import { readFile } from "node:fs/promises";

/**
 * Resolve a capability input from the sandbox input payload when configured.
 *
 * The input argument remains the fallback for compatibility with runners
 * that have not adopted the file-backed transport.
 *
 * @internal
 */
export async function resolveRuntimeInput<T>(fallback: T): Promise<T> {
	const inputPayloadPath = process.env.NOTION_INPUT_PAYLOAD_PATH;
	if (inputPayloadPath === undefined) {
		return fallback;
	}

	let serializedInput: string;

	try {
		serializedInput = await readFile(inputPayloadPath, "utf8");
	} catch (error) {
		if (error instanceof Error && "code" in error && error.code === "ENOENT") {
			return fallback;
		}

		throw error;
	}

	return JSON.parse(serializedInput) as T;
}