mod camera;
mod config;
mod content;
mod input;
mod renderer;
mod sim;

use futures::executor;
use rand::random_range;
use std::{collections::VecDeque, sync::Arc, time::Instant};
use winit::{
    application::ApplicationHandler,
    event::WindowEvent::{self},
    event_loop::{ActiveEventLoop, ControlFlow, EventLoop},
    window::Window,
};

use crate::{
    camera::Camera,
    config::WINDOW_TITLE,
    content::{
        entities::{
            entity_bullet_emitter::entity_bullet_emitter_def, entity_cube::entity_cube_def,
            entity_grenade::entity_grenade_def,
        },
        materials::MaterialId,
    },
    input::{
        Input::{self},
        InputManager,
    },
    renderer::RendererState,
    sim::{cell::Cell, rb_manager::DebugRenderMode, sim_manager::SimManager},
};

pub type Error = Box<dyn std::error::Error>;
pub type Result<T> = std::result::Result<T, Error>;

struct Config {
    brush_radius: f32,
    brush_material: MaterialId,
    dropper_material: MaterialId,
    use_threading: bool,
    cells_render: bool,
    debug_render: bool,
    debug_render_mode: DebugRenderMode,
}

struct Diagnostics {
    frame_times: VecDeque<f32>,
    fps: f32,
}

struct App {
    // core
    window: Option<Arc<Window>>,
    renderer_state: Option<RendererState>,

    // game
    input_manager: InputManager,
    camera: Option<Camera>,
    sim_manager: Option<SimManager>,

    // renderer
    last_render: Instant,

    // state
    config: Config,
    diagnostics: Diagnostics,
}

impl App {
    // called as often as possible
    // delta time is the real seconds elapsed since the last time this was called
    fn update(&mut self, delta_time: f32) {
        // apply inputs
        if let Some(camera) = &mut self.camera {
            camera.handle_camera_input(&self.input_manager, delta_time)
        }

        if let Some(sim) = &mut self.sim_manager {
            // --TEST SPAWNING--
            if self.input_manager.pressed(Input::Action1) {
                sim.create_entity(entity_cube_def(
                    self.input_manager.world_mouse_pos,
                    self.config.dropper_material,
                ));
            }

            if self.input_manager.pressed(Input::Action2) {
                sim.create_entity(entity_grenade_def(self.input_manager.world_mouse_pos, 3.0));
            }

            if self.input_manager.pressed(Input::Action3) {
                sim.create_entity(entity_bullet_emitter_def(
                    self.input_manager.world_mouse_pos,
                    3.0,
                ));
            }

            sim.update(&self.config, &self.input_manager, delta_time);
            self.input_manager.reset_for_frame();
        }
    }
}

impl Default for App {
    fn default() -> Self {
        Self {
            window: None,
            renderer_state: None,

            input_manager: InputManager::new(),

            camera: None,

            sim_manager: Some(SimManager::new()),

            last_render: Instant::now(),

            config: Config {
                use_threading: true,
                brush_radius: 10.0,
                brush_material: MaterialId::Sand,
                dropper_material: MaterialId::Wood,
                cells_render: true,
                debug_render: false,
                debug_render_mode: DebugRenderMode::default(),
            },
            diagnostics: Diagnostics {
                fps: 0.0,
                frame_times: VecDeque::new(),
            },
        }
    }
}

impl ApplicationHandler for App {
    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
        let window = Arc::new(
            event_loop
                .create_window(Window::default_attributes().with_title(WINDOW_TITLE))
                .unwrap(),
        );

        self.window = Some(window.clone());
        self.renderer_state = Some(executor::block_on(RendererState::new(window.clone())));

        let size = window.inner_size();
        self.camera = Some(Camera::new((size.width as i32, size.height as i32)));
    }

    fn window_event(
        &mut self,
        event_loop: &ActiveEventLoop,
        _: winit::window::WindowId,
        event: WindowEvent,
    ) {
        if let Some(renderer_state) = &mut self.renderer_state
            && let Some(window) = &mut self.window
        {
            let egui_response = renderer_state.egui_state.on_window_event(window, &event);
            // if egui consumed the event, it means we shouldn't treat any e.g., mouse clicks
            if egui_response.consumed {
                return;
            }
        }

        if let Some(camera) = &self.camera {
            self.input_manager.apply_event(&event, &camera);
        }

        match event {
            WindowEvent::Resized(size) => {
                if let Some(renderer_state) = &mut self.renderer_state
                    && let Some(camera) = &mut self.camera
                {
                    renderer_state.resize(size.width, size.height);
                    camera.resize((size.width as i32, size.height as i32));
                }
            }
            WindowEvent::CloseRequested => {
                event_loop.exit();
            }
            WindowEvent::RedrawRequested => {
                #[cfg(feature = "profiler")]
                puffin::GlobalProfiler::lock().new_frame();

                puffin::profile_scope!("redraw_requested");
                // compute FPS diagnostics
                let now = Instant::now();
                let delta_time = (now - self.last_render).as_secs_f32();
                self.last_render = now;

                self.diagnostics.frame_times.push_back(delta_time);

                if self.diagnostics.frame_times.len() > 30 {
                    self.diagnostics.frame_times.pop_front();
                }

                let average_frame_time = self.diagnostics.frame_times.iter().sum::<f32>()
                    / self.diagnostics.frame_times.len() as f32;

                self.diagnostics.fps = 1.0 / average_frame_time;

                self.update(delta_time);

                if let Some(renderer_state) = &mut self.renderer_state
                    && let Some(sim) = &mut self.sim_manager
                    && let Some(camera) = &mut self.camera
                {
                    renderer_state.render(
                        sim,
                        camera,
                        &mut self.config,
                        &self.diagnostics,
                        &self.input_manager,
                    );
                }
            }
            _ => {}
        }
    }

    fn about_to_wait(&mut self, _: &ActiveEventLoop) {
        if let Some(window) = &self.window {
            window.request_redraw();
        } else {
            panic!("No window!")
        }
    }
}

#[cfg(feature = "profiler")]
fn start_profiler() {
    let _server = puffin_http::Server::new("127.0.0.1:8585").unwrap();
    puffin::set_scopes_on(true);
    std::mem::forget(_server); // keep serving for the process lifetime

    std::process::Command::new("puffin_viewer")
        .args(["--url", "127.0.0.1:8585"])
        .spawn()
        .ok(); // don't die if it isn't installed
}

fn main() -> Result<()> {
    #[cfg(feature = "profiler")]
    start_profiler();

    let event_loop = EventLoop::new()?;
    event_loop.set_control_flow(ControlFlow::Poll);

    let mut app = App::default();
    event_loop.run_app(&mut app)?;

    Ok(())
}