From f668dd14a88ce3ef4ea71e1a750f91c4a7c78f53 Mon Sep 17 00:00:00 2001
From: ccamel <camel.christophe@gmail.com>
Date: Wed, 22 Mar 2023 10:57:31 +0100
Subject: [PATCH] feat(logic): introduce weithted_meter gas meter

---
 x/logic/meter/weighted_meter.go | 90 +++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 x/logic/meter/weighted_meter.go

diff --git a/x/logic/meter/weighted_meter.go b/x/logic/meter/weighted_meter.go
new file mode 100644
index 00000000..832ea3a8
--- /dev/null
+++ b/x/logic/meter/weighted_meter.go
@@ -0,0 +1,90 @@
+package meter
+
+import (
+	"math"
+
+	"github.com/cosmos/cosmos-sdk/types"
+)
+
+// WeightedMeterDecorator is decorator that wraps a gas meter and adds a weight multiplier to the consumed gas.
+type WeightedMeterDecorator struct {
+	decorated types.GasMeter
+	weight    uint64
+}
+
+// WithWeightedMeter returns a new WeightedMeterDecorator with the given weight.
+func WithWeightedMeter(decorated types.GasMeter, weight uint64) types.GasMeter {
+	return &WeightedMeterDecorator{
+		decorated: decorated,
+		weight:    weight,
+	}
+}
+
+// GasConsumed returns the amount of gas consumed by the decorated gas meter.
+func (m *WeightedMeterDecorator) GasConsumed() types.Gas {
+	return m.decorated.GasConsumed()
+}
+
+// GasConsumedToLimit returns the amount of gas consumed by the decorated gas meter.
+func (m *WeightedMeterDecorator) GasConsumedToLimit() types.Gas {
+	return m.decorated.GasConsumedToLimit()
+}
+
+// GasRemaining returns the amount of gas remaining in the decorated gas meter.
+func (m *WeightedMeterDecorator) GasRemaining() types.Gas {
+	return m.decorated.GasRemaining()
+}
+
+// Limit returns the limit of the decorated gas meter.
+func (m *WeightedMeterDecorator) Limit() types.Gas {
+	return m.decorated.Limit()
+}
+
+// ConsumeGas consumes the given amount of gas from the decorated gas meter.
+func (m *WeightedMeterDecorator) ConsumeGas(amount types.Gas, descriptor string) {
+	consumed, overflow := multiplyUint64Overflow(m.decorated.GasConsumed(), amount)
+	if overflow {
+		m.decorated.ConsumeGas(math.MaxUint64, descriptor)
+	} else {
+		m.decorated.ConsumeGas(consumed, descriptor)
+	}
+}
+
+// RefundGas refunds the given amount of gas to the decorated gas meter.
+func (m *WeightedMeterDecorator) RefundGas(amount types.Gas, descriptor string) {
+	consumed, overflow := multiplyUint64Overflow(m.decorated.GasConsumed(), amount)
+	if overflow {
+		m.decorated.RefundGas(math.MaxUint64, descriptor)
+	} else {
+		m.decorated.RefundGas(consumed, descriptor)
+	}
+}
+
+// IsPastLimit returns true if the decorated gas meter is past the limit.
+func (m *WeightedMeterDecorator) IsPastLimit() bool {
+	return m.decorated.IsPastLimit()
+}
+
+// IsOutOfGas returns true if the decorated gas meter is out of gas.
+func (m *WeightedMeterDecorator) IsOutOfGas() bool {
+	return m.decorated.IsOutOfGas()
+}
+
+// String returns the decorated gas meter's string representation.
+func (m *WeightedMeterDecorator) String() string {
+	return m.decorated.String()
+}
+
+// multiplyUint64Overflow returns the product of a and b and a boolean indicating whether the product overflows.
+func multiplyUint64Overflow(a, b uint64) (uint64, bool) {
+	if a == 0 || b == 0 {
+		return 0, false
+	}
+
+	c := a * b
+	if c/a != b || c/b != a {
+		return 0, true
+	}
+
+	return c, false
+}