import path from "node:path";
import { createTestSession } from "@marcfargas/pi-test-harness";
import { findNu } from "../runtime.ts";

const rounds = Number(process.env.NUSHELL_BENCH_ROUNDS ?? 25);
const warmups = Number(process.env.NUSHELL_BENCH_WARMUPS ?? 3);
if (
	!Number.isSafeInteger(rounds) ||
	rounds < 1 ||
	!Number.isSafeInteger(warmups) ||
	warmups < 0
)
	throw new Error(
		"Benchmark rounds must be positive integers; warmups may be zero",
	);
if (!findNu()) throw new Error("nu executable missing on PATH");

const t = await createTestSession({
	cwd: process.cwd(),
	extensions: [path.resolve(import.meta.dirname, "../index.ts")],
});
try {
	const runner = t.session.extensionRunner;
	const ctx = runner.createCommandContext();
	const fresh = runner.extensions[0]?.tools.get("nu")?.definition;
	const persistent = runner.extensions[0]?.tools.get("nu_session")?.definition;
	if (!fresh || !persistent) throw new Error("Nushell tools not registered");
	const exec = async (tool: typeof fresh) => {
		const result = await tool.execute(
			"bench",
			{ command: "1 + 2" },
			undefined,
			undefined,
			ctx,
		);
		if (
			!result.content.some(
				(part) => part.type === "text" && part.text.includes("3"),
			)
		)
			throw new Error("Incorrect benchmark output");
	};
	const measure = async (
		name: string,
		call: () => Promise<void>,
		record: boolean,
	) => {
		const start = process.hrtime.bigint();
		await call();
		if (record)
			console.log(`${name}\t1\t${process.hrtime.bigint() - start} ns/op`);
	};
	console.log(`goos: ${process.platform}`);
	console.log(`goarch: ${process.arch}`);
	console.log("pkg: pi-ext/nushell");
	console.log(`node: ${process.version}`);
	for (let index = -warmups; index < rounds; index++) {
		const record = index >= 0;
		await runner.getCommand("nushell")?.handler("reset", ctx);
		await measure("BenchmarkNuSessionCold", () => exec(persistent), record);
		if (index % 2 === 0) {
			await measure("BenchmarkNuFresh", () => exec(fresh), record);
			await measure("BenchmarkNuSessionWarm", () => exec(persistent), record);
		} else {
			await measure("BenchmarkNuSessionWarm", () => exec(persistent), record);
			await measure("BenchmarkNuFresh", () => exec(fresh), record);
		}
	}
	await runner.getCommand("nushell")?.handler("reset", ctx);
} finally {
	t.dispose();
}