use crossterm::{
    event::{
        self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode, KeyEvent, KeyModifiers,
    },
    execute,
    terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
};
use std::{error::Error, io};
use tui::{
    backend::{Backend, CrosstermBackend},
    layout::{Constraint, Direction, Layout},
    style::{Color, Modifier, Style},
    text::{Span, Spans},
    widgets::{Block, Borders, Tabs},
    Frame, Terminal,
};

struct App<'a> {
    pub titles: Vec<&'a str>,
    pub index: usize,
}

impl<'a> App<'a> {
    fn new() -> App<'a> {
        App {
            titles: vec!["constants", "compressor", "power"],
            index: 0,
        }
    }

    pub fn next(&mut self) {
        self.index = (self.index + 1) % self.titles.len();
    }

    pub fn previous(&mut self) {
        if self.index > 0 {
            self.index -= 1;
        } else {
            self.index = self.titles.len() - 1;
        }
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    // setup terminal
    enable_raw_mode()?;
    let mut stdout = io::stdout();
    execute!(stdout, EnterAlternateScreen, EnableMouseCapture)?;
    let backend = CrosstermBackend::new(stdout);
    let mut terminal = Terminal::new(backend)?;

    // create app and run it
    let app = App::new();
    let res = run_app(&mut terminal, app);

    // restore terminal
    disable_raw_mode()?;
    execute!(
        terminal.backend_mut(),
        LeaveAlternateScreen,
        DisableMouseCapture
    )?;
    terminal.show_cursor()?;

    if let Err(err) = res {
        println!("{:?}", err)
    }
    Ok(())
}

fn run_app<B: Backend>(terminal: &mut Terminal<B>, mut app: App) -> io::Result<()> {
    loop {
        terminal.draw(|f| ui(f, &app))?;
        if let Event::Key(key) = event::read()? {
            match key {
                KeyEvent {
                    modifiers: KeyModifiers::CONTROL,
                    code,
                } => match code {
                    KeyCode::Char('h') => app.previous(),
                    KeyCode::Char('l') => app.next(),
                    KeyCode::Char('c') => return Ok(()),
                    _ => {}
                },
                KeyEvent {
                    modifiers: KeyModifiers::NONE,
                    code,
                } => match code {
                    KeyCode::Char('q') => return Ok(()),
                    KeyCode::Esc => return Ok(()),
                    _ => {}
                },
                _ => {}
            }
        }
    }
}

fn ui<B: Backend>(f: &mut Frame<B>, app: &App) {
    let size = f.size();
    let chunks = Layout::default()
        .direction(Direction::Vertical)
        .constraints(
            [
                Constraint::Length(3),      // tabs
                Constraint::Percentage(45), // inputs
                Constraint::Percentage(45), // graph
            ]
            .as_ref(),
        )
        .split(size);

    let block = Block::default().style(Style::default().bg(Color::Black).fg(Color::White));
    f.render_widget(block, size);
    let titles = app
        .titles
        .iter()
        .map(|t| Spans::from(Span::styled(*t, Style::default().fg(Color::Green))))
        .collect();
    let tabs = Tabs::new(titles)
        .block(Block::default().borders(Borders::ALL).title("Tabs"))
        .select(app.index)
        .style(Style::default().fg(Color::Cyan))
        .highlight_style(
            Style::default()
                .add_modifier(Modifier::BOLD)
                .bg(Color::Black),
        );
    f.render_widget(tabs, chunks[0]);
    let (inputs, graph) = match app.index {
        0 => (
            Block::default().title("Constants").borders(Borders::ALL),
            Block::default(),
        ),
        1 => (
            Block::default().title("Compressor").borders(Borders::ALL),
            Block::default()
                .title("Compressor Graph")
                .borders(Borders::ALL),
        ),
        2 => (
            Block::default().title("Power").borders(Borders::ALL),
            Block::default().title("Power Graph").borders(Borders::ALL),
        ),
        _ => unreachable!(),
    };
    f.render_widget(inputs, chunks[1]);
    f.render_widget(graph, chunks[2]);
}