use std::{collections::BTreeMap, net::SocketAddr, sync::OnceLock, time::Duration};

use crossterm::event::{Event, EventStream, KeyCode, KeyEvent, KeyEventKind};
use futures::{FutureExt, StreamExt};
use joecalsend::{
    Config, JoecalState, JoecalUploadRequest, Listeners, TransferEvent, UploadDialog,
    error::{LocalSendError, Result},
    models::Device,
};
use julid::Julid;
use log::{LevelFilter, error, info};
use ratatui::{DefaultTerminal, Frame};
use tokio::{
    sync::mpsc::{UnboundedReceiver, unbounded_channel},
    task::JoinSet,
};

pub mod widgets;

pub type Peers = BTreeMap<SocketAddr, (String, String)>;

pub struct App {
    pub state: OnceLock<JoecalState>,
    pub screen: Vec<CurrentScreen>,
    pub events: EventStream,
    // addr -> (alias, fingerprint)
    pub peers: Peers,
    pub uploads: BTreeMap<Julid, JoecalUploadRequest>,
    // for getting messages back from the web server or web client about things we've done; the
    // other end is held by the state
    transfer_event_rx: OnceLock<UnboundedReceiver<TransferEvent>>,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum CurrentScreen {
    Main,
    Sending,
    Receiving,
    Stopping,
    Logging,
}

impl Default for App {
    fn default() -> Self {
        Self::new()
    }
}

impl App {
    pub fn new() -> Self {
        App {
            state: Default::default(),
            screen: vec![CurrentScreen::Main],
            peers: Default::default(),
            events: Default::default(),
            uploads: Default::default(),
            transfer_event_rx: Default::default(),
        }
    }

    #[tokio::main]
    pub async fn start_and_run(
        &mut self,
        terminal: &mut DefaultTerminal,
        config: Config,
        device: Device,
    ) -> Result<()> {
        let (transfer_event_tx, transfer_event_rx) = unbounded_channel();

        let state = JoecalState::new(device, transfer_event_tx)
            .await
            .expect("Could not create JoecalState");

        let _ = self.transfer_event_rx.set(transfer_event_rx);

        let mut handles = JoinSet::new();
        state.start(&config, &mut handles).await;
        let _ = self.state.set(state);
        loop {
            terminal.draw(|frame| self.draw(frame))?;
            self.handle_events().await?;

            if let Some(&top) = self.screen.last()
                && top == CurrentScreen::Stopping
            {
                self.state.get().unwrap().stop().await;
                break;
            }

            let peers = self.state.get().unwrap().peers.lock().await;
            self.peers.clear();
            peers.iter().for_each(|(fingerprint, (addr, device))| {
                let alias = device.alias.clone();
                self.peers
                    .insert(addr.to_owned(), (alias, fingerprint.to_owned()));
            });
        }

        shutdown(&mut handles).await;

        Ok(())
    }

    async fn handle_events(&mut self) -> Result<()> {
        tokio::select! {
            event = self.events.next().fuse() => {
                if let Some(Ok(evt)) = event {
                    match evt {
                        Event::Key(key)
                            if key.kind == KeyEventKind::Press
                                => self.handle_key_event(key),
                        Event::Mouse(_) => {}
                        Event::Resize(_, _) => {}
                        _ => {}
                    }
                }
            }
            transfer_event = self.transfer_event_rx.get_mut().unwrap().recv() => {
                if let Some(event) = transfer_event {
                    match event {
                        TransferEvent::UploadRequest { id, request } => {
                            self.uploads.insert(id, request);
                        }
                        TransferEvent::Sent => {}
                        TransferEvent::Received(id) => {
                            self.uploads.remove(&id);
                        }
                        _ => {}
                    }
                }
            }
            _ = tokio::time::sleep(Duration::from_millis(200)) => {}
        }

        Ok(())
    }

    fn handle_key_event(&mut self, key_event: KeyEvent) {
        match self.screen.last().unwrap() {
            CurrentScreen::Logging => match key_event.code {
                KeyCode::Esc => self.pop(),
                KeyCode::Left => change_log_level(-1),
                KeyCode::Right => change_log_level(1),
                KeyCode::Char('q') => self.exit(),
                _ => {}
            },
            _ => match key_event.code {
                KeyCode::Char('q') => self.exit(),
                KeyCode::Char('s') => self.send(),
                KeyCode::Char('r') => self.recv(),
                KeyCode::Char('l') => self.logs(),
                KeyCode::Esc => self.pop(),
                _ => {}
            },
        }
    }

    fn draw(&self, frame: &mut Frame) {
        frame.render_widget(self, frame.area());
    }

    fn exit(&mut self) {
        self.screen.push(CurrentScreen::Stopping);
    }

    fn send(&mut self) {
        let last = self.screen.last();
        match last {
            Some(CurrentScreen::Sending) => {}
            _ => self.screen.push(CurrentScreen::Sending),
        }
    }

    fn recv(&mut self) {
        let last = self.screen.last();
        match last {
            Some(CurrentScreen::Receiving) => {}
            _ => self.screen.push(CurrentScreen::Receiving),
        }
    }

    fn logs(&mut self) {
        let last = self.screen.last();
        match last {
            Some(CurrentScreen::Logging) => {}
            _ => self.screen.push(CurrentScreen::Logging),
        }
    }

    fn pop(&mut self) {
        self.screen.pop();
        if self.screen.last().is_none() {
            self.screen.push(CurrentScreen::Main);
        }
    }
}

fn change_log_level(delta: isize) {
    let level = log::max_level() as isize;
    let max = log::LevelFilter::max() as isize;
    let level = (level + delta).clamp(0, max) as usize;
    // levelfilter is repr(usize) so this is safe
    let level = unsafe { std::mem::transmute::<usize, LevelFilter>(level) };

    log::set_max_level(level);
}

async fn shutdown(handles: &mut JoinSet<Listeners>) {
    let mut alarm = tokio::time::interval(tokio::time::Duration::from_secs(5));
    alarm.tick().await;
    loop {
        tokio::select! {
            join_result = handles.join_next() => {
                match join_result {
                    Some(handle) => match handle {
                        Ok(h) => info!("Stopped {h:?}"),
                        Err(e) => error!("Got error {e:?}"),
                    }
                    None => break,
                }
            }
            _ = alarm.tick() => {
                info!("Exit timeout reached, aborting all unjoined tasks");
                handles.abort_all();
                break;
            },
        }
    }
}