Function requestFromExtension

apps/cli/src/commands/cli/list.ts:145–197

* Send a request to the extension and wait for a matching response message. * Returns `undefined` from `extract` to skip non-matching messages, or the * parsed value to resolve the promise.

(
	host: ExtensionHost,
	request: WebviewMessage,
	extract: (message: Record<string, unknown>) => T | undefined,
)

 * parsed value to resolve the promise.
 */
function requestFromExtension<T>(
	host: ExtensionHost,
	request: WebviewMessage,
	extract: (message: Record<string, unknown>) => T | undefined,
): Promise<T> {
	return new Promise<T>((resolve, reject) => {
		let settled = false

		const cleanup = () => {
			clearTimeout(timeoutId)
			host.off("extensionWebviewMessage", onMessage)
			offError()
		}

		const finish = (fn: () => void) => {
			if (settled) return
			settled = true
			cleanup()
			fn()
		}

		const onMessage = (message: unknown) => {
			if (!isRecord(message)) {
				return
			}

			let result: T | undefined
			try {
				result = extract(message)
			} catch (error) {
				finish(() => reject(error instanceof Error ? error : new Error(String(error))))
				return
			}

			if (result !== undefined) {
				finish(() => resolve(result))
			}
		}

		const offError = host.client.on("error", (error) => {
			finish(() => reject(error))
		})

		const timeoutId = setTimeout(() => {
			finish(() =>
				reject(new Error(`Timed out waiting for ${request.type} response after ${REQUEST_TIMEOUT_MS}ms`)),
			)
		}, REQUEST_TIMEOUT_MS)

		host.on("extensionWebviewMessage", onMessage)
		host.sendToExtension(request)
	})
}

function requestCommands(host: ExtensionHost): Promise<CommandLike[]> {
	return requestFromExtension(host, { type: "requestCommands" }, (message) => {