feat: opt-in positive slippage fee for integrators (#101)

* feat: Positive Slippage Fee

* fix: rename ethToTakerAssetRate to takerAssetPriceForOneEth

* fix: rename takerAssetPriceForOneEth to takerAssetsPerEth

* fix: export AffiliateFeeType

* rebased off development

* Add a gasOverhead for non-deterministic operations

* CHANGELOGs

* rename outputTokens to outputAmount

* Confirm transformer addresses on Mainnet and Ropsten

* fix import

Co-authored-by: Jacob Evans <jacob@dekz.net>

packages/protocol-utils/src/transformer_utils.ts

@@ -242,7 +242,7 @@ export function decodePayTakerTransformerData(encoded: string): PayTakerTransfor
 }
 
 /**
- * ABI encoder for `PayTakerTransformer.TransformData`
+ * ABI encoder for `affiliateFeetransformer.TransformData`
  */
 export const affiliateFeeTransformerDataEncoder = AbiEncoder.create({
     name: 'data',
@@ -317,3 +317,39 @@ export function getTransformerAddress(deployer: string, nonce: number): string {
         ethjs.rlphash([deployer, nonce] as any).slice(12),
     );
 }
+
+/**
+ * ABI encoder for `PositiveSlippageFeeTransformer.TransformData`
+ */
+export const positiveSlippageFeeTransformerDataEncoder = AbiEncoder.create({
+    name: 'data',
+    type: 'tuple',
+    components: [
+        { name: 'token', type: 'address' },
+        { name: 'bestCaseAmount', type: 'uint256' },
+        { name: 'recipient', type: 'address' },
+    ],
+});
+
+/**
+ * `PositiveSlippageFeeTransformer.TransformData`
+ */
+export interface PositiveSlippageFeeTransformerData {
+    token: string;
+    bestCaseAmount: BigNumber;
+    recipient: string;
+}
+
+/**
+ * ABI-encode a `PositiveSlippageFeeTransformer.TransformData` type.
+ */
+export function encodePositiveSlippageFeeTransformerData(data: PositiveSlippageFeeTransformerData): string {
+    return positiveSlippageFeeTransformerDataEncoder.encode(data);
+}
+
+/**
+ * ABI-decode a `PositiveSlippageFeeTransformer.TransformData` type.
+ */
+export function decodePositiveSlippageFeeTransformerData(encoded: string): PositiveSlippageFeeTransformerData {
+    return positiveSlippageFeeTransformerDataEncoder.decode(encoded);
+}