From 6edfb17134884dfa56275dc880997ada03ed4192 Mon Sep 17 00:00:00 2001
From: tate <tate@ens.domains>
Date: Thu, 15 Feb 2024 12:42:44 +1100
Subject: [PATCH] typed support + api

---
 src/index.test.ts  | 10 ++++++++++
 src/index.ts       |  9 ++++++---
 src/types.ts       | 23 ++++++++++++++++-------
 src/utils/evm.ts   | 14 +++++++++++++-
 src/utils/index.ts |  1 +
 5 files changed, 46 insertions(+), 11 deletions(-)

diff --git a/src/index.test.ts b/src/index.test.ts
index 297c7038..af086f3a 100644
--- a/src/index.test.ts
+++ b/src/index.test.ts
@@ -44,6 +44,16 @@ test("evm coin type", () => {
   expect(coder.decode).toBeFunction();
 });
 
+test("unknown evm coin type", () => {
+  const coder = getCoderByCoinType(2147483659);
+  expect(coder.coinType).toBe(2147483659);
+  expect(coder.name).toBe("Unknown Chain (11)");
+  expect(coder.evmChainId).toBe(11);
+  expect(coder.isUnknownChain).toBeTrue();
+  expect(coder.encode).toBeFunction();
+  expect(coder.decode).toBeFunction();
+});
+
 const nonEvmCoinNames = Object.keys(nonEvmCoinNameToTypeMap);
 const evmCoinNames = Object.keys(evmCoinNameToTypeMap);
 
diff --git a/src/index.ts b/src/index.ts
index 821f8e24..225f86ec 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -66,21 +66,24 @@ export const getCoderByCoinName = <
 };
 
 export const getCoderByCoinType = <
-  TCoinType extends CoinType | number = CoinType | number
+  const TCoinType extends CoinType | number = CoinType | number
 >(
   coinType: TCoinType
 ): GetCoderByCoinType<TCoinType> => {
-  const names = coinTypeToNameMap[String(coinType) as keyof typeof coinTypeToNameMap];
+  const names =
+    coinTypeToNameMap[String(coinType) as keyof typeof coinTypeToNameMap];
   // https://docs.ens.domains/ens-improvement-proposals/ensip-11-evmchain-address-resolution
   if (coinType >= SLIP44_MSB) {
     // EVM coin
     const evmChainId = coinTypeToEvmChainId(coinType);
-    const name = names ? names[0] : `Chain(${evmChainId})`; // name is derivable
+    const isUnknownChain = !names;
+    const name = isUnknownChain ? `Unknown Chain (${evmChainId})` : names[0]; // name is derivable
     const ethFormat = formats["eth"];
     return {
       name,
       coinType: coinType as EvmCoinType,
       evmChainId,
+      isUnknownChain,
       encode: ethFormat.encode,
       decode: ethFormat.decode,
     } as GetCoderByCoinType<TCoinType>;
diff --git a/src/types.ts b/src/types.ts
index f6f71a58..3f68f198 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,4 +1,4 @@
-import type { Subtract } from "ts-arithmetic";
+import type { GtOrEq, Subtract } from "ts-arithmetic";
 import type * as formats from "./coins.js";
 import type {
   coinNameToTypeMap,
@@ -20,7 +20,7 @@ type NonEvmCoinTypeToFormat = {
 };
 export type CoinTypeToFormatMap = {
   [key in CoinType]: key extends EvmCoinType
-    ? Prettify<GetEvmCoin<CoinTypeToNameMap[`${key}`][0]>>
+    ? Prettify<GetEvmCoin<key>>
     : key extends keyof NonEvmCoinTypeToFormat
     ? NonEvmCoinTypeToFormat[key]
     : never;
@@ -35,12 +35,16 @@ export type EvmCoinType = EvmCoinMap[EvmCoinName];
 export type EvmChainId = Subtract<EvmCoinType, typeof SLIP44_MSB>;
 
 export type GetEvmCoin<
-  TEvmName extends EvmCoinName,
-  TCoinType extends CoinNameToTypeMap[TEvmName] = CoinNameToTypeMap[TEvmName]
+  TCoinType extends number,
+  TChainId extends number = Subtract<TCoinType, typeof SLIP44_MSB>,
+  TCoinName extends string = TCoinType extends EvmCoinType
+    ? CoinTypeToNameMap[`${TCoinType}`][0]
+    : `Unknown Chain (${TChainId})`
 > = {
-  name: TEvmName;
+  name: TCoinName;
   coinType: TCoinType;
-  evmChainId: Subtract<TCoinType, typeof SLIP44_MSB>;
+  evmChainId: TChainId;
+  isUnknownChain: TCoinType extends EvmCoinType ? false : true;
   encode: EncoderFunction;
   decode: DecoderFunction;
 };
@@ -52,6 +56,7 @@ export type CoinParameters = {
   name: string;
   coinType: number;
   evmChainId?: number;
+  isUnknownChain?: boolean;
 };
 
 export type CoinCoder = {
@@ -72,7 +77,11 @@ export type GetCoderByCoinName<TCoinName extends CoinName | string> =
   TCoinName extends CoinName ? CoinNameToFormatMap[TCoinName] : Coin;
 
 export type GetCoderByCoinType<TCoinType extends CoinType | number> =
-  TCoinType extends CoinType ? CoinTypeToFormatMap[TCoinType] : Coin;
+  TCoinType extends CoinType
+    ? CoinTypeToFormatMap[TCoinType]
+    : GtOrEq<TCoinType, typeof SLIP44_MSB> extends 1
+    ? Prettify<GetEvmCoin<TCoinType>>
+    : Coin;
 
 export type ParseInt<T> = T extends `${infer N extends number}` ? N : never;
 
diff --git a/src/utils/evm.ts b/src/utils/evm.ts
index d4b8416e..441e048e 100644
--- a/src/utils/evm.ts
+++ b/src/utils/evm.ts
@@ -1,8 +1,20 @@
-import type { Add, Lt, Subtract } from "ts-arithmetic";
+import type { Add, GtOrEq, Lt, Subtract } from "ts-arithmetic";
 import type { EvmChainId, EvmCoinType } from "../types.js";
 
 export const SLIP44_MSB = 0x80000000;
 
+export const isEvmCoinType = <
+  TCoinType extends EvmCoinType | number = EvmCoinType | number
+>(
+  coinType: TCoinType
+) =>
+  ((coinType & SLIP44_MSB) !== 0) as GtOrEq<
+    TCoinType,
+    typeof SLIP44_MSB
+  > extends 1
+    ? true
+    : false;
+
 type EvmChainIdToCoinType<
   TChainId extends EvmChainId | number = EvmChainId | number
 > = Lt<TChainId, typeof SLIP44_MSB> extends 1
diff --git a/src/utils/index.ts b/src/utils/index.ts
index a3aceaf2..7122e3dd 100644
--- a/src/utils/index.ts
+++ b/src/utils/index.ts
@@ -41,6 +41,7 @@ export {
   SLIP44_MSB,
   coinTypeToEvmChainId,
   evmChainIdToCoinType,
+  isEvmCoinType,
 } from "./evm.js";
 export { validateFlowAddress } from "./flow.js";
 export { decodeLeb128, encodeLeb128 } from "./leb128.js";