--gc.

modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/Args.kt

@@ -26,6 +26,9 @@ class Args {
             "actually running them")
     var dryRun: Boolean = false
 
+    @Parameter(names = arrayOf("--gc"), description = "Delete old files")
+    var gc: Boolean = false
+
     @Parameter(names = arrayOf("--help", "--usage"), description = "Display the help")
     var usage: Boolean = false
 

modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/misc/Io.kt

@@ -0,0 +1,68 @@
+package com.beust.kobalt.misc
+
+import java.io.File
+import java.nio.file.Files
+import java.nio.file.Paths
+import java.nio.file.StandardCopyOption
+
+class Io(val dryRun: Boolean = false) {
+    fun mkdirs(dir: String) {
+        log("mkdirs $dir")
+        if (! dryRun) {
+            File(dir).mkdirs()
+        }
+    }
+
+    fun rm(path: String) {
+        log("rm $path")
+
+        if (! dryRun) {
+            File(path).deleteRecursively()
+        }
+    }
+
+    fun moveFile(from: File, toDir: File) {
+        log("mv $from $toDir")
+        if (! dryRun) {
+            require(from.exists(), { -> "$from should exist" })
+            require(from.isFile, { -> "$from should be a file" })
+            require(toDir.isDirectory, { -> "$toDir should be a file"})
+
+            val toFile = File(toDir, from.name)
+            Files.move(Paths.get(from.absolutePath), Paths.get(toFile.absolutePath), StandardCopyOption.ATOMIC_MOVE)
+        }
+    }
+
+    fun copyDirectory(from: File, toDir: File) {
+        log("cp -r $from $toDir")
+
+        if (! dryRun) {
+            KFiles.copyRecursively(from, toDir)
+            require(from.exists(), { -> "$from should exist" })
+            require(from.isDirectory, { -> println("$from should be a directory")})
+            require(toDir.isDirectory, { -> println("$toDir should be a file")})
+
+        }
+    }
+
+    fun rmDir(dir: File) {
+        log("rm -rf $dir")
+
+        if (! dryRun) {
+            require(dir.isDirectory,  { -> println("$dir should be a directory")})
+            dir.deleteRecursively()
+        }
+    }
+
+    fun mkdir(dir: File) {
+        log("rm -rf $dir")
+        if (! dryRun) {
+            dir.mkdirs()
+        }
+    }
+
+    private fun log(s: String) {
+        log(1, "[Io] $s")
+    }
+
+}

src/main/kotlin/com/beust/kobalt/Main.kt

@@ -9,6 +9,7 @@ import com.beust.kobalt.app.*
 import com.beust.kobalt.app.remote.DependencyData
 import com.beust.kobalt.app.remote.KobaltClient
 import com.beust.kobalt.app.remote.KobaltServer
+import com.beust.kobalt.internal.Gc
 import com.beust.kobalt.internal.KobaltSettings
 import com.beust.kobalt.internal.PluginInfo
 import com.beust.kobalt.internal.TaskManager
@@ -169,7 +170,9 @@ private class Main @Inject constructor(
             server.run()
         } else {
             // Options that don't need Build.kt to be parsed first
-            if (args.update) {
+            if (args.gc) {
+                Gc().run()
+            } else if (args.update) {
                 // --update
                 updateKobalt.updateKobalt()
             } else {

src/main/kotlin/com/beust/kobalt/internal/Gc.kt

@@ -0,0 +1,41 @@
+package com.beust.kobalt.internal
+
+import com.beust.kobalt.api.Kobalt
+import com.beust.kobalt.misc.Io
+import com.beust.kobalt.misc.KFiles
+import java.io.File
+import java.nio.file.Files
+
+/**
+ * Clean up old Kobalt files.
+ */
+class Gc {
+    fun run() {
+        // Delete all the distributions except the current one
+        val dist = KFiles.distributionsDir
+        val version = Kobalt.version
+        val tmpDir = Files.createTempDirectory("kobalt")
+
+        // Zipfile
+        val io = Io(dryRun = true)
+        val zipFileName = "kobalt-$version.zip"
+        io.moveFile(File(KFiles.joinDir(dist, zipFileName)), tmpDir.toFile())
+
+        // Distribution directory
+        val zipDirectoryName = "kobalt-$version"
+        val zipDirectory = File(KFiles.joinDir(dist, zipDirectoryName))
+        io.copyDirectory(zipDirectory, tmpDir.toFile())
+
+        // Delete the whole dist directory and recreate it
+        File(dist).let { distFile ->
+            io.rmDir(distFile)
+            io.mkdir(distFile)
+
+            // Copy the files back
+            tmpDir.toFile().absolutePath.let { fromPath ->
+                io.moveFile(File(KFiles.joinDir(fromPath, zipFileName)), distFile)
+                io.copyDirectory(File(KFiles.joinDir(fromPath, zipDirectoryName)), distFile)
+            }
+        }
+    }
+}