From 5f5153820f83944d2eda0b4aabcc803d7280ca4c Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Tue, 12 Jan 2021 11:48:26 +0100
Subject: [PATCH] Add absolutely minimal implementation of chunking

---
 dagger/chunking.nim    | 10 ++++++++++
 dagger/merkledag.nim   |  3 +++
 tests/testChunking.nim | 31 +++++++++++++++++++++++++++++++
 3 files changed, 44 insertions(+)
 create mode 100644 dagger/chunking.nim
 create mode 100644 dagger/merkledag.nim
 create mode 100644 tests/testChunking.nim

diff --git a/dagger/chunking.nim b/dagger/chunking.nim
new file mode 100644
index 00000000..4b15a48f
--- /dev/null
+++ b/dagger/chunking.nim
@@ -0,0 +1,10 @@
+import ./merkledag
+
+export merkledag
+
+proc createChunks*(file: File): MerkleDag =
+  let contents = file.readAll()
+  MerkleDag(data: cast[seq[byte]](contents))
+
+proc assembleChunks*(dag: MerkleDag, output: File) =
+  output.write(cast[string](dag.data))
diff --git a/dagger/merkledag.nim b/dagger/merkledag.nim
new file mode 100644
index 00000000..4466aba7
--- /dev/null
+++ b/dagger/merkledag.nim
@@ -0,0 +1,3 @@
+type
+  MerkleDag* = object
+    data*: seq[byte]
diff --git a/tests/testChunking.nim b/tests/testChunking.nim
new file mode 100644
index 00000000..5442f21b
--- /dev/null
+++ b/tests/testChunking.nim
@@ -0,0 +1,31 @@
+import std/unittest
+import std/os
+import pkg/dagger/chunking
+
+suite "chunking":
+
+  var input, output: File
+
+  setup:
+    input = open("tests/input.txt", fmReadWrite)
+    output = open("tests/output.txt", fmReadWrite)
+    input.write("foo")
+    input.setFilePos(0)
+
+  teardown:
+    input.close()
+    output.close()
+    removeFile("tests/input.txt")
+    removeFile("tests/output.txt")
+
+  test "creates a Merkle DAG from a file":
+    check createChunks(input) != MerkleDag.default
+
+  test "creates a file from a Merkle DAG":
+    let dag = createChunks(input)
+    assembleChunks(dag, output)
+
+    input.setFilePos(0)
+    output.setFilePos(0)
+    check output.readAll() == input.readAll()
+