use crate::{Color, Vec2};
use crate::abi::UiPanel;

pub struct DrawContext {
    panel: UiPanel,
}

impl DrawContext {
    pub fn new(panel: UiPanel) -> Self {
        Self { panel }
    }

    pub fn draw_triangle(&self, v1: &Vec2, v2: &Vec2, v3: &Vec2, color: &Color) {
        self.panel.draw_triangle(v1, v2, v3, color)
    }

    pub fn draw_circle(&self, center: &Vec2, radius: f32, color: &Color) {
        use std::f32::consts::PI;

        let delta = PI / 16.0;
        let limit = PI * 2.0 + delta;

        let mut last_spoke = Vec2::new(radius + center.x, center.y);
        let mut theta = delta;
        while theta < limit {
            let new_spoke = Vec2::from_angle(theta) * radius + *center;
            self.draw_triangle(&center, &last_spoke, &new_spoke, &color);
            last_spoke = new_spoke;
            theta += delta;
        }
    }

    pub fn draw_ring(&self, center: &Vec2, radius: f32, thickness: f32, color: &Color) {
        use std::f32::consts::PI;

        let delta = PI / 64.0;
        let limit = PI * 2.0 + delta;

        let mut last_spoke = glam::Vec2::new(radius + center.x, center.y);
        let mut last_theta = 0.0;
        let mut theta = delta;
        while theta < limit {
            let angle = Vec2::from_angle(theta);
            let new_spoke = angle * radius + *center;
            let new_spoke2 = angle * (radius + thickness) + *center;
            let last_spoke2 = Vec2::from_angle(last_theta) * (radius + thickness) + *center;

            self.draw_triangle(&new_spoke2, &last_spoke, &new_spoke, &color);
            self.draw_triangle(&new_spoke2, &last_spoke2, &last_spoke, &color);

            last_spoke = new_spoke;
            last_theta = theta;
            theta += delta;
        }
    }

    pub fn draw_rect(&self, xy: &Vec2, size: &Vec2, color: &Color) {
        let v1 = *xy;
        let v2 = v1 + Vec2::new(size.x, 0.0);
        let v3 = v1 + Vec2::new(0.0, size.y);
        let v4 = v1 + *size;

        self.draw_triangle(&v1, &v2, &v3, &color);
        self.draw_triangle(&v2, &v3, &v4, &color);
    }
}