// This file is part of Deja-vu.
//
// Deja-vu is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Deja-vu is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Deja-vu. If not, see <https://www.gnu.org/licenses/>.
//
use std::{
    iter::zip,
    sync::{Arc, Mutex},
    thread::{self, JoinHandle},
};

use color_eyre::Result;
use crossterm::event::KeyEvent;
use ratatui::{
    layout::{Constraint, Direction, Layout},
    prelude::Rect,
};
use serde::{Deserialize, Serialize};
use tokio::sync::mpsc;
use tracing::{debug, info};

use crate::{
    action::Action,
    components::{
        footer::Footer,
        fps::FpsCounter,
        left::Left,
        popup::{Popup, Type},
        right::Right,
        title::Title,
        Component,
    },
    config::Config,
    system::disk::{get_disks, Disk},
    tui::{Event, Tui},
};

pub struct App {
    config: Config,
    tick_rate: f64,
    frame_rate: f64,
    components: Vec<Box<dyn Component>>,
    disks: Arc<Mutex<Vec<Disk>>>,
    should_quit: bool,
    should_suspend: bool,
    cur_mode: Mode,
    prev_mode: Mode,
    selections: Vec<Option<usize>>,
    last_tick_key_events: Vec<KeyEvent>,
    action_tx: mpsc::UnboundedSender<Action>,
    action_rx: mpsc::UnboundedReceiver<Action>,
}

#[derive(Default, Debug, Copy, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub enum Mode {
    #[default]
    ScanDisks,
    SelectDisks,
    SelectParts,
    Confirm,
    Done,
}

impl App {
    pub fn new(tick_rate: f64, frame_rate: f64) -> Result<Self> {
        let (action_tx, action_rx) = mpsc::unbounded_channel();
        Ok(Self {
            tick_rate,
            frame_rate,
            components: vec![
                Box::new(Title::new()),
                Box::new(FpsCounter::default()),
                Box::new(Left::new()),
                Box::new(Right::new()),
                Box::new(Footer::new()),
                Box::new(Popup::new()),
            ],
            disks: Arc::new(Mutex::new(Vec::new())),
            should_quit: false,
            should_suspend: false,
            config: Config::new()?,
            cur_mode: Mode::ScanDisks,
            prev_mode: Mode::ScanDisks,
            selections: vec![None, None],
            last_tick_key_events: Vec::new(),
            action_tx,
            action_rx,
        })
    }

    pub fn next_mode(&mut self) -> Option<Mode> {
        let new_mode = match self.cur_mode {
            Mode::ScanDisks => Mode::SelectDisks,
            Mode::SelectDisks | Mode::SelectParts => {
                if self.selections[1].is_some() {
                    Mode::Confirm
                } else {
                    self.cur_mode
                }
            }
            Mode::Done => Mode::Done,
            Mode::Confirm => match self.prev_mode {
                Mode::SelectDisks => Mode::SelectParts,
                Mode::SelectParts => Mode::Done,
                _ => self.cur_mode,
            },
        };
        if new_mode != self.cur_mode {
            if self.cur_mode != Mode::Confirm {
                self.prev_mode = self.cur_mode;
            }
            Some(new_mode)
        } else {
            None
        }
    }

    pub async fn run(&mut self) -> Result<()> {
        let disk_wrapper = Arc::clone(&self.disks);
        let _ = lazy_get_disks(disk_wrapper);
        let mut tui = Tui::new()?
            // .mouse(true) // uncomment this line to enable mouse support
            .tick_rate(self.tick_rate)
            .frame_rate(self.frame_rate);
        tui.enter()?;

        for component in self.components.iter_mut() {
            component.register_action_handler(self.action_tx.clone())?;
        }
        for component in self.components.iter_mut() {
            component.register_config_handler(self.config.clone())?;
        }
        for component in self.components.iter_mut() {
            component.init(tui.size()?)?;
        }

        let action_tx = self.action_tx.clone();
        loop {
            self.handle_events(&mut tui).await?;
            self.handle_actions(&mut tui)?;
            if self.should_suspend {
                tui.suspend()?;
                action_tx.send(Action::Resume)?;
                action_tx.send(Action::ClearScreen)?;
                // tui.mouse(true);
                tui.enter()?;
            } else if self.should_quit {
                tui.stop()?;
                break;
            }
        }
        tui.exit()?;
        Ok(())
    }

    async fn handle_events(&mut self, tui: &mut Tui) -> Result<()> {
        let Some(event) = tui.next_event().await else {
            return Ok(());
        };
        let action_tx = self.action_tx.clone();
        match event {
            Event::Quit => action_tx.send(Action::Quit)?,
            Event::Tick => action_tx.send(Action::Tick)?,
            Event::Render => action_tx.send(Action::Render)?,
            Event::Resize(x, y) => action_tx.send(Action::Resize(x, y))?,
            Event::Key(key) => self.handle_key_event(key)?,
            _ => {}
        }
        for component in self.components.iter_mut() {
            if let Some(action) = component.handle_events(Some(event.clone()))? {
                action_tx.send(action)?;
            }
        }
        Ok(())
    }

    fn handle_key_event(&mut self, key: KeyEvent) -> Result<()> {
        let action_tx = self.action_tx.clone();
        let Some(keymap) = self.config.keybindings.get(&self.cur_mode) else {
            return Ok(());
        };
        match keymap.get(&vec![key]) {
            Some(action) => {
                info!("Got action: {action:?}");
                action_tx.send(action.clone())?;
            }
            _ => {
                // If the key was not handled as a single key action,
                // then consider it for multi-key combinations.
                self.last_tick_key_events.push(key);

                // Check for multi-key combinations
                if let Some(action) = keymap.get(&self.last_tick_key_events) {
                    info!("Got action: {action:?}");
                    action_tx.send(action.clone())?;
                }
            }
        }
        Ok(())
    }

    fn handle_actions(&mut self, tui: &mut Tui) -> Result<()> {
        while let Ok(action) = self.action_rx.try_recv() {
            if action != Action::Tick && action != Action::Render {
                debug!("{action:?}");
            }
            match action {
                Action::Tick => {
                    self.last_tick_key_events.drain(..);
                    // Continue to next screen if shared disks has been set
                    if self.cur_mode == Mode::ScanDisks {
                        if let Ok(_) = &self.disks.try_lock() {
                            self.action_tx.send(Action::NextScreen)?;
                        }
                    }
                }
                Action::Quit => self.should_quit = true,
                Action::Suspend => self.should_suspend = true,
                Action::Resume => self.should_suspend = false,
                Action::ClearScreen => tui.terminal.clear()?,
                Action::Resize(w, h) => self.handle_resize(tui, w, h)?,
                Action::Render => self.render(tui)?,
                Action::PrevScreen => {
                    self.action_tx.send(Action::SetMode(self.prev_mode))?;
                }
                Action::NextScreen => {
                    if let Some(mode) = self.next_mode() {
                        self.action_tx.send(Action::SetMode(mode))?;
                    }
                }
                Action::ScanDisks => {
                    let disk_wrapper = Arc::clone(&self.disks);
                    let _ = lazy_get_disks(disk_wrapper);
                    self.action_tx.send(Action::SetMode(Mode::ScanDisks))?;
                }
                Action::Select(one, two) => {
                    self.selections[0] = one;
                    self.selections[1] = two;
                }
                Action::SetMode(new_mode) => {
                    self.cur_mode = new_mode;
                    match new_mode {
                        Mode::ScanDisks => {
                            self.prev_mode = self.cur_mode;
                        }
                        Mode::SelectDisks | Mode::SelectParts => {
                            let disks = self.disks.lock().unwrap();
                            self.action_tx.send(Action::UpdateDiskList(disks.clone()))?;
                        }
                        Mode::Done => {
                            self.action_tx.send(Action::DisplayPopup(
                                Type::Success,
                                String::from("COMPLETE\n\n\nThank you for using this tool!"),
                            ))?;
                        }
                        _ => {}
                    }
                }
                _ => {}
            }
            for component in self.components.iter_mut() {
                if let Some(action) = component.update(action.clone())? {
                    self.action_tx.send(action)?
                };
            }
        }
        Ok(())
    }

    fn handle_resize(&mut self, tui: &mut Tui, w: u16, h: u16) -> Result<()> {
        tui.resize(Rect::new(0, 0, w, h))?;
        self.render(tui)?;
        Ok(())
    }

    fn render(&mut self, tui: &mut Tui) -> Result<()> {
        tui.draw(|frame| {
            if let [header, _body, footer, left, right, popup] = get_chunks(frame.area())[..] {
                let component_areas = vec![
                    header, // Title Bar
                    header, // FPS Counter
                    left, right, footer, popup,
                ];
                for (component, area) in zip(self.components.iter_mut(), component_areas) {
                    if let Err(err) = component.draw(frame, area) {
                        let _ = self
                            .action_tx
                            .send(Action::Error(format!("Failed to draw: {:?}", err)));
                    }
                }
            };
        })?;
        Ok(())
    }
}

fn centered_rect(percent_x: u16, percent_y: u16, r: Rect) -> Rect {
    // Cut the given rectangle into three vertical pieces
    let popup_layout = Layout::default()
        .direction(Direction::Vertical)
        .constraints([
            Constraint::Percentage((100 - percent_y) / 2),
            Constraint::Percentage(percent_y),
            Constraint::Percentage((100 - percent_y) / 2),
        ])
        .split(r);

    // Then cut the middle vertical piece into three width-wise pieces
    Layout::default()
        .direction(Direction::Horizontal)
        .constraints([
            Constraint::Percentage((100 - percent_x) / 2),
            Constraint::Percentage(percent_x),
            Constraint::Percentage((100 - percent_x) / 2),
        ])
        .split(popup_layout[1])[1] // Return the middle chunk
}

fn get_chunks(r: Rect) -> Vec<Rect> {
    let mut chunks: Vec<Rect> = Vec::with_capacity(6);

    // Main sections
    chunks.extend(
        Layout::default()
            .direction(Direction::Vertical)
            .constraints([
                Constraint::Length(3),
                Constraint::Min(1),
                Constraint::Length(3),
            ])
            .split(r)
            .to_vec(),
    );

    // Left/Right
    chunks.extend(
        Layout::default()
            .direction(Direction::Horizontal)
            .constraints([Constraint::Percentage(50), Constraint::Percentage(50)])
            .split(centered_rect(90, 90, chunks[1]))
            .to_vec(),
    );

    // Popup
    chunks.push(centered_rect(60, 25, r));

    // Done
    chunks
}

fn lazy_get_disks(disk_wrapper: Arc<Mutex<Vec<Disk>>>) -> JoinHandle<()> {
    thread::spawn(move || {
        let mut disks = disk_wrapper.lock().unwrap();
        *disks = get_disks();
    })
}