use glam::{IVec2, Vec2};

use crate::{
    config::PIXELS_TO_METRES,
    sim::{
        cell::{
            cell::Cell,
            materials::{MaterialForm, MaterialId},
        },
        cell_sim::world::World,
        lib::ray::AwDda,
        particle_sim::particle::Particle,
    },
};

pub mod particle;

pub struct ParticleManager {
    pub particles: Vec<Particle>,
}

const PARTICLE_GRAVITY: f32 = 9.81 * PIXELS_TO_METRES;

impl ParticleManager {
    pub fn particle_tick(&mut self, world: &mut World, delta_time: f32) {
        let mut i = 0;
        'outer: while i < self.particles.len() {
            let p = &mut self.particles[i];

            p.life -= delta_time;
            if p.life <= 0.0 {
                self.particles.swap_remove(i);
                continue 'outer;
            }

            p.velocity.y += PARTICLE_GRAVITY * delta_time;
            let dt_velocity = p.velocity * delta_time;

            let mut dda = AwDda::new(p.position, p.position + p.velocity * delta_time);

            if let Some(prev) = dda.next() {
                if let Some(cell) = world.get_cell_from_game_position(prev.x, prev.y)
                    && [MaterialForm::Solid, MaterialForm::Powder]
                        .contains(&cell.material.def().form)
                {
                    // the particle is already inside a collider, we should just kill it
                    self.particles.swap_remove(i);
                    continue 'outer;
                }

                for cell in dda.map(|p| world.get_cell_from_game_position(p.x, p.y)) {
                    if let Some(cell) = cell
                        && [MaterialForm::Solid, MaterialForm::Powder]
                            .contains(&cell.material.def().form)
                    {
                        // write ourselves to the board
                        world.set_cell_from_game_position(
                            prev.x,
                            prev.y,
                            Cell::from_material(p.material),
                            false,
                        );
                        self.particles.swap_remove(i);
                        continue 'outer;
                    }
                }
            }

            // no collision, just move
            p.position = p.position + dt_velocity;
            i += 1;
        }
    }

    pub fn new() -> Self {
        ParticleManager {
            particles: Vec::new(),
        }
    }
}