import PageSpinner from "@/Element/PageSpinner";
import { sha256 } from "@noble/hashes/sha256";
import { randomBytes } from "@noble/hashes/utils";
import { base64, base64urlnopad, hex } from "@scure/base";
import { useEffect, useState } from "react";
import { useLocation } from "react-router-dom";

export default function AlbyOAuth() {
  const location = useLocation();
  const alby = getAlbyOAuth();
  const [error, setError] = useState("");

  async function setupWallet(token: string) {
    const auth = await alby.getToken(token);
    console.debug(auth);
  }

  useEffect(() => {
    if (location.search) {
      const params = new URLSearchParams(location.search);
      const token = params.get("code");
      if (token) {
        setupWallet(token).catch(e => {
          setError((e as Error).message);
        });
      }
    }
  }, [location]);

  if (!location.search) return;
  return (
    <>
      <h1>Alby Wallet Connection</h1>
      {!error && <PageSpinner />}
      {error && <b className="warning">{error}</b>}
    </>
  );
}

export function getAlbyOAuth() {
  const clientId = "35EQp6crss";
  const clientSecret = "DTUPIqOjsjwxZXcJwF5C";
  const redirectUrl = `${window.location.protocol}//${window.location.host}/settings/wallet/alby`;
  const scopes = ["invoices:create", "invoices:read", "transactions:read", "balance:read", "payments:send"];

  const ec = new TextEncoder();
  const code_verifier = hex.encode(randomBytes(64));
  window.sessionStorage.setItem("alby-code", code_verifier);

  const params = new URLSearchParams();
  params.set("client_id", clientId);
  params.set("response_type", "code");
  params.set("code_challenge", base64urlnopad.encode(sha256(code_verifier)));
  params.set("code_challenge_method", "S256");
  params.set("redirect_uri", redirectUrl);
  params.set("scope", scopes.join(" "));

  const tokenUrl = "https://api.getalby.com/oauth/token";
  const authUrl = `https://getalby.com/oauth?${params}`;

  return {
    tokenUrl,
    authUrl,
    getToken: async (token: string) => {
      const code = window.sessionStorage.getItem("alby-code");
      if (!code) throw new Error("Alby code is missing!");
      window.sessionStorage.removeItem("alby-code");

      const form = new URLSearchParams();
      form.set("client_id", clientId);
      form.set("code_verifier", code);
      form.set("grant_type", "authorization_code");
      form.set("redirect_uri", redirectUrl);
      form.set("code", token);

      const req = await fetch(tokenUrl, {
        method: "POST",
        headers: {
          accept: "application/json",
          "content-type": "application/x-www-form-urlencoded",
          authorization: `Basic ${base64.encode(ec.encode(`${clientId}:${clientSecret}`))}`,
        },
        body: form,
      });

      const data = await req.json();
      if (req.ok) {
        return data.access_token as string;
      } else {
        throw new Error(data.error_description as string);
      }
    },
  };
}