use crate::task::Task;

use ::std::sync::{Arc, RwLock, atomic::{AtomicBool, Ordering::*}};
use ::std::time::Duration;
use ::dizzle::{Usually, Apply, impl_from};
use ::crossterm::event::{
    read, Event, KeyEvent, KeyCode, KeyModifiers, KeyEventKind, KeyEventState
};

/// Spawn the TUI input thread which reads keys from the terminal.
pub fn tui_input <T: Apply<TuiEvent, Usually<T>> + Send + Sync + 'static> (
    exited: &Arc<AtomicBool>, state: &Arc<RwLock<T>>, poll: Duration
) -> Result<Task, std::io::Error> {
    let exited = exited.clone();
    let state = state.clone();
    Task::new_poll(exited.clone(), poll, move |_| {
        let event = read().unwrap();
        match event {

            // Hardcoded exit.
            Event::Key(KeyEvent {
                modifiers: KeyModifiers::CONTROL,
                code:      KeyCode::Char('c'),
                kind:      KeyEventKind::Press,
                state:     KeyEventState::NONE
            }) => { exited.store(true, Relaxed); },

            // Handle all other events by the state:
            event => {
                if let Err(e) = state.write().unwrap().apply(&TuiEvent(event)) {
                    panic!("{e}")
                }
            },

        }
    })
}

/// TUI input loop event.
#[derive(Debug, Clone, Eq, PartialEq, PartialOrd)]
pub struct TuiEvent(pub Event);
impl_from!(TuiEvent: |e: Event| TuiEvent(e));
impl_from!(TuiEvent: |c: char|  TuiEvent(Event::Key(KeyEvent::new(KeyCode::Char(c), KeyModifiers::NONE))));
impl Ord for TuiEvent {
    fn cmp (&self, other: &Self) -> std::cmp::Ordering {
        self.partial_cmp(other)
            .unwrap_or_else(||format!("{:?}", self).cmp(&format!("{other:?}"))) // FIXME perf
    }
}

/// TUI key spec.
#[derive(Debug, Clone, Eq, PartialEq, PartialOrd)]
pub struct TuiKey(pub Option<KeyCode>, pub KeyModifiers);
impl TuiKey {
    const SPLIT: char = '/';
    pub fn from_crossterm (event: KeyEvent) -> Self {
        Self(Some(event.code), event.modifiers)
    }
    pub fn to_crossterm (&self) -> Option<Event> {
        self.0.map(|code|Event::Key(KeyEvent {
            code,
            modifiers: self.1,
            kind:  KeyEventKind::Press,
            state: KeyEventState::NONE,
        }))
    }
    pub fn named (token: &str) -> Option<KeyCode> {
        use KeyCode::*;
        Some(match token {
            "up"                => Up,
            "down"              => Down,
            "left"              => Left,
            "right"             => Right,
            "esc"    | "escape" => Esc,
            "enter"  | "return" => Enter,
            "delete" | "del"    => Delete,
            "backspace"         => Backspace,
            "tab"               => Tab,
            "space"             => Char(' '),
            "comma"             => Char(','),
            "period"            => Char('.'),
            "plus"              => Char('+'),
            "minus" | "dash"    => Char('-'),
            "equal" | "equals"  => Char('='),
            "underscore"        => Char('_'),
            "backtick"          => Char('`'),
            "lt"                => Char('<'),
            "gt"                => Char('>'),
            "cbopen"  | "openbrace"  => Char('{'),
            "cbclose" | "closebrace" => Char('}'),
            "bropen"  | "openbracket"  => Char('['),
            "brclose" | "closebracket" => Char(']'),
            "pgup" | "pageup"   => PageUp,
            "pgdn" | "pagedown" => PageDown,
            "f1"                => F(1),
            "f2"                => F(2),
            "f3"                => F(3),
            "f4"                => F(4),
            "f5"                => F(5),
            "f6"                => F(6),
            "f7"                => F(7),
            "f8"                => F(8),
            "f9"                => F(9),
            "f10"               => F(10),
            "f11"               => F(11),
            "f12"               => F(12),
            _ => return None,
        })
    }
}