use common::Point2D;
use ::{point, time_scope};
use core::render::Renderer;
use noise::{NoiseFn, OpenSimplex, Seedable};
use rand::Rng;
use sprites::SpriteManager;

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

#[derive(Default)]
pub struct Level {
    pub gravity: Point2D<f64>,
    pub grid: Grid,
    iterations: u8,
    walls: Vec<Vec<Point2D<isize>>>,
}

impl Level {
    pub fn new(gravity: Point2D<f64>) -> Self {
	let mut lvl = Level { gravity, grid: Grid::generate(10), iterations: 10, walls: vec!() };
	lvl.filter_regions();
	lvl
    }

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

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

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

    pub fn filter_regions(&mut self) {
	self.grid.filter_regions();
	let mut walls = vec!();
	for mut r in self.grid.find_regions() {
	    if r.value {
		let mut outline = r.outline(self.grid.cell_size);
		for i in 2..(outline.len() - 2) {
//		    outline[i] = (outline[i - 1] + outline[i] + outline[i + 1]) / 3;
		    outline[i] = (outline[i - 2] + outline[i - 1] + outline[i] + outline[i + 1] + outline[i + 2]) / 5;
		}
		walls.push(outline);
	    }
	}
	self.walls = walls;
    }

    pub fn render(&mut self, renderer: &mut Renderer, _sprites: &SpriteManager) {
	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();
		}
	    }
	}

	let off = (size / 2) as i32;
	for wall in &self.walls {
	    for w in wall.windows(2) {
		renderer.draw_line((w[0].x as i32 + off, w[0].y as i32 + off), (w[1].x as i32 + off, w[1].y as i32 + off), (255, 255, 0));
	    }
	    let last = wall.len() - 1;
	    renderer.draw_line((wall[0].x as i32 + off, wall[0].y as i32 + off), (wall[last].x as i32 + off, wall[last].y as i32 + off), (255, 255, 0));
	}
    }
}

////////// 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 {
	time_scope!("grid generation");

	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) {
	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();
	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| rng.gen_range(0, 100) > (45 + (150.0 * noise.get([_x as f64 / 40.0, _y as f64 / 10.0])) as usize), 1); // more horizontal platforms
	// let w = self.width as f64;
	// self.set_each(|_x, _y| rng.gen_range(0, 100) > (45 + ((15 * _x) as f64 / w) as usize), 1); // opens up to the right
    }

    #[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
	}
    }

    fn find_regions(&self) -> Vec<Region> {
	time_scope!("finding all regions");
	let mut regions = vec!();
	let mut marked = vec!(vec!(false; self.height); self.width);
	for x in 0..self.width {
	    for y in 0..self.height {
		if !marked[x][y] {
		    regions.push(self.get_region_at_point(x, y, &mut marked));
		}
	    }
	}
	regions
    }

    fn get_region_at_point(&self, x: usize, y: usize, marked: &mut Vec<Vec<bool>>) -> Region {
	let value = self.cells[x][y];
	let mut cells = vec!();
	let mut queue = vec!((x, y));
	marked[x][y] = true;

	while let Some(p) = queue.pop() {
	    cells.push(p);
	    for i in &[(-1, 0), (1, 0), (0, -1), (0, 1)] {
		let ip = (p.0 as isize + i.0, p.1 as isize + i.1);
		if ip.0 >= 0 && ip.0 < self.width as isize && ip.1 >= 0 && ip.1 < self.height as isize {
		    let up = (ip.0 as usize, ip.1 as usize);
		    if self.cells[up.0][up.1] == value && !marked[up.0][up.1] {
			marked[up.0][up.1] = true;
			queue.push(up);
		    }
		}
	    }
	}

	Region { value, cells }
    }

    fn delete_region(&mut self, region: &Region) {
	for c in &region.cells {
	    self.cells[c.0][c.1] = !region.value;
	}
    }

    pub fn filter_regions(&mut self) {
	let min_wall_size = 0.0015;
	println!("grid size: ({}, {}) = {} cells", self.width, self.height, self.width * self.height);
	println!("min wall size: {}", (self.width * self.height) as f64 * min_wall_size);

	// delete all smaller wall regions
	for r in self.find_regions().iter().filter(|r| r.value) {
	    let percent = r.cells.len() as f64 / (self.width * self.height) as f64;
	    if percent < min_wall_size {
		println!("delete wall region of size {}", r.cells.len());
		self.delete_region(r);
	    }
	}

	// delete all rooms but the largest
	let regions = self.find_regions(); // check again, because if a removed room contains a removed wall, the removed wall will become a room
	let mut rooms: Vec<&Region> = regions.iter().filter(|r| !r.value).collect();
	rooms.sort_by_key(|r| r.cells.len());
	rooms.reverse();
	while rooms.len() > 1 {
	    self.delete_region(rooms.pop().unwrap());
	}
    }
}

////////// REGION //////////////////////////////////////////////////////////////

struct Region {
    value: bool,
    cells: Vec<(usize, usize)>,
}

impl Region {
    fn enclosing_rect(&self) -> (usize, usize, usize, usize) {
	let mut min = (usize::MAX, usize::MAX);
	let mut max = (0, 0);
	for c in &self.cells {
	    if      c.0 < min.0 { min.0 = c.0; }
	    else if c.0 > max.0 { max.0 = c.0; }
	    if      c.1 < min.1 { min.1 = c.1; }
	    else if c.1 > max.1 { max.1 = c.1; }
	}
	(min.0, min.1, 1 + max.0 - min.0, 1 + max.1 - min.1)
    }

    pub fn outline(&mut self, scale: usize) -> Vec<Point2D<isize>> {
	let rect = self.enclosing_rect();
	let (ox, oy, w, h) = rect;
	let grid = self.grid(&rect);
	let mut marked = vec!(vec!(false; h); w);
	let mut outline = vec!();

	let (mut p, mut dir) = self.find_first_point_of_outline(&rect, &grid);
//	println!("starting at {:?} with dir {:?}", p, dir);
	marked[p.x as usize][p.y as usize] = true;
	loop {
	    outline.push((p + (ox as isize, oy as isize)) * scale as isize);
	    let result = self.find_next_point_of_outline(&grid, p, dir);
	    p = result.0;
	    dir = result.1;
//	    println!("next at {:?} with dir {:?}", p, dir);
	    if marked[p.x as usize][p.y as usize] {
		// we're back at the beginning
		break;
	    }
	    marked[p.x as usize][p.y as usize] = true;
	}

	outline
    }

    fn grid(&self, rect: &(usize, usize, usize, usize)) -> Vec<Vec<bool>> {
	let (x, y, w, h) = rect;
	let mut grid = vec!(vec!(false; *h); *w);
	for c in &self.cells {
	    grid[c.0 - x][c.1 - y] = true;
	}
	grid
    }

    fn find_first_point_of_outline(&self, rect: &(usize, usize, usize, usize), grid: &Vec<Vec<bool>>) -> (Point2D<isize>, Point2D<isize>) {
	let (ox, oy, w, h) = rect;
	let is_outer_wall = (ox, oy) == (&0, &0); // we know this is always the outer wall of the level
    	for x in 0..*w {
    	    for y in 0..*h {
		if is_outer_wall && !grid[x][y] {
		    return (point!(x as isize, y as isize - 1), point!(0, 1)) // one step back because we're not on a wall tile
		}
		else if !is_outer_wall && grid[x][y] {
		    return (point!(x as isize, y as isize), point!(1, 0))
		}
    	    }
    	}
	panic!("no wall found!");
    }

    fn find_next_point_of_outline(&self, grid: &Vec<Vec<bool>>, p: Point2D<isize>, dir: Point2D<isize>) -> (Point2D<isize>, Point2D<isize>) {
	let left = match dir.into() {
	    (-1, 0) => (0, 1),
	    (0, 1) => (1, 0),
	    (1, 0) => (0, -1),
	    (0, -1) => (-1, 0),
	    _ => (0, 0),
	};
	let right = match dir.into() {
	    (0, 1) => (-1, 0),
	    (1, 0) => (0, 1),
	    (0, -1) => (1, 0),
	    (-1, 0) => (0, -1),
	    _ => (0, 0),
	};
	if self.check(p + dir, grid) {
//	    println!("{:?} is true", p + dir);
	    if self.check(p + dir + left, grid) {
//		println!("going left to {:?}", p + dir + left);
		return (p + dir + left, left.into())
	    } else {
		return (p + dir, dir)
	    }
	} else {
//	    println!("{:?} is false", p + dir);
	    if self.check(p + dir + right, grid) {
//		println!("going right to {:?}", p + dir + right);
		return (p + dir + right, dir)
	    } else {
//		println!("going right from p to {:?}", p + right);
		return (p + right, right.into())
	    }
	}
    }

    fn check(&self, p: Point2D<isize>, grid: &Vec<Vec<bool>>) -> bool {
	if p.x < 0 || p.x >= grid.len() as isize || p.y < 0 || p.y >= grid[0].len() as isize {
	    false
	} else {
	    grid[p.x as usize][p.y as usize]
	}
    }
}