feat: icrc map token metadata to record (#798)

# Motivation I've been implementing the same mapper repeatedly, and today I needed it in another library (the oisy-wallet-signer). Instead of reimplementing it again, I added a utility to the ledger-icrc library to map the token metadata information from a ledger response provided in form of Candid arrays into a structured record. # Changes - Add utility `mapTokenMetadata`. --------- Signed-off-by: David Dal Busco <[email protected]> Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>
dfinity · Dec 23, 2024 · 73a6c8a · 73a6c8a
1 parent d810d76
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -9,6 +9,7 @@
 - Add support for `get_subnet_types_to_subnets` to `@dfinity/cmc`.
 - Support `VotingPowerEconomics`, `potential_voting_power` and `deciding_voting_power` in `@dfinity/nns`.
 - Add utility `isEmptyString` (the opposite of existing `notEmptyString`).
+- Add utility `mapTokenMetadata` in `@dfinity/ledger-icrc` to map the token metadata information from a ledger response into a structured record.
 
 # 2024.11.27-1230Z
 

diff --git a/packages/ledger-icrc/README.md b/packages/ledger-icrc/README.md
@@ -58,6 +58,7 @@ const data = await metadata({});
 
 - [encodeIcrcAccount](#gear-encodeicrcaccount)
 - [decodeIcrcAccount](#gear-decodeicrcaccount)
+- [mapTokenMetadata](#gear-maptokenmetadata)
 - [decodePayment](#gear-decodepayment)
 
 #### :gear: encodeIcrcAccount
@@ -73,7 +74,7 @@ Parameters:
 
 - `account`: : Principal, subaccount?: Uint8Array }
 
-[:link: Source](https://github.com/dfinity/ic-js/tree/main/packages/ledger-icrc/src/utils/ledger.utils.ts#L21)
+[:link: Source](https://github.com/dfinity/ic-js/tree/main/packages/ledger-icrc/src/utils/ledger.utils.ts#L27)
 
 #### :gear: decodeIcrcAccount
 
@@ -88,7 +89,26 @@ Parameters:
 
 - `accountString`: string
 
-[:link: Source](https://github.com/dfinity/ic-js/tree/main/packages/ledger-icrc/src/utils/ledger.utils.ts#L61)
+[:link: Source](https://github.com/dfinity/ic-js/tree/main/packages/ledger-icrc/src/utils/ledger.utils.ts#L67)
+
+#### :gear: mapTokenMetadata
+
+Maps the token metadata information from a ledger response into a structured record.
+
+This utility processes an array of metadata key-value pairs provided by the ledger
+and extracts specific fields, such as symbol, name, fee, decimals, and logo. It then
+constructs a `IcrcTokenMetadata` record. If any required fields are missing,
+the function returns `undefined`.
+
+| Function           | Type                                                                      |
+| ------------------ | ------------------------------------------------------------------------- |
+| `mapTokenMetadata` | `(response: IcrcTokenMetadataResponse) => IcrcTokenMetadata or undefined` |
+
+Parameters:
+
+- `response`: - An array of key-value pairs representing token metadata.
+
+[:link: Source](https://github.com/dfinity/ic-js/tree/main/packages/ledger-icrc/src/utils/ledger.utils.ts#L111)
 
 #### :gear: decodePayment
 

diff --git a/packages/ledger-icrc/src/types/ledger.responses.ts b/packages/ledger-icrc/src/types/ledger.responses.ts
@@ -19,3 +19,11 @@ export interface IcrcAccount {
   owner: Principal;
   subaccount?: Subaccount;
 }
+
+export interface IcrcTokenMetadata {
+  name: string;
+  symbol: string;
+  fee: bigint;
+  decimals: number;
+  icon?: string;
+}
diff --git a/packages/ledger-icrc/src/utils/ledger.utils.spec.ts b/packages/ledger-icrc/src/utils/ledger.utils.spec.ts
@@ -1,6 +1,14 @@
 import { Principal } from "@dfinity/principal";
 import { mockPrincipal } from "../mocks/ledger.mock";
-import { decodeIcrcAccount, encodeIcrcAccount } from "./ledger.utils";
+import {
+  IcrcMetadataResponseEntries,
+  type IcrcTokenMetadataResponse,
+} from "../types/ledger.responses";
+import {
+  decodeIcrcAccount,
+  encodeIcrcAccount,
+  mapTokenMetadata,
+} from "./ledger.utils";
 
 describe("ledger-utils", () => {
   const ownerText =
@@ -114,4 +122,123 @@ describe("ledger-utils", () => {
       expect(decodeIcrcAccount(encodeIcrcAccount(account4))).toEqual(account4);
     });
   });
+
+  describe("mapTokenMetadata", () => {
+    const validResponse: IcrcTokenMetadataResponse = [
+      [IcrcMetadataResponseEntries.SYMBOL, { Text: "TKN" }],
+      [IcrcMetadataResponseEntries.NAME, { Text: "Token" }],
+      [IcrcMetadataResponseEntries.FEE, { Nat: 10_000n }],
+      [IcrcMetadataResponseEntries.DECIMALS, { Nat: 8n }],
+      [IcrcMetadataResponseEntries.LOGO, { Text: "a-logo" }],
+    ];
+
+    it("should map token metadata", () => {
+      const result = mapTokenMetadata(validResponse);
+
+      expect(result).toEqual({
+        name: "Token",
+        symbol: "TKN",
+        fee: 10_000n,
+        decimals: 8,
+        icon: "a-logo",
+      });
+    });
+
+    const missingFieldCases: [string, IcrcTokenMetadataResponse][] = [
+      [
+        "missing field symbol",
+        validResponse.filter(
+          ([key]) => key !== IcrcMetadataResponseEntries.SYMBOL,
+        ),
+      ],
+      [
+        "missing field name",
+        validResponse.filter(
+          ([key]) => key !== IcrcMetadataResponseEntries.NAME,
+        ),
+      ],
+      [
+        "missing field fee",
+        validResponse.filter(
+          ([key]) => key !== IcrcMetadataResponseEntries.FEE,
+        ),
+      ],
+      [
+        "missing field decimals",
+        validResponse.filter(
+          ([key]) => key !== IcrcMetadataResponseEntries.DECIMALS,
+        ),
+      ],
+    ];
+
+    it.each(missingFieldCases)(
+      "should return undefined for %s",
+      (_, response) => {
+        const result = mapTokenMetadata(response);
+        expect(result).toBeUndefined();
+      },
+    );
+
+    const invalidFieldCases: [string, IcrcTokenMetadataResponse][] = [
+      [
+        "invalid symbol value",
+        validResponse.map(([key, value]) =>
+          key === IcrcMetadataResponseEntries.SYMBOL
+            ? [key, { Nat: BigInt(1) }]
+            : [key, value],
+        ),
+      ],
+      [
+        "invalid name value",
+        validResponse.map(([key, value]) =>
+          key === IcrcMetadataResponseEntries.NAME
+            ? [key, { Nat: BigInt(1) }]
+            : [key, value],
+        ),
+      ],
+      [
+        "invalid fee value",
+        validResponse.map(([key, value]) =>
+          key === IcrcMetadataResponseEntries.FEE
+            ? [key, { Text: "100" }]
+            : [key, value],
+        ),
+      ],
+      [
+        "invalid decimals value",
+        validResponse.map(([key, value]) =>
+          key === IcrcMetadataResponseEntries.DECIMALS
+            ? [key, { Text: "8" }]
+            : [key, value],
+        ),
+      ],
+    ];
+
+    it.each(invalidFieldCases)(
+      "should return undefined for %s",
+      (_, response) => {
+        const result = mapTokenMetadata(response);
+        expect(result).toBeUndefined();
+      },
+    );
+
+    test("should return empty if response metadata is empty", () => {
+      const result = mapTokenMetadata([]);
+      expect(result).toBeUndefined();
+    });
+
+    test("should map a metadata without logo", () => {
+      const responseWithoutLogo = validResponse.filter(
+        ([key]) => key !== IcrcMetadataResponseEntries.LOGO,
+      );
+
+      const result = mapTokenMetadata(responseWithoutLogo);
+      expect(result).toEqual({
+        name: "Token",
+        symbol: "TKN",
+        fee: 10_000n,
+        decimals: 8,
+      });
+    });
+  });
 });
diff --git a/packages/ledger-icrc/src/utils/ledger.utils.ts b/packages/ledger-icrc/src/utils/ledger.utils.ts
@@ -4,10 +4,16 @@ import {
   encodeBase32,
   hexStringToUint8Array,
   isNullish,
+  nonNullish,
   notEmptyString,
   uint8ArrayToHexString,
 } from "@dfinity/utils";
-import type { IcrcAccount } from "../types/ledger.responses";
+import type {
+  IcrcAccount,
+  IcrcTokenMetadata,
+  IcrcTokenMetadataResponse,
+} from "../types/ledger.responses";
+import { IcrcMetadataResponseEntries } from "../types/ledger.responses";
 
 const MAX_SUBACCOUNT_HEX_LENGTH = 64;
 
@@ -89,3 +95,60 @@ export const decodeIcrcAccount = (accountString: string): IcrcAccount => {
 
   return account;
 };
+
+/**
+ * Maps the token metadata information from a ledger response into a structured record.
+ *
+ * This utility processes an array of metadata key-value pairs provided by the ledger
+ * and extracts specific fields, such as symbol, name, fee, decimals, and logo. It then
+ * constructs a `IcrcTokenMetadata` record. If any required fields are missing,
+ * the function returns `undefined`.
+ *
+ * @param {IcrcTokenMetadataResponse} response - An array of key-value pairs representing token metadata.
+ *
+ * @returns {IcrcTokenMetadata | undefined} - A structured metadata record or `undefined` if required fields are missing.
+ */
+export const mapTokenMetadata = (
+  response: IcrcTokenMetadataResponse,
+): IcrcTokenMetadata | undefined => {
+  const nullishToken = response.reduce<Partial<IcrcTokenMetadata>>(
+    (acc, [key, value]) => {
+      switch (key) {
+        case IcrcMetadataResponseEntries.SYMBOL:
+          acc = { ...acc, ...("Text" in value && { symbol: value.Text }) };
+          break;
+        case IcrcMetadataResponseEntries.NAME:
+          acc = { ...acc, ...("Text" in value && { name: value.Text }) };
+          break;
+        case IcrcMetadataResponseEntries.FEE:
+          acc = { ...acc, ...("Nat" in value && { fee: value.Nat }) };
+          break;
+        case IcrcMetadataResponseEntries.DECIMALS:
+          acc = {
+            ...acc,
+            ...("Nat" in value && { decimals: Number(value.Nat) }),
+          };
+          break;
+        case IcrcMetadataResponseEntries.LOGO:
+          acc = { ...acc, ...("Text" in value && { icon: value.Text }) };
+      }
+
+      return acc;
+    },
+    {},
+  );
+
+  const isIcrcTokenMetadata = (
+    arg: Partial<IcrcTokenMetadata>,
+  ): arg is IcrcTokenMetadata =>
+    nonNullish(arg.symbol) &&
+    nonNullish(arg.name) &&
+    nonNullish(arg.fee) &&
+    nonNullish(arg.decimals);
+
+  if (!isIcrcTokenMetadata(nullishToken)) {
+    return undefined;
+  }
+
+  return nullishToken;
+};