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

use crossterm::event::{Event, EventStream, KeyCode, KeyEvent, KeyEventKind};
use futures::{FutureExt, StreamExt};
use jocalsend::{JocalService, ReceiveDialog, ReceiveRequest, TransferEvent, error::Result};
use julid::Julid;
use log::{LevelFilter, debug, error, warn};
use ratatui::{
    Frame,
    widgets::{ListState, TableState},
};
use ratatui_explorer::FileExplorer;
use tokio::sync::mpsc::UnboundedReceiver;
use tui_input::{Input, backend::crossterm::EventHandler};

pub mod widgets;

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Peer {
    pub alias: String,
    pub fingerprint: String,
    pub addr: SocketAddr,
}

pub struct App {
    pub service: JocalService,
    pub events: EventStream,
    // addr -> (alias, fingerprint)
    pub peers: Vec<Peer>,
    pub peer_state: ListState,
    pub receive_requests: BTreeMap<Julid, ReceiveRequest>,
    screen: Vec<CurrentScreen>,
    receiving_state: TableState,
    // for getting messages back from the web server or web client about things we've done; the
    // other end is held by the service
    event_listener: UnboundedReceiver<TransferEvent>,
    file_picker: FileExplorer,
    text: Option<String>,
    input: Input,
}

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

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SendingScreen {
    Files,
    Peers,
    Text,
}

impl App {
    pub fn new(service: JocalService, event_listener: UnboundedReceiver<TransferEvent>) -> Self {
        App {
            service,
            event_listener,
            screen: vec![CurrentScreen::Main],
            file_picker: FileExplorer::new().expect("could not create file explorer"),
            text: None,
            events: Default::default(),
            peers: Default::default(),
            peer_state: Default::default(),
            receive_requests: Default::default(),
            receiving_state: Default::default(),
            input: Default::default(),
        }
    }

    pub 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, evt).await,
                        Event::Mouse(_) => {}
                        Event::Resize(_, _) => {}
                        _ => {}
                    }
                }
            }
            transfer_event = self.event_listener.recv() => {
                if let Some(event) = transfer_event {
                    debug!("got transferr event {event:?}");
                    match event {
                        TransferEvent::ReceiveRequest { id, request } => {
                            self.receive_requests.insert(id, request);
                        }
                        TransferEvent::Cancelled(id) | TransferEvent::Received(id) => {
                            self.receive_requests.remove(&id);
                        }
                    }
                }
            }
            _ = tokio::time::sleep(Duration::from_millis(200)) => {}
        }

        Ok(())
    }

    pub fn screen(&self) -> CurrentScreen {
        *self.screen.last().unwrap()
    }
    pub fn screen_mut(&mut self) -> &mut CurrentScreen {
        self.screen.last_mut().unwrap()
    }

    async fn handle_key_event(&mut self, key_event: KeyEvent, event: crossterm::event::Event) {
        let code = key_event.code;
        let mode = self.screen.last_mut().unwrap();
        match mode {
            CurrentScreen::Main
            | CurrentScreen::Logging
            | CurrentScreen::Receiving
            | CurrentScreen::Sending(SendingScreen::Files)
            | CurrentScreen::Sending(SendingScreen::Peers) => match code {
                KeyCode::Esc => self.pop(),
                KeyCode::Char('q') => self.exit(),
                KeyCode::Char('s') => self.send(),
                KeyCode::Char('r') => self.recv(),
                KeyCode::Char('l') => self.logs(),
                KeyCode::Char('m') => self.main(),
                _ => match mode {
                    CurrentScreen::Logging => match code {
                        KeyCode::Left => change_log_level(-1),
                        KeyCode::Right => change_log_level(1),
                        _ => {}
                    },
                    CurrentScreen::Receiving => match code {
                        KeyCode::Up => self.receiving_state.select_previous(),
                        KeyCode::Down => self.receiving_state.select_next(),
                        KeyCode::Char('a') => self.accept(),
                        KeyCode::Char('d') => self.deny(),
                        _ => {}
                    },
                    CurrentScreen::Sending(sending_screen) => match sending_screen {
                        SendingScreen::Files => match code {
                            KeyCode::Char('t') => *sending_screen = SendingScreen::Text,
                            KeyCode::Tab => *sending_screen = SendingScreen::Peers,
                            KeyCode::Enter => self.chdir_or_send_file().await,
                            _ => self.file_picker.handle(&event).unwrap_or_default(),
                        },
                        SendingScreen::Peers => match code {
                            KeyCode::Tab => *sending_screen = SendingScreen::Files,
                            KeyCode::Char('t') => *sending_screen = SendingScreen::Text,
                            KeyCode::Enter => self.send_content().await,
                            KeyCode::Up => self.peer_state.select_previous(),
                            KeyCode::Down => self.peer_state.select_next(),
                            _ => {}
                        },
                        SendingScreen::Text => unreachable!(),
                    },
                    CurrentScreen::Main => {}
                    CurrentScreen::Stopping => unreachable!(),
                },
            },
            // we only need to deal with sending text now
            CurrentScreen::Sending(sending_screen) => match sending_screen {
                SendingScreen::Text => match code {
                    KeyCode::Tab => *sending_screen = SendingScreen::Peers,
                    KeyCode::Enter => self.send_text().await,
                    KeyCode::Esc => {
                        self.text = None;
                        self.input.reset();
                        *sending_screen = SendingScreen::Files;
                    }
                    _ => {
                        if let Some(changed) = self.input.handle_event(&event)
                            && changed.value
                        {
                            if self.input.value().is_empty() {
                                self.text = None;
                            } else {
                                self.text = Some(self.input.to_string());
                            }
                        }
                    }
                },
                // we've already handled the other sending modes
                SendingScreen::Files | SendingScreen::Peers => unreachable!(),
            },
            CurrentScreen::Stopping => {}
        }
    }

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

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

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

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

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

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

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

    // accept a content receive request
    fn accept(&mut self) {
        let Some(idx) = self.receiving_state.selected() else {
            return;
        };
        // keys are sorted, so we can use the table selection index
        let keys: Vec<_> = self.receive_requests.keys().collect();
        let Some(key) = keys.get(idx) else {
            warn!("could not get id from selection index {idx}");
            return;
        };
        let Some(req) = self.receive_requests.get(key) else {
            return;
        };
        if let Err(e) = req.tx.send(ReceiveDialog::Approve) {
            error!("got error sending upload confirmation: {e:?}");
        };
    }

    // reject an content receive request
    fn deny(&mut self) {
        let Some(idx) = self.receiving_state.selected() else {
            return;
        };
        // keys are sorted, so we can use the table selection index
        let keys: Vec<_> = self.receive_requests.keys().cloned().collect();
        let Some(key) = keys.get(idx) else {
            warn!("could not get id from selection index {idx}");
            return;
        };
        let Some(req) = self.receive_requests.get(key).cloned() else {
            return;
        };
        if let Err(e) = req.tx.send(ReceiveDialog::Deny) {
            error!("got error sending upload confirmation: {e:?}");
        };
        self.receive_requests.remove(key);
    }

    async fn chdir_or_send_file(&mut self) {
        let file = self.file_picker.current().path().clone();
        if file.is_dir()
            && let Err(e) = self.file_picker.set_cwd(&file)
        {
            error!("could not list directory {file:?}: {e}");
            return;
        }

        let Some(peer_idx) = self.peer_state.selected() else {
            warn!("no peer selected to send to");
            return;
        };
        let Some(peer) = self.peers.get(peer_idx) else {
            warn!("invalid peer index {peer_idx}");
            return;
        };

        if file.is_file() {
            debug!("sending {file:?}");
            if let Err(e) = self.service.send_file(&peer.fingerprint, file).await {
                error!("got error sending content: {e:?}");
            }
        }
    }

    // send content to selected peer, or change directories in the file explorer
    async fn send_text(&mut self) {
        debug!("sending text");

        let Some(peer_idx) = self.peer_state.selected() else {
            debug!("no peer selected to send to");
            return;
        };
        let Some(peer) = self.peers.get(peer_idx) else {
            warn!("invalid peer index {peer_idx}");
            return;
        };

        let Some(text) = &self.text else {
            debug!("no text to send");
            return;
        };

        if let Err(e) = self.service.send_text(&peer.fingerprint, text).await {
            error!("got error sending \"{text}\" to {}: {e:?}", peer.alias);
        }
    }

    async fn send_content(&mut self) {
        if self.text.is_some() {
            self.send_text().await;
        } else {
            self.chdir_or_send_file().await;
        }
    }
}

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);
}