Add TypeScript declaration file

package.json

@@ -6,6 +6,7 @@
   "bugs": "https://github.com/TRUEPIC/webhook-verifier-nodejs/issues",
   "license": "MIT",
   "main": "./src/main.js",
+  "types": "./src/main.d.ts",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/TRUEPIC/webhook-verifier-nodejs.git"

src/main.d.ts

@@ -0,0 +1,36 @@
+/**
+ * Options for verifying a Truepic webhook.
+ */
+interface VerifyTruepicWebhookOptions {
+  /** The full URL that received the request and is registered with Truepic. */
+  url: string
+  /** The shared secret that's registered with Truepic. */
+  secret: string
+  /** The value of the `truepic-signature` header from the request. */
+  header: string
+  /** The raw body (unparsed JSON) from the request. */
+  body: string
+  /** The number of minutes allowed between the request being sent and received. Defaults to `5`. */
+  leewayMinutes?: number
+}
+
+/**
+ * The custom error thrown when webhook verification fails.
+ */
+declare class TruepicWebhookVerifierError extends Error {
+  constructor(message: string)
+  name: 'TruepicWebhookVerifierError'
+}
+
+/**
+ * Verify a webhook from Truepic Vision or Lens.
+ */
+declare function verifyTruepicWebhook(
+  options: VerifyTruepicWebhookOptions,
+): true
+
+declare namespace verifyTruepicWebhook {
+  export { TruepicWebhookVerifierError }
+}
+
+export = verifyTruepicWebhook