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

	import java.io.PrintWriter
	import java.io.File
	import LogManager._
	import std.Transform
	import Def.ScopedKey
	import Scope.GlobalScope
	import MainLogging._
	import BasicKeys.explicitGlobalLogLevels
	import Keys.{logLevel, logManager, persistLogLevel, persistTraceLevel, sLog, state, traceLevel}
	import scala.Console.{BLUE,RESET}

object LogManager
{
	def construct(data: Settings[Scope], state: State) = (task: ScopedKey[_], to: PrintWriter) =>
	{
		val manager = logManager in task.scope get data getOrElse defaultManager(state.globalLogging.console)
		manager(data, state, task, to)
	}
	@deprecated("Use defaultManager to explicitly specify standard out.", "0.13.0")
	lazy val default: LogManager = defaultManager(StandardMain.console)

	def defaultManager(console: ConsoleOut): LogManager = withLoggers((sk,s) => defaultScreen(console))

	@deprecated("Explicitly specify standard out.", "0.13.0")
	def defaults(extra: ScopedKey[_] => Seq[AbstractLogger]): LogManager = defaults(extra, StandardMain.console)

	def defaults(extra: ScopedKey[_] => Seq[AbstractLogger], console: ConsoleOut): LogManager  =
		withLoggers((task,state) => defaultScreen(console, suppressedMessage(task, state)), extra = extra)

	def withScreenLogger(mk: (ScopedKey[_], State) => AbstractLogger): LogManager = withLoggers(screen = mk)

	def withLoggers(screen: (ScopedKey[_], State) => AbstractLogger = (sk, s) => defaultScreen(s.globalLogging.console),
		backed: PrintWriter => AbstractLogger = defaultBacked(),
		extra: ScopedKey[_] => Seq[AbstractLogger] = _ => Nil): LogManager = new LogManager {
			def apply(data: Settings[Scope], state: State, task: ScopedKey[_], to: PrintWriter): Logger =
				defaultLogger(data, state, task, screen(task, state), backed(to), extra(task).toList)
		}

	def defaultLogger(data: Settings[Scope], state: State, task: ScopedKey[_], console: AbstractLogger, backed: AbstractLogger, extra: List[AbstractLogger]): Logger =
	{
		val scope = task.scope
		// to change from global being the default to overriding, switch the order of state.get and data.get
		def getOr[T](key: AttributeKey[T], default: T): T = data.get(scope, key) orElse state.get(key) getOrElse default
		val screenLevel = getOr(logLevel.key, Level.Info)
		val backingLevel = getOr(persistLogLevel.key, Level.Debug)
		val screenTrace = getOr(traceLevel.key, defaultTraceLevel(state))
		val backingTrace = getOr(persistTraceLevel.key, Int.MaxValue)
		val extraBacked = state.globalLogging.backed :: Nil
		multiLogger( new MultiLoggerConfig(console, backed, extraBacked ::: extra, screenLevel, backingLevel, screenTrace, backingTrace) )
	}
	def defaultTraceLevel(state: State): Int =
		if(state.interactive) -1 else Int.MaxValue
	def suppressedMessage(key: ScopedKey[_], state: State): SuppressedTraceContext => Option[String] =
	{
		lazy val display = Project.showContextKey(state)
		def commandBase = "last " + display(unwrapStreamsKey(key))
		def command(useColor: Boolean) = if(useColor) BLUE + commandBase + RESET else "'" + commandBase + "'"
		context => Some( "Stack trace suppressed: run %s for the full output.".format(command(context.useColor)))
	}
	def unwrapStreamsKey(key: ScopedKey[_]): ScopedKey[_] = key.scope.task match {
		case Select(task) => ScopedKey(key.scope.copy(task = Global), task)
		case _ => key // should never get here
	}

	// if global logging levels are not explicitly set, set them from project settings
	private[sbt] def setGlobalLogLevels(s: State, data: Settings[Scope]): State =
		if(hasExplicitGlobalLogLevels(s))
			s
		else {
			val logging = s.globalLogging
			def get[T](key: SettingKey[T]) = key in GlobalScope get data
			def transfer(l: AbstractLogger, traceKey: SettingKey[Int], levelKey: SettingKey[Level.Value]) {
				get(traceKey).foreach(l.setTrace)
				get(levelKey).foreach(l.setLevel)
			}
			logging.full match {
				case a: AbstractLogger => transfer(a, traceLevel, logLevel)
				case _ => ()
			}
			transfer(logging.backed, persistTraceLevel, persistLogLevel)
			s
		}

	def setGlobalLogLevel(s: State, level: Level.Value): State = {
		s.globalLogging.full match {
			case a: AbstractLogger => a.setLevel(level)
			case _ => ()
		}
		s.put(BasicKeys.explicitGlobalLogLevels, true).put(Keys.logLevel.key, level)
	}

	private[this] def setExplicitGlobalLogLevels(s: State, flag: Boolean): State =
		s.put(BasicKeys.explicitGlobalLogLevels, flag)
	private[this] def hasExplicitGlobalLogLevels(s: State): Boolean =
		State.getBoolean(s, BasicKeys.explicitGlobalLogLevels, default=false)

	private[sbt] def settingsLogger(state: State): Def.Setting[_]  =
		// strict to avoid retaining a reference to `state`
		sLog in GlobalScope :== globalWrapper(state)

	// construct a Logger that delegates to the global logger, but only holds a weak reference
	//  this is an approximation to the ideal that would invalidate the delegate after loading completes
	private[this] def globalWrapper(s: State): Logger = {
		val ref = new java.lang.ref.WeakReference(s.globalLogging.full)
		new Logger {
			private[this] def slog: Logger = Option(ref.get) getOrElse sys.error("Settings logger used after project was loaded.")

			override val ansiCodesSupported = slog.ansiCodesSupported
			override def trace(t: => Throwable) = slog.trace(t)
			override def success(message: => String) = slog.success(message)
			override def log(level: Level.Value, message: => String) = slog.log(level, message)
		}
	}
}

trait LogManager
{
	def apply(data: Settings[Scope], state: State, task: ScopedKey[_], writer: PrintWriter): Logger
}