/**
 * Everything you need for the `ts-for-gir self-update` command is located here
 */

import { chmodSync, existsSync, renameSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";

import { APP_NAME, APP_VERSION } from "@ts-for-gir/lib";

import type { SelfUpdateCommandArgs } from "../types/index.ts";

const REPO = "gjsify/ts-for-gir";
const GITHUB_API = "https://api.github.com";
const GJS_ASSET_NAME = "ts-for-gir-gjs";

function getCurrentBinaryPath(): string | null {
	const p = process.argv[1] ?? null;
	if (!p) return null;
	// Refuse to update in dev mode (source file or node_modules path)
	if (p.endsWith(".ts") || p.includes("node_modules")) return null;
	return p;
}

async function fetchJson(url: string): Promise<unknown> {
	const headers: Record<string, string> = {
		Accept: "application/vnd.github.v3+json",
		"User-Agent": `ts-for-gir/${APP_VERSION}`,
	};
	const token = process.env.GITHUB_TOKEN;
	if (token) headers.Authorization = `token ${token}`;

	const response = await fetch(url, { headers });
	if (!response.ok) {
		throw new Error(`HTTP ${response.status} from ${url}`);
	}
	return response.json();
}

async function downloadBinary(url: string, destPath: string): Promise<void> {
	const response = await fetch(url, {
		headers: { "User-Agent": `ts-for-gir/${APP_VERSION}` },
	});
	if (!response.ok) {
		throw new Error(`HTTP ${response.status} downloading binary`);
	}
	const buffer = await response.arrayBuffer();
	const tmpPath = join(tmpdir(), `ts-for-gir-update-${Date.now()}`);
	writeFileSync(tmpPath, Buffer.from(buffer));
	chmodSync(tmpPath, 0o755);
	renameSync(tmpPath, destPath); // atomic on POSIX
}

const command = "self-update";
const description = "Update ts-for-gir to the latest version from GitHub releases";
const examples: ReadonlyArray<[string, string?]> = [
	[`${APP_NAME} self-update`, "Check for updates and install the latest version"],
	[`${APP_NAME} self-update --check`, "Only check for a newer version, do not install"],
	[`${APP_NAME} self-update --force`, "Force reinstall even if already on the latest version"],
];

const builder = (yargs: import("yargs").Argv) =>
	yargs
		.option("check", {
			description: "Only check for a newer version, do not install",
			type: "boolean",
			default: false,
		})
		.option("force", {
			description: "Force reinstall even if already on the latest version",
			type: "boolean",
			default: false,
		})
		.example(examples as [string, string?][]);

const handler = async (args: SelfUpdateCommandArgs): Promise<void> => {
	console.log(`Checking for updates... (current: v${APP_VERSION})`);

	let release: Record<string, unknown>;
	try {
		release = (await fetchJson(`${GITHUB_API}/repos/${REPO}/releases/latest`)) as Record<string, unknown>;
	} catch (err) {
		const msg = err instanceof Error ? err.message : String(err);
		process.stderr.write(`Failed to fetch release information: ${msg}\n`);
		process.exitCode = 1;
		return;
	}

	const latestVersion = (release.tag_name as string).replace(/^v/, "");

	if (latestVersion === APP_VERSION && !args.force) {
		console.log(`Already up to date (v${APP_VERSION})`);
		return;
	}

	if (args.check) {
		console.log(`New version available: v${latestVersion} (current: v${APP_VERSION})`);
		console.log(`Run \`${APP_NAME} self-update\` to install it.`);
		return;
	}

	console.log(`Updating to v${latestVersion}...`);

	const assets = release.assets as Array<Record<string, string>>;
	const asset = assets.find((a) => a.name === GJS_ASSET_NAME);
	if (!asset) {
		process.stderr.write(
			`No GJS binary found in release ${release.tag_name}.\n` +
				"self-update requires the GJS bundle to be installed via install.js.\n" +
				"For npm installations use: npm update -g @ts-for-gir/cli\n",
		);
		process.exitCode = 1;
		return;
	}

	const currentPath = getCurrentBinaryPath();
	if (!currentPath || !existsSync(currentPath)) {
		process.stderr.write(
			"Cannot determine current binary path for update.\n" +
				"self-update only works when running the installed GJS binary.\n",
		);
		process.exitCode = 1;
		return;
	}

	try {
		await downloadBinary(asset.browser_download_url, currentPath);
		console.log(`Successfully updated to v${latestVersion}`);
	} catch (err) {
		const msg = err instanceof Error ? err.message : String(err);
		process.stderr.write(`Update failed: ${msg}\n`);
		process.exitCode = 1;
	}
};

export const selfUpdate = {
	command,
	description,
	builder,
	handler,
	examples,
};