fix: correct protocol fee calculation (#45)

src/limit-order/extensions/fee-taker/fee-calculator.spec.ts

@@ -0,0 +1,31 @@
+import {FeeCalculator} from './fee-calculator'
+import {IntegratorFee} from './integrator-fee'
+import {WhitelistHalfAddress} from './whitelist-half-address'
+import {Fees} from './fees'
+import {Address} from '../../../address'
+import {Bps} from '../../../bps'
+
+describe('FeeCalculator', () => {
+    it('should calculate protocol fee amount', () => {
+        // https://etherscan.io/tx/0x8f95dc0e6e836ca0abdad88e20cf61b0caf7c5463d67b577740f3084d428e56e
+
+        const calculator = new FeeCalculator(
+            Fees.integratorFee(
+                new IntegratorFee(
+                    new Address('0x8e097e5e0493de033270a01b324caf31f464dc67'),
+                    new Address('0x90cbe4bdd538d6e9b379bff5fe72c3d67a521de5'),
+                    new Bps(10n),
+                    new Bps(6000n)
+                )
+            ),
+            WhitelistHalfAddress.new([Address.fromBigInt(1n)])
+        )
+
+        const protocolFee = calculator.getProtocolFee(
+            Address.ZERO_ADDRESS,
+            18442227n
+        )
+
+        expect(protocolFee).toBe(7377n)
+    })
+})

src/limit-order/extensions/fee-taker/fee-calculator.ts

@@ -98,12 +98,7 @@ export class FeeCalculator {
             Fees.BASE_1E5 + fees.resolverFee + fees.integratorFee
         )
 
-        return mulDiv(
-            total,
-            Fees.BASE_1E2 -
-                BigInt(this.fees.integrator.share.toFraction(Fees.BASE_1E2)),
-            Fees.BASE_1E2
-        )
+        return total - this.getIntegratorFee(taker, orderTakingAmount)
     }
 
     /**