export interface OAuthUiState {
  code: string | null;
  state: string | null;
  error: string | null;
}

const STATE_STORAGE_KEY = "omo.dashboard.oauth.state";

export function readOAuthUiState(): OAuthUiState {
  const params = new URLSearchParams(window.location.search);
  return {
    code: params.get("code"),
    state: params.get("state"),
    error: params.get("error"),
  };
}

export function buildDiscordAuthorizeUrl(
  clientId: string,
  redirectUri: string,
): string {
  const state = crypto.randomUUID();
  window.localStorage.setItem(STATE_STORAGE_KEY, state);

  const url = new URL("https://discord.com/oauth2/authorize");
  url.searchParams.set("client_id", clientId);
  url.searchParams.set("response_type", "code");
  url.searchParams.set("scope", "identify guilds");
  url.searchParams.set("redirect_uri", redirectUri);
  url.searchParams.set("state", state);
  url.searchParams.set("prompt", "consent");

  return url.toString();
}

export function isExpectedOAuthState(state: string | null): boolean {
  if (!state) {
    return false;
  }

  const expected = window.localStorage.getItem(STATE_STORAGE_KEY);
  return expected === state;
}

export function clearOAuthQueryParams(): void {
  const url = new URL(window.location.href);
  url.searchParams.delete("code");
  url.searchParams.delete("state");
  url.searchParams.delete("error");
  window.history.replaceState({}, document.title, url.toString());
}