1 files changed, 46 insertions, 0 deletions
diff --git a/src/Erebos/Sync.hs b/src/Erebos/Sync.hs
new file mode 100644
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--- /dev/null
+++ b/src/Erebos/Sync.hs
@@ -0,0 +1,46 @@
+module Erebos.Sync (
+    SyncService(..),
+) where
+
+import Control.Monad
+import Control.Monad.Reader
+
+import Data.List
+
+import Erebos.Identity
+import Erebos.Service
+import Erebos.State
+import Erebos.Storage
+import Erebos.Storage.Merge
+
+data SyncService = SyncPacket (Stored SharedState)
+
+instance Service SyncService where
+    serviceID _ = mkServiceID "a4f538d0-4e50-4082-8e10-7e3ec2af175d"
+
+    serviceHandler packet = do
+        let SyncPacket added = fromStored packet
+        pid <- asks svcPeerIdentity
+        self <- svcSelf
+        when (finalOwner pid `sameIdentity` finalOwner self) $ do
+            updateLocalHead_ $ \ls -> do
+                let current = sort $ lsShared $ fromStored ls
+                    updated = filterAncestors (added : current)
+                if current /= updated
+                   then mstore (fromStored ls) { lsShared = updated }
+                   else return ls
+
+    serviceNewPeer = notifyPeer . lsShared . fromStored =<< svcGetLocal
+    serviceStorageWatchers _ = (:[]) $ SomeStorageWatcher (lsShared . fromStored) notifyPeer
+
+instance Storable SyncService where
+    store' (SyncPacket smsg) = store' smsg
+    load' = SyncPacket <$> load'
+
+notifyPeer :: [Stored SharedState] -> ServiceHandler SyncService ()
+notifyPeer shared = do
+    pid <- asks svcPeerIdentity
+    self <- svcSelf
+    when (finalOwner pid `sameIdentity` finalOwner self) $ do
+        forM_ shared $ \sh ->
+            replyStoredRef =<< (mstore . SyncPacket) sh