State returns a random string suitable as a state value.

DefaultRedirectURL is the default URL to which to redirect clients after a code has been obtained.

DirectAuthURLMode queries the remote proxy to get an auth URL that goes directly to the OAuth2 provider web page the user must go to in order to obtain authorization.

ProxiedAuthURLMode makes an auth URL that goes to the remote proxy, not directly to the provider.

Browser gets an OAuth2 code via the web browser.

LocalAppSource implements oauth2.TokenSource for OAuth2 client apps that have the client app credentials (Client ID and Secret) available locally.

RemoteAppSource implements oauth2.TokenSource for OAuth2 client apps that have their credentials (Client ID and Secret, as well as endpoint info) stored remotely.

Getter is a type that can get an OAuth2 auth code.

AuthURLMode describes what kind of auth URL a RemoteAppSource should obtain.