pub mod error;
pub mod message;

use std::collections::HashMap;
use std::sync::{Arc, Mutex};
use std::time::Instant;

use serde::de::DeserializeOwned;
use serde::{Deserialize, Serialize};
use tokio::io::{
    AsyncBufReadExt, AsyncRead, AsyncReadExt, AsyncWriteExt, BufReader,
    BufWriter,
};
use tokio::net::tcp::OwnedWriteHalf;
use tokio::net::{TcpStream, ToSocketAddrs};
use tokio::sync::oneshot;
use tracing::{debug, error, trace, warn};

pub use error::{ConnectionError, MessageError};
use message::{
    Command, GetTitleResponse, Hello, NavigateParams, NewSessionParams,
    NewSessionResponse,
};

#[derive(Debug, Deserialize, Serialize)]
struct Message(u8, u32, Option<String>, Option<serde_json::Value>);

type SenderMap = HashMap<u32, oneshot::Sender<Option<serde_json::Value>>>;

pub struct Marionette {
    ts: Instant,
    stream: BufWriter<OwnedWriteHalf>,
    sender: Arc<Mutex<SenderMap>>,
}

impl Marionette {
    pub async fn connect<A>(addr: A) -> Result<Self, ConnectionError>
    where
        A: ToSocketAddrs,
    {
        let conn = TcpStream::connect(addr).await?;
        let (read, write) = conn.into_split();
        let stream = BufWriter::new(write);
        let mut rstream = BufReader::new(read);
        let ts = Instant::now();
        let sender = Arc::new(Mutex::new(HashMap::new()));
        let buf = Self::next_message(&mut rstream).await?;
        let hello: Hello = serde_json::from_slice(&buf)?;
        debug!("Received hello: {:?}", hello);
        Self::start_recv_loop(rstream, sender.clone());
        Ok(Self { ts, stream, sender })
    }

    pub async fn get_title(&mut self) -> Result<String, std::io::Error> {
        let res: GetTitleResponse =
            self.send_message(Command::GetTitle).await?.unwrap();
        debug!("Received message: {:?}", res);
        Ok(res.value)
    }

    pub async fn navigate<U>(&mut self, url: U) -> Result<(), std::io::Error>
    where
        U: Into<String>,
    {
        let res: Option<serde_json::Value> = self
            .send_message(Command::Navigate(NavigateParams {
                url: url.into(),
            }))
            .await?;
        debug!("Received message: {:?}", res);
        Ok(())
    }

    pub async fn new_session(
        &mut self,
    ) -> Result<NewSessionResponse, std::io::Error> {
        let res = self
            .send_message(Command::NewSession(NewSessionParams {
                strict_file_interactability: true,
            }))
            .await?
            .unwrap();
        debug!("Received message: {:?}", res);
        Ok(res)
    }

    pub async fn send_message<T>(
        &mut self,
        command: Command,
    ) -> Result<Option<T>, std::io::Error>
    where
        T: DeserializeOwned,
    {
        let value = serde_json::to_value(command)?;
        let (command, params) = (
            value.get("command").unwrap().as_str().unwrap().into(),
            value.get("params").cloned(),
        );
        let msgid = (self.ts.elapsed().as_millis() % u32::MAX as u128) as u32;
        let message = Message(0, msgid, Some(command), params);
        let message = serde_json::to_string(&message)?;
        let message = format!("{}:{}", message.len(), message);
        trace!("Sending message: {}", message);
        let (tx, rx) = oneshot::channel();
        {
            let mut sender = self.sender.lock().unwrap();
            sender.insert(msgid, tx);
        }
        self.stream.write_all(message.as_bytes()).await?;
        self.stream.flush().await?;
        let Some(r) = rx.await.unwrap() else {
            return Ok(None)
        };
        Ok(serde_json::from_value(r)?)
    }

    fn start_recv_loop<T>(
        mut stream: BufReader<T>,
        sender: Arc<Mutex<SenderMap>>,
    ) where
        T: AsyncRead + Send + Unpin + 'static,
    {
        tokio::spawn(async move {
            loop {
                let buf = match Self::next_message(&mut stream).await {
                    Ok(b) => b,
                    Err(e) => {
                        error!("Error receiving message: {:?}", e);
                        break;
                    }
                };
                let msg: Message = match serde_json::from_slice(&buf[..]) {
                    Ok(m) => m,
                    Err(e) => {
                        warn!("Error parsing message: {}", e);
                        continue;
                    }
                };
                let msgid = msg.1;
                let value = msg.3;
                let mut sender = sender.lock().unwrap();
                if let Some(s) = sender.remove(&msgid) {
                    if s.send(value).is_err() {
                        warn!("Failed to send result to caller");
                    }
                } else {
                    warn!("Got unsolicited message {} ({:?})", msgid, value);
                }
            }
        });
    }

    async fn next_message<T>(
        stream: &mut BufReader<T>,
    ) -> Result<Vec<u8>, MessageError>
    where
        T: AsyncRead + Unpin,
    {
        let mut buf = vec![];
        stream.read_until(b':', &mut buf).await?;
        let length: usize =
            std::str::from_utf8(&buf[..buf.len() - 1])?.parse()?;
        trace!("Message length: {:?}", length);
        let mut buf = vec![0; length];
        stream.read_exact(&mut buf[..]).await?;
        trace!("Received message: {:?}", buf);
        Ok(buf)
    }
}