feat(incentivization): add codec for eligibility proof and status (#2419)

* incentivization: add codec for eligibility proofs

* add codec for eligibility proof and eligibility status

* address minor comments

* make status code mandatory in eligibility status

tests/all_tests_waku.nim

@@ -42,7 +42,8 @@ import
   ./waku_filter_v2/test_all,
   ./waku_peer_exchange/test_all,
   ./waku_lightpush/test_all,
-  ./waku_relay/test_all
+  ./waku_relay/test_all,
+  ./incentivization/test_all
 
 import
   # Waku v2 tests

tests/incentivization/test_all.nim

@@ -0,0 +1,2 @@
+import
+  ./test_rpc_codec

tests/incentivization/test_rpc_codec.nim

@@ -0,0 +1,32 @@
+import
+  std/options,
+  std/strscans,
+  testutils/unittests,
+  chronicles,
+  chronos,
+  libp2p/crypto/crypto
+
+import
+  ../../../waku/incentivization/rpc,
+  ../../../waku/incentivization/rpc_codec
+
+
+suite "Waku Incentivization Eligibility Codec":
+
+    asyncTest "encode eligibility proof":
+      var byteSequence: seq[byte] = @[1, 2, 3, 4, 5, 6, 7, 8]
+      let epRpc = EligibilityProof(proofOfPayment: some(byteSequence))
+      let encoded = encode(epRpc)
+      let decoded = EligibilityProof.decode(encoded.buffer).get()
+      check:
+          epRpc == decoded
+    
+    asyncTest "encode eligibility status":
+      let esRpc = EligibilityStatus(
+        statusCode: uint32(200),
+        statusDesc: some("OK")
+      )
+      let encoded = encode(esRpc)
+      let decoded = EligibilityStatus.decode(encoded.buffer).get()
+      check:
+        esRpc == decoded

waku/incentivization/rpc.nim

@@ -0,0 +1,17 @@
+import
+  json_serialization,
+  std/options
+import
+  ../waku_core
+
+# Implementing the RFC:
+# https://github.com/vacp2p/rfc/tree/master/content/docs/rfcs/73
+
+type
+
+  EligibilityProof* = object
+    proofOfPayment*: Option[seq[byte]]
+
+  EligibilityStatus* = object
+    statusCode*: uint32
+    statusDesc*: Option[string]

waku/incentivization/rpc_codec.nim

@@ -0,0 +1,59 @@
+import
+  std/options
+import
+  ../common/protobuf,
+  ../waku_core,
+  ./rpc
+
+
+# Codec for EligibilityProof
+
+proc encode*(epRpc: EligibilityProof): ProtoBuffer = 
+  var pb = initProtoBuffer()
+  if epRpc.proofOfPayment.isSome():
+    let proofOfPayment = epRpc.proofOfPayment.get()
+    pb.write3(1, proofOfPayment)
+  else:
+    # there is no proof
+    discard
+  pb
+
+proc decode*(T: type EligibilityProof, buffer: seq[byte]): ProtobufResult[T] = 
+  let pb = initProtoBuffer(buffer)
+  var epRpc = EligibilityProof()
+  var proofOfPayment = newSeq[byte]()
+  if not ?pb.getField(1, proofOfPayment):
+    epRpc.proofOfPayment = none(seq[byte])
+  else:
+    epRpc.proofOfPayment = some(proofOfPayment)
+  ok(epRpc)
+
+
+# Codec for EligibilityStatus
+
+proc encode*(esRpc: EligibilityStatus): ProtoBuffer = 
+  var pb = initProtoBuffer()
+  pb.write3(1, esRpc.statusCode)
+  if esRpc.statusDesc.isSome():
+    pb.write3(2, esRpc.statusDesc.get())
+  pb
+
+proc decode*(T: type EligibilityStatus, buffer: seq[byte]): ProtobufResult[T] = 
+  let pb = initProtoBuffer(buffer)
+  var esRpc = EligibilityStatus()
+  # status code
+  var code = uint32(0)
+  if not ?pb.getField(1, code):
+    # status code is mandatory
+    return err(ProtobufError.missingRequiredField("status_code"))
+  else:
+    esRpc.statusCode = code
+  # status description
+  var description = ""
+  if not ?pb.getField(2, description):
+    esRpc.statusDesc = none(string)
+  else:
+    esRpc.statusDesc = some(description)
+  ok(esRpc)
+  
+