package sbt

	import Types.idFun
	import BuildDependencies._

final class BuildDependencies private(val classpath: DependencyMap[ClasspathDep[ProjectRef]], val aggregate: DependencyMap[ProjectRef])
{
	def classpathRefs(ref: ProjectRef): Seq[ProjectRef] = classpath(ref) map getID
	def classpathTransitiveRefs(ref: ProjectRef): Seq[ProjectRef] = classpathTransitive(ref)

	lazy val classpathTransitive: DependencyMap[ProjectRef] = transitive(classpath, getID)
	lazy val aggregateTransitive: DependencyMap[ProjectRef] = transitive(aggregate, idFun[ProjectRef])

	def addClasspath(ref: ProjectRef, deps: ClasspathDep[ProjectRef]*): BuildDependencies =
		new BuildDependencies( classpath.updated(ref, deps ++ classpath.getOrElse(ref, Nil)), aggregate)
	def addAggregate(ref: ProjectRef, deps: ProjectRef*): BuildDependencies =
		new BuildDependencies(classpath, aggregate.updated(ref, deps ++ aggregate.getOrElse(ref, Nil)))
}
object BuildDependencies
{
	def apply(classpath: DependencyMap[ClasspathDep[ProjectRef]], aggregate: DependencyMap[ProjectRef]): BuildDependencies =
		new BuildDependencies(classpath, aggregate)

	type DependencyMap[D] = Map[ProjectRef, Seq[D]]
	def transitive[D](deps: DependencyMap[D], extract: D => ProjectRef): DependencyMap[ProjectRef] =
		for( (ref, _) <- deps ) yield
		{
			val sorted = Dag.topologicalSort(ref)(d => deps(d) map extract)
			(ref, sorted dropRight 1)
		}
	val getID: ClasspathDep[ProjectRef] => ProjectRef = _.project
}