[Perpetual]: Fix open interest (#879)

* fix open interest

* coment

x/perpetual/keeper/get_net_open_interest.go

@@ -7,27 +7,22 @@ import (
 )
 
 // GetNetOpenInterest calculates the net open interest for a given pool.
+// Note: Net open interest should always be in terms of trading asset
 func (k Keeper) GetNetOpenInterest(ctx sdk.Context, pool types.Pool) math.Int {
-	uusdc, found := k.assetProfileKeeper.GetEntry(ctx, "uusdc")
-	if !found {
-		return sdk.ZeroInt()
+	// account custody from long position
+	totalCustodyLong := sdk.ZeroInt()
+	for _, asset := range pool.PoolAssetsLong {
+		totalCustodyLong = totalCustodyLong.Add(asset.Custody)
 	}
 
-	var err error
-
-	// Calculate liabilities for long and short assets using the separate helper function
-	assetLiabilitiesLong, err := k.CalcTotalLiabilities(ctx, pool.PoolAssetsLong, pool.AmmPoolId, uusdc.Denom)
-	if err != nil {
-		return sdk.ZeroInt()
-	}
-
-	assetLiabilitiesShort, err := k.CalcTotalLiabilities(ctx, pool.PoolAssetsShort, pool.AmmPoolId, uusdc.Denom)
-	if err != nil {
-		return sdk.ZeroInt()
+	// account liabilities from short position
+	totalLiabilityShort := sdk.ZeroInt()
+	for _, asset := range pool.PoolAssetsShort {
+		totalLiabilityShort = totalLiabilityShort.Add(asset.Liabilities)
 	}
 
-	// Net Open Interest = Long Liabilities - Short Liabilities
-	netOpenInterest := assetLiabilitiesLong.Sub(assetLiabilitiesShort)
+	// Net Open Interest = Long custody - Short Liabilities
+	netOpenInterest := totalCustodyLong.Sub(totalLiabilityShort)
 
 	return netOpenInterest
 }