/* sbt -- Simple Build Tool
 * Copyright 2010 Mark Harrah
 */
package sbt
package std

import java.io.{ InputStream, IOException, OutputStream, Reader, Writer }
import java.io.{ BufferedInputStream, BufferedOutputStream, BufferedReader, BufferedWriter, PrintWriter }
import java.io.{ Closeable, File, FileInputStream, FileOutputStream, InputStreamReader, OutputStreamWriter }

import Path._

// no longer specific to Tasks, so 'TaskStreams' should be renamed
/**
 * Represents a set of streams associated with a context.
 * In sbt, this is a named set of streams for a particular scoped key.
 * For example, logging for test:compile is by default sent to the "out" stream in the test:compile context.
 */
sealed trait TaskStreams[Key] {
  /** The default stream ID, used when an ID is not provided. */
  def default = outID

  def outID = "out"
  def errorID = "err"

  /**
   * Provides a reader to read text from the stream `sid` for `key`.
   * It is the caller's responsibility to coordinate writing to the stream.
   * That is, no synchronization or ordering is provided and so this method should only be called when writing is complete.
   */
  def readText(key: Key, sid: String = default): BufferedReader

  /**
   * Provides an output stream to read from the stream `sid` for `key`.
   * It is the caller's responsibility to coordinate writing to the stream.
   * That is, no synchronization or ordering is provided and so this method should only be called when writing is complete.
   */
  def readBinary(a: Key, sid: String = default): BufferedInputStream

  final def readText(a: Key, sid: Option[String]): BufferedReader = readText(a, getID(sid))
  final def readBinary(a: Key, sid: Option[String]): BufferedInputStream = readBinary(a, getID(sid))

  def key: Key

  /** Provides a writer for writing text to the stream with the given ID. */
  def text(sid: String = default): PrintWriter

  /** Provides an output stream for writing to the stream with the given ID. */
  def binary(sid: String = default): BufferedOutputStream

  /** A cache directory that is unique to the context of this streams instance.*/
  def cacheDirectory: File

  // default logger
  /** Obtains the default logger. */
  final lazy val log: Logger = log(default)

  /** Creates a Logger that logs to stream with ID `sid`.*/
  def log(sid: String): Logger

  private[this] def getID(s: Option[String]) = s getOrElse default
}
sealed trait ManagedStreams[Key] extends TaskStreams[Key] {
  def open()
  def close()
  def isClosed: Boolean
}

trait Streams[Key] {
  def apply(a: Key): ManagedStreams[Key]
  def use[T](key: Key)(f: TaskStreams[Key] => T): T =
    {
      val s = apply(key)
      s.open()
      try { f(s) } finally { s.close() }
    }
}
trait CloseableStreams[Key] extends Streams[Key] with java.io.Closeable
object Streams {
  private[this] val closeQuietly = (c: Closeable) => try { c.close() } catch { case _: IOException => () }

  def closeable[Key](delegate: Streams[Key]): CloseableStreams[Key] = new CloseableStreams[Key] {
    private[this] val streams = new collection.mutable.HashMap[Key, ManagedStreams[Key]]

    def apply(key: Key): ManagedStreams[Key] =
      synchronized {
        streams.get(key) match {
          case Some(s) if !s.isClosed => s
          case _ =>
            val newS = delegate(key)
            streams.put(key, newS)
            newS
        }
      }

    def close(): Unit =
      synchronized { streams.values.foreach(_.close()); streams.clear() }
  }

  def apply[Key](taskDirectory: Key => File, name: Key => String, mkLogger: (Key, PrintWriter) => Logger): Streams[Key] = new Streams[Key] {

    def apply(a: Key): ManagedStreams[Key] = new ManagedStreams[Key] {
      private[this] var opened: List[Closeable] = Nil
      private[this] var closed = false

      def readText(a: Key, sid: String = default): BufferedReader =
        make(a, sid)(f => new BufferedReader(new InputStreamReader(new FileInputStream(f), IO.defaultCharset)))

      def readBinary(a: Key, sid: String = default): BufferedInputStream =
        make(a, sid)(f => new BufferedInputStream(new FileInputStream(f)))

      def text(sid: String = default): PrintWriter =
        make(a, sid)(f => new PrintWriter(new DeferredWriter(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(f), IO.defaultCharset)))))

      def binary(sid: String = default): BufferedOutputStream =
        make(a, sid)(f => new BufferedOutputStream(new FileOutputStream(f)))

      lazy val cacheDirectory: File = {
        val dir = taskDirectory(a)
        IO.createDirectory(dir)
        dir
      }

      def log(sid: String): Logger = mkLogger(a, text(sid))

      def make[T <: Closeable](a: Key, sid: String)(f: File => T): T = synchronized {
        checkOpen()
        val file = taskDirectory(a) / sid
        IO.touch(file, false)
        val t = f(file)
        opened ::= t
        t
      }

      def key: Key = a
      def open(): Unit = ()
      def isClosed: Boolean = synchronized { closed }

      def close(): Unit = synchronized {
        if (!closed) {
          closed = true
          opened foreach closeQuietly
        }
      }
      def checkOpen(): Unit = synchronized {
        if (closed) sys.error("Streams for '" + name(a) + "' have been closed.")
      }
    }
  }
}