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;
	/** Every save, newest first, checkpoint included. */
	saveIds: string[];
	/** Strips a path from every save with koh3, so tests can sync before and after. */
	strip(path: string): Promise<void>;
};

// The smallest valid PNG (1×1), so the fixture has a real binary file.
const PNG = Uint8Array.from(
	atob(
		"iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg==",
	),
	(c) => c.charCodeAt(0),
);

const README = `# Demo

A small repo for **Kepr's** tests.

See [the guide](docs/guide.md), [the site](https://example.com) and [a trap](javascript:alert(1)).

![logo](docs/logo.png)

<script>alert("raw html")</script>
`;

/**
 * Builds a genuine Koh 3 folder remote with koh3 itself, under a throwaway HOME. The line is:
 * "add docs, a secret and a deep helper" (flagged) → a second later "add readme and entry point"
 * (agent and session) → a checkpoint → "say hello" (head).
 */
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/lib/deep"), { recursive: true });
	await mkdir(join(repoDir, "docs"));
	const koh = (...args: string[]) => run(repoDir, home, args);

	koh("init");
	koh("remote", "folder", bucketDir);
	await writeFile(join(repoDir, "docs/guide.md"), "# Guide\n\nRead me.\n");
	await writeFile(join(repoDir, "docs/logo.png"), PNG);
	await writeFile(join(repoDir, "secret.txt"), "hunter2\n");
	await writeFile(join(repoDir, "src/lib/deep/util.ts"), "export const one = 1;\n");
	koh("save", "add docs, a secret and a deep helper");
	const first = JSON.parse(koh("log", "--json")).head_id as string;
	koh("flag", first, "--reason", "holds a secret");
	// Saves a second apart, so the timeline has time to spread over.
	Bun.sleepSync(1100);
	await writeFile(join(repoDir, "README.md"), README);
	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),
		strip: (path) => strip(repoDir, home, path),
	};
}

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

function env(home: string) {
	return { PATH: process.env.PATH, HOME: home, NO_COLOR: "1" };
}

// `koh strip` insists on a terminal and a typed confirmation, so it runs under a Bun PTY.
async function strip(cwd: string, home: string, path: string): Promise<void> {
	let output = "";
	const proc = Bun.spawn(["koh3", "strip", path], {
		cwd,
		env: env(home),
		terminal: { cols: 120, rows: 24, data: (_term, data) => (output += data.toString()) },
	});
	proc.terminal?.write(`y\n${path}\n`);
	const code = await proc.exited;
	proc.terminal?.close();
	if (code !== 0) throw new Error(`koh3 strip ${path} failed: ${output}`);
}