From 045f07c616886273c4acce5cc0fa4797269a54aa Mon Sep 17 00:00:00 2001
From: Aaryamann Challani <43716372+rymnc@users.noreply.github.com>
Date: Fri, 16 Jun 2023 11:33:41 +0530
Subject: [PATCH] feat(rln-relay): metadata ffi api (#1803)

* feat(rln-relay): metadata ffi api

* chore(rln-relay): bump to latest master after merge

* fix(rln-relay): naming, visibility, tests
---
 .../v2/waku_rln_relay/test_waku_rln_relay.nim | 30 +++++++++++++
 vendor/zerokit                                |  2 +-
 waku/v2/waku_rln_relay/rln/rln_interface.nim  | 13 ++++++
 waku/v2/waku_rln_relay/rln/wrappers.nim       | 43 +++++++++++++++++++
 4 files changed, 87 insertions(+), 1 deletion(-)

diff --git a/tests/v2/waku_rln_relay/test_waku_rln_relay.nim b/tests/v2/waku_rln_relay/test_waku_rln_relay.nim
index 12444bfa8..60c4496f7 100644
--- a/tests/v2/waku_rln_relay/test_waku_rln_relay.nim
+++ b/tests/v2/waku_rln_relay/test_waku_rln_relay.nim
@@ -238,6 +238,36 @@ suite "Waku rln relay":
     check:
       rln.removeMember(MembershipIndex(0))
 
+  test "setMetadata rln utils":
+    # create an RLN instance which also includes an empty Merkle tree
+    let rlnInstance = createRLNInstance()
+    require:
+      rlnInstance.isOk()
+    let rln = rlnInstance.get()
+    check:
+      rln.setMetadata(RlnMetadata(lastProcessedBlock: 128)).isOk()
+
+  test "getMetadata rln utils":
+    # create an RLN instance which also includes an empty Merkle tree
+    let rlnInstance = createRLNInstance()
+    require:
+      rlnInstance.isOk()
+    let rln = rlnInstance.get()
+    
+    require:
+      rln.setMetadata(RlnMetadata(lastProcessedBlock: 128)).isOk()
+
+    let metadataRes = rln.getMetadata()
+
+    require:
+      metadataRes.isOk()
+
+    let metadata = metadataRes.get()
+
+    check:
+      metadata.lastProcessedBlock == 128
+ 
+
   test "Merkle tree consistency check between deletion and insertion":
     # create an RLN instance
     let rlnInstance = createRLNInstance()
diff --git a/vendor/zerokit b/vendor/zerokit
index 9cc86e526..2793fe0e2 160000
--- a/vendor/zerokit
+++ b/vendor/zerokit
@@ -1 +1 @@
-Subproject commit 9cc86e526ee0b34b20e4110dc3e4fded03a046d2
+Subproject commit 2793fe0e24f7b48813fe3b6e9a0e6e5ee4a4c8ce
diff --git a/waku/v2/waku_rln_relay/rln/rln_interface.nim b/waku/v2/waku_rln_relay/rln/rln_interface.nim
index 728927036..34def0f28 100644
--- a/waku/v2/waku_rln_relay/rln/rln_interface.nim
+++ b/waku/v2/waku_rln_relay/rln/rln_interface.nim
@@ -175,3 +175,16 @@ proc poseidon*(input_buffer: ptr Buffer,
 ## inputs_buffer holds the hash input as a byte seq
 ## the hash output is generated and populated inside output_buffer
 ## the output_buffer contains 32 bytes hash output
+
+#-------------------------------- Persistent Metadata utils -------------------------------------------
+
+proc set_metadata*(ctx: ptr RLN, input_buffer: ptr Buffer): bool {.importc: "set_metadata".}
+## sets the metadata stored by ctx to the value passed by input_buffer
+## the input_buffer holds a serialized representation of the metadata (format to be defined)
+## input_buffer holds the metadata as a byte seq
+## the return bool value indicates the success or failure of the operation
+
+proc get_metadata*(ctx: ptr RLN, output_buffer: ptr Buffer): bool {.importc: "get_metadata".}
+## gets the metadata stored by ctx and populates the passed pointer output_buffer with it
+## the output_buffer holds the metadata as a byte seq
+## the return bool value indicates the success or failure of the operation
diff --git a/waku/v2/waku_rln_relay/rln/wrappers.nim b/waku/v2/waku_rln_relay/rln/wrappers.nim
index b23e095a7..9fbd24ba4 100644
--- a/waku/v2/waku_rln_relay/rln/wrappers.nim
+++ b/waku/v2/waku_rln_relay/rln/wrappers.nim
@@ -346,3 +346,46 @@ proc getMerkleRoot*(rlnInstance: ptr RLN): MerkleNodeResult =
 
   var rootValue = cast[ptr MerkleNode] (root.`ptr`)[]
   return ok(rootValue)
+
+type
+  RlnMetadata* = object
+    lastProcessedBlock*: uint64
+
+proc serialize(metadata: RlnMetadata): seq[byte] =
+  ## serializes the metadata
+  ## returns the serialized metadata
+  return @(metadata.lastProcessedBlock.toBytes())
+
+proc setMetadata*(rlnInstance: ptr RLN, metadata: RlnMetadata): RlnRelayResult[void] =
+  ## sets the metadata of the RLN instance
+  ## returns an error if the metadata could not be set
+  ## returns void if the metadata is set successfully
+
+  # serialize the metadata
+  let metadataBytes = serialize(metadata)
+  var metadataBuffer = metadataBytes.toBuffer()
+  let metadataBufferPtr = addr metadataBuffer
+
+  # set the metadata
+  let metadataSet = set_metadata(rlnInstance, metadataBufferPtr)
+  if not metadataSet:
+    return err("could not set the metadata")
+  return ok()
+
+proc getMetadata*(rlnInstance: ptr RLN): RlnRelayResult[RlnMetadata] =
+  ## gets the metadata of the RLN instance
+  ## returns an error if the metadata could not be retrieved
+  ## returns the metadata if the metadata is retrieved successfully
+
+  # read the metadata
+  var
+    metadata {.noinit.}: Buffer = Buffer()
+    metadataPtr = addr(metadata)
+    getMetadataSuccessful = get_metadata(rlnInstance, metadataPtr)
+  if not getMetadataSuccessful:
+    return err("could not get the metadata")
+  if not metadata.len == 8:
+    return err("wrong output size")
+
+  var metadataValue = cast[ptr uint64] (metadata.`ptr`)[]
+  return ok(RlnMetadata(lastProcessedBlock: metadataValue))