From 6930bab827886bd7608b2572c7f1573b81a091d9 Mon Sep 17 00:00:00 2001
From: Philipp Kant <philipp.kant7@gmail.com>
Date: Mon, 14 Sep 2020 14:27:15 +0200
Subject: [PATCH] Define function for current circulation

and use it in the API, and in the rewards calculation.

Fixes #1838
---
 .../src/Shelley/Spec/Ledger/API/Wallet.hs          |  9 ++++-----
 .../src/Shelley/Spec/Ledger/LedgerState.hs         | 14 +++++++++++---
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/API/Wallet.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/API/Wallet.hs
index 0f844f4e30f..8cb5beec63a 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/API/Wallet.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/API/Wallet.hs
@@ -12,7 +12,6 @@ where
 import qualified Cardano.Crypto.VRF as VRF
 import Cardano.Ledger.Crypto (VRF)
 import Cardano.Ledger.Era (Crypto, Era)
-import qualified Cardano.Ledger.Val as Val
 import Cardano.Slotting.EpochInfo (epochInfoRange)
 import Cardano.Slotting.Slot (SlotNo)
 import qualified Data.ByteString.Short as BSS
@@ -35,12 +34,12 @@ import Shelley.Spec.Ledger.Delegation.Certificates (IndividualPoolStake (..), un
 import qualified Shelley.Spec.Ledger.EpochBoundary as EB
 import Shelley.Spec.Ledger.Keys (KeyHash, KeyRole (..), SignKeyVRF)
 import Shelley.Spec.Ledger.LedgerState
-  ( AccountState (..),
-    DPState (..),
+  ( DPState (..),
     EpochState (..),
     LedgerState (..),
     NewEpochState (..),
     UTxOState (..),
+    circulation,
     stakeDistr,
   )
 import Shelley.Spec.Ledger.OverlaySchedule (isOverlaySlot)
@@ -60,8 +59,8 @@ import Shelley.Spec.Ledger.UTxO (UTxO (..))
 getTotalStake :: Globals -> ShelleyState era -> Coin
 getTotalStake globals ss =
   let supply = Coin . fromIntegral $ maxLovelaceSupply globals
-      EpochState acnt _ _ _ _ _ = nesEs ss
-   in supply Val.~~ (_reserves acnt)
+      es = nesEs ss
+   in circulation es supply
 
 -- | Calculate the Non-Myopic Pool Member Rewards for a set of credentials.
 -- For each given credential, this function returns a map from each stake
diff --git a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/LedgerState.hs b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/LedgerState.hs
index 972152d6ce2..374d0a7bf83 100644
--- a/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/LedgerState.hs
+++ b/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/LedgerState.hs
@@ -86,6 +86,7 @@ module Shelley.Spec.Ledger.LedgerState
     NewEpochEnv (..),
     getGKeys,
     updateNES,
+    circulation,
   )
 where
 
@@ -918,7 +919,7 @@ createRUpd ::
   EpochState era ->
   Coin ->
   ShelleyBase (RewardUpdate era)
-createRUpd slotsPerEpoch b@(BlocksMade b') (EpochState acnt ss ls pr _ nm) total = do
+createRUpd slotsPerEpoch b@(BlocksMade b') es@(EpochState acnt ss ls pr _ nm) total = do
   asc <- asks activeSlotCoeff
   let SnapShot stake' delegs' poolParams = _pstakeGo ss
       Coin reserves = _reserves acnt
@@ -937,9 +938,9 @@ createRUpd slotsPerEpoch b@(BlocksMade b') (EpochState acnt ss ls pr _ nm) total
       Coin rPot = _feeSS ss <> deltaR1
       deltaT1 = floor $ intervalValue (_tau pr) * fromIntegral rPot
       _R = Coin $ rPot - deltaT1
-      circulation = total Val.~~ (_reserves acnt)
+      totalStake = circulation es total
       (rs_, newLikelihoods) =
-        reward pr b _R (Map.keysSet $ _rewards ds) poolParams stake' delegs' circulation asc slotsPerEpoch
+        reward pr b _R (Map.keysSet $ _rewards ds) poolParams stake' delegs' totalStake asc slotsPerEpoch
       deltaR2 = _R Val.~~ (Map.foldr (<>) mempty rs_)
       blocksMade = fromIntegral $ Map.foldr (+) 0 b' :: Integer
   pure $
@@ -951,6 +952,13 @@ createRUpd slotsPerEpoch b@(BlocksMade b') (EpochState acnt ss ls pr _ nm) total
         nonMyopic = (updateNonMypopic nm _R newLikelihoods)
       }
 
+-- | Calculate the current circulation
+--
+-- This is used in the rewards calculation, and for API endpoints for pool ranking.
+circulation :: EpochState era -> Coin -> Coin
+circulation (EpochState acnt _ _ _ _ _) supply =
+  supply Val.~~ (_reserves acnt)
+
 -- | Update new epoch state
 updateNES ::
   NewEpochState era ->