use std::sync::mpsc::channel;
use std::time::{Duration, Instant};

use clap::Parser;
use egui::{Color32, FontId, Layout, RichText, Ui};
use egui_extras::{Size, StripBuilder};

use crate::{cli::Cli, util::*, AIRHORN, DIGIT_FACTOR, PREDATOR_FONT, TEXT_FACTOR};

mod state;
use state::{ChronoState, NextTimerState, TimerState};
mod eframe_app;
mod gui;
use gui::*;

#[derive(Debug, Clone, Copy)]
pub enum CountDirection {
    Up,
    Down,
}

#[derive(Debug, Clone)]
pub struct Timer {
    direction: CountDirection,
    duration: Duration,
    state: TimerState,
    tstart: Instant, // so we can blink
    alarm: Option<Vec<u8>>,
}

impl Timer {
    pub fn new(ctx: &eframe::CreationContext) -> Self {
        let cli = Cli::parse();
        let predator = cli.predator;
        let seconds = cli.hours.unwrap_or(0) * 3600
            + cli.minutes.unwrap_or(0) * 60
            + cli.seconds.unwrap_or(0);
        let duration = Duration::from_secs(seconds);

        let direction = if cli.count_up {
            CountDirection::Up
        } else {
            CountDirection::Down
        };

        let alarm = if let Some(path) = cli.alarm {
            let buffer = std::fs::read(&path)
                .unwrap_or_else(|_| panic!("Could not open {:?} for reading.", path));
            Some(buffer)
        } else if cli.airhorn {
            Some(AIRHORN.to_owned())
        } else {
            None
        };

        if predator {
            let mut fonts = egui::FontDefinitions::default();
            fonts.font_data.insert(
                "predator".to_owned(),
                egui::FontData::from_static(PREDATOR_FONT),
            );
            fonts
                .families
                .entry(egui::FontFamily::Monospace)
                .or_default()
                .insert(0, "predator".to_owned());
            ctx.egui_ctx.set_fonts(fonts);
        }
        ctx.egui_ctx.request_repaint_after(Duration::from_secs(1));
        let mut timer = Timer {
            duration,
            direction,
            state: TimerState::Unstarted,
            tstart: Instant::now(),
            alarm,
        };
        if cli.running {
            let cs = ChronoState {
                remaining: duration,
                updated: Instant::now(),
            };

            timer.state = TimerState::Running(cs);
        }
        timer
    }

    fn unstarted(&mut self, ui: &mut Ui, size: f32) {
        let tsize = size * 0.5;
        let start = RichText::new("START")
            .font(FontId::monospace(tsize))
            .color(Color32::WHITE)
            .background_color(Color32::LIGHT_GREEN);

        StripBuilder::new(ui)
            .size(Size::remainder())
            .cell_layout(Layout::centered_and_justified(egui::Direction::TopDown))
            .horizontal(|mut strip| {
                strip.cell(|ui| {
                    if ui.button(start).clicked() {
                        let dur = self.duration;
                        self.state = TimerState::Running(ChronoState {
                            updated: Instant::now(),
                            remaining: dur,
                        });
                    }
                });
            });
    }

    fn running(&mut self, ui: &mut Ui, size: f32, cs: ChronoState) {
        let tsize = size * TEXT_FACTOR;
        let text = RichText::new("PAUSE")
            .font(FontId::monospace(tsize))
            .color(Color32::GOLD);

        let elapsed = Instant::now() - cs.updated;
        let remaining = cs.remaining.saturating_sub(elapsed);
        if remaining.is_zero() {
            if let Some(alarm_file) = &self.alarm {
                let alarm_file = alarm_file.to_owned();
                std::thread::spawn(move || alarm(alarm_file));
            }
            self.state = TimerState::Finished;
            return;
        }

        let (sender, rx) = channel();
        {
            // if we're counting up, do the right thing
            let remaining = match self.direction {
                CountDirection::Down => remaining,
                CountDirection::Up => self.duration - remaining,
            };
            // now the numbers
            let color = Color32::DARK_GRAY;
            let tsize = size * DIGIT_FACTOR;
            one_button(
                ui,
                text,
                state::NextTimerState::Paused,
                sender,
                remaining,
                color,
                tsize,
            )
        }

        let cs = ChronoState {
            remaining,
            updated: Instant::now(),
        };

        if rx.recv().is_ok() {
            self.state = TimerState::Paused(cs);
        } else {
            self.state = TimerState::Running(cs);
        }
    }

    fn paused(&mut self, ui: &mut Ui, vsize: f32, cs: ChronoState) {
        let tsize = vsize * TEXT_FACTOR;

        let remaining = cs.remaining;
        let resume = RichText::new("RESUME")
            .color(Color32::GREEN)
            .font(FontId::monospace(tsize));
        let reset = RichText::new("RESET")
            .color(Color32::RED)
            .font(FontId::monospace(tsize));

        let (sender, rx) = channel();
        {
            let color = {
                let blink = (Instant::now() - self.tstart).as_secs() % 2 == 0;
                if blink {
                    Color32::BLACK
                } else {
                    Color32::DARK_GRAY
                }
            };
            // if we're counting up, do the right thing
            let remaining = match self.direction {
                CountDirection::Down => remaining,
                CountDirection::Up => self.duration - remaining,
            };

            two_button(
                ui,
                resume,
                reset,
                NextTimerState::Running,
                NextTimerState::Unstarted,
                sender,
                remaining,
                color,
                vsize * DIGIT_FACTOR,
            );
        }

        let cs = ChronoState {
            remaining,
            updated: Instant::now(),
        };
        if let Ok(s) = rx.recv() {
            match s {
                NextTimerState::Running => {
                    self.state = TimerState::Running(cs);
                }
                NextTimerState::Unstarted => {
                    self.state = TimerState::Unstarted;
                }
                _ => unreachable!(),
            }
        } else {
            self.state = TimerState::Paused(cs);
        }
    }

    fn finished(&mut self, ui: &mut Ui, vsize: f32) {
        let remaining = match self.direction {
            CountDirection::Up => self.duration,
            CountDirection::Down => Duration::from_nanos(0),
        };

        let tsize = vsize * 0.3;
        let reset = RichText::new("RESTART")
            .color(Color32::DARK_GREEN)
            .font(FontId::monospace(tsize));
        let color = {
            let blink = (Instant::now() - self.tstart).as_secs() % 2 == 0;
            if blink {
                Color32::BLACK
            } else {
                Color32::DARK_GRAY
            }
        };
        let (sender, rx) = channel();

        one_button(
            ui,
            reset,
            NextTimerState::Unstarted,
            sender,
            remaining,
            color,
            tsize,
        );
        if rx.recv().is_ok() {
            self.state = TimerState::Unstarted;
        }
    }
}