// Copyright 2019-2023 Tauri Programme within The Commons Conservancy
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT

//! [![](https://github.com/tauri-apps/plugins-workspace/raw/v2/plugins/websocket/banner.png)](https://github.com/tauri-apps/plugins-workspace/tree/v2/plugins/websocket)
//!
//! Expose a WebSocket server to your Tauri frontend.

#![doc(
    html_logo_url = "https://github.com/tauri-apps/tauri/raw/dev/app-icon.png",
    html_favicon_url = "https://github.com/tauri-apps/tauri/raw/dev/app-icon.png"
)]

use futures_util::{stream::SplitSink, SinkExt, StreamExt};
use http::header::{HeaderName, HeaderValue};
use serde::{ser::Serializer, Deserialize, Serialize};
use tauri::{
    ipc::Channel,
    plugin::{Builder as PluginBuilder, TauriPlugin},
    Manager, Runtime, State, Window,
};
use tokio::{net::TcpStream, sync::Mutex};
use tokio_tungstenite::{
    connect_async_with_config,
    tungstenite::{
        client::IntoClientRequest,
        protocol::{CloseFrame as ProtocolCloseFrame, WebSocketConfig},
        Message,
    },
    MaybeTlsStream, WebSocketStream,
};

use std::collections::HashMap;
use std::str::FromStr;

type Id = u32;
type WebSocket = WebSocketStream<MaybeTlsStream<TcpStream>>;
type WebSocketWriter = SplitSink<WebSocket, Message>;
type Result<T> = std::result::Result<T, Error>;

#[derive(Debug, thiserror::Error)]
enum Error {
    #[error(transparent)]
    Websocket(#[from] tokio_tungstenite::tungstenite::Error),
    #[error("connection not found for the given id: {0}")]
    ConnectionNotFound(Id),
    #[error(transparent)]
    InvalidHeaderValue(#[from] tokio_tungstenite::tungstenite::http::header::InvalidHeaderValue),
    #[error(transparent)]
    InvalidHeaderName(#[from] tokio_tungstenite::tungstenite::http::header::InvalidHeaderName),
}

impl Serialize for Error {
    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        serializer.serialize_str(self.to_string().as_str())
    }
}

#[derive(Default)]
struct ConnectionManager(Mutex<HashMap<Id, WebSocketWriter>>);

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ConnectionConfig {
    pub write_buffer_size: Option<usize>,
    pub max_write_buffer_size: Option<usize>,
    pub max_message_size: Option<usize>,
    pub max_frame_size: Option<usize>,
    #[serde(default)]
    pub accept_unmasked_frames: bool,
    pub headers: Option<Vec<(String, String)>>,
}

impl From<ConnectionConfig> for WebSocketConfig {
    fn from(config: ConnectionConfig) -> Self {
        // Disabling the warning on max_send_queue which we don't use anymore since it was deprecated.
        #[allow(deprecated)]
        Self {
            max_send_queue: None,
            write_buffer_size: config.write_buffer_size.unwrap_or(128 * 1024),
            max_write_buffer_size: config.max_write_buffer_size.unwrap_or(usize::MAX),
            // This may be harmful since if it's not provided from js we're overwriting the default value with None, meaning no size limit.
            max_message_size: config.max_message_size,
            // This may be harmful since if it's not provided from js we're overwriting the default value with None, meaning no size limit.
            max_frame_size: config.max_frame_size,
            accept_unmasked_frames: config.accept_unmasked_frames,
        }
    }
}

#[derive(Deserialize, Serialize)]
struct CloseFrame {
    pub code: u16,
    pub reason: String,
}

#[derive(Deserialize, Serialize)]
#[serde(tag = "type", content = "data")]
enum WebSocketMessage {
    Text(String),
    Binary(Vec<u8>),
    Ping(Vec<u8>),
    Pong(Vec<u8>),
    Close(Option<CloseFrame>),
}

#[tauri::command]
async fn connect<R: Runtime>(
    window: Window<R>,
    url: String,
    on_message: Channel,
    config: Option<ConnectionConfig>,
) -> Result<Id> {
    let id = rand::random();
    let mut request = url.into_client_request()?;

    if let Some(headers) = config.as_ref().and_then(|c| c.headers.as_ref()) {
        for (k, v) in headers {
            let header_name = HeaderName::from_str(k.as_str())?;
            let header_value = HeaderValue::from_str(v.as_str())?;
            request.headers_mut().insert(header_name, header_value);
        }
    }

    let (ws_stream, _) = connect_async_with_config(request, config.map(Into::into), false).await?;

    tauri::async_runtime::spawn(async move {
        let (write, read) = ws_stream.split();
        let manager = window.state::<ConnectionManager>();
        manager.0.lock().await.insert(id, write);
        read.for_each(move |message| {
            let window_ = window.clone();
            let on_message_ = on_message.clone();
            async move {
                if let Ok(Message::Close(_)) = message {
                    let manager = window_.state::<ConnectionManager>();
                    manager.0.lock().await.remove(&id);
                }

                let response = match message {
                    Ok(Message::Text(t)) => {
                        serde_json::to_value(WebSocketMessage::Text(t)).unwrap()
                    }
                    Ok(Message::Binary(t)) => {
                        serde_json::to_value(WebSocketMessage::Binary(t)).unwrap()
                    }
                    Ok(Message::Ping(t)) => {
                        serde_json::to_value(WebSocketMessage::Ping(t)).unwrap()
                    }
                    Ok(Message::Pong(t)) => {
                        serde_json::to_value(WebSocketMessage::Pong(t)).unwrap()
                    }
                    Ok(Message::Close(t)) => {
                        serde_json::to_value(WebSocketMessage::Close(t.map(|v| CloseFrame {
                            code: v.code.into(),
                            reason: v.reason.into_owned(),
                        })))
                        .unwrap()
                    }
                    Ok(Message::Frame(_)) => serde_json::Value::Null, // This value can't be recieved.
                    Err(e) => serde_json::to_value(Error::from(e)).unwrap(),
                };

                let _ = on_message_.send(response);
            }
        })
        .await;
    });

    Ok(id)
}

#[tauri::command]
async fn send(
    manager: State<'_, ConnectionManager>,
    id: Id,
    message: WebSocketMessage,
) -> Result<()> {
    if let Some(write) = manager.0.lock().await.get_mut(&id) {
        write
            .send(match message {
                WebSocketMessage::Text(t) => Message::Text(t),
                WebSocketMessage::Binary(t) => Message::Binary(t),
                WebSocketMessage::Ping(t) => Message::Ping(t),
                WebSocketMessage::Pong(t) => Message::Pong(t),
                WebSocketMessage::Close(t) => Message::Close(t.map(|v| ProtocolCloseFrame {
                    code: v.code.into(),
                    reason: std::borrow::Cow::Owned(v.reason),
                })),
            })
            .await?;
        Ok(())
    } else {
        Err(Error::ConnectionNotFound(id))
    }
}

pub fn init<R: Runtime>() -> TauriPlugin<R> {
    PluginBuilder::new("websocket")
        .js_init_script(include_str!("api-iife.js").to_string())
        .invoke_handler(tauri::generate_handler![connect, send])
        .setup(|app, _api| {
            app.manage(ConnectionManager::default());
            Ok(())
        })
        .build()
}