From 8e173236e40866505846027f75b86f7980b183f7 Mon Sep 17 00:00:00 2001
From: Thomas Bruyelle <thomas.bruyelle@tendermint.com>
Date: Mon, 25 Nov 2024 14:29:03 +0100
Subject: [PATCH] fix(photon): handle when minted uphoton < 1

---
 x/photon/keeper/msg_server.go      |  8 ++++----
 x/photon/keeper/msg_server_test.go | 18 +++++++++++++++++-
 x/photon/types/errors.go           |  9 ++++-----
 3 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/x/photon/keeper/msg_server.go b/x/photon/keeper/msg_server.go
index 7b90a0dd..40a32cd2 100644
--- a/x/photon/keeper/msg_server.go
+++ b/x/photon/keeper/msg_server.go
@@ -42,14 +42,14 @@ func (k msgServer) MintPhoton(goCtx context.Context, msg *types.MsgMintPhoton) (
 		uphotonSupply   = k.bankKeeper.GetSupply(ctx, types.Denom).Amount.ToLegacyDec()
 		conversionRate  = k.conversionRate(ctx, bondDenomSupply, uphotonSupply)
 		bondDenomToBurn = msg.Amount
-		uphotonToMint   = bondDenomToBurn.Amount.ToLegacyDec().Mul(conversionRate)
+		uphotonToMint   = bondDenomToBurn.Amount.ToLegacyDec().Mul(conversionRate).RoundInt()
 	)
 	// If no photon to mint, do not burn bondDenomToBurn, returns an error
 	if uphotonToMint.IsZero() {
-		return nil, types.ErrNoMintablePhotons
+		return nil, types.ErrZeroMintPhotons
 	}
 	// If photonToMint + photonSupply > photonMaxSupply, returns an error
-	if uphotonSupply.Add(uphotonToMint).GT(sdk.NewDec(types.MaxSupply)) {
+	if uphotonSupply.Add(uphotonToMint.ToLegacyDec()).GT(sdk.NewDec(types.MaxSupply)) {
 		return nil, types.ErrNotEnoughPhotons
 	}
 
@@ -60,7 +60,7 @@ func (k msgServer) MintPhoton(goCtx context.Context, msg *types.MsgMintPhoton) (
 	// 4) move PHOTONs from this module address to msg signer address
 	var (
 		coinsToBurn = sdk.NewCoins(bondDenomToBurn)
-		coinsToMint = sdk.NewCoins(sdk.NewCoin(types.Denom, uphotonToMint.RoundInt()))
+		coinsToMint = sdk.NewCoins(sdk.NewCoin(types.Denom, uphotonToMint))
 	)
 	// 1) Send atone to photon module for burn
 	to, err := sdk.AccAddressFromBech32(msg.ToAddress)
diff --git a/x/photon/keeper/msg_server_test.go b/x/photon/keeper/msg_server_test.go
index 483b5fc8..6760a2d3 100644
--- a/x/photon/keeper/msg_server_test.go
+++ b/x/photon/keeper/msg_server_test.go
@@ -1,6 +1,7 @@
 package keeper_test
 
 import (
+	"math"
 	"testing"
 
 	"github.com/atomone-hub/atomone/x/photon/testutil"
@@ -61,7 +62,7 @@ func TestMsgServerMintPhoton(t *testing.T) {
 				m.BankKeeper.EXPECT().GetSupply(ctx, "uatone").Return(sdk.NewInt64Coin("uatone", atoneSupply))
 				m.BankKeeper.EXPECT().GetSupply(ctx, types.Denom).Return(sdk.NewInt64Coin(types.Denom, types.MaxSupply))
 			},
-			expectedErr: "no more photon can be minted",
+			expectedErr: "no mintable photon after rounding, try higher burn",
 		},
 		{
 			name:   "fail: photon_supply+minted>max",
@@ -77,6 +78,21 @@ func TestMsgServerMintPhoton(t *testing.T) {
 			},
 			expectedErr: "not enough photon can be minted",
 		},
+		{
+			name:   "fail: atone_supply >> photon_supply",
+			params: types.Params{MintDisabled: false},
+			msg: &types.MsgMintPhoton{
+				ToAddress: toAddress.String(),
+				Amount:    sdk.NewInt64Coin(appparams.BondDenom, 1),
+			},
+			setup: func(ctx sdk.Context, m testutil.Mocks) {
+				m.StakingKeeper.EXPECT().BondDenom(ctx).Return(appparams.BondDenom)
+				m.BankKeeper.EXPECT().GetSupply(ctx, appparams.BondDenom).
+					Return(sdk.NewInt64Coin(appparams.BondDenom, math.MaxInt))
+				m.BankKeeper.EXPECT().GetSupply(ctx, types.Denom).Return(sdk.NewInt64Coin(types.Denom, 0))
+			},
+			expectedErr: "no mintable photon after rounding, try higher burn",
+		},
 		{
 			name:   "ok: photon_supply=0",
 			params: types.Params{MintDisabled: false},
diff --git a/x/photon/types/errors.go b/x/photon/types/errors.go
index 3f671144..4b409189 100644
--- a/x/photon/types/errors.go
+++ b/x/photon/types/errors.go
@@ -6,9 +6,8 @@ import (
 
 // x/photon module sentinel errors
 var (
-	ErrMintDisabled      = sdkerrors.Register(ModuleName, 1, "photon mint disabled")                             //nolint:staticcheck
-	ErrBurnInvalidDenom  = sdkerrors.Register(ModuleName, 2, "invalid burned amount denom: expected bond denom") //nolint:staticcheck
-	ErrNoMintablePhotons = sdkerrors.Register(ModuleName, 3, "no more photon can be minted")                     //nolint:staticcheck
-	ErrNotEnoughPhotons  = sdkerrors.Register(ModuleName, 4, "not enough photon can be minted")                  //nolint:staticcheck
-
+	ErrMintDisabled     = sdkerrors.Register(ModuleName, 1, "photon mint disabled")                               //nolint:staticcheck
+	ErrBurnInvalidDenom = sdkerrors.Register(ModuleName, 2, "invalid burned amount denom: expected bond denom")   //nolint:staticcheck
+	ErrZeroMintPhotons  = sdkerrors.Register(ModuleName, 3, "no mintable photon after rounding, try higher burn") //nolint:staticcheck
+	ErrNotEnoughPhotons = sdkerrors.Register(ModuleName, 4, "not enough photon can be minted")                    //nolint:staticcheck
 )