Implementing trading functionality in Asset Class

src/coinbase/address.ts

@@ -10,6 +10,8 @@ import { Amount, Destination, TransferStatus } from "./types";
 import { Transfer } from "./transfer";
 import { delay, destinationToAddressHexString } from "./utils";
 import { ATOMIC_UNITS_PER_USDC, WEI_PER_ETHER, WEI_PER_GWEI } from "./constants";
+import { Asset } from "./asset";
+import { Trade } from "./trade";
 
 /**
  * A representation of a blockchain address, which is a user-controlled account on a network.
@@ -263,6 +265,119 @@ export class Address {
     throw new Error("Transfer timed out");
   }
 
+  /**
+   * Trades the given amount of the given Asset for another Asset. Only same-network Trades are supported.
+   *
+   * @param amount - The amount of the Asset to send.
+   * @param fromAssetId - The ID of the Asset to trade from. For Ether, eth, gwei, and wei are supported.
+   * @param toAssetId - The ID of the Asset to trade to. For Ether, eth, gwei, and wei are supported.
+   * @returns The Trade object.
+   * @throws {Error} Will throw an error if the private key is not loaded, or if the asset IDs are unsupported, or if there are insufficient funds.
+   */
+  public async trade(amount: Amount, fromAssetId: string, toAssetId: string): Promise<Trade> {
+    await this.validateCanTrade(amount, fromAssetId, toAssetId);
+    const trade = await this.createTrade(amount, fromAssetId, toAssetId);
+    // NOTE: Trading does not yet support server signers at this point.
+    const signed_payload = await trade.getTransaction().sign(this.key!);
+    const approveTransactionSignedPayload = trade.getApproveTransaction()
+      ? await trade.getApproveTransaction()!.sign(this.key!)
+      : undefined;
+
+    return this.broadcastTrade(trade, signed_payload, approveTransactionSignedPayload);
+  }
+
+  /**
+   * Creates a trade model for the specified amount and assets.
+   *
+   * @param amount - The amount of the Asset to send.
+   * @param fromAssetId - The ID of the Asset to trade from. For Ether, eth, gwei, and wei are supported.
+   * @param toAssetId - The ID of the Asset to trade to. For Ether, eth, gwei, and wei are supported.
+   * @returns A promise that resolves to a Trade object representing the new trade.
+   */
+  private async createTrade(
+    amount: Amount,
+    fromAssetId: string,
+    toAssetId: string,
+  ): Promise<Trade> {
+    const tradeRequestPayload = {
+      amount: Asset.toAtomicAmount(new Decimal(amount.toString()), fromAssetId).toString(),
+      from_asset_id: Asset.primaryDenomination(fromAssetId),
+      to_asset_id: Asset.primaryDenomination(toAssetId),
+    };
+    const tradeModel = await Coinbase.apiClients.trade!.createTrade(
+      this.getWalletId(),
+      this.getId(),
+      tradeRequestPayload,
+    );
+    return new Trade(tradeModel?.data);
+  }
+
+  /**
+   * Broadcasts a trade using the provided signed payloads.
+   *
+   * @param trade - The Trade object representing the trade.
+   * @param signedPayload - The signed payload of the trade.
+   * @param approveTransactionPayload - The signed payload of the approval transaction, if any.
+   * @returns A promise that resolves to a Trade object representing the broadcasted trade.
+   */
+  private async broadcastTrade(
+    trade: Trade,
+    signedPayload: string,
+    approveTransactionPayload?: string,
+  ): Promise<Trade> {
+    const broadcastTradeRequest = {
+      signed_payload: signedPayload,
+      approve_transaction_signed_payload: approveTransactionPayload
+        ? approveTransactionPayload
+        : undefined,
+    };
+
+    const response = await Coinbase.apiClients.trade!.broadcastTrade(
+      this.getWalletId(),
+      this.getId(),
+      trade.getId(),
+      broadcastTradeRequest,
+    );
+
+    return new Trade(response.data);
+  }
+
+  /**
+   * Checks if trading is possible and raises an error if not.
+   *
+   * @param amount - The amount of the Asset to send.
+   * @param fromAssetId - The ID of the Asset to trade from. For Ether, eth, gwei, and wei are supported.
+   * @param toAssetId - The ID of the Asset to trade to. For Ether, eth, gwei, and wei are supported.
+   * @throws {Error} Will throw an error if the private key is not loaded, or if the asset IDs are unsupported, or if there are insufficient funds.
+   */
+  private async validateCanTrade(amount: Amount, fromAssetId: string, toAssetId: string) {
+    if (!this.canSign()) {
+      throw new Error("Cannot trade from address without private key loaded");
+    }
+    if (!Asset.isSupported(fromAssetId)) {
+      throw new Error(`Unsupported from asset: ${fromAssetId}`);
+    }
+    if (!Asset.isSupported(toAssetId)) {
+      throw new Error(`Unsupported to asset: ${toAssetId}`);
+    }
+    const currentBalance = await this.getBalance(fromAssetId);
+    amount = new Decimal(amount.toString());
+    if (currentBalance.lessThan(amount)) {
+      throw new Error(
+        `Insufficient funds: ${amount} requested, but only ${currentBalance} available`,
+      );
+    }
+  }
+
+  /**
+   * Returns whether the Address has a private key backing it to sign transactions.
+   *
+   * @returns Whether the Address has a private key backing it to sign transactions.
+   */
+  public canSign(): boolean {
+    return !!this.key;
+  }
+
   /**
    * Returns a string representation of the address.
    *

src/coinbase/asset.ts

@@ -1,5 +1,11 @@
 import Decimal from "decimal.js";
-import { ATOMIC_UNITS_PER_USDC, WEI_PER_ETHER, WEI_PER_GWEI } from "./constants";
+import {
+  ATOMIC_UNITS_PER_USDC,
+  SUPPORTED_ASSET_IDS,
+  WEI_PER_ETHER,
+  WEI_PER_GWEI,
+} from "./constants";
+import { Coinbase } from "./coinbase";
 
 /** A representation of an Asset. */
 export class Asset {
@@ -8,7 +14,7 @@ export class Asset {
    * to whole units of the specified asset ID.
    *
    * @param {Decimal} atomicAmount - The amount in atomic units.
-   * @param {string} assetId - The assset ID.
+   * @param {string} assetId - The asset ID.
    * @returns The amount in whole units of the asset with the specified ID.
    */
   static fromAtomicAmount(atomicAmount: Decimal, assetId: string): Decimal {
@@ -25,4 +31,48 @@ export class Asset {
         return atomicAmount;
     }
   }
+
+  /**
+   * Converts the amount of the Asset to the atomic units of the primary denomination of the Asset.
+   *
+   * @param amount - The amount to normalize.
+   * @param assetId - The ID of the Asset being transferred.
+   * @returns The normalized amount in atomic units.
+   */
+  static toAtomicAmount(amount: Decimal, assetId: string): Decimal {
+    switch (assetId) {
+      case "eth":
+        return amount.mul(WEI_PER_ETHER);
+      case "gwei":
+        return amount.mul(WEI_PER_GWEI);
+      case "usdc":
+        return amount.mul(ATOMIC_UNITS_PER_USDC);
+      case "weth":
+        return amount.mul(WEI_PER_ETHER);
+      default:
+        return amount;
+    }
+  }
+
+  /**
+   * Returns the primary denomination for the provided Asset ID.
+   *
+   * @param assetId - The Asset ID.
+   * @returns The primary denomination for the Asset ID.
+   */
+  public static primaryDenomination(assetId: string): string {
+    return [Coinbase.assets.Gwei, Coinbase.assets.Wei].includes(assetId)
+      ? Coinbase.assets.Eth
+      : assetId;
+  }
+
+  /**
+   * Returns whether the provided asset ID is supported.
+   *
+   * @param assetId - The Asset ID.
+   * @returns Whether the Asset ID is supported.
+   */
+  public static isSupported(assetId): boolean {
+    return SUPPORTED_ASSET_IDS.has(assetId);
+  }
 }

src/coinbase/constants.ts

@@ -4,3 +4,4 @@ export const WEI_PER_ETHER = new Decimal("1000000000000000000");
 export const WEI_PER_GWEI = new Decimal("1000000000");
 export const GWEI_PER_ETHER = new Decimal("1000000000");
 export const ATOMIC_UNITS_PER_USDC = new Decimal("1000000");
+export const SUPPORTED_ASSET_IDS = new Set(["eth", "gwei", "wei", "usdc", "weth"]);