#!/usr/bin/env node

import { exec as execCb, spawnSync } from "child_process";
import { createHash, randomUUID } from "crypto";
import {
	chmodSync,
	copyFileSync,
	createWriteStream,
	existsSync,
	mkdirSync,
	readFileSync,
	readdirSync,
	rmSync,
} from "fs";
import { arch, homedir, platform } from "os";
import { resolve, join } from "path";
import { Readable } from "stream";
import { finished } from "stream/promises";
import extractZip from "extract-zip";

const __dirname = import.meta.dirname;
const cwd = resolve(__dirname, "..");
const PLAYWRIGHT_SKIP =
	process.env.PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD === "1" ||
	process.env.PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD === "true";
const RTK_SKIP =
	process.env.SF_SKIP_RTK_INSTALL === "1" ||
	process.env.SF_SKIP_RTK_INSTALL === "true" ||
	process.env.SF_RTK_DISABLED === "1" ||
	process.env.SF_RTK_DISABLED === "true";

const RTK_VERSION = "0.37.0";
const RTK_REPO = "rtk-ai/rtk";
const RTK_ENV = { ...process.env, RTK_TELEMETRY_DISABLED: "1" };
const managedBinDir = join(
	process.env.SF_HOME || join(homedir(), ".sf"),
	"agent",
	"bin",
);
const managedBinaryPath = join(
	managedBinDir,
	platform() === "win32" ? "rtk.exe" : "rtk",
);

function run(cmd) {
	return new Promise((resolvePromise) => {
		execCb(cmd, { cwd }, (error, stdout, stderr) => {
			resolvePromise({ ok: !error, stdout, stderr });
		});
	});
}

function logWarn(message) {
	process.stderr.write(`[forge] postinstall: ${message}\n`);
}

function resolveAssetName() {
	const currentPlatform = platform();
	const currentArch = arch();
	if (currentPlatform === "darwin" && currentArch === "arm64")
		return "rtk-aarch64-apple-darwin.tar.gz";
	if (currentPlatform === "darwin" && currentArch === "x64")
		return "rtk-x86_64-apple-darwin.tar.gz";
	if (currentPlatform === "linux" && currentArch === "arm64")
		return "rtk-aarch64-unknown-linux-gnu.tar.gz";
	if (currentPlatform === "linux" && currentArch === "x64")
		return "rtk-x86_64-unknown-linux-musl.tar.gz";
	if (currentPlatform === "win32" && currentArch === "x64")
		return "rtk-x86_64-pc-windows-msvc.zip";
	return null;
}

function parseChecksums(text) {
	const checksums = new Map();
	for (const rawLine of text.split(/\r?\n/)) {
		const line = rawLine.trim();
		if (!line) continue;
		const match = line.match(/^([a-f0-9]{64})\s+(.+)$/i);
		if (!match) continue;
		checksums.set(match[2], match[1].toLowerCase());
	}
	return checksums;
}

function sha256File(path) {
	const hash = createHash("sha256");
	hash.update(readFileSync(path));
	return hash.digest("hex");
}

async function downloadToFile(url, destination) {
	const response = await fetch(url, {
		headers: { "User-Agent": "sf-pi-postinstall" },
	});
	if (!response.ok) {
		throw new Error(`download failed (${response.status}) for ${url}`);
	}
	if (!response.body) {
		throw new Error(`download returned no body for ${url}`);
	}
	const output = createWriteStream(destination);
	await finished(Readable.fromWeb(response.body).pipe(output));
}

function findBinaryRecursively(rootDir, binaryName) {
	const stack = [rootDir];
	while (stack.length > 0) {
		const current = stack.pop();
		if (!current) continue;
		const entries = readdirSync(current, { withFileTypes: true });
		for (const entry of entries) {
			const fullPath = join(current, entry.name);
			if (entry.isFile() && entry.name === binaryName) return fullPath;
			if (entry.isDirectory()) stack.push(fullPath);
		}
	}
	return null;
}

function validateRtkBinary(binaryPath) {
	const result = spawnSync(binaryPath, ["rewrite", "git status"], {
		encoding: "utf-8",
		env: RTK_ENV,
		stdio: ["ignore", "pipe", "ignore"],
		timeout: 5000,
	});
	return (
		!result.error &&
		result.status === 0 &&
		(result.stdout || "").trim() === "rtk git status"
	);
}

async function ensureRtkInstalled() {
	if (RTK_SKIP) return;
	const assetName = resolveAssetName();
	if (!assetName) return;
	if (existsSync(managedBinaryPath) && validateRtkBinary(managedBinaryPath))
		return;

	const tempRoot = join(
		managedBinDir,
		`.rtk-postinstall-${randomUUID().slice(0, 8)}`,
	);
	const archivePath = join(tempRoot, assetName);
	const extractDir = join(tempRoot, "extract");
	const releaseBase = `https://github.com/${RTK_REPO}/releases/download/v${RTK_VERSION}`;

	mkdirSync(tempRoot, { recursive: true });
	mkdirSync(managedBinDir, { recursive: true });

	try {
		const checksumsResponse = await fetch(`${releaseBase}/checksums.txt`, {
			headers: { "User-Agent": "sf-pi-postinstall" },
		});
		if (!checksumsResponse.ok) {
			throw new Error(
				`failed to fetch RTK checksums (${checksumsResponse.status})`,
			);
		}

		const checksums = parseChecksums(await checksumsResponse.text());
		const expectedSha = checksums.get(assetName);
		if (!expectedSha) {
			throw new Error(`missing checksum for ${assetName}`);
		}

		await downloadToFile(`${releaseBase}/${assetName}`, archivePath);
		const actualSha = sha256File(archivePath);
		if (actualSha !== expectedSha) {
			throw new Error(`checksum mismatch for ${assetName}`);
		}

		mkdirSync(extractDir, { recursive: true });
		if (assetName.endsWith(".zip")) {
			await extractZip(archivePath, { dir: extractDir });
		} else {
			const extractResult = spawnSync(
				"tar",
				["xzf", archivePath, "-C", extractDir],
				{
					encoding: "utf-8",
					timeout: 30000,
				},
			);
			if (extractResult.error || extractResult.status !== 0) {
				throw new Error(
					extractResult.error?.message ||
						extractResult.stderr?.trim() ||
						`failed to extract ${assetName}`,
				);
			}
		}

		const extractedBinary = findBinaryRecursively(
			extractDir,
			platform() === "win32" ? "rtk.exe" : "rtk",
		);
		if (!extractedBinary) {
			throw new Error(`RTK binary not found in ${assetName}`);
		}

		copyFileSync(extractedBinary, managedBinaryPath);
		if (platform() !== "win32") {
			chmodSync(managedBinaryPath, 0o755);
		}

		if (!validateRtkBinary(managedBinaryPath)) {
			rmSync(managedBinaryPath, { force: true });
			throw new Error("downloaded RTK binary failed validation");
		}
	} catch (error) {
		logWarn(`RTK install skipped: ${describeFetchError(error)}`);
	} finally {
		rmSync(tempRoot, { recursive: true, force: true });
	}
}

function describeFetchError(err) {
	const base = err?.message || String(err);
	const cause = err?.cause;
	if (!cause) return base;
	const code = cause.code || cause.errno;
	const causeMsg = cause.message || "";
	const detail = code
		? `${code}${causeMsg && causeMsg !== code ? ` — ${causeMsg}` : ""}`
		: causeMsg;
	return detail ? `${base} (${detail})` : base;
}

if (!PLAYWRIGHT_SKIP) {
	await run("npx playwright install chromium");
}

await ensureRtkInstalled();