Refactor the requestRedemption fn

We do not want to expose the low-level function from chain handles(see `buildRedemptionData` from `EthereumBridge` handle). The goal of `src/ethereum.ts` is to translate domain-level objects into low-level Ethereum chain primitives and perform a call. Instead of having `buildRedemptionData` in `Bridge` interface here we modify the `approveAndCall` interface and replace `extraData: Hex` with domain-level objects, as accepted by `buildRedemptionData`. Here we also rename the `approveAndCall` to `requestRedemption` and explain in the docs it happens via `approveAndCall`- although `requestRedemption` does not exist on the Solidity code of TBTC token, having it in `TBTCToken` Typescript API is fine given we abstract the complexity and make the API human-readable.
keep-network · Jul 4, 2023 · 9249ee5 · 9249ee5
1 parent 759cc78
commit 9249ee5
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diff --git a/typescript/src/chain.ts b/typescript/src/chain.ts
@@ -244,26 +244,6 @@ export interface Bridge {
    * Returns the attached WalletRegistry instance.
    */
   walletRegistry(): Promise<WalletRegistry>
-
-  /**
-   * Builds the redemption data required to request a redemption via
-   * @see TBTCToken#approveAndCall - the built data should be passed as
-   * `extraData` the @see TBTCToken#approveAndCall function.
-   * @param redeemer On-chain identifier of the redeemer.
-   * @param walletPublicKey The Bitcoin public key of the wallet. Must be in the
-   *        compressed form (33 bytes long with 02 or 03 prefix).
-   * @param mainUtxo The main UTXO of the wallet. Must match the main UTXO
-   *        held by the on-chain Bridge contract.
-   * @param redeemerOutputScript The output script that the redeemed funds will
-   *        be locked to. Must be un-prefixed and not prepended with length.
-   * @returns The
-   */
-  buildRedemptionData(
-    redeemer: Identifier,
-    walletPublicKey: string,
-    mainUtxo: UnspentTransactionOutput,
-    redeemerOutputScript: string
-  ): Hex
 }
 
 /**
@@ -401,6 +381,40 @@ export interface TBTCVault {
   getOptimisticMintingFinalizedEvents: GetEvents.Function<OptimisticMintingFinalizedEvent>
 }
 
+/**
+ * Represnts data required to request redemption.
+ */
+export interface RequestRedemptionData {
+  /**
+   * On-chain identifier of the redeemer.
+   */
+  redeemer: Identifier
+  /**
+   * The Bitcoin public key of the wallet. Must be in the compressed form (33
+   * bytes long with 02 or 03 prefix).
+   */
+  walletPublicKey: string
+  /**
+   * The main UTXO of the wallet. Must match the main UTXO held by the on-chain
+   * Bridge contract.
+   */
+  mainUtxo: UnspentTransactionOutput
+  /**
+   * The output script that the redeemed funds will be locked to. Must be
+   * un-prefixed and not prepended with length.
+   */
+  redeemerOutputScript: string
+  /**
+   * The amount to be redeemed with the precision of the tBTC on-chain token
+   * contract.
+   */
+  amount: BigNumber
+  /**
+   * The vault address.
+   */
+  vault: Identifier
+}
+
 /**
  * Interface for communication with the TBTC v2 token on-chain contract.
  */
@@ -418,18 +432,13 @@ export interface TBTCToken {
   totalSupply(blockNumber?: number): Promise<BigNumber>
 
   /**
-   * Calls `receiveApproval` function on spender previously approving the spender
-   * to withdraw from the caller multiple times, up to the `amount` amount. If
-   * this function is called again, it overwrites the current allowance with
-   * `amount`.
-   * @param spender Address of contract authorized to spend.
-   * @param amount The max amount they can spend.
-   * @param extraData Extra information to send to the approved contract.
+   * Requests redemption in one transacion using the `approveAndCall` function
+   * from the tBTC on-chain token contract. Then the tBTC token contract calls
+   * the `receiveApproval` function from the `TBTCVault` contract which burns
+   * tBTC tokens and requests redemption.
+   * @param requestRedemptionData Data required to request redemption @see
+   *        {@link RequestRedemptionData}.
    * @returns Transaction hash of the approve and call transaction.
    */
-  approveAndCall(
-    spender: Identifier,
-    amount: BigNumber,
-    extraData: Hex
-  ): Promise<Hex>
+  requestRedemption(requestRedemptionData: RequestRedemptionData): Promise<Hex>
 }
diff --git a/typescript/src/ethereum.ts b/typescript/src/ethereum.ts
@@ -5,6 +5,7 @@ import {
   TBTCToken as ChainTBTCToken,
   Identifier as ChainIdentifier,
   GetEvents,
+  RequestRedemptionData,
 } from "./chain"
 import {
   BigNumber,
@@ -488,39 +489,6 @@ export class Bridge
     redeemerOutputScript: string,
     amount: BigNumber
   ): Promise<void> {
-    const redemptionData = this.parseRequestRedemptionTransactionData(
-      walletPublicKey,
-      mainUtxo,
-      redeemerOutputScript
-    )
-
-    await sendWithRetry<ContractTransaction>(async () => {
-      return await this._instance.requestRedemption(
-        redemptionData.walletPublicKeyHash,
-        redemptionData.mainUtxo,
-        redemptionData.prefixedRawRedeemerOutputScript,
-        amount
-      )
-    }, this._totalRetryAttempts)
-  }
-
-  /**
-   * Parses the request redemption data to the proper form.
-   * @param walletPublicKey - The Bitcoin public key of the wallet. Must be in
-   *        the compressed form (33 bytes long with 02 or 03 prefix).
-   * @param mainUtxo - The main UTXO of the wallet. Must match the main UTXO
-   *        held by the on-chain contract.
-   * @param redeemerOutputScript - The output script that the redeemed funds
-   *        will be locked to. Must be un-prefixed and not prepended with
-   *        length.
-   * @returns Parsed data that can be passed to the contract to request
-   * redemption.
-   */
-  private parseRequestRedemptionTransactionData = (
-    walletPublicKey: string,
-    mainUtxo: UnspentTransactionOutput,
-    redeemerOutputScript: string
-  ) => {
     const walletPublicKeyHash = `0x${computeHash160(walletPublicKey)}`
 
     const mainUtxoParam = {
@@ -539,11 +507,14 @@ export class Bridge
       rawRedeemerOutputScript,
     ]).toString("hex")}`
 
-    return {
-      walletPublicKeyHash,
-      mainUtxo: mainUtxoParam,
-      prefixedRawRedeemerOutputScript,
-    }
+    await sendWithRetry<ContractTransaction>(async () => {
+      return await this._instance.requestRedemption(
+        walletPublicKeyHash,
+        mainUtxoParam,
+        prefixedRawRedeemerOutputScript,
+        amount
+      )
+    }, this._totalRetryAttempts)
   }
 
   // eslint-disable-next-line valid-jsdoc
@@ -724,37 +695,6 @@ export class Bridge
       signerOrProvider: this._instance.signer || this._instance.provider,
     })
   }
-
-  // eslint-disable-next-line valid-jsdoc
-  /**
-   * @see {ChainBridge#buildRedemptionData}
-   */
-  buildRedemptionData(
-    redeemer: ChainIdentifier,
-    walletPublicKey: string,
-    mainUtxo: UnspentTransactionOutput,
-    redeemerOutputScript: string
-  ): Hex {
-    const redemptionData = this.parseRequestRedemptionTransactionData(
-      walletPublicKey,
-      mainUtxo,
-      redeemerOutputScript
-    )
-
-    return Hex.from(
-      utils.defaultAbiCoder.encode(
-        ["address", "bytes20", "bytes32", "uint32", "uint64", "bytes"],
-        [
-          redeemer.identifierHex,
-          redemptionData.walletPublicKeyHash,
-          redemptionData.mainUtxo.txHash,
-          redemptionData.mainUtxo.txOutputIndex,
-          redemptionData.mainUtxo.txOutputValue,
-          redemptionData.prefixedRawRedeemerOutputScript,
-        ]
-      )
-    )
-  }
 }
 
 /**
@@ -1161,19 +1101,79 @@ export class TBTCToken
     })
   }
 
-  async approveAndCall(
-    spender: ChainIdentifier,
-    amount: BigNumber,
-    extraData: Hex
+  // eslint-disable-next-line valid-jsdoc
+  /**
+   * @see {ChainTBTCToken#requestRedemption}
+   */
+  async requestRedemption(
+    requestRedemptionData: RequestRedemptionData
   ): Promise<Hex> {
+    const { vault, amount, ...restData } = requestRedemptionData
+
+    const extraData = this.buildRequestRedemptionData(restData)
+
     const tx = await sendWithRetry<ContractTransaction>(async () => {
       return await this._instance.approveAndCall(
-        spender.identifierHex,
+        vault.identifierHex,
         amount,
         extraData.toPrefixedString()
       )
     }, this._totalRetryAttempts)
 
     return Hex.from(tx.hash)
   }
+
+  private buildRequestRedemptionData(
+    requestRedemptionData: Omit<RequestRedemptionData, "amount" | "vault">
+  ): Hex {
+    const { redeemer, ...restData } = requestRedemptionData
+    const { walletPublicKeyHash, mainUtxo, prefixedRawRedeemerOutputScript } =
+      this.buildBridgeRequestRedemptionData(restData)
+
+    return Hex.from(
+      utils.defaultAbiCoder.encode(
+        ["address", "bytes20", "bytes32", "uint32", "uint64", "bytes"],
+        [
+          redeemer.identifierHex,
+          walletPublicKeyHash,
+          mainUtxo.txHash,
+          mainUtxo.txOutputIndex,
+          mainUtxo.txOutputValue,
+          prefixedRawRedeemerOutputScript,
+        ]
+      )
+    )
+  }
+
+  private buildBridgeRequestRedemptionData(
+    data: Pick<
+      RequestRedemptionData,
+      "mainUtxo" | "walletPublicKey" | "redeemerOutputScript"
+    >
+  ) {
+    const { walletPublicKey, mainUtxo, redeemerOutputScript } = data
+    const walletPublicKeyHash = `0x${computeHash160(walletPublicKey)}`
+
+    const mainUtxoParam = {
+      // The Ethereum Bridge expects this hash to be in the Bitcoin internal
+      // byte order.
+      txHash: mainUtxo.transactionHash.reverse().toPrefixedString(),
+      txOutputIndex: mainUtxo.outputIndex,
+      txOutputValue: mainUtxo.value,
+    }
+
+    // Convert the output script to raw bytes buffer.
+    const rawRedeemerOutputScript = Buffer.from(redeemerOutputScript, "hex")
+    // Prefix the output script bytes buffer with 0x and its own length.
+    const prefixedRawRedeemerOutputScript = `0x${Buffer.concat([
+      Buffer.from([rawRedeemerOutputScript.length]),
+      rawRedeemerOutputScript,
+    ]).toString("hex")}`
+
+    return {
+      walletPublicKeyHash,
+      mainUtxo: mainUtxoParam,
+      prefixedRawRedeemerOutputScript,
+    }
+  }
 }
diff --git a/typescript/src/redemption.ts b/typescript/src/redemption.ts
@@ -66,7 +66,6 @@ export interface RedemptionRequest {
  * @param amount - The amount to be redeemed with the precision of the tBTC
  *        on-chain token contract.
  * @param vault - The vault address.
- * @param bridge - Handle to the Bridge on-chain contract.
  * @param tBTCToken - Handle to the TBTCToken on-chain contract.
  * @returns Transaction hash of the request redemption transaction.
  */
@@ -77,17 +76,16 @@ export async function requestRedemption(
   redeemerOutputScript: string,
   amount: BigNumber,
   vault: Identifier,
-  bridge: Bridge,
   tBTCToken: TBTCToken
 ): Promise<Hex> {
-  const redemptionData = bridge.buildRedemptionData(
+  return await tBTCToken.requestRedemption({
     redeemer,
     walletPublicKey,
     mainUtxo,
-    redeemerOutputScript
-  )
-
-  return await tBTCToken.approveAndCall(vault, amount, redemptionData)
+    redeemerOutputScript,
+    amount,
+    vault,
+  })
 }
 
 /**

diff --git a/typescript/test/redemption.test.ts b/typescript/test/redemption.test.ts
@@ -46,7 +46,6 @@ describe("Redemption", () => {
     const redeemerOutputScript =
       data.pendingRedemptions[0].pendingRedemption.redeemerOutputScript
     const amount = data.pendingRedemptions[0].pendingRedemption.requestedAmount
-    const bridge: MockBridge = new MockBridge()
     const vault = Address.from("0xb622eA9D678ddF15135a20d59Ff26D28eC246bfB")
     const token: MockTBTCToken = new MockTBTCToken()
     const redeemer = Address.from("0x117284D8C50f334a1E2b7712649cB23C7a04Ae74")
@@ -61,26 +60,22 @@ describe("Redemption", () => {
         redeemerOutputScript,
         amount,
         vault,
-        bridge,
         token
       )
     })
 
     it("should submit redemption proof with correct arguments", () => {
-      const bridgeLog = bridge.buildRedemptionDataLog
-      const tokenLog = token.approveAndCallLog
-
-      expect(bridgeLog.length).to.equal(1)
-      expect(bridgeLog[0].walletPublicKey).to.equal(
-        redemptionProof.expectedRedemptionProof.walletPublicKey
-      )
-      expect(bridgeLog[0].mainUtxo).to.equal(mainUtxo)
-      expect(bridgeLog[0].redeemerOutputScript).to.equal(redeemerOutputScript)
-      expect(bridgeLog[0].redeemer).to.equal(redeemer)
+      const tokenLog = token.requestRedemptionLog
 
       expect(tokenLog.length).to.equal(1)
-      expect(tokenLog[0].spender).to.equal(vault)
-      expect(tokenLog[0].amount).to.equal(amount)
+      expect(tokenLog[0]).to.deep.equal({
+        redeemer,
+        walletPublicKey,
+        mainUtxo,
+        redeemerOutputScript,
+        amount,
+        vault,
+      })
     })
   })