From af0c45479aca7291dbcc5cd5117ef937247a2826 Mon Sep 17 00:00:00 2001
From: toteki <63419657+toteki@users.noreply.github.com>
Date: Wed, 27 Sep 2023 08:09:52 -0600
Subject: [PATCH] price mode support

---
 CHANGELOG.md                |  1 +
 x/leverage/keeper/oracle.go | 27 ++++++++++++++++++++-------
 x/leverage/types/errors.go  |  1 +
 x/leverage/types/oracle.go  |  4 +++-
 4 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4065a56351..bf3dd420d0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -49,6 +49,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 ### Improvements
 
 - [2261](https://github.com/umee-network/umee/pull/2261) Use go 1.21
+- [22XX](https://github.com/umee-network/umee/pull/22XX) Leverage transactions accept spot prices up to 3 minutes old, and leverage queries use most recet spot price when required.
 
 ### Bug Fixes
 
diff --git a/x/leverage/keeper/oracle.go b/x/leverage/keeper/oracle.go
index 7173c5cc43..1d1f0db220 100644
--- a/x/leverage/keeper/oracle.go
+++ b/x/leverage/keeper/oracle.go
@@ -12,6 +12,9 @@ import (
 	oracletypes "github.com/umee-network/umee/v6/x/oracle/types"
 )
 
+// TODO: parameterize this
+const maxSpotPriceAge = 180 // 3 minutes
+
 var ten = sdk.MustNewDecFromStr("10")
 
 // TokenPrice returns the USD value of a token's symbol denom, e.g. `UMEE` (rather than `uumee`).
@@ -26,8 +29,9 @@ func (k Keeper) TokenPrice(ctx sdk.Context, baseDenom string, mode types.PriceMo
 		return sdk.ZeroDec(), t.Exponent, types.ErrBlacklisted
 	}
 
-	// if a token is exempt from historic pricing, all price modes return Spot price
-	if t.HistoricMedians == 0 {
+	// if a token is exempt from historic pricing, all price modes return Spot price.
+	// price mode last is unaffected.
+	if t.HistoricMedians == 0 && mode != types.PriceModeLast {
 		mode = types.PriceModeSpot
 	}
 
@@ -39,9 +43,20 @@ func (k Keeper) TokenPrice(ctx sdk.Context, baseDenom string, mode types.PriceMo
 		if err != nil {
 			return sdk.ZeroDec(), t.Exponent, errors.Wrap(err, "oracle")
 		}
+		if mode != types.PriceModeLast {
+			// unless price mode is last price, require spot price to be recent
+			blockTime := ctx.BlockTime().Unix()
+			priceTime := spotPrice.Timestamp.Unix()
+			priceAge := blockTime - priceTime
+			if priceAge < 0 || priceAge > maxSpotPriceAge {
+				return sdk.ZeroDec(), t.Exponent, types.ErrExpiredOraclePrice.Wrapf(
+					"price: %d, block: %d", priceTime, blockTime)
+			}
+		}
 	}
-	if mode != types.PriceModeSpot {
-		// historic price is required for modes other than spot
+
+	if mode != types.PriceModeSpot && mode != types.PriceModeLast {
+		// historic price is required for modes other than spot and last
 		var numStamps uint32
 		historicPrice, numStamps, err = k.oracleKeeper.MedianOfHistoricMedians(
 			ctx, strings.ToUpper(t.SymbolDenom), uint64(t.HistoricMedians))
@@ -57,10 +72,8 @@ func (k Keeper) TokenPrice(ctx sdk.Context, baseDenom string, mode types.PriceMo
 		}
 	}
 
-	// TODO: need to use spotPrice.Timestamp to make a decision about the price
-
 	switch mode {
-	case types.PriceModeSpot:
+	case types.PriceModeSpot, types.PriceModeLast:
 		price = spotPrice.Rate
 	case types.PriceModeHistoric:
 		price = historicPrice
diff --git a/x/leverage/types/errors.go b/x/leverage/types/errors.go
index 01d2ee0595..39dc32ca82 100644
--- a/x/leverage/types/errors.go
+++ b/x/leverage/types/errors.go
@@ -40,6 +40,7 @@ var (
 	ErrUndercollateralized   = errors.Register(ModuleName, 402, "borrow positions are undercollateralized")
 	ErrLiquidationIneligible = errors.Register(ModuleName, 403, "borrower not eligible for liquidation")
 	ErrNoHistoricMedians     = errors.Register(ModuleName, 405, "insufficient historic medians available")
+	ErrExpiredOraclePrice    = errors.Register(ModuleName, 406, "no recent oracle price")
 
 	// 5XX = Market Conditions
 	ErrLendingPoolInsufficient = errors.Register(ModuleName, 500, "lending pool insufficient")
diff --git a/x/leverage/types/oracle.go b/x/leverage/types/oracle.go
index afed86226c..490cf3a163 100644
--- a/x/leverage/types/oracle.go
+++ b/x/leverage/types/oracle.go
@@ -4,8 +4,10 @@ package types
 type PriceMode uint64
 
 const (
-	// Spot mode requests the most recent prices from oracle
+	// Spot mode requests the most recent prices from oracle, unless they are too old.
 	PriceModeSpot PriceMode = iota
+	// Last mode requests the most recent price, regardless of price age.
+	PriceModeLast
 	// Historic mode requests the median of the most recent historic medians
 	PriceModeHistoric
 	// High mode uses the higher of either Spot or Historic prices