use std::io;
use std::panic;

use crossterm::event::{DisableMouseCapture, EnableMouseCapture};
use crossterm::terminal::{self, EnterAlternateScreen, LeaveAlternateScreen};
use tui::backend::CrosstermBackend;
use tui::Terminal;

use crate::app::{App, AppResult};
use crate::events::event::EventHandler;
use crate::screens::render::render;

/// Representation of a terminal user interface.
///
/// It is responsible for setting up the terminal,
/// initializing the interface and handling the draw events.
#[derive(Debug)]
pub struct Tui {
    /// Interface to the Terminal.
    terminal: Terminal<CrosstermBackend<io::Stdout>>,
    /// Terminal event handler.
    pub events: EventHandler,
}

impl Tui {
    /// Constructs a new instance of [`Tui`].
    pub fn new(terminal: Terminal<CrosstermBackend<io::Stdout>>, events: EventHandler) -> Self {
        Self { terminal, events }
    }

    /// Initializes the terminal interface.
    ///
    /// It enables the raw mode and sets terminal properties.
    pub fn init(&mut self) -> AppResult<()> {
        let mut stdout = io::stdout();
        terminal::enable_raw_mode()?;
        crossterm::execute!(stdout, EnterAlternateScreen, EnableMouseCapture)?;

        let backend = CrosstermBackend::new(stdout);
        let _terminal = Terminal::new(backend)?;
        // Define a custom panic hook to reset the terminal properties.
        // This way, you won't have your terminal messed up if an unexpected error happens.
        let panic_hook = panic::take_hook();
        panic::set_hook(Box::new(move |panic| {
            Self::reset().expect("failed to reset the terminal");
            panic_hook(panic);
        }));

        self.terminal.hide_cursor()?;
        self.terminal.clear()?;
        Ok(())
    }

    /// [`Draw`] the terminal interface by [`rendering`] the widgets.
    ///
    /// [`Draw`]: tui::Terminal::draw
    /// [`rendering`]: crate::ui:render
    pub fn draw(&mut self, app: &mut App) -> AppResult<()> {
        self.terminal.draw(|frame| render(app, frame))?;
        Ok(())
    }

    /// Resets the terminal interface.
    ///
    /// This function is also used for the panic hook to revert
    /// the terminal properties if unexpected errors occur.
    fn reset() -> AppResult<()> {
        terminal::disable_raw_mode()?;
        crossterm::execute!(io::stdout(), LeaveAlternateScreen, DisableMouseCapture)?;
        Ok(())
    }

    /// Exits the terminal interface.
    ///
    /// It disables the raw mode and reverts back the terminal properties.
    pub fn exit(&mut self) -> AppResult<()> {
        Self::reset()?;
        self.terminal.show_cursor()?;
        Ok(())
    }
}
