import { redirect, type Cookies } from "@sveltejs/kit";

export interface ClientOptions {
	id: string;
	secret: string;
	redirectURI: string;
}

export interface CallbackOptions {
	url: URL;
	cookies: Cookies;
	cookie: string;
	authorise: string;
	redirect?: string;
	client: ClientOptions;
	verifier?: string;
}

export const callback = async (options: CallbackOptions) => {
	const { url, cookies, cookie, authorise, client } = options;
	const formData = new FormData();

	formData.append("grant_type", "authorization_code");
	formData.append("client_id", client.id);
	formData.append("client_secret", client.secret);
	formData.append("redirect_uri", client.redirectURI);
	formData.append("code", url.searchParams.get("code") || "null");

	if (options.verifier) formData.append("code_verifier", options.verifier);

	cookies.set(
		cookie,
		JSON.stringify(
			await (
				await fetch(authorise, {
					method: "POST",
					body: formData,
				})
			).json(),
		),
		{
			path: "/",
			maxAge: 31536000 / 2,
			httpOnly: false,
			sameSite: "lax",
			secure: false,
		},
	);

	redirect(303, options.redirect ?? "/");
};