//! Demonstrating how to create a custom Flow
//! here we open the browser for the user, making the use of InstalledAppFlow more convenient as
//! nothing has to be copy/pasted. Reason, the browser will open, the user accepts the requested
//! scope by clicking through e.g. the google oauth2, after this is done a local webserver started
//! by InstalledFlowAuthenticator will consume the token coming from the oauth2 server = no copy or
//! paste needed to continue with the operation.
use std::future::Future;
use std::pin::Pin;
use yup_oauth2::authenticator_delegate::{DefaultInstalledFlowDelegate, InstalledFlowDelegate};

/// async function to be pinned by the `present_user_url` method of the trait
/// we use the existing `DefaultInstalledFlowDelegate::present_user_url` method as a fallback for
/// when the browser did not open for example, the user still see's the URL.
async fn browser_user_url(url: &str, need_code: bool) -> Result<String, String> {
    if webbrowser::open(url).is_ok() {
        println!("webbrowser was successfully opened.");
    }
    let def_delegate = DefaultInstalledFlowDelegate;
    def_delegate.present_user_url(url, need_code).await
}

/// our custom delegate struct we will implement a flow delegate trait for:
/// in this case we will implement the `InstalledFlowDelegated` trait
#[derive(Copy, Clone)]
struct InstalledFlowBrowserDelegate;

/// here we implement only the present_user_url method with the added webbrowser opening
/// the other behaviour of the trait does not need to be changed.
impl InstalledFlowDelegate for InstalledFlowBrowserDelegate {
    /// the actual presenting of URL and browser opening happens in the function defined above here
    /// we only pin it
    fn present_user_url<'a>(
        &'a self,
        url: &'a str,
        need_code: bool,
    ) -> Pin<Box<dyn Future<Output = Result<String, String>> + Send + 'a>> {
        Box::pin(browser_user_url(url, need_code))
    }
}

#[tokio::main]
async fn main() {
    // Put your client secret in the working directory!
    let sec = yup_oauth2::read_application_secret("client_secret.json")
        .await
        .expect("client secret couldn't be read.");
    let auth = yup_oauth2::InstalledFlowAuthenticator::builder(
        sec,
        yup_oauth2::InstalledFlowReturnMethod::HTTPRedirect,
    )
    .persist_tokens_to_disk("tokencache.json")
    // use our custom flow delegate instead of default
    .flow_delegate(Box::new(InstalledFlowBrowserDelegate))
    .build()
    .await
    .expect("InstalledFlowAuthenticator failed to build");

    let scopes = &["https://www.googleapis.com/auth/drive.file"];

    match auth.token(scopes).await {
        Err(e) => println!("error: {:?}", e),
        Ok(t) => println!("The token is {:?}", t),
    }
}