Swap and add encoding (Uniswap#7)

Author: ewilz

src/approveAndCall.ts

@@ -0,0 +1,64 @@
+import { Interface } from '@ethersproject/abi'
+import invariant from 'tiny-invariant'
+import { abi } from '@uniswap/swap-router-contracts/artifacts/contracts/interfaces/IApproveAndCall.sol/IApproveAndCall.json'
+import { Currency, Token } from '@uniswap/sdk-core'
+import { NonfungiblePositionManager } from '@uniswap/v3-sdk'
+
+export enum ApprovalTypes {
+  NOT_REQUIRED = 0,
+  MAX = 1,
+  MAX_MINUS_ONE = 2,
+  ZERO_THEN_MAX = 3,
+  ZERO_THEN_MAX_MINUS_ONE = 4,
+}
+
+export abstract class ApproveAndCall {
+  public static INTERFACE: Interface = new Interface(abi)
+
+  /**
+   * Cannot be constructed.
+   */
+  private constructor() {}
+
+  public static encodeApproveMax(token: Token): string {
+    return ApproveAndCall.INTERFACE.encodeFunctionData('approveMax', [token.address])
+  }
+
+  public static encodeApproveMaxMinusOne(token: Token): string {
+    return ApproveAndCall.INTERFACE.encodeFunctionData('approveMaxMinusOne', [token.address])
+  }
+
+  public static encodeApproveZeroThenMax(token: Token): string {
+    return ApproveAndCall.INTERFACE.encodeFunctionData('approveZeroThenMax', [token.address])
+  }
+
+  public static encodeApproveZeroThenMaxMinusOne(token: Token): string {
+    return ApproveAndCall.INTERFACE.encodeFunctionData('approveZeroThenMaxMinusOne', [token.address])
+  }
+
+  public static encodeCallPositionManager(calldatas: string[]): string {
+    invariant(calldatas.length > 0, 'NULL_CALLDATA')
+
+    if (calldatas.length == 1) {
+      return ApproveAndCall.INTERFACE.encodeFunctionData('callPositionManager', calldatas)
+    } else {
+      const encodedMulticall = NonfungiblePositionManager.INTERFACE.encodeFunctionData('multicall', [calldatas])
+      return ApproveAndCall.INTERFACE.encodeFunctionData('callPositionManager', [encodedMulticall])
+    }
+  }
+
+  public static encodeApprove(token: Currency, approvalType: ApprovalTypes): string {
+    switch (approvalType) {
+      case ApprovalTypes.MAX:
+        return ApproveAndCall.encodeApproveMax(token.wrapped)
+      case ApprovalTypes.MAX_MINUS_ONE:
+        return ApproveAndCall.encodeApproveMaxMinusOne(token.wrapped)
+      case ApprovalTypes.ZERO_THEN_MAX:
+        return ApproveAndCall.encodeApproveZeroThenMax(token.wrapped)
+      case ApprovalTypes.ZERO_THEN_MAX_MINUS_ONE:
+        return ApproveAndCall.encodeApproveZeroThenMaxMinusOne(token.wrapped)
+      default:
+        throw 'Error: invalid ApprovalType'
+    }
+  }
+}