use futures_channel::mpsc::{self, Receiver, Sender};
use futures_util::{
	future::FutureExt,
	io::{BufReader, BufWriter},
	pin_mut, select,
	sink::SinkExt,
	stream::{self, StreamExt},
};
use serde::{Deserialize, Serialize};
use soketto::handshake;
use soketto::handshake::{server::Response, Server};
use std::net::SocketAddr;
use std::time::Duration;
use tokio::net::TcpStream;
use tokio_util::compat::{Compat, TokioAsyncReadCompatExt};

pub use hyper::{Body, HeaderMap, StatusCode, Uri};

type Error = Box<dyn std::error::Error>;

pub struct TestContext;

impl TestContext {
	pub fn ok(&self) -> Result<(), anyhow::Error> {
		Ok(())
	}
	pub fn err(&self) -> Result<(), anyhow::Error> {
		Err(anyhow::anyhow!("RPC context failed"))
	}
}

/// Request Id
#[derive(Debug, PartialEq, Clone, Hash, Eq, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
#[serde(untagged)]
pub enum Id {
	/// No id (notification)
	Null,
	/// Numeric id
	Num(u64),
	/// String id
	Str(String),
}

#[derive(Debug)]
pub struct HttpResponse {
	pub status: StatusCode,
	pub header: HeaderMap,
	pub body: String,
}

/// WebSocket client to construct with arbitrary payload to construct bad payloads.
pub struct WebSocketTestClient {
	tx: soketto::Sender<BufReader<BufWriter<Compat<TcpStream>>>>,
	rx: soketto::Receiver<BufReader<BufWriter<Compat<TcpStream>>>>,
}

impl WebSocketTestClient {
	pub async fn new(url: SocketAddr) -> Result<Self, Error> {
		let socket = TcpStream::connect(url).await?;
		let mut client = handshake::Client::new(BufReader::new(BufWriter::new(socket.compat())), "test-client", "/");
		match client.handshake().await {
			Ok(handshake::ServerResponse::Accepted { .. }) => {
				let (tx, rx) = client.into_builder().finish();
				Ok(Self { tx, rx })
			}
			r => Err(format!("WebSocketHandshake failed: {:?}", r).into()),
		}
	}

	pub async fn send_request_text(&mut self, msg: impl AsRef<str>) -> Result<String, Error> {
		self.tx.send_text(msg).await?;
		self.tx.flush().await?;
		let mut data = Vec::new();
		self.rx.receive_data(&mut data).await?;
		String::from_utf8(data).map_err(Into::into)
	}

	pub async fn send_request_binary(&mut self, msg: &[u8]) -> Result<String, Error> {
		self.tx.send_binary(msg).await?;
		self.tx.flush().await?;
		let mut data = Vec::new();
		self.rx.receive_data(&mut data).await?;
		String::from_utf8(data).map_err(Into::into)
	}

	pub async fn close(&mut self) -> Result<(), Error> {
		self.tx.close().await.map_err(Into::into)
	}
}

#[derive(Debug, Clone)]
pub enum ServerMode {
	// Send out a hardcoded response on every connection.
	Response(String),
	// Send out a subscription ID on a request and continuously send out data on the subscription.
	Subscription { subscription_id: String, subscription_response: String },
}

/// JSONRPC v2 dummy WebSocket server that sends a hardcoded response.
pub struct WebSocketTestServer {
	local_addr: SocketAddr,
	exit: Sender<()>,
}

impl WebSocketTestServer {
	// Spawns a dummy `JSONRPC v2` WebSocket server that sends out a pre-configured `hardcoded response` for every connection.
	pub async fn with_hardcoded_response(sockaddr: SocketAddr, response: String) -> Self {
		let listener = async_std::net::TcpListener::bind(sockaddr).await.unwrap();
		let local_addr = listener.local_addr().unwrap();
		let (tx, rx) = mpsc::channel::<()>(4);
		tokio::spawn(server_backend(listener, rx, ServerMode::Response(response)));

		Self { local_addr, exit: tx }
	}

	// Spawns a dummy `JSONRPC v2` WebSocket server that sends out a pre-configured subscription ID and subscription response.
	//
	// NOTE: ignores the actual subscription and unsubscription method.
	pub async fn with_hardcoded_subscription(
		sockaddr: SocketAddr,
		subscription_id: String,
		subscription_response: String,
	) -> Self {
		let listener = async_std::net::TcpListener::bind(sockaddr).await.unwrap();
		let local_addr = listener.local_addr().unwrap();
		let (tx, rx) = mpsc::channel::<()>(4);
		tokio::spawn(server_backend(listener, rx, ServerMode::Subscription { subscription_id, subscription_response }));

		Self { local_addr, exit: tx }
	}

	pub fn local_addr(&self) -> SocketAddr {
		self.local_addr
	}

	pub async fn close(&mut self) {
		self.exit.send(()).await.unwrap();
	}
}

async fn server_backend(listener: async_std::net::TcpListener, mut exit: Receiver<()>, mode: ServerMode) {
	let mut connections = Vec::new();

	loop {
		let conn_fut = listener.accept().fuse();
		let exit_fut = exit.next();
		pin_mut!(exit_fut, conn_fut);

		select! {
			_ = exit_fut => break,
			conn = conn_fut => {
				if let Ok((stream, _)) = conn {
					let (tx, rx) = mpsc::channel::<()>(4);
					let handle = tokio::spawn(connection_task(stream, mode.clone(), rx));
					connections.push((handle, tx));
				}
			}
		}
	}

	// close connections
	for (handle, mut exit) in connections {
		// If the actual connection was never established i.e., returned early
		// It will most likely be caught on the client-side but just to be explicit.
		exit.send(()).await.expect("WebSocket connection was never established");
		handle.await.unwrap();
	}
}

async fn connection_task(socket: async_std::net::TcpStream, mode: ServerMode, mut exit: Receiver<()>) {
	let mut server = Server::new(socket);

	let websocket_key = match server.receive_request().await {
		Ok(req) => req.into_key(),
		Err(_) => return,
	};

	let accept = server.send_response(&Response::Accept { key: &websocket_key, protocol: None }).await;

	if accept.is_err() {
		return;
	}

	let (mut sender, receiver) = server.into_builder().finish();

	let ws_stream = stream::unfold(receiver, move |mut receiver| async {
		let mut buf = Vec::new();
		let ret = match receiver.receive_data(&mut buf).await {
			Ok(_) => Ok(buf),
			Err(err) => Err(err),
		};
		Some((ret, receiver))
	});
	pin_mut!(ws_stream);

	loop {
		let next_ws = ws_stream.next().fuse();
		let next_exit = exit.next().fuse();
		let time_out = tokio::time::sleep(Duration::from_secs(1)).fuse();
		pin_mut!(time_out, next_exit, next_ws);

		select! {
			_ = time_out => {
				if let ServerMode::Subscription { subscription_response, .. } = &mode {
					if let Err(e) = sender.send_text(&subscription_response).await {
						log::warn!("send response to subscription: {:?}", e);
					}
				}
			}
			ws = next_ws => {
				// Got a request on the connection but don't care about the contents.
				// Just send out the pre-configured hardcoded responses.
				if let Some(Ok(_)) = ws {
					match &mode {
						ServerMode::Response(r) => {
							if let Err(e) = sender.send_text(&r).await {
								log::warn!("send response to request error: {:?}", e);
							}
						}
						ServerMode::Subscription { subscription_id, .. } => {
							if let Err(e) = sender.send_text(&subscription_id).await {
								log::warn!("send subscription id error: {:?}", e);
							}
						}
					}
				}
			}
			_ = next_exit => break,
		}
	}
}