Start to implement database migration.

src/main/scala/util/Migration.scala

@@ -0,0 +1,65 @@
+package util
+
+import java.io._
+import org.apache.commons.io.FileUtils
+
+object Migration {
+  
+  /**
+   * Define Migrator interface.
+   */
+  trait Migrator {
+    def migrate(): Unit
+  }
+  
+  /**
+   * Migrate H2 database by SQL files.
+   */
+  case class DatabaseMigrator(sqlPath: String) extends Migrator {
+    def migrate(): Unit = {
+      // TODO
+    }
+  }
+  
+  case class Version(majorVersion: Int, minorVersion: Int, migrators: Migrator*)
+  
+  /**
+   * The history of versions. A head of this sequence is the current BitBucket version.
+   * Migration#migrate() updates the data directory to move to the head version.
+   */
+  val versions = Seq(
+      Version(1, 0, DatabaseMigrator("migration/1.0/createdb.sql"))
+  )
+  
+  /**
+   * The head version of BitBucket.
+   */
+  val headVersion = versions.head
+  
+  /**
+   * The version file (GITBUCKET_HOME/version).
+   */
+  val versionFile = new File(Directory.GitBucketHome, "version")
+  
+  /**
+   * Returns the current version
+   */
+  def getCurrentVersion(): Version = {
+    FileUtils.readFileToString(versionFile).split(".") match {
+      case Array(majorVersion, minorVersion) => {
+        versions.find { v => v.majorVersion == majorVersion.toInt && v.minorVersion == minorVersion.toInt }.get
+      }
+    }
+  }
+  
+  /**
+   * Do migrate old data directory to the head version.
+   */
+  def migrate(): Unit = {
+    val currentVersion = getCurrentVersion()
+    versions.takeWhile(_ != currentVersion).reverse.foreach(_.migrators.foreach(_.migrate()))
+    FileUtils.writeStringToFile(versionFile, headVersion.majorVersion + "." + headVersion.minorVersion)
+  }
+  
+  
+}