use nalgebra::{Vector2, vector};
use rapier2d_f64::prelude::{RigidBodyHandle, RigidBodySet, ColliderBuilder, RigidBodyBuilder, ColliderSet};
use starkingdoms_protocol::{PlanetType, ProtocolPlanet};

use crate::{SCALE, manager::ClientHandlerMessage};

//const GRAVITY: f64 = 0.001;
const GRAVITY: f64 = 0.00006674;

#[derive(Clone)]
pub struct Planet {
    pub planet_type: PlanetType,
    pub body_handle: RigidBodyHandle,
    pub position: (f64, f64),
    pub radius: f64,
    pub mass: f64
}

impl Planet {
    pub fn gravity(&self, position: (f64, f64), mass: f64) -> (f64, f64) {
        let distance = ((position.0 - self.position.0).powi(2) + (position.1 - self.position.1).powi(2)).sqrt();
        let force = GRAVITY * ((self.mass * mass) / distance * distance);
        let mut direction = Vector2::new(self.position.0 - position.0, self.position.1 - position.1);
        direction.set_magnitude(force);
        (direction.x, direction.y)
    }
}

#[derive(Default, Clone)]
pub struct Planets {
    pub planets: Vec<Planet>,
}

impl Planets {
    pub fn make_planet(planets: &mut Vec<Planet>, planet_type: PlanetType, mass: f64, radius: f64, position: (f64, f64), rigid_body_set: &mut RigidBodySet, collider_set: &mut ColliderSet) {
        let collider = ColliderBuilder::ball(radius / SCALE)
            .build();
        let body = RigidBodyBuilder::fixed()
            .translation(vector![position.0, position.1])
            .additional_mass(0.0);
        let body_handle = rigid_body_set.insert(body);

        collider_set.insert_with_parent(collider, body_handle, rigid_body_set);

        planets.push(Planet {
            planet_type,
            body_handle,
            position,
            radius,
            mass,
        });
    }

    pub fn new(rigid_body_set: &mut RigidBodySet, collider_set: &mut ColliderSet) -> Planets {
        let mut planets = Vec::new();
        
        Planets::make_planet(
            &mut planets,
            PlanetType::Earth,
            2000.0,
            1000.0,
            (100.0, 100.0),
            rigid_body_set,
            collider_set,
        );

        Planets { planets }
    }

    pub fn to_protocol(&self) -> ClientHandlerMessage {
        let mut planets = vec![];

        for planet in self.planets.clone() {
            planets.push(ProtocolPlanet {
                planet_type: planet.planet_type,
                x: planet.position.0 * SCALE,
                y: planet.position.1 * SCALE,
                radius: planet.radius, // DO NOT * SCALE
            });
        }

        ClientHandlerMessage::PlanetData {
            planets
        }
    }

    pub fn gravity(&self, position: (f64, f64), mass: f64) -> (f64, f64) {
        let mut direction = Vector2::zeros();
        for planet in self.planets.clone() {
            let planet_grav = planet.gravity(position, mass);
            direction.x = planet_grav.0;
            direction.y = planet_grav.1;
        }
        (direction.x, direction.y)
    }
}