From 271f7d7523ec399b11e7a8599ba104cf718c4bf9 Mon Sep 17 00:00:00 2001
From: Dmitriy Ryajov <dryajov@gmail.com>
Date: Fri, 27 Aug 2021 11:03:21 -0600
Subject: [PATCH] add block stream abstraction

---
 dagger/blockstream.nim        | 29 +++++++++++++++++++++++++++++
 dagger/chunkedblockstream.nim | 28 ++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 dagger/blockstream.nim
 create mode 100644 dagger/chunkedblockstream.nim

diff --git a/dagger/blockstream.nim b/dagger/blockstream.nim
new file mode 100644
index 00000000..96f0eac2
--- /dev/null
+++ b/dagger/blockstream.nim
@@ -0,0 +1,29 @@
+## Nim-Dagger
+## Copyright (c) 2021 Status Research & Development GmbH
+## Licensed under either of
+##  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
+##  * MIT license ([LICENSE-MIT](LICENSE-MIT))
+## at your option.
+## This file may not be copied, modified, or distributed except according to
+## those terms.
+
+{.push raises: [Defect].}
+
+import pkg/questionable
+import pkg/questionable/results
+import ./blocktype
+
+export blocktype
+
+type
+  BlockStreamRef* = ref object of RootObj
+
+method nextBlock*(b: BlockStreamRef): ?!Block {.base.} =
+  doAssert(false, "Not implemented!")
+
+iterator items*(b: BlockStreamRef): Block =
+  while true:
+    without blk =? b.nextBlock():
+      break
+
+    yield blk
diff --git a/dagger/chunkedblockstream.nim b/dagger/chunkedblockstream.nim
new file mode 100644
index 00000000..49b6b6f5
--- /dev/null
+++ b/dagger/chunkedblockstream.nim
@@ -0,0 +1,28 @@
+## Nim-Dagger
+## Copyright (c) 2021 Status Research & Development GmbH
+## Licensed under either of
+##  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
+##  * MIT license ([LICENSE-MIT](LICENSE-MIT))
+## at your option.
+## This file may not be copied, modified, or distributed except according to
+## those terms.
+
+{.push raises: [Defect].}
+
+import pkg/questionable
+import pkg/questionable/results
+
+import ./blockstream
+import ./chunker
+
+type
+  ChunkedBlockStreamRef* = ref object of BlockStreamRef
+    chunker*: Chunker
+
+method nextBlock*(c: ChunkedBlockStreamRef): ?!Block =
+  let data: seq[byte] = c.chunker.getBytes()
+  if data.len > 0:
+    return success Block.new(data)
+
+proc new*(T: type ChunkedBlockStreamRef, chunker: Chunker): T =
+  T(chunker: chunker)