Add createFromPem helper function (#33)

ts/consumer/package.json

@@ -8,9 +8,12 @@
   },
   "dependencies": {
     "@dfinity/agent": "^1.0.0",
-    "@dfinity/principal": "^1.0.0"
+    "@dfinity/identity-secp256k1": "^1.0.0",
+    "@dfinity/principal": "^1.0.0",
+    "pem-file": "^1.0.1"
   },
   "devDependencies": {
+    "@types/node": "^20.11.19",
     "prettier": "^3.2.5",
     "prettier-plugin-organize-imports": "^3.2.4"
   }

ts/consumer/src/client.ts

@@ -1,19 +1,31 @@
-import { Principal } from "@dfinity/principal";
 import { Actor, HttpAgent } from "@dfinity/agent";
+import { Principal } from "@dfinity/principal";
+import { Secp256k1KeyIdentity } from "@dfinity/identity-secp256k1";
+import pemfile from "pem-file";
 import { EventSinkCanister, idlFactory } from "./candid/idl";
 import type { EventsResponse, RemoveEventsResponse } from "./types";
 import { candidEventsResponse, candidRemoveEventsResponse } from "./mappers";
 
 export class Client {
   private readonly canister: EventSinkCanister;
 
-  public constructor(canisterId: Principal, agent: HttpAgent) {
+  public constructor(canisterId: string | Principal, agent: HttpAgent) {
     this.canister = Actor.createActor(idlFactory, {
       agent,
       canisterId,
     });
   }
 
+  public static createFromPem(canisterId: string | Principal, pem: string): Client {
+    const buf = pemfile.decode(pem);
+    if (buf.length != 118) {
+      throw 'expecting byte length 118 but got ' + buf.length;
+    }
+    const identity = Secp256k1KeyIdentity.fromSecretKey(buf.subarray(7, 39));
+    const httpAgent = new HttpAgent({ identity });
+    return new Client(canisterId, httpAgent);
+  }
+
   public async events(start: bigint, length: bigint): Promise<EventsResponse> {
     const candid = await this.canister.events({
       start,

ts/consumer/src/external-types.d.ts

@@ -0,0 +1,3 @@
+declare module "pem-file" {
+    export function decode(pem: string | Buffer): Buffer;
+}