use fpnum::{fp, FPNum, FPPoint};

use hwphysics::{

    self as hwp,

    common::{GearId, Millis},

    physics::{PositionData, VelocityData},

};

use integral_geometry::{Point, Rect, Size};

use land2d::Land2D;

use landgen::{

    outline_template::OutlineTemplate, template_based::TemplatedLandGenerator,

    LandGenerationParameters, LandGenerator,

};

use lfprng::LaggedFibonacciPRNG;

use crate::render::{camera::Camera, GearEntry, GearRenderer, MapRenderer};

struct GameState {

    land: Land2D<u32>,

    physics: hwp::World,

}

impl GameState {

    fn new(land: Land2D<u32>, physics: hwp::World) -> Self {

        Self { land, physics }

    }

}

pub struct World {

    random_numbers_gen: LaggedFibonacciPRNG,

    feature_size: u8,

    preview: Option<Land2D<u8>>,

    game_state: Option<GameState>,

    map_renderer: Option<MapRenderer>,

    gear_renderer: Option<GearRenderer>,

    camera: Camera,

    gear_entries: Vec<GearEntry>,

}

impl World {

    pub fn new() -> Self {

        Self {

            random_numbers_gen: LaggedFibonacciPRNG::new(&[]),

            feature_size: 5,

            preview: None,

            game_state: None,

            map_renderer: None,

            gear_renderer: None,

            camera: Camera::new(),

            gear_entries: vec![],

        }

    }

    pub fn create_renderer(&mut self, width: u16, height: u16) {

        let land_tile_size = Size::square(512);

        self.map_renderer = Some(MapRenderer::new(land_tile_size));

        self.camera = Camera::with_size(Size::new(width as usize, height as usize));

        use mapgen::{theme::Theme, MapGenerator};

        if let Some(ref state) = self.game_state {

            self.camera.position = state.land.play_box().center();

            let theme =

            let texture = MapGenerator::new().make_texture(&state.land, &theme);

            if let Some(ref mut renderer) = self.map_renderer {

                renderer.init(&texture);

            }

        }

    }

    pub fn set_seed(&mut self, seed: &[u8]) {

        self.random_numbers_gen = LaggedFibonacciPRNG::new(seed);

    }

    pub fn set_feature_size(&mut self, feature_size: u8) {

        self.feature_size = feature_size;

    }

    pub fn preview(&self) -> &Option<Land2D<u8>> {

        &self.preview

    }

    pub fn generate_preview(&mut self) {

        fn template() -> OutlineTemplate {

            let mut template = OutlineTemplate::new(Size::new(4096, 2048));

            template.islands = vec![vec![

                Rect::from_size_coords(100, 2050, 1, 1),

                Rect::from_size_coords(100, 500, 400, 1200),

                Rect::from_size_coords(3600, 500, 400, 1200),

                Rect::from_size_coords(3900, 2050, 1, 1),

            ]];

            template.fill_points = vec![Point::new(1, 0)];

            template

        }

        // based on old engine min_distance... dunno if this is the correct place tho

        let distance_divisor = (self.feature_size as u32).pow(2) / 8 + 10;

        let params = LandGenerationParameters::new(0u8, u8::MAX, distance_divisor, false, false);

        let landgen = TemplatedLandGenerator::new(template());

        self.preview = Some(landgen.generate_land(&params, &mut self.random_numbers_gen));

    }

    pub fn dispose_preview(&mut self) {

        self.preview = None

    }

    pub fn init(&mut self, template: OutlineTemplate) {

        let params = LandGenerationParameters::new(0u32, u32::MAX, 5, false, false);

        let landgen = TemplatedLandGenerator::new(template);

        let land = landgen.generate_land(&params, &mut self.random_numbers_gen);

        let physics = hwp::World::new(land.size());

        self.game_state = Some(GameState::new(land, physics));

    }

    pub fn move_camera(&mut self, position_shift: Point, zoom_shift: f32) {

        self.camera.zoom += zoom_shift;

        self.camera.position += Point::new(

            (position_shift.x as f32 / self.camera.zoom) as i32,

            (position_shift.y as f32 / self.camera.zoom) as i32,

        );

    }

    pub fn render(&mut self) {

        if let Some(ref mut renderer) = self.map_renderer {

            unsafe {

                gl::ClearColor(0.4f32, 0f32, 0.2f32, 1f32);

                gl::Clear(gl::COLOR_BUFFER_BIT);

            }

            renderer.render(&self.camera);

        }

        self.gear_entries.clear();

        let mut gear_entries = std::mem::take(&mut self.gear_entries);

        if let Some(ref mut renderer) = self.gear_renderer {

            if let Some(ref mut state) = self.game_state {

                state

                    .physics

                    .iter_data()

                    .run(|(pos,): (&mut PositionData,)| {

                        gear_entries.push(GearEntry::new(

                            f64::from(pos.0.x()) as f32,

                            f64::from(pos.0.y()) as f32,

                            Size::square(256),

                        ))

                    });

            }

            renderer.render(&self.camera, &gear_entries);

        }

        self.gear_entries = gear_entries;

    }

    fn create_gear(&mut self, position: Point) {

        if let Some(ref mut state) = self.game_state {

            let id = state.physics.new_gear().unwrap();

            let fp_position = FPPoint::new(position.x.into(), position.y.into());

            state.physics.add_gear_data(id, &PositionData(fp_position));

            state

                .physics

                .add_gear_data(id, &VelocityData(FPPoint::zero()))

        }

    }

    pub fn step(&mut self) {

        if let Some(ref mut state) = self.game_state {

            let next = self.random_numbers_gen.next().unwrap();

            if next % 32 == 0 {

                let position = Point::new(

                    (self.random_numbers_gen.next().unwrap() % state.land.width() as u32) as i32,

                    0,

                );

                self.create_gear(position);

            }

        }

        if let Some(ref mut state) = self.game_state {

            state.physics.step(Millis::new(1), &state.land);

        }

    }

}