MkDir command implementation

Author: geektimus

filesystem/src/main/scala/com/codingmaniacs/scala/exercises/fs/State.scala

@@ -24,7 +24,10 @@ package com.codingmaniacs.scala.exercises.fs
 import com.codingmaniacs.scala.exercises.fs.directories.Directory
 
 class State(val root: Directory, val workingDir: Directory, val output: String) {
-  def show(): Unit = print(State.SHELL_PROMPT)
+
+  def show(): Unit =
+    println(output)
+  print(State.SHELL_PROMPT)
 
   def setMessage(message: String): State = State(root, workingDir, message)
 }

filesystem/src/main/scala/com/codingmaniacs/scala/exercises/fs/commands/Command.scala

@@ -29,8 +29,29 @@ trait Command {
 
 object Command {
 
+  val MKDIR = "mkdir"
+
+  def emptyCommand: Command = new Command {
+    override def apply(state: State): State = state
+  }
+
+  def incompleteCommand(name: String): Command = new Command {
+    override def apply(state: State): State =
+      state.setMessage(s"$name is an incomplete command")
+  }
+
   def from(input: String): Command = {
-    print(input)
-    new UnknownCommand
+    val tokens = input.split(" ")
+    if (input.isEmpty || tokens.isEmpty) {
+      emptyCommand
+    } else if (MKDIR.equals(tokens(0))) {
+      if (tokens.length < 2) {
+        incompleteCommand(MKDIR)
+      } else {
+        new MkDir(tokens(1))
+      }
+    } else {
+      new UnknownCommand
+    }
   }
 }

filesystem/src/main/scala/com/codingmaniacs/scala/exercises/fs/commands/MkDir.scala

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2019 Geektimus
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package com.codingmaniacs.scala.exercises.fs.commands
+
+import com.codingmaniacs.scala.exercises.fs.State
+import com.codingmaniacs.scala.exercises.fs.directories.{ DirEntry, Directory }
+
+class MkDir(name: String) extends Command {
+
+  def updateStructure(currentDir: Directory, paths: List[String], newEntry: DirEntry): Directory =
+    if (paths.isEmpty) {
+      currentDir.addEntry(newEntry)
+    } else {
+      val oldEntry = currentDir.findEntry(paths.head).asDirectory
+      currentDir.replaceEntry(oldEntry.name, updateStructure(oldEntry, paths.tail, newEntry))
+    }
+
+  override def apply(state: State): State = {
+    val wd = state.workingDir
+    if (wd.hasEntry(name)) {
+      state.setMessage(s"$name already exists")
+    } else if (name.contains(Directory.SEPARATOR)) {
+      state.setMessage(s"$name must not contain separators")
+    } else if (checkIllegal(name)) {
+      state.setMessage(s"$name: illegal entry name!")
+    } else {
+      performMkDir(state, name)
+    }
+  }
+
+  def checkIllegal(name: String): Boolean =
+    name.contains(".")
+
+  def performMkDir(state: State, name: String): State = {
+    val wd = state.workingDir
+
+    val filesInFolder = wd.getAllFoldersInPath
+
+    val newDir = Directory.empty(wd.path, name)
+
+    val newRoot = updateStructure(state.root, filesInFolder, newDir)
+
+    val newWD = newRoot.findDescendant(filesInFolder)
+
+    State(newRoot, newWD)
+
+  }
+}

filesystem/src/main/scala/com/codingmaniacs/scala/exercises/fs/directories/DirEntry.scala

@@ -21,4 +21,8 @@
 
 package com.codingmaniacs.scala.exercises.fs.directories
 
-abstract class DirEntry(val parentPath: String, val name: String)
+abstract class DirEntry(val parentPath: String, val name: String) {
+  def path: String = s"$parentPath${Directory.SEPARATOR}$name"
+
+  def asDirectory: Directory
+}

filesystem/src/main/scala/com/codingmaniacs/scala/exercises/fs/directories/Directory.scala

@@ -21,11 +21,43 @@
 
 package com.codingmaniacs.scala.exercises.fs.directories
 
+import scala.annotation.tailrec
+
 class Directory(
   override val parentPath: String,
   override val name: String,
   val contents: List[DirEntry]
-) extends DirEntry(parentPath, name)
+) extends DirEntry(parentPath, name) {
+
+  def hasEntry(name: String): Boolean = findEntry(name) != null
+
+  def getAllFoldersInPath: List[String] =
+    path.substring(1).split(Directory.SEPARATOR).toList.filter(p => !p.isEmpty)
+
+  def findDescendant(paths: List[String]): Directory =
+    if (paths.isEmpty) this
+    else findEntry(paths.head).asDirectory.findDescendant(paths.tail)
+
+  def addEntry(newEntry: DirEntry): Directory =
+    new Directory(parentPath, name, contents :+ newEntry)
+
+  def findEntry(entryName: String): DirEntry = {
+
+    @tailrec
+    def findEntryHelper(name: String, contentsList: List[DirEntry]): DirEntry =
+      if (contentsList.isEmpty) {
+        null
+      } else if (contentsList.head.name.equals(name)) {
+        contentsList.headOption.get
+      } else findEntryHelper(name, contentsList.tail)
+    findEntryHelper(entryName, contents)
+  }
+
+  def replaceEntry(entryName: String, newEntry: Directory): Directory =
+    new Directory(parentPath, name, contents.filter(p => !p.name.equals(entryName)) :+ newEntry)
+
+  override def asDirectory: Directory = this
+}
 
 object Directory {
   val SEPARATOR = "/"