import { join } from "jsr:@std/path";
import { serveDir } from "jsr:@std/http/file-server";

const scriptDir = import.meta.dirname ?? ".";
const root = join(scriptDir, "..", "..");
const port = Number(Deno.env.get("PORT") ?? "8080");

function trimPathLine(line: string): string {
	let s = line.trim();
	if (!s || s.startsWith("#")) return "";
	if ((s.startsWith('"') && s.endsWith('"')) || (s.startsWith("'") && s.endsWith("'"))) {
		s = s.slice(1, -1);
	}
	return s.trim();
}

/** Optional one-line file in repo root: absolute path to `ChatRequest/Database.json`. */
function readOptionalPathFile(): string | undefined {
	try {
		const pathFile = join(root, "chat-request-database.path");
		const raw = Deno.readTextFileSync(pathFile);
		for (const line of raw.split(/\r?\n/)) {
			const p = trimPathLine(line);
			if (p) return p;
		}
	} catch {
		// missing or unreadable
	}
	return undefined;
}

const chatRequestDatabase =
	Deno.env.get("CHAT_REQUEST_DATABASE")?.trim() || readOptionalPathFile();

function isSafeProxyPath(path: string): boolean {
	if (!path) return false;
	if (!path.startsWith("/")) return false;
	if (path.includes("://")) return false;
	if (path.includes("\\") || path.includes("\r") || path.includes("\n")) return false;
	return true;
}

async function proxyApiRequest(req: Request, upstreamBase: string): Promise<Response> {
	const url = new URL(req.url);
	const path = url.searchParams.get("path") ?? "";
	if (!isSafeProxyPath(path)) {
		return new Response("Invalid path\n", { status: 400 });
	}
	const upstream = new URL(`${upstreamBase}${path}`);
	for (const [key, value] of url.searchParams.entries()) {
		if (key === "path") continue;
		upstream.searchParams.append(key, value);
	}
	try {
		const upstreamRes = await fetch(upstream, { method: "GET" });
		const headers = new Headers();
		const contentType = upstreamRes.headers.get("content-type");
		if (contentType) headers.set("content-type", contentType);
		headers.set("cache-control", "no-store");
		return new Response(upstreamRes.body, {
			status: upstreamRes.status,
			statusText: upstreamRes.statusText,
			headers,
		});
	} catch (error) {
		const message = error instanceof Error ? error.message : String(error);
		return new Response(`Proxy request failed: ${message}\n`, { status: 502 });
	}
}

function isChatRequestFilename(pathname: string): boolean {
	const base = pathname.split("/").pop() ?? "";
	return base === "ChatRequest.json" || base === "database.json";
}

Deno.serve({ port, hostname: "127.0.0.1" }, async (req) => {
	const url = new URL(req.url);
	if (req.method === "GET" && url.pathname === "/api/beatleader") {
		return proxyApiRequest(req, "https://api.beatleader.com");
	}
	if (req.method === "GET" && url.pathname === "/api/beatsaver") {
		return proxyApiRequest(req, "https://api.beatsaver.com");
	}
	if (req.method === "GET" && chatRequestDatabase && isChatRequestFilename(url.pathname)) {
		try {
			let text = await Deno.readTextFile(chatRequestDatabase);
			if (text.charCodeAt(0) === 0xfeff) text = text.slice(1);
			return new Response(text, {
				headers: {
					"Content-Type": "application/json; charset=utf-8",
					"Cache-Control": "no-store",
				},
			});
		} catch (e) {
			if (e instanceof Deno.errors.NotFound) {
				console.error(`CHAT_REQUEST_DATABASE not found: ${chatRequestDatabase}`);
				return new Response(null, { status: 404 });
			}
			const msg = e instanceof Error ? e.message : String(e);
			console.error(`CHAT_REQUEST_DATABASE read error (${chatRequestDatabase}): ${msg}`);
			return new Response(`Failed to read CHAT_REQUEST_DATABASE: ${msg}\n`, { status: 500 });
		}
	}
	return serveDir(req, { fsRoot: root, showDirListing: false });
});

console.log(`Overlay: http://127.0.0.1:${port}/index.html`);
if (chatRequestDatabase) {
	console.log(`Chat request database file: ${chatRequestDatabase}`);
} else {
	console.warn(
		"No database path: set CHAT_REQUEST_DATABASE or create chat-request-database.path (see README). " +
			"Otherwise /ChatRequest.json is only served from this folder if the file exists.",
	);
}