From 66038f42285c757c0bfcd5ed3d8cdf72fadc21b4 Mon Sep 17 00:00:00 2001
From: Jonathan Knowles <jonathan.knowles@iohk.io>
Date: Thu, 2 Jul 2020 08:43:37 +0000
Subject: [PATCH] Assign precedence values to pool certificates extracted from
 Shelley blocks.

---
 .../src/Cardano/Wallet/Shelley/Pools.hs       | 24 ++++++++++++++-----
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/lib/shelley/src/Cardano/Wallet/Shelley/Pools.hs b/lib/shelley/src/Cardano/Wallet/Shelley/Pools.hs
index d5fc060dfe9..7e92c06a141 100644
--- a/lib/shelley/src/Cardano/Wallet/Shelley/Pools.hs
+++ b/lib/shelley/src/Cardano/Wallet/Shelley/Pools.hs
@@ -53,7 +53,6 @@ import Cardano.Wallet.Primitive.Types
     , PoolId
     , PoolRegistrationCertificate (..)
     , PoolRetirementCertificate (..)
-    , Precedence (..)
     , ProtocolParameters
     , SlotId
     , SlotLength (..)
@@ -362,13 +361,26 @@ monitorStakePools tr gp nl db@DBLayer{..} = do
                         liftIO $ traceWith tr $ MsgErrProduction e
                     Right () ->
                         pure ()
-            forM_ registrations $ \case
-                Registration cert -> do
+
+            -- A Shelley block can contain multiple certificates relating to
+            -- the same pool.
+            --
+            -- The order in which certificates appear within a block determines
+            -- their precedence relative to one another.
+            --
+            -- Certificates that appear later in a block have higher precedence
+            -- than certificates that appear earlier.
+            --
+            -- TODO: Insert link to the specification to justify this decision.
+            --
+            let precedences = [minBound ..]
+            forM_ (registrations `zip` precedences) $ \case
+                (Registration cert, precedence) -> do
                     liftIO $ traceWith tr $ MsgStakePoolRegistration cert
-                    putPoolRegistration (slot, minBound) cert
-                Retirement cert -> do
+                    putPoolRegistration (slot, precedence) cert
+                (Retirement cert, precedence) -> do
                     liftIO $ traceWith tr $ MsgStakePoolRetirement cert
-                    putPoolRetirement (slot, minBound) cert
+                    putPoolRetirement (slot, precedence) cert
         pure Continue
 
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