use {point, time_scope};
use common::Point;
use super::{Grid, Level};
use noise::{NoiseFn, OpenSimplex, Seedable};
use rand::Rng;

////////// LEVEL GENERATOR /////////////////////////////////////////////////////

#[derive(Debug, Default)]
pub struct LevelGenerator {
    pub seed: u32,
    pub iterations: u8,
    pub wall_smooth_radius: u8,
}

impl LevelGenerator {
    pub fn new(seed: u32) -> Self{
	LevelGenerator {
	    seed,
	    iterations: 5,
	    wall_smooth_radius: 2,
	}
    }

    pub fn generate(&self) -> Level {
	println!("new level from {:?}", self);
	time_scope!("level 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
//	self.simplex_noise(&mut grid);
	self.random_noise(&mut grid);

	// smooth with cellular automata
	self.smooth(&mut grid);
//	grid.smooth_until_equilibrium(&mut grid);

	// increase resolution
	for _i in 0..1 {
	    grid = self.subdivide(&mut grid);
	    self.smooth(&mut grid);
//	    self.smooth_until_equilibrium(&mut grid);
	}

	self.filter_regions(&mut grid);

	let walls = self.find_walls(&grid);
	Level {
	    gravity: point!(0.0, 0.1),
	    grid,
	    walls,
	}
    }

    #[allow(dead_code)]
    fn simplex_noise(&self, grid: &mut Grid<bool>) {
	let noise = OpenSimplex::new().set_seed(self.seed);
	self.set_each(grid, |x, y| noise.get([x as f64 / 12.0, y as f64 / 12.0]) > 0.055, 1);
    }

    #[allow(dead_code)]
    fn random_noise(&self, grid: &mut Grid<bool>) {
	let mut rng: rand::prelude::StdRng = rand::SeedableRng::seed_from_u64(self.seed as u64);
	let noise = OpenSimplex::new().set_seed(self.seed);
	self.set_each(grid, |_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(&self, grid: &mut Grid<bool>) {
	let distance = 1;
	for _i in 0..self.iterations {
	    let mut next = vec!(vec!(true; grid.height); grid.width);
	    for x in distance..(grid.width - distance) {
	    	for y in distance..(grid.height - distance) {
		    match self.neighbours(&grid.cells, x, y, distance) {
			n if n < 4 => next[x][y] = false,
			n if n > 4 => next[x][y] = true,
			_ => next[x][y] = grid.cells[x][y]
		    }
		}
	    }
	    if grid.cells == next {
		break; // exit early
	    } else {
		grid.cells = next;
	    }
	}
    }

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

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

    fn subdivide(&self, grid: &mut Grid<bool>) -> Grid<bool> {
	let (width, height) = (grid.width * 2, grid.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] = grid.cells[x / 2][y / 2];
	    }
	}
	Grid {
	    cell_size: grid.cell_size / 2,
	    width,
	    height,
	    cells
	}
    }

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

    fn get_region_at_point(&self, grid: &Grid<bool>, x: usize, y: usize, marked: &mut Vec<Vec<bool>>) -> Region {
	let value = grid.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 < grid.width as isize && ip.1 >= 0 && ip.1 < grid.height as isize {
		    let up = (ip.0 as usize, ip.1 as usize);
		    if grid.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(&self, grid: &mut Grid<bool>, region: &Region) {
	for c in &region.cells {
	    grid.cells[c.0][c.1] = !region.value;
	}
    }

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

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

	// delete all rooms but the largest
	let regions = self.find_regions(grid); // 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(grid, rooms.pop().unwrap());
	}
    }

    fn find_walls(&self, grid: &Grid<bool>) -> Vec<Vec<Point<isize>>> {
	let mut walls = vec!();
	for r in self.find_regions(&grid) {
	    if r.value {
		let mut outline = r.outline(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);
	    }
	}
	walls
    }
}

////////// 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(&self, scale: usize) -> Vec<Point<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 directions = vec!((1, 0), (1, 1), (0, 1), (-1, 1), (-1, 0), (-1, -1), (0, -1), (1, -1)); // 8 directions rotating right from starting direction right

	let start = self.find_first_point_of_outline(&rect, &grid);
	let mut p = start;
	marked[p.x as usize][p.y as usize] = true;
	loop {
	    outline.push((p + (ox as isize, oy as isize)) * scale as isize);
	    self.find_next_point_of_outline(&grid, &mut p, &mut directions);
	    if p == start {
		break;
	    }
	    marked[p.x as usize][p.y as usize] = true;
	}

	outline
    }

    #[allow(dead_code)]
    fn print_grid(&self, grid: &Vec<Vec<bool>>) {
	let w = grid.len();
	let h = grid[0].len();
	let mut g = vec!(vec!(false; w); h);
    	for x in 0..w {
    	    for y in 0..h {
		g[y][x] = grid[x][y];
	    }
	}
	println!("grid {} x {}", w, h);
	print!("    ");
	for n in 0..w {
	    print!("{}", n % 10);
	}
	println!();
	for (n, row) in g.iter().enumerate() {
	    print!("{:>3}|", n);
	    for col in row {
		print!("{}", if *col { "#" } else { " " });
	    }
	    println!("|");
	}
    }

    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>>) -> Point<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); // 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);
		}
    	    }
    	}
	panic!("no wall found!");
    }

    fn find_next_point_of_outline(&self, grid: &Vec<Vec<bool>>, p: &mut Point<isize>, directions: &mut Vec<(isize, isize)>) {
	directions.rotate_left(2);
	loop {
	    let d = directions[0];
	    if self.check(*p + d, grid) {
		*p += d;
		break;
	    }
	    directions.rotate_right(1);
	}
    }

    fn check(&self, p: Point<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]
	}
    }
}