const GAME_SIZE: (u32, u32) = (500, 800);
use std::{
    collections::HashMap,
    num::NonZeroU32,
    process,
    rc::Rc,
    time::{Duration, Instant},
};

use softbuffer::Buffer;
use winit::{
    dpi::PhysicalSize,
    event::{Event, KeyEvent, StartCause, WindowEvent},
    event_loop::{ControlFlow, EventLoop},
    keyboard::{Key, NamedKey},
    raw_window_handle::{HasDisplayHandle, HasWindowHandle},
    window::WindowBuilder,
};

use self::objs::{MovingObject, World};

type RenderFn = fn(&mut render::RenderCtx<'_, '_>, &mut World, &GameTimer);
// core game engine struct
pub struct Engine {
    event_loop: EventLoop<()>,
    render_fn: RenderFn,
    world: World,
}

impl Engine {
    pub fn new() -> Self {
        let event_loop = EventLoop::new().unwrap();

        Self {
            event_loop,
            render_fn: |_, _, _| {},
            world: World::new(),
        }
    }

    pub fn insert_into_world(&mut self, obj: Rc<dyn MovingObject>) -> usize {
        self.world.insert(obj)
    }

    // sets the render function for the game
    pub fn set_render_fn(mut self, f: RenderFn) -> Self {
        self.render_fn = f;
        self
    }

    // runs the game and consumes self, this will finish the process
    pub fn run(self) -> ! {
        let Self {
            event_loop,
            mut world,
            render_fn,
        } = self;

        // set up window
        let window = WindowBuilder::new()
            .with_inner_size(winit::dpi::Size::Physical(PhysicalSize::new(1200, 700)))
            .build(&event_loop)
            .unwrap();

        // set up softbuffer
        let context = softbuffer::Context::new(window.display_handle().unwrap()).unwrap();
        let mut surface =
            softbuffer::Surface::new(&context, window.window_handle().unwrap()).unwrap();

        let mut timer = GameTimer::new();

        event_loop
            .run(|event, elwt| {
                // shoddy vsync
                elwt.set_control_flow(ControlFlow::WaitUntil(
                    Instant::now() + Duration::from_millis(1000 / 60),
                ));

                match event {
                    // redraw
                    Event::NewEvents(StartCause::ResumeTimeReached { .. }) => {
                        window.request_redraw();
                    }
                    Event::WindowEvent {
                        window_id,
                        event: WindowEvent::RedrawRequested,
                    } => {
                        if window_id == window.id() {
                            if let (Some(width), Some(height)) = {
                                let size = window.inner_size();
                                (NonZeroU32::new(size.width), NonZeroU32::new(size.height))
                            } {
                                surface.resize(width, height).unwrap();
                                let mut buffer = surface.buffer_mut().unwrap();

                                let mut ctx =
                                    render::RenderCtx::new(buffer, (width, height), GAME_SIZE);

                                // render
                                render_fn(&mut ctx, &mut world, &timer);
                                ctx.force_present();
                                timer.frame_update();
                            }
                        }
                    }
                    // crash game to exit lol
                    Event::WindowEvent {
                        window_id: _window_id,
                        event:
                            WindowEvent::CloseRequested
                            | WindowEvent::KeyboardInput {
                                event:
                                    KeyEvent {
                                        logical_key: Key::Named(NamedKey::Escape),
                                        ..
                                    },
                                ..
                            },
                    } => todo!(),
                    // potential future keyboard handling
                    Event::WindowEvent {
                        window_id: _window_id,
                        event:
                            WindowEvent::KeyboardInput {
                                device_id: _device_id,
                                event: _event,
                                is_synthetic: _is_synthetic,
                            },
                    } => {}
                    _ => {}
                }
            })
            .unwrap();
        process::exit(0);
    }
}

pub struct GameTimer {
    game_start: Instant,
    last_frame: Instant,
    stopwatches: HashMap<String, Instant>,
}

impl GameTimer {
    pub fn new() -> Self {
        Self {
            game_start: Instant::now(),
            last_frame: Instant::now(),
            stopwatches: HashMap::new(),
        }
    }

    pub fn frame_update(&mut self) {
        self.last_frame = Instant::now()
    }

    pub fn delta_t(&self) -> f32 {
        Instant::now().duration_since(self.last_frame).as_secs_f32()
    }

    pub fn game_time_passed(&self) -> f32 {
        Instant::now().duration_since(self.game_start).as_secs_f32()
    }

    pub fn start_stopwatch(&mut self, name: impl ToString) {
        let _ = self.stopwatches.insert(name.to_string(), Instant::now());
    }

    pub fn get_stopwatch_time(&self, name: &str) -> Option<f32> {
        self.stopwatches
            .get(name)
            .map(|start_time| Instant::now().duration_since(*start_time).as_secs_f32())
    }

    pub fn delete_stopwatch(&mut self, name: &str) {
        let _ = self.stopwatches.remove(name);
    }
}

mod render;

pub mod objs {
    use std::rc::Rc;

    use super::render::RenderCtx;

    pub struct World {
        objects: Vec<Rc<dyn MovingObject>>,
    }

    impl World {
        pub fn new() -> Self {
            Self {
                objects: Vec::new(),
            }
        }

        pub fn insert(&mut self, obj: Rc<dyn MovingObject>) -> usize {
            self.objects.push(obj);
            self.objects.len() - 1
        }

        pub fn get(&self, i: usize) -> Rc<dyn MovingObject> {
            self.objects[i].clone()
        }

        pub fn get_mut(&mut self, i: usize) -> &mut Rc<dyn MovingObject> {
            &mut self.objects[i]
        }

        pub fn draw_all(&self, ctx: &mut RenderCtx<'_, '_>) {
            self.objects.iter().for_each(|obj| obj.display(ctx))
        }
    }

    #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    pub struct Rect {
        pos: Position,
        size: Size,
    }

    impl Rect {
        pub fn new(x: u32, y: u32, height: u32, width: u32) -> Self {
            Self {
                pos: Position::new(x, y),
                size: Size::new(width, height),
            }
        }

        pub fn square(x: u32, y: u32, size: u32) -> Self {
            Self {
                pos: Position::new(x, y),
                size: Size::new(size, size),
            }
        }
    }

    impl Object for Rect {
        fn position(&self) -> Position {
            self.pos
        }

        fn size(&self) -> Size {
            self.size
        }
    }

    #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    pub struct MovingRect {
        prev_pos: Position,
        current: Rect,
    }

    impl MovingRect {
        pub fn new(x: u32, y: u32, height: u32, width: u32) -> Self {
            Self {
                prev_pos: Position::new(x, y),
                current: Rect::new(x, y, height, width),
            }
        }

        pub fn square(x: u32, y: u32, size: u32) -> Self {
            Self {
                prev_pos: Position::new(x, y),
                current: Rect::square(x, y, size),
            }
        }
    }

    impl Object for MovingRect {
        fn position(&self) -> Position {
            self.current.position()
        }

        fn size(&self) -> Size {
            self.current.size()
        }
    }

    impl MovingObject for MovingRect {
        fn previous_pos(&self) -> Position {
            self.prev_pos
        }

        fn update_pos(&mut self, x: u32, y: u32) {
            self.prev_pos = self.current.pos;
            self.current.pos = Position::new(x, y);
        }
    }

    #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    pub struct Position {
        x: u32,
        y: u32,
    }

    impl Position {
        pub fn new(x: u32, y: u32) -> Self {
            Self { x, y }
        }
    }

    #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    pub struct Size {
        width: u32,
        height: u32,
    }

    impl Size {
        pub fn new(width: u32, height: u32) -> Self {
            Self { width, height }
        }
    }

    pub trait Object {
        fn position(&self) -> Position;
        fn size(&self) -> Size;
        fn display(&self, ctx: &mut RenderCtx<'_, '_>) {
            let Position { x, y } = self.position();
            let Size { width, height } = self.size();
            ctx.rect(x, y, width, height, 0xffffff);
        }
    }

    pub trait MovingObject: Object {
        fn previous_pos(&self) -> Position;
        fn update_pos(&mut self, x: u32, y: u32);
        fn move_obj(&mut self, x: i32, y: i32) {
            let Position { x: cur_x, y: cur_y } = self.position();

            self.update_pos(
                cur_x.saturating_add_signed(x),
                cur_y.saturating_add_signed(y),
            )
        }

        // TODO: damage
        fn draw_move(&self, ctx: &mut RenderCtx<'_, '_>) {
            let Position {
                x: prev_x,
                y: prev_y,
            } = self.previous_pos();
            let Size { width, height } = self.size();

            ctx.rect(prev_x, prev_y, width, height, 0x000000);
            self.display(ctx);
        }
    }
}