Expose past redemption requested events getter (#677)

Refs: keep-network/keep-core#3664

Here we expose the `Bridge.getRedemptionRequestedEvents` method that
allows fetching past redemption requested events from the `Bridge`
contract.

typescript/src/bitcoin.ts

@@ -639,3 +639,43 @@ export function createAddressFromOutputScript(
     .getAddress()
     ?.toString(toBcoinNetwork(network))
 }
+
+/**
+ * Reads the leading compact size uint from the provided variable length data.
+ *
+ * WARNING: CURRENTLY, THIS FUNCTION SUPPORTS ONLY 1-BYTE COMPACT SIZE UINTS
+ * AND WILL THROW ON COMPACT SIZE UINTS OF DIFFERENT BYTE LENGTH.
+ *
+ * @param varLenData Variable length data preceded by a compact size uint.
+ * @returns An object holding the value of the compact size uint along with the
+ *          compact size uint byte length.
+ */
+export function readCompactSizeUint(varLenData: Hex): {
+  value: number
+  byteLength: number
+} {
+  // The varLenData is prefixed with the compact size uint. According to the docs
+  // (https://developer.bitcoin.org/reference/transactions.html#compactsize-unsigned-integers)
+  // a compact size uint can be 1, 3, 5 or 9 bytes. To determine the exact length,
+  // we need to look at the discriminant byte which is always the first byte of
+  // the compact size uint.
+  const discriminant = varLenData.toString().slice(0, 2)
+
+  switch (discriminant) {
+    case "ff":
+    case "fe":
+    case "fd": {
+      throw new Error(
+        "support for 3, 5 and 9 bytes compact size uints is not implemented yet"
+      )
+    }
+    default: {
+      // The discriminant tells the compact size uint is 1 byte. That means
+      // the discriminant represent the value itself.
+      return {
+        value: parseInt(discriminant, 16),
+        byteLength: 1,
+      }
+    }
+  }
+}

typescript/src/chain.ts

@@ -17,7 +17,7 @@ import {
   OptimisticMintingRequestedEvent,
 } from "./optimistic-minting"
 import { Hex } from "./hex"
-import { RedemptionRequest } from "./redemption"
+import { RedemptionRequest, RedemptionRequestedEvent } from "./redemption"
 import {
   DkgResultApprovedEvent,
   DkgResultChallengedEvent,
@@ -260,6 +260,12 @@ export interface Bridge {
    * @returns The hash of the UTXO.
    */
   buildUtxoHash(utxo: UnspentTransactionOutput): Hex
+
+  /**
+   * Get emitted RedemptionRequested events.
+   * @see GetEventsFunction
+   */
+  getRedemptionRequestedEvents: GetEvents.Function<RedemptionRequestedEvent>
 }
 
 /**

typescript/src/ethereum.ts

@@ -27,12 +27,13 @@ import {
   DepositRevealedEvent,
 } from "./deposit"
 import { getEvents, sendWithRetry } from "./ethereum-helpers"
-import { RedemptionRequest } from "./redemption"
+import { RedemptionRequest, RedemptionRequestedEvent } from "./redemption"
 import {
   compressPublicKey,
   computeHash160,
   DecomposedRawTransaction,
   Proof,
+  readCompactSizeUint,
   TransactionHash,
   UnspentTransactionOutput,
 } from "./bitcoin"
@@ -762,6 +763,48 @@ export class Bridge
       )
     )
   }
+
+  // eslint-disable-next-line valid-jsdoc
+  /**
+   * @see {ChainBridge#getDepositRevealedEvents}
+   */
+  async getRedemptionRequestedEvents(
+    options?: GetEvents.Options,
+    ...filterArgs: Array<unknown>
+  ): Promise<RedemptionRequestedEvent[]> {
+    // FIXME: Filtering by indexed walletPubKeyHash field may not work
+    //        until https://github.com/ethers-io/ethers.js/pull/4244 is
+    //        included in the currently used version of ethers.js.
+    //        Ultimately, we should upgrade ethers.js to include that fix.
+    //        Short-term, we can workaround the problem as presented in:
+    //        https://github.com/threshold-network/token-dashboard/blob/main/src/threshold-ts/tbtc/index.ts#L1041C1-L1093C1
+    const events: EthersEvent[] = await this.getEvents(
+      "RedemptionRequested",
+      options,
+      ...filterArgs
+    )
+
+    return events.map<RedemptionRequestedEvent>((event) => {
+      const prefixedRedeemerOutputScript = Hex.from(
+        event.args!.redeemerOutputScript
+      )
+      const redeemerOutputScript = prefixedRedeemerOutputScript
+        .toString()
+        .slice(readCompactSizeUint(prefixedRedeemerOutputScript).byteLength * 2)
+
+      return {
+        blockNumber: BigNumber.from(event.blockNumber).toNumber(),
+        blockHash: Hex.from(event.blockHash),
+        transactionHash: Hex.from(event.transactionHash),
+        walletPublicKeyHash: Hex.from(event.args!.walletPubKeyHash).toString(),
+        redeemer: new Address(event.args!.redeemer),
+        redeemerOutputScript: redeemerOutputScript,
+        requestedAmount: BigNumber.from(event.args!.requestedAmount),
+        treasuryFee: BigNumber.from(event.args!.treasuryFee),
+        txMaxFee: BigNumber.from(event.args!.txMaxFee),
+      }
+    })
+  }
 }
 
 /**

typescript/src/redemption.ts

@@ -8,7 +8,7 @@ import {
   Client as BitcoinClient,
   TransactionHash,
 } from "./bitcoin"
-import { Bridge, Identifier, TBTCToken } from "./chain"
+import { Bridge, Event, Identifier, TBTCToken } from "./chain"
 import { assembleTransactionProof } from "./proof"
 import { determineWalletMainUtxo, WalletState } from "./wallet"
 import { BitcoinNetwork } from "./bitcoin-network"
@@ -56,6 +56,20 @@ export interface RedemptionRequest {
   requestedAt: number
 }
 
+/**
+ * Represents an event emitted on redemption request.
+ */
+export type RedemptionRequestedEvent = Omit<
+  RedemptionRequest,
+  "requestedAt"
+> & {
+  /**
+   * Public key hash of the wallet that is meant to handle the redemption. Must
+   * be an unprefixed hex string (without 0x prefix).
+   */
+  walletPublicKeyHash: string
+} & Event
+
 /**
  * Requests a redemption of tBTC into BTC.
  * @param walletPublicKey - The Bitcoin public key of the wallet. Must be in the

typescript/test/bitcoin.test.ts

@@ -13,6 +13,7 @@ import {
   targetToDifficulty,
   createOutputScriptFromAddress,
   createAddressFromOutputScript,
+  readCompactSizeUint,
 } from "../src/bitcoin"
 import { calculateDepositRefundLocktime } from "../src/deposit"
 import { BitcoinNetwork } from "../src/bitcoin-network"
@@ -506,4 +507,41 @@ describe("Bitcoin", () => {
       })
     })
   })
+
+  describe("readCompactSizeUint", () => {
+    context("when the compact size uint is 1-byte", () => {
+      it("should return the the uint value and byte length", () => {
+        expect(readCompactSizeUint(Hex.from("bb"))).to.be.eql({
+          value: 187,
+          byteLength: 1,
+        })
+      })
+    })
+
+    context("when the compact size uint is 3-byte", () => {
+      it("should throw", () => {
+        expect(() => readCompactSizeUint(Hex.from("fd0302"))).to.throw(
+          "support for 3, 5 and 9 bytes compact size uints is not implemented yet"
+        )
+      })
+    })
+
+    context("when the compact size uint is 5-byte", () => {
+      it("should throw", () => {
+        expect(() => readCompactSizeUint(Hex.from("fe703a0f00"))).to.throw(
+          "support for 3, 5 and 9 bytes compact size uints is not implemented yet"
+        )
+      })
+    })
+
+    context("when the compact size uint is 9-byte", () => {
+      it("should throw", () => {
+        expect(() => {
+          return readCompactSizeUint(Hex.from("ff57284e56dab40000"))
+        }).to.throw(
+          "support for 3, 5 and 9 bytes compact size uints is not implemented yet"
+        )
+      })
+    })
+  })
 })

typescript/test/utils/mock-bridge.ts

@@ -5,7 +5,7 @@ import {
   UnspentTransactionOutput,
 } from "../../src/bitcoin"
 import { BigNumberish, BigNumber, utils, constants } from "ethers"
-import { RedemptionRequest } from "../redemption"
+import { RedemptionRequest, RedemptionRequestedEvent } from "../redemption"
 import {
   Deposit,
   DepositRevealedEvent,
@@ -365,4 +365,11 @@ export class MockBridge implements Bridge {
       )
     )
   }
+
+  getRedemptionRequestedEvents(
+    options?: GetEvents.Options,
+    ...filterArgs: Array<any>
+  ): Promise<RedemptionRequestedEvent[]> {
+    throw new Error("not implemented")
+  }
 }