use crate::graph::{Edge, EdgesVec, VerticesVec};
use eframe::egui::{Color32, Pos2, Rect, Ui};
use eframe::epaint::{CornerRadius, Stroke};

pub fn render_graph<D>(
    ui: &mut Ui,
    vertices: &VerticesVec,
    vertex_locations: &mut [(f32, f32)],
    edges: &EdgesVec<D>,
    normalized_intensity: impl Fn(&Edge<D>) -> f64,
) {
    let canvas = ui.painter();
    let rect = ui.available_size();
    let start = ui.cursor();

    let rect = Rect::from_min_max(start.min, rect.to_pos2());
    canvas.rect_filled(rect, CornerRadius::same(0), Color32::from_rgb(0, 0, 0));

    for e in edges.iter() {
        let p1 = vertex_locations[e.vertex1_index];
        let p2 = vertex_locations[e.vertex2_index];

        canvas.line_segment(
            [
                Pos2::new(
                    p1.0 * rect.width() + rect.min.x,
                    p1.1 * rect.height() + rect.min.y,
                ),
                Pos2::new(
                    p2.0 * rect.width() + rect.min.x,
                    p2.1 * rect.height() + rect.min.y,
                ),
            ],
            Stroke::new(1.0, intensity2color(normalized_intensity(e))),
        );
    }
}

fn intensity2color(intensity: f64) -> Color32 {
    let scale = |base: f64, coefficient: u8| -> u8 {
        return ((intensity - base) * 5.0 * (coefficient as f64)) as u8;
    };

    match intensity {
        f64::NEG_INFINITY..0.2 => {
            return Color32::from_rgb(
                50 - scale(0.0, 50),
                50 - scale(0.0, 50),
                50 + scale(0.0, 155),
            );
        }
        0.2..0.4 => {
            return Color32::from_rgb(0, scale(0.2, 255), 255);
        }
        0.4..0.6 => {
            return Color32::from_rgb(0, 255, 255 - scale(0.4, 255));
        }
        0.6..0.8 => {
            return Color32::from_rgb(scale(0.6, 255) as u8, 255, 0);
        }
        0.8..f64::INFINITY => {
            return Color32::from_rgb(255, 255 - scale(0.8, 255), 0);
        }
        _ => unreachable!(),
    }
}