use core::render::Renderer;
use geometry::{Point, Dimension, Intersection, Angle, ToAngle, supercover_line};
use sprites::SpriteManager;
use std::rc::Rc;
use {point, dimen};

mod lvlgen;

pub use self::lvlgen::LevelGenerator;

////////// LEVEL ///////////////////////////////////////////////////////////////

#[derive(Default)]
pub struct Level {
    pub gravity: Point<f64>,
    pub grid: Grid<bool>,
    walls: Vec<Rc<WallRegion>>,
    wall_grid: Grid<Vec<Rc<WallEdge>>>,
}

impl Level {
    pub fn new(gravity: Point<f64>, grid: Grid<bool>, mut walls: Vec<WallRegion>) -> Self {
	let size = (2560, 1440); // TODO: get actual size from walls or something
	let wall_grid = Level::build_wall_grid(&mut walls, &size.into());
	dbg!(&wall_grid.scale);
	Level {
	    gravity,
	    grid,
	    walls: walls.into_iter().map(|i| Rc::new(i)).collect(),
	    wall_grid,
	}
    }

    /// Creates a grid of wall edges for fast lookup
    fn build_wall_grid(walls: &mut Vec<WallRegion>, lvlsize: &Dimension<usize>) -> Grid<Vec<Rc<WallEdge>>> {
	let size = dimen!(lvlsize.width / 20, lvlsize.height / 20); // TODO: make sure all walls fit within the grid bounds
	let cs = point!(lvlsize.width / size.width, lvlsize.height / size.height);
	//let cs = point!(scale.width as f64, scale.height as f64);
	let mut grid = Grid {
	    cells: vec!(vec!(vec!(); size.height); size.width),
	    size,
	    scale: dimen!(cs.x as f64, cs.y as f64),
	};

	for wall in walls {
	    for edge in &wall.edges {
		for c in grid.grid_coordinates_on_line(edge.p1, edge.p2) {
		    grid.cells[c.x][c.y].push(Rc::clone(edge));
		}
	    }
	}

	grid
    }

    pub fn render(&mut self, renderer: &mut Renderer, _sprites: &SpriteManager, debug_mode: bool) {
	if debug_mode {
	    // original grid
	    renderer.canvas().set_draw_color((64, 64, 64));
	    let size = &self.grid.scale;
	    for x in 0..self.grid.size.width {
		for y in 0..self.grid.size.height {
		    if self.grid.cells[x][y] {
			renderer.canvas().fill_rect(sdl2::rect::Rect::new(
			    x as i32 * size.width as i32,
			    y as i32 * size.height as i32,
			    size.width as u32,
			    size.height as u32)).unwrap();
		    }
		}
	    }

	    // wall grid
	    renderer.canvas().set_draw_color((0, 32, 0));
	    let size = &self.wall_grid.scale;
	    for x in 0..self.wall_grid.size.width {
		for y in 0..self.wall_grid.size.height {
		    if !self.wall_grid.cells[x][y].is_empty() {
			let num = self.wall_grid.cells[x][y].len();
			renderer.canvas().set_draw_color((0, 32*num as u8, 0));
			renderer.canvas().fill_rect(sdl2::rect::Rect::new(
			    x as i32 * size.width as i32,
			    y as i32 * size.height as i32,
			    size.width as u32,
			    size.height as u32)).unwrap();
		    }
		}
	    }

	    // wall normals
	    for wall in &self.walls {
		for e in &wall.edges {
		    let c = (e.p1 + e.p2) / 2.0;
		    let a = (e.p2 - e.p1).to_angle() + std::f64::consts::FRAC_PI_2.radians();

		    renderer.draw_line(
		        <(i32, i32)>::from(c.to_i32()),
		        <(i32, i32)>::from((c + Point::from(a) * 10.0).to_i32()),
		        (0, 128, 255));
		}
	    }
	}

	// walls
	for wall in &self.walls {
	    for e in &wall.edges {
		if !debug_mode {
		    let c = (e.p1 + e.p2) / 2.0;
		    let a = (e.p2 - e.p1).to_angle() - std::f64::consts::FRAC_PI_2.radians();

		    renderer.draw_line(
			<(i32, i32)>::from(c.to_i32()),
			<(i32, i32)>::from((c + Point::from(a) * 10.0).to_i32()),
			(255, 128, 0));

		    renderer.draw_line(
			<(i32, i32)>::from(e.p1.to_i32()),
			<(i32, i32)>::from((c + Point::from(a) * 20.0).to_i32()),
			(96, 48, 0));
		    renderer.draw_line(
			<(i32, i32)>::from(e.p2.to_i32()),
			<(i32, i32)>::from((c + Point::from(a) * 20.0).to_i32()),
		        (96, 48, 0));
		}

		renderer.draw_line(
		    <(i32, i32)>::from(e.p1.to_i32()),
		    <(i32, i32)>::from(e.p2.to_i32()),
		    (255, 255, 0));
	    }
	}
    }

    pub fn intersect_walls(&self, p1: Point<f64>, p2: Point<f64>) -> IntersectResult {
	for c in self.wall_grid.grid_coordinates_on_line(p1, p2) {
	    for w in &self.wall_grid.cells[c.x][c.y] {
		if let Intersection::Point(p) = Intersection::lines(p1, p2, w.p1, w.p2) {
		    if w.point_is_in_front(p1) {
			let wall = Wall {
			    region: Rc::clone(&self.walls[w.region]),
			    edge: Rc::clone(w),
			};
			return IntersectResult::Intersection(wall, p)
		    }
		}
	    }
	}
	IntersectResult::None
    }
}

pub enum IntersectResult {
    Intersection(Wall, Point<f64>),
    None
}

////////// GRID ////////////////////////////////////////////////////////////////

#[derive(Debug, Default)]
pub struct Grid<T> {
    pub size: Dimension<usize>,
    pub scale: Dimension<f64>,
    pub cells: Vec<Vec<T>>,
}

impl<T> Grid<T> {
    // pub fn at<C>(&self, c: C) -> Option<&T>
    // where C: Into<(isize, isize)>
    // {
    // 	let c = c.into();
    // 	if c.0 >= 0 && c.0 < self.size.width as isize && c.1 >= 0 && c.1 < self.size.height as isize {
    // 	    Some(&self.cells[c.0 as usize][c.1 as usize])
    // 	} else {
    // 	    None
    // 	}
    // }

    pub fn to_grid_coordinate<C>(&self, c: C) -> Option<Point<usize>>
    where C: Into<(isize, isize)>
    {
	let c = c.into();
	if c.0 >= 0 && c.0 < self.size.width as isize && c.1 >= 0 && c.1 < self.size.height as isize {
	    Some(point!(c.0 as usize, c.1 as usize))
	} else {
	    None
	}
    }

    /// Returns a list of grid coordinates that a line in world coordinates passes through.
    pub fn grid_coordinates_on_line(&self, p1: Point<f64>, p2: Point<f64>) -> Vec<Point<usize>> {
	supercover_line(p1 / self.scale, p2 / self.scale)
	    .iter()
	    .map(|c| self.to_grid_coordinate(*c))
	    .flatten()
	    .collect()
    }
}

////////// WALL REGION /////////////////////////////////////////////////////////

#[derive(Debug, Default)]
pub struct WallRegion {
    edges: Vec<Rc<WallEdge>>,
}

impl WallRegion {
    pub fn new(points: Vec<Point<f64>>) -> Self {
	let index: RegionIndex = 0; // use as param
	let mut edges = Vec::with_capacity(points.len());

	for i in 0..points.len() {
	    let edge = Rc::new(WallEdge {
		region: index,
		id: i,
		p1: points[i],
		p2: points[(i + 1) % points.len()],
	    });
	    edges.push(edge);
	}

	WallRegion { edges }
    }

    fn next(&self, index: EdgeIndex) -> Rc<WallEdge> {
    	let index = (index + 1) % self.edges.len();
    	Rc::clone(&self.edges[index])
    }

    fn previous(&self, index: EdgeIndex) -> Rc<WallEdge> {
    	let index = (index + self.edges.len() + 1) % self.edges.len();
    	Rc::clone(&self.edges[index])
    }
}

////////// WALL EDGE ///////////////////////////////////////////////////////////

type RegionIndex = usize;
type EdgeIndex = usize;

#[derive(Debug, Default)]
struct WallEdge {
    region: RegionIndex,
    id: EdgeIndex,
    pub p1: Point<f64>,
    pub p2: Point<f64>,
}

impl WallEdge {
    fn point_is_in_front(&self, p: Point<f64>) -> bool {
	let cross = (self.p2 - self.p1).cross_product(p - self.p1);
	cross > 0.0
    }
}

////////// WALL ////////////////////////////////////////////////////////////////

pub struct Wall {
    region: Rc<WallRegion>,
    edge: Rc<WallEdge>,
}

impl Wall {
    #[allow(dead_code)]
    pub fn next(self) -> Wall {
	Wall {
	    edge: self.region.next(self.edge.id),
	    region: self.region,
	}
    }

    #[allow(dead_code)]
    pub fn previous(self) -> Wall {
	Wall {
	    edge: self.region.previous(self.edge.id),
	    region: self.region,
	}
    }

    pub fn normal(&self) -> Angle {
	(self.edge.p2 - self.edge.p1).to_angle() + std::f64::consts::FRAC_PI_2.radians()
    }
}