.owner}/${repository.name}/issues/milestones")
     } getOrElse NotFound
   })
 
   get("/:owner/:repository/issues/milestones/:milestoneId/open")(collaboratorsOnly { repository =>
     getMilestone(repository.owner, repository.name, params("milestoneId").toInt).map { milestone =>
       openMilestone(milestone)
-      redirect("/%s/%s/issues/milestones".format(repository.owner, repository.name))
+      redirect(s"/${repository.owner}/${repository.name}/issues/milestones")
     } getOrElse NotFound
   })
 
   get("/:owner/:repository/issues/milestones/:milestoneId/delete")(collaboratorsOnly { repository =>
     getMilestone(repository.owner, repository.name, params("milestoneId").toInt).map { milestone =>
       deleteMilestone(repository.owner, repository.name, milestone.milestoneId)
-      redirect("/%s/%s/issues/milestones".format(repository.owner, repository.name))
+      redirect(s"/${repository.owner}/${repository.name}/issues/milestones")
     } getOrElse NotFound
   })
 
diff --git a/src/main/scala/app/RepositorySettingsController.scala b/src/main/scala/app/RepositorySettingsController.scala
index a5c79b4..08f6474 100644
--- a/src/main/scala/app/RepositorySettingsController.scala
+++ b/src/main/scala/app/RepositorySettingsController.scala
@@ -31,7 +31,7 @@
    * Redirect to the Options page.
    */
   get("/:owner/:repository/settings")(ownerOnly { repository =>
-    redirect("/%s/%s/settings/options".format(repository.owner, repository.name))
+    redirect(s"/${repository.owner}/${repository.name}/settings/options")
   })
   
   /**
@@ -47,7 +47,7 @@
   post("/:owner/:repository/settings/options", optionsForm)(ownerOnly { (form, repository) =>
     saveRepositoryOptions(repository.owner, repository.name, form.description, form.defaultBranch, form.isPrivate)
     flash += "info" -> "Repository settings has been updated."
-    redirect("/%s/%s/settings/options".format(repository.owner, repository.name))
+    redirect(s"/${repository.owner}/${repository.name}/settings/options")
   })
   
   /**
@@ -70,7 +70,7 @@
    */
   post("/:owner/:repository/settings/collaborators/add", collaboratorForm)(ownerOnly { (form, repository) =>
     addCollaborator(repository.owner, repository.name, form.userName)
-    redirect("/%s/%s/settings/collaborators".format(repository.owner, repository.name))
+    redirect(s"/${repository.owner}/${repository.name}/settings/collaborators")
   })
 
   /**
@@ -78,7 +78,7 @@
    */
   get("/:owner/:repository/settings/collaborators/remove")(ownerOnly { repository =>
     removeCollaborator(repository.owner, repository.name, params("name"))
-    redirect("/%s/%s/settings/collaborators".format(repository.owner, repository.name))
+    redirect(s"/${repository.owner}/${repository.name}/settings/collaborators")
   })
 
   /**
@@ -98,7 +98,7 @@
     FileUtils.deleteDirectory(getWikiRepositoryDir(repository.owner, repository.name))
     FileUtils.deleteDirectory(getTemporaryDir(repository.owner, repository.name))
 
-    redirect("/%s".format(repository.owner))
+    redirect(s"/${repository.owner}")
   })
 
   /**
diff --git a/src/main/scala/app/RepositoryViewerController.scala b/src/main/scala/app/RepositoryViewerController.scala
index 4ba43cb..a70c254 100644
--- a/src/main/scala/app/RepositoryViewerController.scala
+++ b/src/main/scala/app/RepositoryViewerController.scala
@@ -58,13 +58,14 @@
   get("/:owner/:repository/commits/:branch")(referrersOnly { repository =>
     val branchName = params("branch")
     val page       = params.getOrElse("page", "1").toInt
-
     JGitUtil.withGit(getRepositoryDir(repository.owner, repository.name)){ git =>
-      val (logs, hasNext) = JGitUtil.getCommitLog(git, branchName, page, 30)
-
-      repo.html.commits(Nil, branchName, repository, logs.splitWith{ (commit1, commit2) =>
-        view.helpers.date(commit1.time) == view.helpers.date(commit2.time)
-      }, page, hasNext)
+      JGitUtil.getCommitLog(git, branchName, page, 30) match {
+        case Right((logs, hasNext)) =>
+          repo.html.commits(Nil, branchName, repository, logs.splitWith{ (commit1, commit2) =>
+            view.helpers.date(commit1.time) == view.helpers.date(commit2.time)
+          }, page, hasNext)
+        case Left(_) => NotFound
+      }
     }
   })
   
@@ -77,12 +78,14 @@
     val page       = params.getOrElse("page", "1").toInt
 
     JGitUtil.withGit(getRepositoryDir(repository.owner, repository.name)){ git =>
-      val (logs, hasNext) = JGitUtil.getCommitLog(git, branchName, page, 30, path)
-
-      repo.html.commits(path.split("/").toList, branchName, repository,
-        logs.splitWith{ (commit1, commit2) =>
-          view.helpers.date(commit1.time) == view.helpers.date(commit2.time)
-        }, page, hasNext)
+      JGitUtil.getCommitLog(git, branchName, page, 30, path) match {
+        case Right((logs, hasNext)) =>
+          repo.html.commits(path.split("/").toList, branchName, repository,
+            logs.splitWith{ (commit1, commit2) =>
+              view.helpers.date(commit1.time) == view.helpers.date(commit2.time)
+            }, page, hasNext)
+        case Left(_) => NotFound
+      }
     }
   })
 
@@ -214,27 +217,23 @@
       repo.html.guide(repository)
     } else {
       JGitUtil.withGit(getRepositoryDir(repository.owner, repository.name)){ git =>
+        val revisions = Seq(if(revstr.isEmpty) repository.repository.defaultBranch else revstr, repository.branchList.head)
         // get specified commit
-        val (revCommit, revision) = try {
-          val revision = if(revstr.isEmpty) repository.repository.defaultBranch else revstr
-          (JGitUtil.getRevCommitFromId(git, git.getRepository.resolve(revision)), revision)
-        } catch {
-          case e: NullPointerException => {
-            val revision = repository.branchList.head
-            (JGitUtil.getRevCommitFromId(git, git.getRepository.resolve(revision)), revision)
-          }
-        }
-        // get files
-        val files = JGitUtil.getFileList(git, revision, path)
-        // process README.md
-        val readme = files.find(_.name == "README.md").map { file =>
-          new String(JGitUtil.getContent(Git.open(getRepositoryDir(repository.owner, repository.name)), file.id, true).get, "UTF-8")
-        }
+        revisions.map { rev => (git.getRepository.resolve(rev), rev)}.find(_._1 != null).map { case (objectId, revision) =>
+          val revCommit = JGitUtil.getRevCommitFromId(git, objectId)
 
-        repo.html.files(revision, repository,
-          if(path == ".") Nil else path.split("/").toList, // current path
-          new JGitUtil.CommitInfo(revCommit), // latest commit
-          files, readme)
+          // get files
+          val files = JGitUtil.getFileList(git, revision, path)
+          // process README.md
+          val readme = files.find(_.name == "README.md").map { file =>
+            new String(JGitUtil.getContent(Git.open(getRepositoryDir(repository.owner, repository.name)), file.id, true).get, "UTF-8")
+          }
+
+          repo.html.files(revision, repository,
+            if(path == ".") Nil else path.split("/").toList, // current path
+            new JGitUtil.CommitInfo(revCommit), // latest commit
+            files, readme)
+        } getOrElse NotFound
       }
     }
   }
diff --git a/src/main/scala/app/WikiController.scala b/src/main/scala/app/WikiController.scala
index 405733d..d746367 100644
--- a/src/main/scala/app/WikiController.scala
+++ b/src/main/scala/app/WikiController.scala
@@ -32,7 +32,7 @@
   get("/:owner/:repository/wiki")(referrersOnly { repository =>
     getWikiPage(repository.owner, repository.name, "Home").map { page =>
       wiki.html.page("Home", page, repository, hasWritePermission(repository.owner, repository.name, context.loginAccount))
-    } getOrElse redirect("/%s/%s/wiki/Home/_edit".format(repository.owner, repository.name))
+    } getOrElse redirect(s"/${repository.owner}/${repository.name}/wiki/Home/_edit")
   })
   
   get("/:owner/:repository/wiki/:page")(referrersOnly { repository =>
@@ -40,14 +40,17 @@
 
     getWikiPage(repository.owner, repository.name, pageName).map { page =>
       wiki.html.page(pageName, page, repository, hasWritePermission(repository.owner, repository.name, context.loginAccount))
-    } getOrElse redirect("/%s/%s/wiki/%s/_edit".format(repository.owner, repository.name, pageName)) // TODO URLEncode
+    } getOrElse redirect(s"/${repository.owner}/${repository.name}/wiki/${pageName}/_edit") // TODO URLEncode
   })
   
   get("/:owner/:repository/wiki/:page/_history")(referrersOnly { repository =>
     val pageName = params("page")
 
     JGitUtil.withGit(getWikiRepositoryDir(repository.owner, repository.name)){ git =>
-      wiki.html.history(Some(pageName), JGitUtil.getCommitLog(git, "master", path = pageName + ".md")._1, repository)
+      JGitUtil.getCommitLog(git, "master", path = pageName + ".md") match {
+        case Right((logs, hasNext)) => wiki.html.history(Some(pageName), logs, repository)
+        case Left(_) => NotFound
+      }
     }
   })
   
@@ -82,7 +85,7 @@
     updateLastActivityDate(repository.owner, repository.name)
     recordEditWikiPageActivity(repository.owner, repository.name, loginAccount.userName, form.pageName)
 
-    redirect("/%s/%s/wiki/%s".format(repository.owner, repository.name, form.pageName))
+    redirect(s"/${repository.owner}/${repository.name}/wiki/${form.pageName}")
   })
   
   get("/:owner/:repository/wiki/_new")(collaboratorsOnly {
@@ -98,16 +101,16 @@
     updateLastActivityDate(repository.owner, repository.name)
     recordCreateWikiPageActivity(repository.owner, repository.name, loginAccount.userName, form.pageName)
 
-    redirect("/%s/%s/wiki/%s".format(repository.owner, repository.name, form.pageName))
+    redirect(s"/${repository.owner}/${repository.name}/wiki/${form.pageName}")
   })
   
   get("/:owner/:repository/wiki/:page/_delete")(collaboratorsOnly { repository =>
     val pageName = params("page")
     
-    deleteWikiPage(repository.owner, repository.name, pageName, context.loginAccount.get.userName, "Delete %s".format(pageName))
+    deleteWikiPage(repository.owner, repository.name, pageName, context.loginAccount.get.userName, s"Delete ${pageName}")
     updateLastActivityDate(repository.owner, repository.name)
 
-    redirect("/%s/%s/wiki".format(repository.owner, repository.name))
+    redirect(s"/${repository.owner}/${repository.name}/wiki")
   })
   
   get("/:owner/:repository/wiki/_pages")(referrersOnly { repository =>
@@ -117,7 +120,10 @@
   
   get("/:owner/:repository/wiki/_history")(referrersOnly { repository =>
     JGitUtil.withGit(getWikiRepositoryDir(repository.owner, repository.name)){ git =>
-      wiki.html.history(None, JGitUtil.getCommitLog(git, "master")._1, repository)
+      JGitUtil.getCommitLog(git, "master") match {
+        case Right((logs, hasNext)) => wiki.html.history(None, logs, repository)
+        case Left(_) => NotFound
+      }
     }
   })
 
diff --git a/src/main/scala/service/WikiService.scala b/src/main/scala/service/WikiService.scala
index 76d742c..8c02515 100644
--- a/src/main/scala/service/WikiService.scala
+++ b/src/main/scala/service/WikiService.scala
@@ -68,12 +68,10 @@
     lock(owner.userName, repository){
       val dir = Directory.getWikiRepositoryDir(owner.userName, repository)
       if(!dir.exists){
-        val repo = new RepositoryBuilder().setGitDir(dir).setBare.build
         try {
-          repo.create
-          saveWikiPage(owner.userName, repository, "Home", "Home", "Welcome to the %s wiki!!".format(repository), owner, "Initial Commit")
+          JGitUtil.initRepository(dir)
+          saveWikiPage(owner.userName, repository, "Home", "Home", s"Welcome to the ${repository} wiki!!", owner, "Initial Commit")
         } finally {
-          repo.close
           // once delete cloned repository because initial cloned repository does not have 'branch.master.merge'
           FileUtils.deleteDirectory(Directory.getWikiWorkDir(owner.userName, repository))
         }
diff --git a/src/main/scala/servlet/AutoUpdateListener.scala b/src/main/scala/servlet/AutoUpdateListener.scala
index 266e617..dbfe8cb 100644
--- a/src/main/scala/servlet/AutoUpdateListener.scala
+++ b/src/main/scala/servlet/AutoUpdateListener.scala
@@ -25,7 +25,7 @@
      * If corresponding SQL file does not exist, this method do nothing.
      */
     def update(conn: Connection): Unit = {
-      val sqlPath = "update/%d_%d.sql".format(majorVersion, minorVersion)
+      val sqlPath = s"update/${majorVersion}_${minorVersion}.sql"
       val in = Thread.currentThread.getContextClassLoader.getResourceAsStream(sqlPath)
       if(in != null){
         val sql = IOUtils.toString(in, "UTF-8")
@@ -42,7 +42,7 @@
     /**
      * MAJOR.MINOR
      */
-    val versionString = "%d.%d".format(majorVersion, minorVersion)
+    val versionString = s"${majorVersion}.${minorVersion}"
   }
   
   /**
diff --git a/src/main/scala/util/Directory.scala b/src/main/scala/util/Directory.scala
index b378a99..f2b7f4c 100644
--- a/src/main/scala/util/Directory.scala
+++ b/src/main/scala/util/Directory.scala
@@ -13,13 +13,13 @@
 
   val GitBucketConf = new File(GitBucketHome, "gitbucket.conf")
   
-  val RepositoryHome = "%s/repositories".format(GitBucketHome)
+  val RepositoryHome = s"${GitBucketHome}/repositories"
   
   /**
    * Repository names of the specified user.
    */
   def getRepositories(owner: String): List[String] = {
-    val dir = new File("%s/%s".format(RepositoryHome, owner))
+    val dir = new File(s"${RepositoryHome}/${owner}")
     if(dir.exists){
       dir.listFiles.filter { file =>
         file.isDirectory && !file.getName.endsWith(".wiki.git") 
@@ -33,24 +33,24 @@
    * Substance directory of the repository.
    */
   def getRepositoryDir(owner: String, repository: String): File =
-    new File("%s/%s/%s.git".format(RepositoryHome, owner, repository))
+    new File(s"${RepositoryHome}/${owner}/${repository}.git")
 
   /**
    * Directory for uploaded files by the specified user.
    */
-  def getUserUploadDir(userName: String): File = new File("%s/data/%s/files".format(GitBucketHome, userName))
+  def getUserUploadDir(userName: String): File = new File(s"${GitBucketHome}/data/${userName}/files")
 
   /**
    * Root of temporary directories for the specified repository.
    */
   def getTemporaryDir(owner: String, repository: String): File =
-    new File("%s/tmp/%s/%s".format(GitBucketHome, owner, repository))
+    new File(s"${GitBucketHome}/tmp/${owner}/${repository}")
 
   /**
    * Temporary directory which is used to create an archive to download repository contents.
    */
   def getDownloadWorkDir(owner: String, repository: String, sessionId: String): File = 
-    new File(getTemporaryDir(owner, repository), "download/%s".format(sessionId))
+    new File(getTemporaryDir(owner, repository), s"download/${sessionId}")
   
   /**
    * Temporary directory which is used in the repository creation.
@@ -65,7 +65,7 @@
    * Substance directory of the wiki repository.
    */
   def getWikiRepositoryDir(owner: String, repository: String): File =
-    new File("%s/%s/%s.wiki.git".format(Directory.RepositoryHome, owner, repository))
+    new File(s"${RepositoryHome}/${owner}/${repository}.wiki.git")
   
   /**
    * Wiki working directory which is cloned from the wiki repository.
diff --git a/src/main/scala/util/FileUploadUtil.scala b/src/main/scala/util/FileUploadUtil.scala
index 61f2718..6efacc1 100644
--- a/src/main/scala/util/FileUploadUtil.scala
+++ b/src/main/scala/util/FileUploadUtil.scala
@@ -11,7 +11,7 @@
     new SimpleDateFormat("yyyyMMddHHmmSSsss").format(new java.util.Date(System.currentTimeMillis))
 
   def TemporaryDir(implicit session: HttpSession): java.io.File =
-    new java.io.File(GitBucketHome, "tmp/_upload/%s".format(session.getId))
+    new java.io.File(GitBucketHome, s"tmp/_upload/${session.getId}")
 
   def getTemporaryFile(fileId: String)(implicit session: HttpSession): java.io.File =
     new java.io.File(TemporaryDir, fileId)
diff --git a/src/main/scala/util/JGitUtil.scala b/src/main/scala/util/JGitUtil.scala
index e69fcd3..8d9b6eb 100644
--- a/src/main/scala/util/JGitUtil.scala
+++ b/src/main/scala/util/JGitUtil.scala
@@ -153,7 +153,7 @@
         }
 
         RepositoryInfo(
-          owner, repository, baseUrl + "/git/%s/%s.git".format(owner, repository),
+          owner, repository, s"${baseUrl}/git/${owner}/${repository}.git",
           // commit count
           commitCount,
           // branches
@@ -169,7 +169,7 @@
       } catch {
         // not initialized
         case e: NoHeadException => RepositoryInfo(
-          owner, repository, baseUrl + "/git/%s/%s.git".format(owner, repository), 0, Nil, Nil)
+          owner, repository, s"${baseUrl}/git/${owner}/${repository}.git", 0, Nil, Nil)
 
       }
     }
@@ -253,7 +253,7 @@
    * @param path filters by this path. default is no filter.
    * @return a tuple of the commit list and whether has next
    */
-  def getCommitLog(git: Git, revision: String, page: Int = 1, limit: Int = 0, path: String = ""): (List[CommitInfo], Boolean) = {
+  def getCommitLog(git: Git, revision: String, page: Int = 1, limit: Int = 0, path: String = ""): Either[String, (List[CommitInfo], Boolean)] = {
     val fixedPage = if(page <= 0) 1 else page
     
     @scala.annotation.tailrec
@@ -267,20 +267,25 @@
       }
     
     val revWalk = new RevWalk(git.getRepository)
-    revWalk.markStart(revWalk.parseCommit(git.getRepository.resolve(revision)))
-    if(path.nonEmpty){
-      revWalk.setRevFilter(new RevFilter(){
-        def include(walk: RevWalk, commit: RevCommit): Boolean = {
-          getDiffs(git, commit.getName, false).find(_.newPath == path).nonEmpty
-        }
-        override def clone(): RevFilter = this
-      })
+    val objectId = git.getRepository.resolve(revision)
+    if(objectId == null){
+      Left(s"${revision} can't be resolved.")
+    } else {
+      revWalk.markStart(revWalk.parseCommit(objectId))
+      if(path.nonEmpty){
+        revWalk.setRevFilter(new RevFilter(){
+          def include(walk: RevWalk, commit: RevCommit): Boolean = {
+            getDiffs(git, commit.getName, false).find(_.newPath == path).nonEmpty
+          }
+          override def clone(): RevFilter = this
+        })
+      }
+
+      val commits = getCommitLog(revWalk.iterator, 0, Nil)
+      revWalk.release
+
+      Right(commits)
     }
-    
-    val commits = getCommitLog(revWalk.iterator, 0, Nil)
-    revWalk.release
-    
-    commits
   }
   
   /**
@@ -502,4 +507,20 @@
     }
   }
 
+  def initRepository(dir: java.io.File): Unit = {
+    val repository = new RepositoryBuilder().setGitDir(dir).setBare.build
+    try {
+      repository.create
+      setReceivePack(repository)
+    } finally {
+      repository.close
+    }
+  }
+
+  private def setReceivePack(repository: org.eclipse.jgit.lib.Repository): Unit = {
+    val config = repository.getConfig
+    config.setBoolean("http", null, "receivepack", true)
+    config.save
+  }
+
 }
\ No newline at end of file
diff --git a/src/main/scala/util/Validations.scala b/src/main/scala/util/Validations.scala
index a518978..1d42d99 100644
--- a/src/main/scala/util/Validations.scala
+++ b/src/main/scala/util/Validations.scala
@@ -11,9 +11,9 @@
   def identifier: Constraint = new Constraint(){
     def validate(name: String, value: String): Option[String] =
       if(!value.matches("^[a-zA-Z0-9\\-_]+$")){
-        Some("%s contains invalid character.".format(name))
+        Some(s"${name} contains invalid character.")
       } else if(value.startsWith("_") || value.startsWith("-")){
-        Some("%s starts with invalid character.".format(name))
+        Some(s"${name} starts with invalid character.")
       } else {
         None
       }
diff --git a/src/main/scala/view/Markdown.scala b/src/main/scala/view/Markdown.scala
index c8eb148..91c4945 100644
--- a/src/main/scala/view/Markdown.scala
+++ b/src/main/scala/view/Markdown.scala
@@ -101,7 +101,7 @@
   override def visit(node: TextNode) {
     // convert commit id to link.
     val text = if(enableCommitLink) node.getText.replaceAll("(^|\\W)([0-9a-f]{40})(\\W|$)",
-      "<a href=\"%s/%s/%s/commit/$2\">$2</a>".format(context.path, repository.owner, repository.name))
+      s"""<a href="${context.path}/${repository.owner}/${repository.name}/commit/$$2">$$2</a>""")
     else node.getText
 
     if (abbreviations.isEmpty) {
@@ -116,7 +116,7 @@
     if(enableIssueLink && text.matches("#[\\d]+")){
       // convert issue id to link
       val issueId = text.substring(1).toInt
-      printer.print("<a href=\"%s/%s/%s/issues/%d\">#%d</a>".format(context.path, repository.owner, repository.name, issueId, issueId))
+      printer.print(s"""<a href="${context.path}/${repository.owner}/${repository.name}/issues/${issueId}">#${issueId}</a>""")
     } else {
       printTag(node, "h" + node.getLevel)
     }
diff --git a/src/main/scala/view/helpers.scala b/src/main/scala/view/helpers.scala
index b12f644..d80a4d8 100644
--- a/src/main/scala/view/helpers.scala
+++ b/src/main/scala/view/helpers.scala
@@ -35,9 +35,7 @@
     Html(Markdown.toHtml(value, repository, enableWikiLink, enableCommitLink, enableIssueLink))
   }
 
-  def activityMessage(message: String)(implicit context: app.Context): Html = {
-    val a = s"a $message aa $$1 a"
-    
+  def activityMessage(message: String)(implicit context: app.Context): Html =
     Html(message
       .replaceAll("\\[issue:([^\\s]+?)/([^\\s]+?)#((\\d+))\\]"   , s"""<a href="${context.path}/$$1/$$2/issues/$$3">$$1/$$2#$$3</a>""")
       .replaceAll("\\[repo:([^\\s]+?)/([^\\s]+?)\\]"             , s"""<a href="${context.path}/$$1/$$2\">$$1/$$2</a>""")
@@ -45,23 +43,24 @@
       .replaceAll("\\[tag:([^\\s]+?)/([^\\s]+?)#([^\\s]+?)\\]"   , s"""<a href="${context.path}/$$1/$$2/tree/$$3">$$3</a>""")
       .replaceAll("\\[user:([^\\s]+?)\\]"                        , s"""<a href="${context.path}/$$1">$$1</a>""")
     )
-  }
 
   /**
    * Generates the url to the repository.
    */
   def url(repository: service.RepositoryService.RepositoryInfo)(implicit context: app.Context): String =
-    "%s/%s/%s".format(context.path, repository.owner, repository.name)
+    s"${context.path}/${repository.owner}/${repository.name}"
 
   /**
    * Generates the url to the account page.
    */
-  def url(userName: String)(implicit context: app.Context): String = "%s/%s".format(context.path, userName)
+  def url(userName: String)(implicit context: app.Context): String =
+    s"${context.path}/${userName}"
 
   /**
    * Returns the url to the root of assets.
    */
-  def assets(implicit context: app.Context): String = "%s/assets".format(context.path)
+  def assets(implicit context: app.Context): String =
+    s"${context.path}/assets"
 
   /**
    * Converts issue id and commit id to link.
@@ -71,9 +70,9 @@
       // escape HTML tags
       .replaceAll("&", "&amp;").replaceAll("<", "&lt;").replaceAll(">", "&gt;").replaceAll("\"", "&quot;")
       // convert issue id to link
-      .replaceAll("(^|\\W)#(\\d+)(\\W|$)", "$1<a href=\"%s/%s/%s/issues/$2\">#$2</a>$3".format(context.path, repository.owner, repository.name))
+      .replaceAll("(^|\\W)#(\\d+)(\\W|$)", s"""$$1<a href="${context.path}/${repository.owner}/${repository.name}/issues/$$2">#$$2</a>$$3""")
       // convert commit id to link
-      .replaceAll("(^|\\W)([a-f0-9]{40})(\\W|$)", "$1<a href=\"%s/%s/%s/commit/$2\">$2</a>$3").format(context.path, repository.owner, repository.name))
+      .replaceAll("(^|\\W)([a-f0-9]{40})(\\W|$)", s"""$$1<a href="${context.path}/${repository.owner}/${repository.name}/commit/$$2">$$2</a>$$3"""))
 
 
   /**
diff --git a/src/main/twirl/helper/activities.scala.html b/src/main/twirl/helper/activities.scala.html
index 93519b4..6b1662c 100644
--- a/src/main/twirl/helper/activities.scala.html
+++ b/src/main/twirl/helper/activities.scala.html
@@ -14,10 +14,10 @@
       @activity.additionalInfo.map { additionalInfo =>
         @(activity.activityType match {
           case "create_wiki" => {
-            <div class="small activity-message">Created <a href={"%s/%s/%s/wiki/%s".format(path, activity.userName, activity.repositoryName, additionalInfo)}>{additionalInfo}</a>.</div>
+            <div class="small activity-message">Created <a href={s"${path}/${activity.userName}/${activity.repositoryName}/wiki/${additionalInfo}"}>{additionalInfo}</a>.</div>
           }
           case "edit_wiki" => {
-            <div class="small activity-message">Edited <a href={"%s/%s/%s/wiki/%s".format(path, activity.userName, activity.repositoryName, additionalInfo)}>{additionalInfo}</a>.</div>
+            <div class="small activity-message">Edited <a href={s"${path}/${activity.userName}/${activity.repositoryName}/wiki/${additionalInfo}"}>{additionalInfo}</a>.</div>
           }
           case "push" => {
             <div class="small activity-message">
@@ -26,7 +26,7 @@
                   <div>...</div>
                 } else {
                   <div>
-                    <a href={"%s/%s/%s/commit/%s".format(path, activity.userName, activity.repositoryName, commit.substring(0, 40))} class="monospace">{commit.substring(0, 7)}</a>
+                    <a href={s"${path}/${activity.userName}/${activity.repositoryName}/commit/${commit.substring(0, 40)}"} class="monospace">{commit.substring(0, 7)}</a>
                     <span>{commit.substring(41)}</span>
                   </div>
                 }