use std::future::Future;

use async_graphql::http::WsMessage;
use async_graphql::{Data, ObjectType, Result, Schema, SubscriptionType};
use futures_util::{future, StreamExt};
use warp::filters::ws;
use warp::{Filter, Rejection, Reply};

/// GraphQL subscription filter
///
/// # Examples
///
/// ```no_run
/// use async_graphql::*;
/// use async_graphql_warp::*;
/// use warp::Filter;
/// use futures_util::stream::{Stream, StreamExt};
/// use std::time::Duration;
///
/// struct QueryRoot;
///
/// #[Object]
/// impl QueryRoot {
///     async fn value(&self) -> i32 {
///         // A GraphQL Object type must define one or more fields.
///         100
///     }
/// }
///
/// struct SubscriptionRoot;
///
/// #[Subscription]
/// impl SubscriptionRoot {
///     async fn tick(&self) -> impl Stream<Item = String> {
///         async_stream::stream! {
///             let mut interval = tokio::time::interval(Duration::from_secs(1));
///             loop {
///                 let n = interval.tick().await;
///                 yield format!("{}", n.elapsed().as_secs_f32());
///             }
///         }
///     }
/// }
///
/// tokio::runtime::Runtime::new().unwrap().block_on(async {
///     let schema = Schema::new(QueryRoot, EmptyMutation, SubscriptionRoot);
///     let filter = async_graphql_warp::graphql_subscription(schema)
///         .or(warp::any().map(|| "Hello, World!"));
///     warp::serve(filter).run(([0, 0, 0, 0], 8000)).await;
/// });
/// ```
pub fn graphql_subscription<Query, Mutation, Subscription>(
    schema: Schema<Query, Mutation, Subscription>,
) -> impl Filter<Extract = (impl Reply,), Error = Rejection> + Clone
where
    Query: ObjectType + Sync + Send + 'static,
    Mutation: ObjectType + Sync + Send + 'static,
    Subscription: SubscriptionType + Send + Sync + 'static,
{
    graphql_subscription_with_data(schema, |_| async { Ok(Default::default()) })
}

/// GraphQL subscription filter
///
/// Specifies that a function converts the init payload to data.
pub fn graphql_subscription_with_data<Query, Mutation, Subscription, F, R>(
    schema: Schema<Query, Mutation, Subscription>,
    initializer: F,
) -> impl Filter<Extract = (impl Reply,), Error = Rejection> + Clone
where
    Query: ObjectType + 'static,
    Mutation: ObjectType + 'static,
    Subscription: SubscriptionType + 'static,
    F: FnOnce(serde_json::Value) -> R + Clone + Send + 'static,
    R: Future<Output = Result<Data>> + Send + 'static,
{
    use async_graphql::http::WebSocketProtocols;
    use std::str::FromStr;

    warp::ws()
        .and(warp::header::optional::<String>("sec-websocket-protocol"))
        .map(move |ws: ws::Ws, protocols: Option<String>| {
            let schema = schema.clone();
            let initializer = initializer.clone();

            let protocol = protocols
                .and_then(|protocols| {
                    protocols
                        .split(',')
                        .find_map(|p| WebSocketProtocols::from_str(p.trim()).ok())
                })
                .unwrap_or(WebSocketProtocols::SubscriptionsTransportWS);

            let reply = ws.on_upgrade(move |websocket| {
                let (ws_sender, ws_receiver) = websocket.split();

                async move {
                    let _ = async_graphql::http::WebSocket::with_data(
                        schema,
                        ws_receiver
                            .take_while(|msg| future::ready(msg.is_ok()))
                            .map(Result::unwrap)
                            .map(ws::Message::into_bytes),
                        initializer,
                        protocol,
                    )
                    .map(|msg| match msg {
                        WsMessage::Text(text) => ws::Message::text(text),
                        WsMessage::Close(code, status) => ws::Message::close_with(code, status),
                    })
                    .map(Ok)
                    .forward(ws_sender)
                    .await;
                }
            });

            warp::reply::with_header(
                reply,
                "Sec-WebSocket-Protocol",
                protocol.sec_websocket_protocol(),
            )
        })
}
