From 079d3e6368bc20e4e3b1bcc8ffe4156e94705e1c Mon Sep 17 00:00:00 2001
From: Rahul Garg <rg@vihu.dev>
Date: Wed, 21 Oct 2020 22:39:50 -0700
Subject: [PATCH] Add support for HIP15

---
 include/blockchain_vars.hrl                   |  1 +
 .../v1/blockchain_txn_rewards_v1.erl          | 28 +++++++++++++++++--
 .../v1/blockchain_txn_vars_v1.erl             |  2 ++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/include/blockchain_vars.hrl b/include/blockchain_vars.hrl
index 3911cc7418..bb11d182df 100644
--- a/include/blockchain_vars.hrl
+++ b/include/blockchain_vars.hrl
@@ -179,6 +179,7 @@
 -define(poc_witnesses_percent, poc_witnesses_percent).
 -define(poc_challengers_percent, poc_challengers_percent).
 -define(dc_percent, dc_percent).
+-define(witness_redundancy, witness_redundancy).
 
 %%%
 %%% bundle txn vars
diff --git a/src/transactions/v1/blockchain_txn_rewards_v1.erl b/src/transactions/v1/blockchain_txn_rewards_v1.erl
index 8ce834dd0c..7734290436 100644
--- a/src/transactions/v1/blockchain_txn_rewards_v1.erl
+++ b/src/transactions/v1/blockchain_txn_rewards_v1.erl
@@ -291,6 +291,12 @@ get_reward_vars(Start, End, Ledger) ->
         {ok, R4} -> R4;
         _ -> 1
     end,
+
+    WitnessRedundancy = case blockchain:config(?witness_redundancy, Ledger) of
+                            {ok, WR} -> WR;
+                            _ -> 1
+                        end,
+
     EpochReward = calculate_epoch_reward(Start, End, Ledger),
     #{
         monthly_reward => MonthlyReward,
@@ -300,6 +306,7 @@ get_reward_vars(Start, End, Ledger) ->
         poc_challengees_percent => PocChallengeesPercent,
         poc_challengers_percent => PocChallengersPercent,
         poc_witnesses_percent => PocWitnessesPercent,
+        witness_redundancy => WitnessRedundancy,
         consensus_percent => ConsensusPercent,
         consensus_members => ConsensusMembers,
         dc_percent => DCPercent,
@@ -578,7 +585,7 @@ poc_challengees_rewards_(Version, [Elem|Path], StaticPath, Txn, Chain, Ledger, _
                             Ledger :: blockchain_ledger_v1:ledger(),
                             WitnessRewards :: map()) -> #{{gateway, libp2p_crypto:pubkey_bin()} => non_neg_integer()}.
 poc_witnesses_rewards(Transactions,
-                      #{poc_version := POCVersion},
+                      #{poc_version := POCVersion, witness_redundancy := WitnessRedundancy},
                       Chain,
                       Ledger,
                       WitnessRewards) ->
@@ -604,11 +611,28 @@ poc_witnesses_rewards(Transactions,
                                               [] ->
                                                   Acc1;
                                               ValidWitnesses ->
+                                                  ToAdd = case WitnessRedundancy of
+                                                              1 ->
+                                                                  %% continue with the old thing
+                                                                  1;
+                                                              N ->
+                                                                  L = length(ValidWitnesses),
+                                                                  case L =< N of
+                                                                      true ->
+                                                                          %% Consider ideal redundant coverage when number of valid_witnesses is less than
+                                                                          %% or equal to configured witness_redundancy
+                                                                          1;
+                                                                      false ->
+                                                                          %% Proportional reward_unit as there are more valid_witnesses than necessary
+                                                                          blockchain_utils:normalize_float(N/L)
+                                                                  end
+                                                          end,
+
                                                   lists:foldl(
                                                     fun(WitnessRecord, Map) ->
                                                             Witness = blockchain_poc_witness_v1:gateway(WitnessRecord),
                                                             I = maps:get(Witness, Map, 0),
-                                                            maps:put(Witness, I+1, Map)
+                                                            maps:put(Witness, I+ToAdd, Map)
                                                     end,
                                                     Acc1,
                                                     ValidWitnesses
diff --git a/src/transactions/v1/blockchain_txn_vars_v1.erl b/src/transactions/v1/blockchain_txn_vars_v1.erl
index 702635dc25..2c6d8fec7e 100644
--- a/src/transactions/v1/blockchain_txn_vars_v1.erl
+++ b/src/transactions/v1/blockchain_txn_vars_v1.erl
@@ -914,6 +914,8 @@ validate_var(?poc_challengers_percent, Value) ->
     validate_float(Value, "poc_challengers_percent", 0.0, 1.0);
 validate_var(?dc_percent, Value) ->
     validate_float(Value, "dc_percent", 0.0, 1.0);
+validate_var(?witness_redundancy, Value) ->
+    validate_int(Value, "witness_redundancy", 2, 100, false);
 validate_var(?reward_version, Value) ->
     case Value of
         N when is_integer(N), N >= 1,  N =< 5 ->