feature/filter (#63)

* simplified filter

* add filter

* eol

* Update waku_protocol2.nim

* trigger GitHub actions

* comment

* fix import

* oops

* and

* init filters

* import tables

waku/protocol/v2/filter.nim

@@ -0,0 +1,25 @@
+import 
+  tables
+
+type 
+
+  FilterMessageHandler* = proc(msg: seq[byte]) {.gcsafe, closure.}
+
+  Filter* = object
+    topics: seq[string] # @TODO TOPIC
+    handler: FilterMessageHandler
+    
+  Filters* = Table[string, Filter]
+
+proc init*(T: type Filter, topics: seq[string], handler: FilterMessageHandler): T =
+  result = T(
+    topics: topics,
+    handler: handler
+  )
+
+proc notify*(filters: var Filters, topic: string, msg: seq[byte]) {.gcsafe.} =
+  for filter in filters.mvalues:
+    if filter.topics.len > 0 and topic notin filter.topics:
+      continue
+
+    filter.handler(msg)

waku/protocol/v2/waku_protocol2.nim

@@ -5,6 +5,8 @@
 
 import strutils
 import chronos, chronicles
+import ./filter
+import tables
 import libp2p/protocols/pubsub/pubsub,
        libp2p/protocols/pubsub/pubsubpeer,
        libp2p/protocols/pubsub/floodsub,
@@ -28,6 +30,8 @@ type
     text*: string
     gossip_enabled*: bool
 
+    filters: Filters
+
 method init(w: WakuSub) =
   debug "init"
   proc handler(conn: Connection, proto: string) {.async.} =
@@ -44,6 +48,7 @@ method init(w: WakuSub) =
 
   # XXX: Handler hijack GossipSub here?
   w.handler = handler
+  w.filters = initTable[string, Filter]()
   w.codec = WakuSubCodec
 
 method initPubSub*(w: WakuSub) =
@@ -82,6 +87,10 @@ method subscribeTopic*(w: WakuSub,
   proc handler(topic: string, data: seq[byte]) {.async, gcsafe.} =
     info "Hit NOOP handler", topic
 
+    # Currently we are using the libp2p topic here.
+    # This will need to be change to a Waku topic.
+    w.filters.notify(topic, data)
+
   debug "subscribeTopic", topic=topic, subscribe=subscribe, peerId=peerId
 
   if w.gossip_enabled: