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

use futures::executor;
use glam::Vec2;
use rand::random_range;
use std::{collections::VecDeque, sync::Arc, time::Instant};
use winit::{
    application::ApplicationHandler,
    event::{
        ElementState, KeyEvent, MouseButton,
        WindowEvent::{self},
    },
    event_loop::{ActiveEventLoop, ControlFlow, EventLoop},
    keyboard::{KeyCode, PhysicalKey},
    window::Window,
};

use crate::{
    camera::Camera,
    config::WINDOW_TITLE,
    content::{
        entities::{entity_cube::entity_cube_def, entity_grenade::entity_grenade_def},
        materials::MaterialId,
    },
    renderer::RendererState,
    sim::{
        cell::cell::Cell,
        cell_manager::manager::CellManager,
        lib::force::apply_explosion,
        particle_manager::particle::Particle,
        rb_manager::DebugRenderMode,
        sim_manager::{SimCtx, 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 Input {
    last_mouse_pos_on_screen: Option<(f32, f32)>,
    last_mouse_world_pos: Option<(f32, f32)>,
    last_mouse_chunk_pos: Option<(i32, i32)>,
    last_mouse_local_pos: Option<(u8, u8)>,
    is_lmb_pressed: bool,
    is_rmb_pressed: bool,
    trigger_test_1: bool,
    trigger_test_2: bool,
    trigger_test_3: bool,
    trigger_test_4: bool,
    trigger_test_5: bool,

    // keybindings
    is_up_pressed: bool,
    is_left_pressed: bool,
    is_down_pressed: bool,
    is_right_pressed: bool,
}

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

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

    // game
    input: Input,
    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, delta_time)
        }

        if let Some(sim) = &mut self.sim_manager {
            // --TEST SPAWNING--
            if self.input.trigger_test_1
                && let Some(lm) = self.input.last_mouse_world_pos
            {
                self.input.trigger_test_1 = false;
                sim.create_entity(entity_cube_def(
                    Vec2::new(lm.0, lm.1),
                    self.config.dropper_material,
                ));
            }

            if self.input.trigger_test_2
                && let Some(lm) = self.input.last_mouse_world_pos
            {
                self.input.trigger_test_2 = false;
                sim.create_entity(entity_grenade_def(Vec2::new(lm.0, lm.1), 3.0));
            }

            if self.input.trigger_test_3
                && let Some(lm) = self.input.last_mouse_world_pos
            {
                self.input.trigger_test_3 = false;
                for _ in 0..100 {
                    sim.particle_manager.particles.push(Particle {
                        position: Vec2::new(
                            lm.0 + random_range(-25.0..25.0),
                            lm.1 + random_range(-25.0..25.0),
                        ),
                        velocity: Vec2::ZERO,
                        material: MaterialId::Sand,
                        life: 2.0,
                    })
                }
            }

            if self.input.trigger_test_4
                && let Some(lm) = self.input.last_mouse_world_pos
            {
                let mouse = Vec2::new(lm.0, lm.1);
                self.input.trigger_test_4 = false;
                apply_explosion(
                    &mut SimCtx {
                        cell_manager: &mut sim.cell_manager,
                        particle_manager: &mut sim.particle_manager,
                        rb_manager: &mut sim.rb_manager,
                    },
                    mouse,
                    30,
                    Vec2::new(0.0, -0.6),
                    300.0,
                );
            }

            // --TEST DRAWING--
            if (self.input.is_lmb_pressed || self.input.is_rmb_pressed)
                && let Some(lm) = self.input.last_mouse_world_pos
            {
                // start with the bounding box of the drawing brush circle + some margin
                // clamp the bounding box to the board sie
                let bb_xl = (lm.0 - self.config.brush_radius).round() as i32;
                let bb_xu = (lm.0 + self.config.brush_radius).round() as i32;
                let bb_yl = (lm.1 - self.config.brush_radius).round() as i32;
                let bb_yu = (lm.1 + self.config.brush_radius).round() as i32;

                // for each point, check if the distance is less than the brush size and write the pixel
                for x in bb_xl..bb_xu {
                    for y in bb_yl..bb_yu {
                        let r = random_range(0.0..1.0);
                        if ((x - lm.0.round() as i32).pow(2) + (y - lm.1.round() as i32).pow(2))
                            < (self.config.brush_radius as i32).pow(2)
                            && r > 0.9
                        {
                            let cell = if self.input.is_lmb_pressed {
                                let mut cell = Cell::from_material(self.config.brush_material);
                                // ensure we simulate on the first tick
                                cell.match_parity(sim.cell_manager.seqno);
                                cell
                            } else {
                                Cell::void()
                            };
                            sim.cell_manager.set_cell_from_game_position(
                                x, y, cell, false, // wake the chunk
                            )
                        }
                    }
                }
            }

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

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

            input: Input {
                last_mouse_pos_on_screen: None,
                last_mouse_world_pos: None,
                last_mouse_chunk_pos: None,
                last_mouse_local_pos: None,

                trigger_test_1: false,
                trigger_test_2: false,
                trigger_test_3: false,
                trigger_test_4: false,
                trigger_test_5: false,
                is_lmb_pressed: false,
                is_rmb_pressed: false,
                is_up_pressed: false,
                is_left_pressed: false,
                is_down_pressed: false,
                is_right_pressed: false,
            },

            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)));

        // let surface = SurfaceTexture::new(size.width, size.height, window_ref);

        // let mut pixels = Pixels::new(PIXEL_BUFFER_WIDTH, PIXEL_BUFFER_HEIGHT, surface).unwrap();

        // pixels.set_scaling_mode(ScalingMode::Fill);
    }

    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;
            }
        }

        match event {
            WindowEvent::KeyboardInput {
                event:
                    KeyEvent {
                        physical_key: PhysicalKey::Code(code),
                        state,
                        repeat,
                        ..
                    },
                ..
            } => {
                if let Some(sim) = &mut self.sim_manager {
                    let pressed = state.is_pressed();
                    match code {
                        KeyCode::KeyW => self.input.is_up_pressed = pressed,
                        KeyCode::KeyA => self.input.is_left_pressed = pressed,
                        KeyCode::KeyS => self.input.is_down_pressed = pressed,
                        KeyCode::KeyD => self.input.is_right_pressed = pressed,
                        KeyCode::KeyC => sim.cell_manager = CellManager::from_default_size(),
                        KeyCode::KeyP => sim.particle_manager.particles = Vec::new(),
                        KeyCode::KeyV => {
                            let ids: Vec<u32> = sim.entities.keys().cloned().collect();
                            for id in ids {
                                sim.destroy_entity(id);
                            }
                        }
                        KeyCode::Space if pressed => sim.paused = !sim.paused,
                        KeyCode::KeyX if pressed => sim.ignore_pause_next_tick = true,
                        KeyCode::Digit1 if pressed && !repeat => self.input.trigger_test_1 = true,
                        KeyCode::Digit2 if pressed && !repeat => self.input.trigger_test_2 = true,
                        KeyCode::Digit3 if pressed && !repeat => self.input.trigger_test_3 = true,
                        KeyCode::Digit4 if pressed && !repeat => self.input.trigger_test_4 = true,
                        KeyCode::Digit5 if pressed && !repeat => self.input.trigger_test_5 = true,
                        _ => {}
                    }
                }
            }
            WindowEvent::CursorMoved { position, .. } => {
                self.input.last_mouse_pos_on_screen = Some((position.x as f32, position.y as f32));

                if let Some(camera) = &mut self.camera {
                    let world_pos =
                        camera.screen_position_to_world(position.x as f32, position.y as f32);

                    self.input.last_mouse_world_pos = Some(world_pos);
                    let ((cx, cy), (lx, ly)) =
                        CellManager::split_game_position(world_pos.0 as i32, world_pos.1 as i32);
                    self.input.last_mouse_chunk_pos = Some((cx, cy));
                    self.input.last_mouse_local_pos = Some((lx, ly));
                }
            }
            WindowEvent::MouseInput { state, button, .. } => {
                if button == MouseButton::Left {
                    self.input.is_lmb_pressed = state == ElementState::Pressed
                } else if button == MouseButton::Right {
                    self.input.is_rmb_pressed = state == ElementState::Pressed
                }
            }
            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,
                    );
                }
            }
            _ => {}
        }
    }

    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(())
}