use std::time::Instant;

use color_eyre::eyre::Result;
use ratatui::{prelude::*, widgets::*};

use super::Component;
use crate::{action::Action, tui::Frame};

#[derive(Debug, Clone, PartialEq)]
pub struct FpsCounter {
  app_start_time: Instant,
  app_frames: u32,
  app_fps: f64,

  render_start_time: Instant,
  render_frames: u32,
  render_fps: f64,
}

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

impl FpsCounter {
  pub fn new() -> Self {
    Self {
      app_start_time: Instant::now(),
      app_frames: 0,
      app_fps: 0.0,
      render_start_time: Instant::now(),
      render_frames: 0,
      render_fps: 0.0,
    }
  }

  fn app_tick(&mut self) -> Result<()> {
    self.app_frames += 1;
    let now = Instant::now();
    let elapsed = (now - self.app_start_time).as_secs_f64();
    if elapsed >= 1.0 {
      self.app_fps = self.app_frames as f64 / elapsed;
      self.app_start_time = now;
      self.app_frames = 0;
    }
    Ok(())
  }

  fn render_tick(&mut self) -> Result<()> {
    self.render_frames += 1;
    let now = Instant::now();
    let elapsed = (now - self.render_start_time).as_secs_f64();
    if elapsed >= 1.0 {
      self.render_fps = self.render_frames as f64 / elapsed;
      self.render_start_time = now;
      self.render_frames = 0;
    }
    Ok(())
  }
}

impl Component for FpsCounter {
  fn update(&mut self, action: Action) -> Result<Option<Action>> {
    if let Action::Tick = action {
      self.app_tick()?
    };
    if let Action::Render = action {
      self.render_tick()?
    };
    Ok(None)
  }

  fn draw(&mut self, f: &mut Frame<'_>, rect: Rect) -> Result<()> {
    let rects = Layout::default()
      .direction(Direction::Vertical)
      .constraints(vec![
        Constraint::Length(1), // first row
        Constraint::Min(0),
      ])
      .split(rect);

    let rect = rects[0];

    let s = format!(
      "{:.2} ticks per sec (app) {:.2} frames per sec (render)",
      self.app_fps, self.render_fps
    );
    let block = Block::default().title(block::Title::from(s.dim()).alignment(Alignment::Right));
    f.render_widget(block, rect);
    Ok(())
  }
}