use crate::theme;
use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::style::Color;
use ratatui::widgets::Widget;
use std::cell::RefCell;

thread_local! {
    static PATTERNS: RefCell<Vec<u8>> = const { RefCell::new(Vec::new()) };
}

pub struct Lissajous<'a> {
    left: &'a [f32],
    right: &'a [f32],
    color: Option<Color>,
    gain: f32,
}

impl<'a> Lissajous<'a> {
    pub fn new(left: &'a [f32], right: &'a [f32]) -> Self {
        Self {
            left,
            right,
            color: None,
            gain: 1.0,
        }
    }

    pub fn color(mut self, c: Color) -> Self {
        self.color = Some(c);
        self
    }

    pub fn gain(mut self, g: f32) -> Self {
        self.gain = g;
        self
    }
}

impl Widget for Lissajous<'_> {
    fn render(self, area: Rect, buf: &mut Buffer) {
        if area.width == 0 || area.height == 0 || self.left.is_empty() || self.right.is_empty() {
            return;
        }

        let color = self.color.unwrap_or_else(|| theme::get().meter.low);
        let width = area.width as usize;
        let height = area.height as usize;
        let fine_width = width * 2;
        let fine_height = height * 4;
        let len = self.left.len().min(self.right.len());

        PATTERNS.with(|p| {
            let mut patterns = p.borrow_mut();
            let size = width * height;
            patterns.clear();
            patterns.resize(size, 0);

            for i in 0..len {
                let l = (self.left[i] * self.gain).clamp(-1.0, 1.0);
                let r = (self.right[i] * self.gain).clamp(-1.0, 1.0);

                // X = right channel, Y = left channel (inverted so up = positive)
                let fine_x = ((r + 1.0) * 0.5 * (fine_width - 1) as f32).round() as usize;
                let fine_y = ((1.0 - l) * 0.5 * (fine_height - 1) as f32).round() as usize;
                let fine_x = fine_x.min(fine_width - 1);
                let fine_y = fine_y.min(fine_height - 1);

                let char_x = fine_x / 2;
                let char_y = fine_y / 4;
                let dot_x = fine_x % 2;
                let dot_y = fine_y % 4;

                let bit = match (dot_x, dot_y) {
                    (0, 0) => 0x01,
                    (0, 1) => 0x02,
                    (0, 2) => 0x04,
                    (0, 3) => 0x40,
                    (1, 0) => 0x08,
                    (1, 1) => 0x10,
                    (1, 2) => 0x20,
                    (1, 3) => 0x80,
                    _ => unreachable!(),
                };

                patterns[char_y * width + char_x] |= bit;
            }

            for cy in 0..height {
                for cx in 0..width {
                    let pattern = patterns[cy * width + cx];
                    if pattern != 0 {
                        let ch = char::from_u32(0x2800 + pattern as u32).unwrap_or(' ');
                        buf[(area.x + cx as u16, area.y + cy as u16)]
                            .set_char(ch)
                            .set_fg(color);
                    }
                }
            }
        });
    }
}