/* sbt -- Simple Build Tool
 * Copyright 2009, 2010  Mark Harrah
 */
package xsbt.boot

import Pre._
import java.io.{File, FileInputStream, InputStreamReader}
import java.net.{MalformedURLException, URI, URL}
import java.util.regex.Pattern
import scala.collection.immutable.List
import annotation.tailrec

object Configuration
{
	final val SysPropPrefix = "-D"
	def parse(file: URL, baseDirectory: File) = Using( new InputStreamReader(file.openStream, "utf8") )( (new ConfigurationParser).apply )
	@tailrec def find(args: List[String], baseDirectory: File): (URL, List[String]) =
		args match
		{
			case head :: tail if head.startsWith("@") => (directConfiguration(head.substring(1), baseDirectory), tail)
			case head :: tail if head.startsWith(SysPropPrefix) =>
				setProperty(head stripPrefix SysPropPrefix)
				find(tail, baseDirectory)
			case _ =>
				val propertyConfigured = System.getProperty("sbt.boot.properties")
				val url = if(propertyConfigured == null) configurationOnClasspath else configurationFromFile(propertyConfigured, baseDirectory)
				(url , args)
		}
	def setProperty(head: String)
	{
		val keyValue = head.split("=",2)
		if(keyValue.length != 2)
			System.err.println("Warning: invalid system property '" + head + "'")
		else
			System.setProperty(keyValue(0), keyValue(1))
	}
	def configurationOnClasspath: URL =
	{
		val paths = resourcePaths(guessSbtVersion)
		paths.iterator.map(getClass.getResource).find(neNull) getOrElse
			( multiPartError("Could not finder sbt launch configuration.  Searched classpath for:", paths))
	}
	def directConfiguration(path: String, baseDirectory: File): URL =
	{
		try { new URL(path) }
		catch { case _: MalformedURLException => configurationFromFile(path, baseDirectory) }
	}
	def configurationFromFile(path: String, baseDirectory: File): URL =
	{
		def resolve(against: URI): Option[URL] =
		{
			val resolved = against.resolve(path)
			val exists = try { (new File(resolved)).exists } catch { case _: IllegalArgumentException => false }
			if(exists) Some(resolved.toURL) else None
		}
		val against = resolveAgainst(baseDirectory)
		// use Iterators so that resolution occurs lazily, for performance
		val resolving = against.iterator.flatMap(e => resolve(e).toList.iterator)
		if(!resolving.hasNext) multiPartError("Could not find configuration file '" + path + "'.  Searched:", against)
		resolving.next()
	}
	def multiPartError[T](firstLine: String, lines: List[T]) = error( (firstLine :: lines).mkString("\n\t") )

	def UnspecifiedVersionPart = "Unspecified"
	def DefaultVersionPart = "Default"
	def DefaultBuildProperties = "project/build.properties"
	def SbtVersionProperty = "sbt.version"
	val ConfigurationName = "sbt.boot.properties"
	val JarBasePath = "/sbt/"
	def userConfigurationPath = "/" + ConfigurationName
	def defaultConfigurationPath = JarBasePath + ConfigurationName
	val baseResourcePaths: List[String] = userConfigurationPath :: defaultConfigurationPath :: Nil
	def resourcePaths(sbtVersion: Option[String]): List[String] = 
		versionParts(sbtVersion) flatMap { part =>
			baseResourcePaths map { base =>
				base + part
			}
		}
	def fallbackParts: List[String] = "" :: Nil
	def versionParts(version: Option[String]): List[String] =
		version match {
			case None => UnspecifiedVersionPart :: fallbackParts
			case Some(v) => versionParts(v)
		}
	def versionParts(version: String): List[String] =
	{
		val pattern = Pattern.compile("""(\d+)\.(\d+)\.(\d+)(-.*)?""")
		val m = pattern.matcher(version)
		if(m.matches())
			subPartsIndices map {_.map(m.group).filter(neNull).mkString(".") }
		else
			DefaultVersionPart :: fallbackParts
	}
	private[this] def subPartsIndices = 
		(1 :: 2 :: Nil) ::
		(1 :: 2 :: 3 :: Nil) ::
		(1 :: 2 :: 3 :: 4 :: Nil) ::
		(Nil) ::
		Nil
	// the location of project/build.properties and the name of the property within that file 
	//  that configures the sbt version is configured in sbt.boot.properties.
	// We have to hard code them here in order to use them to determine the location of sbt.boot.properties itself
	def guessSbtVersion: Option[String] =
	{
		val props = ResolveValues.readProperties(new File(DefaultBuildProperties))
		Option(props.getProperty(SbtVersionProperty))
	}

	def resolveAgainst(baseDirectory: File): List[URI] = (baseDirectory toURI) :: (new File(System.getProperty("user.home")) toURI) ::
		toDirectory(classLocation(getClass).toURI) :: Nil

	def classLocation(cl: Class[_]): URL =
	{
		val codeSource = cl.getProtectionDomain.getCodeSource
		if(codeSource == null) error("No class location for " + cl)
		else codeSource.getLocation
	}
	def toDirectory(uri: URI): URI =
		try
		{
			val file = new File(uri)
			val newFile = if(file.isFile) file.getParentFile else file
			newFile.toURI
		}
		catch { case _: Exception => uri }
	private[this] def neNull: AnyRef => Boolean = _ ne null
}