1 files changed, 39 insertions, 0 deletions
diff --git a/common/shared/src/main/scala/Message.scala b/common/shared/src/main/scala/Message.scala
new file mode 100644
index 0000000..7ee36cb
--- /dev/null
+++ b/common/shared/src/main/scala/Message.scala
@@ -0,0 +1,39 @@
+package triad
+
+import java.security.MessageDigest
+import java.time.Instant
+
+case class Message(content: String,
+                   author: String,
+                   timestamp: Instant = Instant.now()) {
+
+  lazy val id: String = {
+    val digest = MessageDigest.getInstance("SHA-256")
+    digest.update(content.getBytes)
+    digest.update(author.getBytes)
+    digest.update((timestamp.getEpochSecond & 0xff).toByte)
+    digest.update(((timestamp.getEpochSecond >> 8) & 0xff).toByte)
+    digest.update(((timestamp.getEpochSecond >> 16) & 0xff).toByte)
+    digest.update(((timestamp.getEpochSecond >> 24) & 0xff).toByte)
+    digest.update(((timestamp.getEpochSecond >> 32) & 0xff).toByte)
+    digest.update(((timestamp.getEpochSecond >> 40) & 0xff).toByte)
+    digest.update(((timestamp.getEpochSecond >> 48) & 0xff).toByte)
+    digest.update(((timestamp.getEpochSecond >> 56) & 0xff).toByte)
+    Message.bytesToHex(digest.digest())
+  }
+
+}
+
+object Message {
+  private def bytesToHex(hash: Array[Byte]): String = {
+    val hexString = new StringBuffer(hash.length * 2)
+    var i = 0
+    while (i < hash.length) {
+      val hex = Integer.toHexString(0xff & hash(i))
+      if (hex.length == 1) hexString.append('0')
+      hexString.append(hex)
+      i += 1
+    }
+    hexString.toString
+  }
+}