Add TODO comments for reverse auction changes

proto/cerc/auction/v1/auction.proto

@@ -109,6 +109,13 @@ message Auction {
     (gogoproto.nullable) = false,
     (gogoproto.moretags) = "json:\"winning_price\" yaml:\"winning_price\""
   ];
+
+  // cosmos.base.v1beta1.Coin maximum_bid
+  // for reverse auctions
+
+  // bool reverse
+  // if true, lowest bidder wins the auction (reverse auction) (supplier / service provider / etc. auctions)
+  // if false, highest bidder wins the auction (forward auction)
 }
 
 // Auctions represent all the auctions in the module

x/auction/keeper/keeper.go

@@ -339,6 +339,8 @@ func (k Keeper) CreateAuction(ctx sdk.Context, msg auctiontypes.MsgCreateAuction
 	commitsEndTime := now.Add(msg.CommitsDuration)
 	revealsEndTime := now.Add(msg.CommitsDuration + msg.RevealsDuration)
 
+	// if it's a reverse auction, take msg.MaximumBid from signerAddress to module account
+
 	auction := auctiontypes.Auction{
 		Id:             auctionId,
 		Status:         auctiontypes.AuctionStatusCommitPhase,
@@ -638,6 +640,10 @@ func (k Keeper) deleteCompletedAuctions(ctx sdk.Context) error {
 func (k Keeper) pickAuctionWinner(ctx sdk.Context, auction *auctiontypes.Auction) error {
 	k.Logger(ctx).Info(fmt.Sprintf("Picking auction %s winner.", auction.Id))
 
+	// Rename variables
+	// bestBid
+	// secondBestBid
+
 	var highestBid *auctiontypes.Bid
 	var secondHighestBid *auctiontypes.Bid
 
@@ -662,6 +668,10 @@ func (k Keeper) pickAuctionWinner(ctx sdk.Context, auction *auctiontypes.Auction
 			continue
 		}
 
+		// implement a comparison function to get a better bid amont two
+		// higher is better for forward auctions
+		// lower is better for reverse auctions
+
 		//nolint: all
 		if highestBid.BidAmount.IsLT(bid.BidAmount) {
 			k.Logger(ctx).Info(fmt.Sprintf("New highest bid %s %s", bid.BidderAddress, bid.BidAmount.String()))
@@ -682,6 +692,8 @@ func (k Keeper) pickAuctionWinner(ctx sdk.Context, auction *auctiontypes.Auction
 		}
 	}
 
+	// in case of reverse auctions, WinningPrice is second lowest bid (secondBestBid)
+
 	// Highest bid is the winner, but pays second highest bid price.
 	auction.Status = auctiontypes.AuctionStatusCompleted
 
@@ -721,6 +733,10 @@ func (k Keeper) pickAuctionWinner(ctx sdk.Context, auction *auctiontypes.Auction
 			}
 		}
 
+		// do this only in forward auctions
+		// in reverse auctions, return the extra amount back to the auction creator (auction.OwnerAddress)
+		// extra amount = maximumBid - secondBestBid
+
 		// Send back locked bid amount to all bidders.
 		sdkErr := k.bankKeeper.SendCoinsFromModuleToAccount(ctx, auctiontypes.ModuleName, bidderAddress, sdk.NewCoins(bid.BidAmount))
 		if sdkErr != nil {
@@ -762,6 +778,9 @@ func (k Keeper) pickAuctionWinner(ctx sdk.Context, auction *auctiontypes.Auction
 			k.Logger(ctx).Error(fmt.Sprintf("Auction error burning coins: %v", sdkErr))
 			panic(sdkErr)
 		}
+	} else {
+		// if no winner
+		// return all funds back to the auction creator
 	}
 
 	// Notify other modules (hook).