import { mkdir, mkdtemp, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { blake3 } from "@noble/hashes/blake3.js";
import { bytesToHex } from "@noble/hashes/utils.js";
import type { ReleaseFile } from "../src/bucket/repo.ts";

/**
 * §4.3 of the resolutions: these tests are pinned to one koh3, so a stale binary cannot make a pass
 * look real. The version is checked before any fixture runs; the message says how to fix it.
 */
const PINNED_KOH = (await Bun.file(join(import.meta.dir, "koh-version.txt")).text()).trim();
const RUNNING_KOH = (() => {
	try {
		return Bun.spawnSync(["koh3", "--version"]).stdout.toString().trim();
	} catch {
		return "";
	}
})();
if (RUNNING_KOH !== `koh ${PINNED_KOH}`) {
	throw new Error(
		`these tests are pinned to koh ${PINNED_KOH}, but koh3 on PATH reports "${RUNNING_KOH}" — ` +
			"install the matching koh3 (see koh3's AGENTS.md), or update tests/koh-version.txt " +
			"once you have verified the new one",
	);
}

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 = `<!-- a leading comment and a centred title are not the intro -->

<p align="center">DEMO</p>

# 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 holding an edit to the guide → "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"));
	await mkdir(join(repoDir, "vendor"));
	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"),
		"// The *one* helper. Deep down.\nexport const one = 1;\n",
	);
	await writeFile(join(repoDir, "vendor/big.c"), "int x;\n".repeat(100));
	koh("save", "add docs, a secret and a deep helper");
	const first = JSON.parse(koh("view", "--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");
	// The guide's edit is first recorded by the checkpoint; the Atlas must credit it to "say hello".
	await writeFile(join(repoDir, "docs/guide.md"), "# Guide\n\nRead me. It is short.\n");
	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("view", "--json")) as { saves: { id: string }[] };
	return {
		bucketDir,
		repo,
		repoDir,
		saveIds: log.saves.map((save) => save.id),
		strip: (path) => stripPath(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. */
export async function stripPath(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}`);
}

/** Repos with one koh3 save each, all offered to one folder remote: enough history for releases. */
export async function makeRepos(names: string[]): Promise<{
	bucketDir: string;
	saves: Record<string, string>;
	/** Runs koh3 in one of the repos, under the fixture's HOME. */
	koh(repo: string, ...args: string[]): string;
}> {
	const root = await mkdtemp(join(tmpdir(), "kepr-repos-"));
	const home = join(root, "home");
	const bucketDir = join(root, "bucket");
	await mkdir(home);
	const saves: Record<string, string> = {};
	for (const [i, name] of names.entries()) {
		const repoDir = join(root, "work", name);
		await mkdir(repoDir, { recursive: true });
		run(repoDir, home, ["init"]);
		if (i === 0) run(repoDir, home, ["remote", "folder", bucketDir]);
		await writeFile(join(repoDir, "README.md"), `# ${name}\n\nThe ${name} project.\n`);
		run(repoDir, home, ["save", `release ${name}`]);
		saves[name] = JSON.parse(run(repoDir, home, ["view", "--json"])).head_id;
	}
	return {
		bucketDir,
		saves,
		koh: (repo, ...args) => run(join(root, "work", repo), home, args),
	};
}

/** A throwaway HOME, a repo folder and a bucket, with koh3 runnable inside (§4.3's pinned binary). */
export async function kohWorkspace(repo = "shipped"): Promise<{
	root: string;
	home: string;
	repoDir: string;
	bucketDir: string;
	run(...args: string[]): string;
}> {
	const root = await mkdtemp(join(tmpdir(), "kepr-workspace-"));
	const home = join(root, "home");
	const repoDir = join(root, "work", repo);
	const bucketDir = join(root, "bucket");
	await mkdir(home);
	await mkdir(repoDir, { recursive: true });
	return { root, home, repoDir, bucketDir, run: (...args) => run(repoDir, home, args) };
}

/** A release file with its bytes, or only as a record declares it (the bytes are then a stand-in). */
export type FixtureFile = { platform: string; name: string; bytes: Uint8Array } | ReleaseFile;

export type FixtureRelease = {
	version: string;
	save: string;
	notes?: string;
	publishedAt?: number;
	files: FixtureFile[];
};

/**
 * Publishes a release straight into a folder remote, in §11.2's order: the files, then release.json,
 * then `releases/latest`. `kohWorkspace` plus `koh3 offer --builds` is the real thing
 * (tests/kohrelease.test.ts); this writes them by hand for fixtures that need several versions, an
 * old release, or hashes that no build produced.
 */
export async function writeRelease(
	bucketDir: string,
	repo: string,
	release: FixtureRelease,
	latest = true,
): Promise<void> {
	const dir = join(bucketDir, repo, "releases", release.version);
	const files: ReleaseFile[] = [];
	for (const file of release.files) {
		const bytes = "bytes" in file ? file.bytes : new TextEncoder().encode(`stand-in ${file.name}`);
		await mkdir(join(dir, file.platform), { recursive: true });
		await writeFile(join(dir, file.platform, file.name), bytes);
		files.push(
			"bytes" in file
				? {
						platform: file.platform,
						name: file.name,
						size: bytes.length,
						blake3: bytesToHex(blake3(bytes)),
						sha256: new Bun.CryptoHasher("sha256").update(bytes).digest("hex"),
					}
				: file,
		);
	}
	const record = {
		format: 1,
		repo,
		version: release.version,
		save: release.save,
		published_at: release.publishedAt ?? 1790000000,
		machine: "fixture",
		notes: release.notes ?? "",
		files,
	};
	await writeFile(join(dir, "release.json"), JSON.stringify(record, null, 2));
	if (latest) await writeFile(join(bucketDir, repo, "releases", "latest"), release.version);
}

/** This machine's platform, which is what `koh build` builds for with no flags. */
export function platform(): string {
	const os = process.platform === "darwin" ? "macos" : "linux";
	const arch = process.arch === "arm64" ? "aarch64" : "x86_64";
	return `${os}-${arch}`;
}