import better.files._

def run(inputDir: File, outputDir: File, n: Int) = {
  val count = new AtomicInteger()
  val outputs = Vector.tabulate(n)(i => outputDir / s"part-$i.csv.gz")
  for {
    writers <- outputs.map(_.newGzipOutputStream().printWriter()).autoClosed
    inputFile <- inputDir.list(_.extension == Some(".csv")).toSeq.sorted(File.Order.bySize)
    line <- inputFile.lineIterator.drop(1)
  } writers(count.incrementAndGet() % n).println(line)
}

libraryDependencies += "com.github.pathikrit" %% "better-files" % version

import mill._, scalalib._

object moduleName extends ScalaModule {
  override def ivyDeps = Agg(
    ivy"com.github.pathikrit::better-files:${version}"
  )
}

import better.files._
import File._
import java.io.{File => JFile}

val f = File("/User/johndoe/Documents")                      // using constructor
val f1: File = file"/User/johndoe/Documents"                 // using string interpolator
val f2: File = "/User/johndoe/Documents".toFile              // convert a string path to a file
val f3: File = new JFile("/User/johndoe/Documents").toScala  // convert a Java file to Scala
val f4: File = root/"User"/"johndoe"/"Documents"             // using root helper to start from root
val f5: File = `~` / "Documents"                             // also equivalent to `home / "Documents"`
val f6: File = "/User"/"johndoe"/"Documents"                 // using file separator DSL
val f7: File = "/User"/'johndoe/'Documents                   // same as above but using Symbols instead of Strings
val f8: File = home/"Documents"/"presentations"/`..`         // use `..` to navigate up to parent

import better.files.{File => ScalaFile, _}
import java.io.File

import better.files._
import java.io.{File => JFile}

val file = root/"tmp"/"test.txt"
file.overwrite("hello")
file.appendLine().append("world")
assert(file.contentAsString() == "hello\nworld")

import better.files.Dsl.SymbolicOperations

file < "hello"     // same as file.overwrite("hello")
file << "world"    // same as file.appendLines("world")
assert(file! == "hello\nworld")

import better.files.Dsl.SymbolicOperations

"hello" `>:` file
"world" >>: file
val bytes: Array[Byte] = file.loadBytes

 (root/"tmp"/"diary.txt")
  .createIfNotExists()
  .appendLine()
  .appendLines("My name is", "Inigo Montoya")
  .moveToDirectory(home/"Documents")
  .renameTo("princess_diary.txt")
  .changeExtensionTo(".md")
  .lines()

val resource        : InputStream   = Resource.getAsStream("foo.txt") //Same as this.getClass().getResource("foo.txt")
val resourceURL     : java.net.URL  = Resource.getUrl("foo.txt")
val rootResourceURL : java.net.URL  = Resource.getUrl()
val resourceAsStr   : String        = Resource.getAsString("foo.txt")

val resource        : InputStream   = Resource.at[MyClass].getAsStream("foo.txt")

val bytes  : Iterator[Byte]            = file.bytes()
val chars  : Iterator[Char]            = file.chars()
val lines  : Iterator[String]          = file.lineIterator()     //file.lines loads all lines in memory

file.writeBytes(bytes)
file.printLines(lines)

val s3 = s1 tee s2
s3.printWriter.println(s"Hello world") // gets written to both s1 and s2

val content: String = file.contentAsString()  // default charset

// custom charset:
import java.nio.charset.Charset
file.contentAsString(charset = Charset.forName("US-ASCII"))

//or simply using implicit conversion from Strings
file.write("hello world", charset = "US-ASCII")

file.contentAsString(charset = Charset.forName("UTF-8"))    // Default incorrect JDK behaviour for UTF-8 (see: JDK-4508058)

file.write("hello world", charset = UnicodeCharset("UTF-8", writeByteOrderMarkers = true))

case class Person(name: String, age: Int)
val person = new Person("Chris", 24)

// Write
file.newOutputStream().asObjectOutputStream.serialize(obj).flush()

// Read
val person2 = file.newInputStream().asObjectInputStream.deserialize[Person]
assert(person == person2)

// Read using custom class loader:
file.newInputStream().asObjectInputStreamUsingClassLoader(classLoader = myClassLoader).deserialize[Person]

val person2: Person = file.writeSerialized(person).readDeserialized()
assert(person == person2)

val file: File = tmp / "hello.txt"
val javaFile     : java.io.File                 = file.toJava
val uri          : java.net.URI                 = file.uri
val url          : java.net.URL                 = file.url
val reader       : java.io.BufferedReader       = file.newBufferedReader()
val outputstream : java.io.OutputStream         = file.newOutputStream()
val writer       : java.io.BufferedWriter       = file.newBufferedWriter()
val inputstream  : java.io.InputStream          = file.newInputStream()
val path         : java.nio.file.Path           = file.path
val fs           : java.nio.file.FileSystem     = file.fileSystem
val channel      : java.nio.channel.FileChannel = file.newFileChannel()
val ram          : java.io.RandomAccessFile     = file.newRandomAccess()
val fr           : java.io.FileReader           = file.newFileReader()
val fw           : java.io.FileWriter           = file.newFileWriter(append = true)
val printer      : java.io.PrintWriter          = file.newPrintWriter()

file1.reader() > file2.writer ()      // pipes a reader to a writer
System.in > file2.out             // pipes an inputstream to an outputstream
src.pipeTo(sink)                  // if you don't like symbols

val bytes   : Iterator[Byte]        = inputstream.bytes()
val bis     : BufferedInputStream   = inputstream.buffered()
val bos     : BufferedOutputStream  = outputstream.buffered()
val reader  : InputStreamReader     = inputstream.reader()
val writer  : OutputStreamWriter    = outputstream.writer()
val printer : PrintWriter           = outputstream.printWriter()
val br      : BufferedReader        = reader.buffered()
val bw      : BufferedWriter        = writer.buffered()
val mm      : MappedByteBuffer      = fileChannel.toMappedByteBuffer()
val str     : String                = inputstream.asString()  //Read a string from an InputStream
val in      : InputStream           = str.inputStream()
val reader  : Reader                = str.reader()
val lines   : Seq[String]           = str.lines()

val dir = "src"/"test"
val matches: Iterator[File] = dir.glob("**/*.{java,scala}")
// above code is equivalent to:
dir.listRecursively().filter(f => f.extension == Some(".java") || f.extension == Some(".scala"))

val matches = dir.globRegex("^\\w*$".r) //equivalent to dir.glob("^\\w*$")(syntax = File.PathMatcherSyntax.regex)

dir.glob("**/*.txt", includePath = false) // JDK default
//OR
dir.glob("*.txt", includePath = true) // better-files default

dir.collectChildren(_.isSymbolicLink) // collect all symlinks in a directory

file.touch()
file.delete()     // unlike the Java API, also works on directories as expected (deletes children recursively)
file.clear()      // If directory, deletes all children; if file clears contents
file.renameTo(newName: String)
file.moveTo(destination)
file.moveToDirectory(destination)
file.copyTo(destination)       // unlike the default API, also works on directories (copies recursively)
file.copyToDirectory(destination)
file.linkTo(destination)                     // ln destination file
file.symbolicLinkTo(destination)             // ln -s destination file
file.setOwner(user: String)      // chown user file
file.setGroup(group: String)     // chgrp group file
Seq(file1, file2) `>:` file3     // same as cat file1 file2 > file3 (must import import better.files.Dsl.SymbolicOperations)
Seq(file1, file2) >>: file3      // same as cat file1 file2 >> file3 (must import import better.files.Dsl.SymbolicOperations)
file.isReadLocked(); file.isWriteLocked(); file.isLocked()
File.numberOfOpenFileDescriptors()        // number of open file descriptors

file.md5() // equivalent to file.checksum("md5")
file.sha1()
file.sha256()
file.sha512()

val md5: String = inputstream.md5.hexDigest()
val md5: String = outputstream.md5.hexDigest()

val md5: String = inputstream.sha512.hexDigest(drainTo = someFile)

File.newTemporaryDirectory()
File.newTemporaryFile()

for {
 tempFile <- File.temporaryFile()
} doSomething(tempFile) // tempFile is auto deleted at the end of this block - even if an exception happens

File.usingTemporaryFile() {tempFile =>
  //do something
}  // tempFile is auto deleted at the end of this block - even if an exception happens

val foo = File.home / "Downloads" / "foo.txt"

for {
 temp <- foo.toTemporary
} doSomething(temp) // foo is deleted at the end of this block - even if an exception happens

import better.files._
import better.files.Dsl._   // must import Dsl._ to bring in these utils

pwd / cwd     // current dir
cp(file1, file2)
mv(file1, file2)
rm(file) /*or*/ del(file)
ls(file) /*or*/ dir(file)
ln(file1, file2)     // hard link
ln_s(file1, file2)   // soft link
cat(file1)
cat(file1) >>: file
touch(file)
mkdir(file)
mkdirs(file)         // mkdir -p
chown(owner, file)
chgrp(owner, file)
chmod_+(permission, files)  // add permission
chmod_-(permission, files)  // remove permission
md5(file); sha1(file); sha256(file); sha512(file)
unzip(zipFile)(targetDir)
zip(file*)(targetZipFile)
ungzip(gzipFile)(targetFile)
gzip(file)(targetGZipFile)

file.name       // simpler than java.io.File#getName
file.extension()
file.contentType()
file.lastModifiedTime ()    // returns JSR-310 time
file.owner()
file.group()
file.isDirectory(); file.isSymbolicLink(); file.isRegularFile()
file.isHidden()
file.hide(); file.unhide()
file.isOwnerExecutable(); file.isGroupReadable() // etc. see file.permissions
file.size()                 // for a directory, computes the directory size
file.posixAttributes(); file.dosAttributes()  // see file.attributes
file.isEmpty(); file.nonEmpty()      // true if file has no content (or no children if directory) or does not exist and vice-versa
file.isParentOf(); file.isChildOf(); file.isSiblingOf(); file.siblings()
file("dos:system") = true  // set custom meta-data for file (similar to Files.setAttribute)

file.isDirectory(LinkOption.NOFOLLOW_LINKS)

file.isDirectory(File.LinkOptions.noFollow)

import java.nio.file.attribute.PosixFilePermission
file.addPermission(PosixFilePermission.OWNER_EXECUTE)      // chmod +X file
file.removePermission(PosixFilePermission.OWNER_WRITE)     // chmod -w file
assert(file.permissionsAsString() == "rw-r--r--")

// The following are all equivalent:
assert(file.permissions contains PosixFilePermission.OWNER_EXECUTE)
assert(file.testPermission(PosixFilePermission.OWNER_EXECUTE))
assert(file.isOwnerExecutable())

file1 == file2    // equivalent to `file1.isSamePathAs(file2)`
file1 === file2   // equivalent to `file1.isSameContentAs(file2)` (works for regular-files and directories)
file1 != file2    // equivalent to `!file1.isSamePathAs(file2)`
file1 !== file2   // equivalent to `!file1.isSameContentAs(file2)`

val files = myDir.list.toSeq
files.sorted(File.Order.byName)
files.max(File.Order.bySize)
files.min(File.Order.byDepth)
files.max(File.Order.byModificationTime)
files.sorted(File.Order.byDirectoriesFirst)

// Unzipping:
val zipFile: File = file"path/to/research.zip"
val research: File = zipFile.unzipTo(destination = home/"Documents"/"research")

// Zipping:
val zipFile: File = directory.zipTo(destination = home/"Desktop"/"toEmail.zip")

// Zipping in:
val zipFile = File("countries.zip").zipIn(Iterator(file"usa.txt", file"russia.txt"))()

// Zipping/Unzipping to temporary files/directories:
val someTempZipFile: File = directory.zip()
val someTempDir: File = someTempZipFile.unzip()
assert(directory === someTempDir)

val fileNames = zipFile.newZipInputStream.mapEntries(_.getName) // gets the file names inside the zip file

File("big-data.csv").gzipTo(File("big-data.csv.gz"))
File("big-data.csv.gz").unGzipTo(File("big-data.csv"))

// GZIP stream handling:
File("countries.gz").newInputStream().asGzipInputStream().lines.take(10).foreach(println)

def write(out: OutputStream, countries: Seq[String]) =
  out.asGzipOutputStream().printWriter().printLines(countries).close()

for {
  in <- file1.newInputStream().autoClosed
  out <- file2.newOutputStream().autoClosed
} in.pipeTo(out)
// The input and output streams are auto-closed once out of scope

for {
 reader <- file.newBufferedReader().autoClosed
} foo(reader)

for {
 reader <- file.bufferedReader()    // returns Dispose[BufferedReader]
} foo(reader)

// or simply:
file.bufferedReader().foreach(foo)

for {
 reader <- file.bufferedReader()
} yield foo(reader)

// Simpler
file.bufferedReader.map(foo).get()

// Even simpler
file.bufferedReader.apply(foo)

def lines(reader: BufferedReader): Iterator[String] = ???

for {
  reader <- file.bufferedReader()
  line <- lines(reader)
} yield line

// or simply
file.bufferedReader.flatMap(lines)

trait Shutdownable {
  def shutdown(): Unit = ()
}

object Shutdownable {
  implicit val disposable: Disposable[Shutdownable] = Disposable(_.shutdown())
}

val s: Shutdownable = ....

for {
  instance <- new Dispose(s)
} doSomething(s)  // s is disposed after this

val lines: List[String] = using(file.newInputStream) { stream =>
  stream.lines.toList   // Must be eager so .toList
}

val lines: Iterator[String] = file.lines()  // This will auto close the underlying stream on iterator exhaustion

lines.find(_ == "hello world") //This will auto close the stream if nothing is found OR if the item is found
lines.take(10).size //This will close the stream even if stream has >10 lines

// If you don't want this auto closing behaviour
lines.nonClosing().take(10).size // This would leave stream open if it has >10 lines and only close if stream has no more elements in it

// If you don't even want it to close when underlying stream has no more elements
lines.nonClosing(closeInTheEnd = false) // This will NEVER close the underlying stream - you should probably never need to do this!

val f1 = File("/tmp/temp.txt")
val data = f1.overwrite(s"""Hello World
  | 1 true
  | 2 3
""".stripMargin)
val scanner: Scanner = data.newScanner()
assert(scanner.next[String] == "Hello")
assert(scanner.lineNumber == 1)
assert(scanner.next[String] == "World")
assert(scanner.next[(Int, Boolean)] == (1, true))
assert(scanner.nextLine() == " 2 3")
assert(!scanner.hasNext)

sealed trait Animal
case class Dog(name: String) extends Animal
case class Cat(name: String) extends Animal

implicit val animalParser: Scannable[Animal] = Scannable {scanner =>
  val name = scanner.next[String]
  if (name == "Garfield") Cat(name) else Dog(name)
}

val scanner = file.newScanner()
println(scanner.next[Animal])

val in = Scanner("""
  12 Bob True
  13 Mary False
  26 Rick True
""")

import shapeless._

type Row = Int :: String :: Boolean :: HNil

val out = Seq.fill(3)(in.next[Row])
assert(out == Seq(
  12 :: "Bob" :: true :: HNil,
  13 :: "Mary" :: false :: HNil,
  26 :: "Rick" :: true :: HNil
))

case class Person(id: Int, name: String, isMale: Boolean)
val out2 = Seq.fill(3)(in.next[Person])

val file = """
  23,foo
  42,bar
"""
val csvScanner = file.newScanner(StringSplitter.on(','))
csvScanner.next[Int]    //23
csvScanner.next[String] //foo

import java.nio.file.{StandardWatchEventKinds => EventType}
val service: java.nio.file.WatchService = myDir.newWatchService
myDir.register(service, events = Seq(EventType.ENTRY_CREATE, EventType.ENTRY_DELETE))

val watcher = new FileMonitor(myDir, recursive = true) {
  override def onCreate(file: File, count: Int) = println(s"$file got created")
  override def onModify(file: File, count: Int) = println(s"$file got modified $count times")
  override def onDelete(file: File, count: Int) = println(s"$file got deleted")
}
watcher.start() 
Thread.sleep(60 * 1000) // The above line starts the monitoring asynchronously 

import java.nio.file.{Path, StandardWatchEventKinds => EventType, WatchEvent}

val watcher = new FileMonitor(myDir, recursive = true) {
  override def onEvent(eventType: WatchEvent.Kind[Path], file: File, count: Int) = eventType match {
    case EventType.ENTRY_CREATE => println(s"$file got created")
    case EventType.ENTRY_MODIFY => println(s"$file got modified $count")
    case EventType.ENTRY_DELETE => println(s"$file got deleted")
  }
}

import akka.actor.{ActorRef, ActorSystem}
import better.files.File.home
import better.files.FileWatcher._
import java.nio.file.{StandardWatchEventKinds => EventType}

implicit val system = ActorSystem("mySystem")

val watcher: ActorRef = (home/"Downloads").newWatcher(recursive = true)

// register partial function for an event
watcher ! on(EventType.ENTRY_DELETE) {
 case file if file.isDirectory => println(s"directory $file got deleted")
 case file                     => println(s"$file got deleted")
}

// watch for multiple events
watcher ! when(events = EventType.ENTRY_CREATE, EventType.ENTRY_MODIFY) {
 case (EventType.ENTRY_CREATE, file) => println(s"$file got created")
 case (EventType.ENTRY_MODIFY, file) => println(s"$file got modified")
}