mod physics_objects;

use pg_sdl::prelude::*;
use pg_sdl::vector2::Vec2;
use pg_sdl::widgets::Widgets;
use physics_objects::{apply_gravity, Mass, Motor, Rod, Spring};
use std::collections::HashMap;

/// PhysicsApp is a pyhsics engine app made to test any kind of 2D physics.
pub struct PhysicsApp {
    masses: Vec<Mass>,
    rods: Vec<Rod>,
    springs: Vec<Spring>,
    motors: Vec<Motor>,
}

impl App for PhysicsApp {
    fn update(&mut self, delta: f32, input: &Input, widgets: &mut Widgets) -> bool {
        if widgets
            .get_mut::<Button>("play")
            .unwrap()
            .state
            .is_pressed()
        {
            if widgets.get::<Slider>("speed").unwrap().get_value() == 0.0 {
                widgets.get_mut::<Slider>("speed").unwrap().set_value(1.0);
                widgets
                    .get_mut::<Button>("play")
                    .unwrap()
                    .set_text("Stop".to_string());
            } else {
                widgets.get_mut::<Slider>("speed").unwrap().set_value(0.0);
                widgets
                    .get_mut::<Button>("play")
                    .unwrap()
                    .set_text("Start".to_string());
            }
        }

        if input.mouse.left_button.is_pressed() {
            let mouse_position = Vec2::from(input.mouse.position);
            self.masses.iter().enumerate().for_each(|(index, mass)| {
                // TODO replace by take_while()
                if mass.collide_point(mouse_position) {
                    self.springs[0].change_end(index);
                }
            });
        } else if input.mouse.left_button.is_released() {
            self.springs[0].change_end(0);
        }

        apply_gravity(&mut self.masses);
        self.springs.iter_mut().for_each(|spring| {
            spring.apply_force(&mut self.masses);
        });

        let delta = delta * widgets.get_mut::<Slider>("speed").unwrap().get_value() * 10.0;

        self.masses.iter_mut().for_each(|mass| mass.update(delta));
        self.motors
            .iter()
            .for_each(|motor| motor.update(delta, &mut self.masses));

        self.masses[0].position = Vec2::from(input.mouse.position);

        // set mass 3 for constraining rod to its initial length
        let delta_length = self.masses[3].position - self.masses[4].position;
        self.masses[3].position =
            self.masses[4].position + delta_length.normalized() * self.rods[0].length;

        let delta_velocity = self.masses[3].velocity - self.masses[4].velocity;
        let v1 = delta_velocity.dot(delta_length.perpendicular());
        self.masses[3].velocity = self.masses[4].velocity + delta_length.perpendicular() * v1;

        true
    }

    fn draw(&mut self, canvas: &mut Canvas<Window>, _text_drawer_: &mut TextDrawer) {
        self.motors
            .iter()
            .for_each(|motor| motor.draw(canvas, &self.masses));
        self.masses.iter().for_each(|mass| mass.draw(canvas));
        self.rods
            .iter()
            .for_each(|rod| rod.draw(canvas, &self.masses));
        self.springs
            .iter()
            .for_each(|spring| spring.draw(canvas, &self.masses));
    }
}

fn main() {
    let my_app = &mut PhysicsApp {
        masses: Vec::from([
            Mass::new(Vec2::new(0.0, 0.0), 0.0, 0.0, Colors::BLACK, true),
            Mass::new(Vec2::new(600.0, 400.0), 1.0, 20.0, Colors::ORANGE, true),
            Mass::new(Vec2::new(600.0, 450.0), 1.0, 15.0, Colors::ORANGE, true),
            Mass::new(Vec2::new(600.0, 550.0), 5.0, 25.0, Colors::RED, false),
            Mass::new(Vec2::new(800.0, 200.0), 1.0, 20.0, Colors::GREEN, true),
            Mass::new(Vec2::new(800.0, 650.0), 1.0, 20.0, Colors::MAGENTA, false),
        ]),
        rods: Vec::from([
            Rod::new(3, 4, 250.0, 10.0, Colors::BROWN),
            Rod::new(3, 5, 50.0, 10.0, Colors::BROWN),
        ]),
        springs: Vec::from([
            Spring::new(0, 0, 1.0, 0.5, 0.0, 20.0, Colors::WHITE),
            Spring::new(2, 3, 0.5, 0.2, 150.0, 40.0, Colors::BEIGE),
        ]),
        motors: Vec::from([Motor::new(1, 2, 0.4, Colors::LIGHT_GREY)]),
    };

    let mut app: PgSdl = PgSdl::init("Spring test", 1200, 720, Some(60), true, Colors::SKY_BLUE);
    app.add_widgets(HashMap::from([
        (
            "play",
            Box::new(Button::new(
                Colors::ORANGE,
                rect!(300, 35, 120, 50),
                Some(9),
                Some(Text::new("Start".to_string(), 18, None)),
            )) as Box<dyn Widget>,
        ),
        (
            "speed",
            Box::new(Slider::new(
                Colors::ORANGE,
                rect!(500, 50, 200, 30),
                Some(20),
                SliderType::Continuous {
                    default_value: 0.0,
                    display: Some(Box::new(|value| format!("{:.2}", value))),
                },
            )),
        ),
    ]));
    app.run(my_app);
}