sbt dependencies artifacts

import sbt._
import Keys._
import Defaults._

/**
 * Provides a way to obtain the location of the main project artifact, and the artifacts of all its dependencies.
 */
object Artifacts {
  val allTheArtifacts = TaskKey[Seq[(sbt.Artifact, java.io.File)]]("all-artifacts")
  val theMainArtifact = TaskKey[File]("main-artifact", "The main custom artifact that should be published")
  val artifactConf = config("Artifact") hide //use this to scope the create artifact to this config

  lazy val settings = inConfig(artifactConf)(Seq(
    allTheArtifacts <<= (thisProjectRef, buildStructure, streams) flatMap allArtifactsTask,
    theMainArtifact <<= artifactsTask,
    artifact in artifactConf <<= (name, version)((n,v) => Artifact(n + "-" + v, "zip", "zip")) //create the Artifact with project name and version, and zip type
  )) ++ addArtifact(artifact in artifactConf, theMainArtifact in artifactConf) ++ Seq(
    theMainArtifact in artifactConf <<= theMainArtifact in artifactConf dependsOn(packageBin in Compile)
  )

  def allArtifactsTask(projectRef: ProjectRef, structure: Load.BuildStructure, s: TaskStreams): Task[Seq[(sbt.Artifact, java.io.File)]] = {
    val projects = dependencies(projectRef, structure, s)
    s.log.info("found projects %s".format(projects))
    projects flatMap {ref => packagedArtifact in Compile in ref.project in packageBin get structure.data } join
  }

  /**
   * Gets the given project's dependencies. This is done recursively, so the dependencies of a dependency are also part of the result.
   * The result may contain duplicates, these are not filtered out at the moment.
   */
  def dependencies(projectRef: ProjectRef, structure: Load.BuildStructure, s: TaskStreams): Seq[ProjectRef] = {
    val deps = Project.getProject(projectRef, structure).toSeq.flatMap(_.dependencies)
    s.log.info("got deps %s for project ref %s".format(deps, projectRef))
    deps flatMap { ref => ref.project +: dependencies(ref.project, structure, s)}
  }

  def artifactsTask = (allTheArtifacts in artifactConf, target in Compile, streams) map {
      (arts, t, s) => {s.log.info("executing task with artifacts %s".format(arts.map(a => a._2)))}
      val result = new File(t, "myFile") //just create a simple file in the target directory for illustration
      result.createNewFile()
      result
  }
}