From a2bc105de2898a23e743b33c51138a6387328677 Mon Sep 17 00:00:00 2001
From: Benjamin DENEUX <b.deneux@okp4.com>
Date: Wed, 23 Aug 2023 11:26:14 +0200
Subject: [PATCH] feat(mint): add new mint function calculation

---
 x/mint/abci.go         | 44 ++++++++++++++++++++++++++++++++++++++++++
 x/mint/types/minter.go |  5 +++--
 2 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/x/mint/abci.go b/x/mint/abci.go
index 1c33e81d..a5ed50ec 100644
--- a/x/mint/abci.go
+++ b/x/mint/abci.go
@@ -1,12 +1,56 @@
 package mint
 
 import (
+	"time"
+
+	"github.com/cosmos/cosmos-sdk/telemetry"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 
 	"github.com/okp4/okp4d/x/mint/keeper"
+	"github.com/okp4/okp4d/x/mint/types"
 )
 
 // BeginBlocker mints new tokens for the previous block.
 func BeginBlocker(ctx sdk.Context, k keeper.Keeper) {
+	defer telemetry.ModuleMeasureSince(types.ModuleName, time.Now(), telemetry.MetricKeyBeginBlocker)
+
+	// fetch stored minter & params
+	minter := k.GetMinter(ctx)
+	params := k.GetParams(ctx)
+
+	// recalculate inflation rate
+	totalSupply := k.TokenSupply(ctx, params.MintDenom)
+	bondedRatio := k.BondedRatio(ctx)
+	minter.Inflation = minter.NextInflation(params, bondedRatio)
+	minter.AnnualProvisions = minter.NextAnnualProvisions(params, totalSupply)
+	k.SetMinter(ctx, minter)
+
+	// mint coins, update supply
+	mintedCoin := minter.BlockProvision(params)
+	mintedCoins := sdk.NewCoins(mintedCoin)
+
+	err := k.MintCoins(ctx, mintedCoins)
+	if err != nil {
+		panic(err)
+	}
+
+	// send the minted coins to the fee collector account
+	err = k.AddCollectedFees(ctx, mintedCoins)
+	if err != nil {
+		panic(err)
+	}
+
+	if mintedCoin.Amount.IsInt64() {
+		defer telemetry.ModuleSetGauge(types.ModuleName, float32(mintedCoin.Amount.Int64()), "minted_tokens")
+	}
 
+	ctx.EventManager().EmitEvent(
+		sdk.NewEvent(
+			types.EventTypeMint,
+			sdk.NewAttribute(types.AttributeKeyBondedRatio, bondedRatio.String()),
+			sdk.NewAttribute(types.AttributeKeyInflation, minter.Inflation.String()),
+			sdk.NewAttribute(types.AttributeKeyAnnualProvisions, minter.AnnualProvisions.String()),
+			sdk.NewAttribute(sdk.AttributeKeyAmount, mintedCoin.Amount.String()),
+		),
+	)
 }
diff --git a/x/mint/types/minter.go b/x/mint/types/minter.go
index 6daf9253..c9db82f6 100644
--- a/x/mint/types/minter.go
+++ b/x/mint/types/minter.go
@@ -44,8 +44,9 @@ func ValidateMinter(minter Minter) error {
 
 // NextInflation return the new inflation rate for the next year
 // Get the current inflation and multiply by (1 - annual reduction factor).
-func (m Minter) NextInflation(params Params) sdk.Dec {
-	return m.Inflation
+func (m Minter) NextInflation(params Params, boundedRatio sdk.Dec) sdk.Dec {
+	bounded := params.BoundingAdjustment.Sub(boundedRatio.Quo(params.TargetBoundingRatio))
+	return params.InflationCoef.Mul(bounded).Mul(sdk.NewDec(100))
 }
 
 // NextAnnualProvisions returns the annual provisions based on current total