improve handling of local file:// urls

This simplifies the extraction location for reusable extraction of
nested archive files. This allows to use a local file:// url in asset
definitions (for purely local use).

src/main/scala/sc4pac/Sc4pac.scala

@@ -194,7 +194,7 @@ trait UpdateService { this: Sc4pac =>
               fallbackFilename,
               tempPluginsRoot / pkgFolder,
               recipe,
-              Some(Extractor.JarExtraction.fromUrl(art.url, context.cache, jarsRoot = jarsRoot, profileRoot = context.profileRoot)),
+              Some(Extractor.JarExtraction.fromUrl(art.url, jarsRoot = jarsRoot)),
               hints = depAsset.archiveType,
               stagingRoot)
           // TODO catch IOExceptions

src/main/scala/sc4pac/extractor.scala

@@ -305,15 +305,11 @@ object Extractor {
     */
   case class JarExtraction(jarsDir: os.Path)
   object JarExtraction {
-    def fromUrl[F[_]](archiveUrl: String, cache: FileCache, jarsRoot: os.Path, profileRoot: os.Path): JarExtraction = {
-      // we use cache to find a consistent archiveSubPath based on the url
-      val archivePath = os.Path(cache.localFile(archiveUrl), profileRoot)
-      val cachePath = os.Path(cache.location, profileRoot)
-      val archiveSubPath = archivePath.subRelativeTo(cachePath)
-      // we hash the the archiveSubPath to keep paths short
+    def fromUrl[F[_]](archiveUrl: String, jarsRoot: os.Path): JarExtraction = {
+      // we hash the the URL to find a deterministic and short storage path
       val hash = JD.Checksum.bytesToString(
         java.security.MessageDigest.getInstance("SHA-1")
-          .digest(archiveSubPath.toString.getBytes("UTF-8"))
+          .digest(archiveUrl.getBytes("UTF-8"))
           .take(4).to(collection.immutable.ArraySeq)  // 4 bytes = 8 hex characters
       )
       JarExtraction(jarsRoot / hash)