import { mkdir, mkdtemp, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";

export type Fixture = { bucketDir: string; repo: string; repoDir: string; saveIds: string[] };

/** Builds a genuine Koh 3 folder remote with koh3 itself, under a throwaway HOME. */
export async function makeKohBucket(repo = "demo"): Promise<Fixture> {
	const root = await mkdtemp(join(tmpdir(), "kepr-fixture-"));
	const home = join(root, "home");
	const bucketDir = join(root, "bucket");
	const repoDir = join(root, "work", repo);
	await mkdir(home);
	await mkdir(join(repoDir, "src"), { recursive: true });
	const koh = (...args: string[]) => run(repoDir, home, args);

	koh("init");
	koh("remote", "folder", bucketDir);
	await writeFile(join(repoDir, "README.md"), "# Demo\n\nA small repo for Kepr's tests.\n");
	await writeFile(join(repoDir, "src/main.ts"), "// Entry point.\nconsole.log('hi');\n");
	koh("save", "add readme and entry point", "--agent", "test-agent", "--session", "fixture");
	koh("checkpoint", "before the second change");
	await writeFile(join(repoDir, "src/main.ts"), "// Entry point.\nconsole.log('hello');\n");
	koh("save", "say hello");
	koh("offer");

	const log = JSON.parse(koh("log", "--json")) as { saves: { id: string }[] };
	return { bucketDir, repo, repoDir, saveIds: log.saves.map((save) => save.id) };
}

function run(cwd: string, home: string, args: string[]): string {
	const result = Bun.spawnSync(["koh3", ...args], {
		cwd,
		env: { PATH: process.env.PATH, HOME: home, NO_COLOR: "1" },
	});
	if (result.exitCode !== 0) {
		throw new Error(
			`koh3 ${args.join(" ")} failed: ${result.stderr.toString()}${result.stdout.toString()}`,
		);
	}
	return result.stdout.toString();
}