use common::Point2D;
use core::render::Renderer;
use rand::Rng;
use sprites::SpriteManager;

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

#[derive(Default)]
pub struct Level {
    pub gravity: Point2D<f64>,
    pub ground: f64,		// just to have something
    pub grid: Grid,
    iterations: u8,
}

impl Level {
    pub fn new(gravity: Point2D<f64>, ground: f64) -> Self {
	Level { gravity, ground, grid: Grid::generate(10), iterations: 10 }
    }

    pub fn regenerate(&mut self) {
	self.grid = Grid::generate(self.iterations);
    }

    pub fn increase_iteration(&mut self) {
	self.iterations += 1;
	self.regenerate();
	println!("iterate {} time(s)", self.iterations);
    }

    pub fn decrease_iteration(&mut self) {
	self.iterations -= 1;
	self.regenerate();
	println!("iterate {} time(s)", self.iterations);
    }

    pub fn render(&mut self, renderer: &mut Renderer, _sprites: &SpriteManager) {
	let w = renderer.viewport().0 as i32;

	renderer.canvas().set_draw_color((64, 64, 64));
	let size = self.grid.cell_size;
	for x in 0..self.grid.width {
	    for y in 0..self.grid.height {
		if self.grid.cells[x][y] {
		    renderer.canvas().fill_rect(sdl2::rect::Rect::new(x as i32 * size as i32, y as i32 * size as i32, size as u32, size as u32)).unwrap();
		}
	    }
	}

	for i in 1..11 {
	    let y = (i * i - 1) as i32 + self.ground as i32;
	    renderer.canvas().set_draw_color((255 - i * 20, 255 - i * 20, 0));
	    renderer.canvas().draw_line((0, y), (w, y)).unwrap();
	}
    }
}

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

#[derive(Default)]
pub struct Grid {
    pub width: usize,
    pub height: usize,
    pub cell_size: usize,
    pub cells: Vec<Vec<bool>>,
}

impl Grid {
    fn generate(iterations: u8) -> Grid {
	let cell_size = 20;
	let (width, height) = (2560 / cell_size, 1440 / cell_size);

	let mut grid = Grid {
	    cell_size,
	    width,
	    height,
	    cells: vec!(vec!(true; height); width),
	};

	// start with some noise
//	grid.simplex_noise();
	grid.random_noise();

	// smooth with cellular automata
	grid.smooth(iterations);
//	grid.smooth_until_equilibrium();

	// increase resolution
	for _i in 0..1 {
	    grid = grid.subdivide();
	    grid.smooth(iterations);
	}

	grid
    }

    #[allow(dead_code)]
    fn simplex_noise(&mut self) {
	use noise::{NoiseFn, OpenSimplex, Seedable};
	let noise = OpenSimplex::new().set_seed(std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).unwrap().as_secs() as u32);
	self.set_each(|x, y| noise.get([x as f64 / 12.0, y as f64 / 12.0]) > 0.055, 1);
    }

    #[allow(dead_code)]
    fn random_noise(&mut self) {
	let mut rng = rand::thread_rng();
	self.set_each(|_x, _y| rng.gen_range(0, 100) > 55, 1);
    }

    #[allow(dead_code)]
    fn smooth(&mut self, iterations: u8) {
	let distance = 1;
	for _i in 0..iterations {
	    let mut next = vec!(vec!(true; self.height); self.width);
	    for x in distance..(self.width - distance) {
	    	for y in distance..(self.height - distance) {
		    match Grid::neighbours(&self.cells, x, y, distance) {
			n if n < 4 => next[x][y] = false,
			n if n > 4 => next[x][y] = true,
			_ => next[x][y] = self.cells[x][y]
		    }
		}
	    }
	    if self.cells == next {
		break; // exit early
	    } else {
		self.cells = next;
	    }
	}
    }

    #[allow(dead_code)]
    fn smooth_until_equilibrium(&mut self) {
	let distance = 1;
	let mut count = 0;
	loop {
	    count += 1;
	    let mut next = vec!(vec!(true; self.height); self.width);
	    for x in distance..(self.width - distance) {
		for y in distance..(self.height - distance) {
		    match Grid::neighbours(&self.cells, x, y, distance) {
			n if n < 4 => next[x][y] = false,
			n if n > 4 => next[x][y] = true,
			_ => next[x][y] = self.cells[x][y]
		    };
		}
	    }
	    if self.cells == next {
		break;
	    } else {
		self.cells = next;
	    }
	}
	println!("{} iterations needed", count);
    }

    fn neighbours(grid: &Vec<Vec<bool>>, px: usize, py: usize, distance: usize) -> u8 {
	let mut count = 0;
	for x in (px - distance)..=(px + distance) {
	    for y in (py - distance)..=(py + distance) {
		if !(x == px && y == py) && grid[x][y] {
		    count += 1;
		}
	    }
	}
	count
    }

    fn set_each<F: FnMut(usize, usize) -> bool>(&mut self, mut func: F, walls: usize) {
    	for x in walls..(self.width - walls) {
    	    for y in walls..(self.height - walls) {
    		self.cells[x][y] = func(x, y);
    	    }
    	}
    }

    fn subdivide(&mut self) -> Grid {
	let (width, height) = (self.width * 2, self.height * 2);
	let mut cells = vec!(vec!(true; height); width);
	for x in 1..(width - 1) {
	    for y in 1..(height - 1) {
		cells[x][y] = self.cells[x / 2][y / 2];
	    }
	}
	Grid {
	    cell_size: self.cell_size / 2,
	    width,
	    height,
	    cells
	}
    }
}