1 files changed, 73 insertions, 0 deletions
diff --git a/scalalib/src/dependency/versions/VersionsFinder.scala b/scalalib/src/dependency/versions/VersionsFinder.scala
new file mode 100644
index 00000000..a9ecc763
--- /dev/null
+++ b/scalalib/src/dependency/versions/VersionsFinder.scala
@@ -0,0 +1,73 @@
+package mill.scalalib.dependency.versions
+
+import mill.define.{BaseModule, Task}
+import mill.eval.Evaluator
+import mill.scalalib.dependency.metadata.MetadataLoaderFactory
+import mill.scalalib.{Dep, JavaModule, Lib}
+import mill.api.Ctx.{Home, Log}
+import mill.api.{Loose, Strict}
+
+private[dependency] object VersionsFinder {
+
+  def findVersions(ctx: Log with Home,
+                   rootModule: BaseModule): Seq[ModuleDependenciesVersions] = {
+    val evaluator =
+      new Evaluator(ctx.home, os.pwd / 'out, os.pwd / 'out, rootModule, ctx.log)
+
+    val javaModules = rootModule.millInternal.modules.collect {
+      case javaModule: JavaModule => javaModule
+    }
+
+    val resolvedDependencies = resolveDependencies(evaluator, javaModules)
+    resolveVersions(resolvedDependencies)
+  }
+
+  private def resolveDependencies(evaluator: Evaluator,
+                                  javaModules: Seq[JavaModule]) =
+    javaModules.map { javaModule =>
+      val depToDependency =
+        eval(evaluator, javaModule.resolveCoursierDependency)
+      val deps = evalOrElse(evaluator, javaModule.ivyDeps, Loose.Agg.empty[Dep])
+
+      val (dependencies, _) =
+        Lib.resolveDependenciesMetadata(javaModule.repositories,
+                                        depToDependency,
+                                        deps)
+
+      (javaModule, dependencies)
+    }
+
+  private def resolveVersions(resolvedDependencies: Seq[ResolvedDependencies]) =
+    resolvedDependencies.map {
+      case (javaModule, dependencies) =>
+        val metadataLoaders =
+          javaModule.repositories.flatMap(MetadataLoaderFactory(_))
+
+        val versions = dependencies.map { dependency =>
+          val currentVersion = Version(dependency.version)
+          val allVersions =
+            metadataLoaders
+              .flatMap(_.getVersions(dependency.module))
+              .toSet
+          DependencyVersions(dependency, currentVersion, allVersions)
+        }
+
+        ModuleDependenciesVersions(javaModule, versions)
+    }
+
+  private def eval[T](evaluator: Evaluator, e: Task[T]): T =
+    evaluator.evaluate(Strict.Agg(e)).values match {
+      case Seq()     => throw new NoSuchElementException
+      case Seq(e: T) => e
+    }
+
+  private def evalOrElse[T](evaluator: Evaluator,
+                            e: Task[T],
+                            default: => T): T =
+    evaluator.evaluate(Strict.Agg(e)).values match {
+      case Seq()     => default
+      case Seq(e: T) => e
+    }
+
+  private type ResolvedDependencies = (JavaModule, Seq[coursier.Dependency])
+}