// 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::time::Instant;

use color_eyre::Result;
use ratatui::{
    Frame,
    layout::{Constraint, Layout, Rect},
    style::{Style, Stylize},
    text::Span,
    widgets::Paragraph,
};

use super::Component;

use crate::action::Action;

#[derive(Debug, Clone, PartialEq)]
pub struct FpsCounter {
    mode: String,

    last_tick_update: Instant,
    tick_count: u32,
    ticks_per_second: f64,

    last_frame_update: Instant,
    frame_count: u32,
    frames_per_second: f64,
}

impl Default for FpsCounter {
    fn default() -> Self {
        Self::new()
    }
}

impl FpsCounter {
    #[must_use]
    pub fn new() -> Self {
        Self {
            mode: String::from(""),
            last_tick_update: Instant::now(),
            tick_count: 0,
            ticks_per_second: 0.0,
            last_frame_update: Instant::now(),
            frame_count: 0,
            frames_per_second: 0.0,
        }
    }

    #[allow(clippy::unnecessary_wraps)]
    fn app_tick(&mut self) -> Result<()> {
        self.tick_count += 1;
        let now = Instant::now();
        let elapsed = (now - self.last_tick_update).as_secs_f64();
        if elapsed >= 1.0 {
            self.ticks_per_second = f64::from(self.tick_count) / elapsed;
            self.last_tick_update = now;
            self.tick_count = 0;
        }
        Ok(())
    }

    #[allow(clippy::unnecessary_wraps)]
    fn render_tick(&mut self) -> Result<()> {
        self.frame_count += 1;
        let now = Instant::now();
        let elapsed = (now - self.last_frame_update).as_secs_f64();
        if elapsed >= 1.0 {
            self.frames_per_second = f64::from(self.frame_count) / elapsed;
            self.last_frame_update = now;
            self.frame_count = 0;
        }
        Ok(())
    }
}

impl Component for FpsCounter {
    fn update(&mut self, action: Action) -> Result<Option<Action>> {
        match action {
            Action::SetMode(mode) => {
                self.mode = format!("{:?}", mode);
            }
            Action::Render => self.render_tick()?,
            Action::Tick => self.app_tick()?,
            _ => {}
        };
        Ok(None)
    }

    fn draw(&mut self, frame: &mut Frame, area: Rect) -> Result<()> {
        let [_, row, _] = Layout::vertical([
            Constraint::Length(1),
            Constraint::Length(1),
            Constraint::Min(0),
        ])
        .areas(area);
        let [_, left, right, _] = Layout::horizontal([
            Constraint::Length(2),
            Constraint::Min(1),
            Constraint::Min(1),
            Constraint::Length(2),
        ])
        .areas(row);

        // Debug
        let span = Span::styled(format!("Mode: {}", &self.mode), Style::new().dim());
        let paragraph = Paragraph::new(span).left_aligned();
        frame.render_widget(paragraph, left);

        // FPS
        let message = format!(
            "{:.2} ticks/sec, {:.2} FPS",
            self.ticks_per_second, self.frames_per_second
        );
        let span = Span::styled(message, Style::new().dim());
        let paragraph = Paragraph::new(span).right_aligned();
        frame.render_widget(paragraph, right);
        Ok(())
    }
}