Add name based UUIDv5 implementation (#197)

Add name based UUIDv5 implementation

modules/core/.js/src/main/scala/io/chrisdavenport/fuuid/PlatformSpecificMethods.scala

@@ -0,0 +1,8 @@
+package io.chrisdavenport.fuuid
+
+import cats.ApplicativeError
+
+object PlatformSpecificMethods {
+  def nameBased[F[_]]: (FUUID, String, ApplicativeError[F, Throwable]) => F[FUUID] = (_, _, AE) =>
+    AE.raiseError(new NotImplementedError("Name based UUIDs are not supported for Scala.js"))
+}

modules/core/.jvm/src/main/scala/io/chrisdavenport/fuuid/PlatformSpecificMethods.scala

@@ -0,0 +1,50 @@
+package io.chrisdavenport.fuuid
+
+import cats._
+import cats.implicits._
+import java.util.UUID
+import java.security.MessageDigest
+
+object PlatformSpecificMethods {
+  def nameBased[F[_]]: (FUUID, String, ApplicativeError[F, Throwable]) => F[FUUID] = (namespace, name, AE) =>
+    Either
+      .catchNonFatal(
+        MessageDigest
+          .getInstance("SHA-1")
+          .digest(
+            uuidBytes(namespace) ++
+              name.getBytes("UTF-8")
+          )
+      )
+      .map { bs =>
+        val cs = bs.take(16) // Truncate 160 bits (20 bytes) SHA-1 to fit into our 128 bits of space
+        cs(6) = (cs(6) & 0x0f).asInstanceOf[Byte] /* clear version                */
+        cs(6) = (cs(6) | 0x50).asInstanceOf[Byte] /* set to version 5, SHA1 UUID  */
+        cs(8) = (cs(8) & 0x3f).asInstanceOf[Byte] /* clear variant                */
+        cs(8) = (cs(8) | 0x80).asInstanceOf[Byte] /* set to IETF variant          */
+        cs
+      }
+      .flatMap(
+        bs =>
+          Either.catchNonFatal {
+            val bb = java.nio.ByteBuffer.allocate(java.lang.Long.BYTES)
+            bb.put(bs, 0, 8)
+            bb.flip
+            val most = bb.getLong
+            bb.flip
+            bb.put(bs, 8, 8)
+            bb.flip
+            val least = bb.getLong
+            FUUID.fromUUID(new UUID(most, least))
+          }
+      )
+      .liftTo[F](AE)
+
+  private def uuidBytes(fuuid: FUUID): Array[Byte] = {
+    val bb = java.nio.ByteBuffer.allocate(2 * java.lang.Long.BYTES)
+    val uuid = FUUID.Unsafe.toUUID(fuuid)
+    bb.putLong(uuid.getMostSignificantBits)
+    bb.putLong(uuid.getLeastSignificantBits)
+    bb.array
+  }
+}

modules/core/.jvm/src/test/scala/io/chrisdavenport/fuuid/FUUIDJvmSpec.scala

@@ -0,0 +1,29 @@
+package io.chrisdavenport.fuuid
+
+import cats.effect.IO
+import org.specs2._
+
+class FUUIDJvmSpec extends mutable.Specification with ScalaCheck {
+
+  "FUUID.nameBased" should {
+    "produce a valid UUID" in {
+      (for {
+        namespace <- FUUID.randomFUUID[IO]
+        namebased <- FUUID.nameBased[IO](namespace, "What up yo!")
+        parsed <- FUUID.fromStringF[IO](namebased.toString)
+      } yield parsed)
+        .attempt
+        .unsafeRunSync
+        .isRight must_=== true
+    }
+
+    "conform to an example" in {
+      val namespace = FUUID.fromStringF[IO]("dc79a6bc-de3c-5bc7-a877-712bea708d8f").unsafeRunSync()
+      val name = "What up yo!"
+
+      val expected = FUUID.fromStringF[IO]("1cce4593-d217-5b33-be0d-2e81462e79d3").unsafeRunSync()
+
+      FUUID.nameBased[IO](namespace, name).unsafeRunSync must_=== expected
+    }
+  }
+}

modules/core/src/main/scala/io/chrisdavenport/fuuid/FUUID.scala

@@ -74,6 +74,13 @@ object FUUID {
       }
   }
 
+  /**
+    * Creates a new name-based UUIDv5.
+    * NOTE: Not implemented for Scala.js!
+    **/ 
+  def nameBased[F[_]](namespace: FUUID, name: String)(implicit AE: ApplicativeError[F, Throwable]): F[FUUID] =
+    PlatformSpecificMethods.nameBased[F](namespace, name, AE)
+
   /**
     * A Home For functions we don't trust
     * Hopefully making it very clear that this code needs

modules/core/src/test/scala/io/chrisdavenport/fuuid/FUUIDSpec.scala

@@ -4,7 +4,7 @@ import java.util.UUID
 import cats.effect.IO
 import org.specs2._
 
-object FUUIDSpec extends mutable.Specification with ScalaCheck {
+class FUUIDSpec extends mutable.Specification with ScalaCheck {
 
   "FUUID.fromString" should {
     "Fail when parsing an invalid string" in {