use std::cmp;

use super::{Cell, Engine, WHITE, BLACK};

pub struct LifeEngine {
    grid: Vec<Vec<bool>>,
}


pub fn new(size: usize) -> LifeEngine {
    let mut life = LifeEngine{grid: vec![vec![false; size]; size]};

    // r pemento
    let centery = size/2;
    let centerx = size/2;

    life.grid[centery][centerx] = true;
    life.grid[centery+1][centerx] =  true;
    life.grid[centery-1][centerx] = true;

    life.grid[centery-1][centerx-1] =  true;
    life.grid[centery][centerx+1] = true;

    life
}


impl Engine for LifeEngine {
    fn evolve(&mut self) -> Vec<Vec<Cell>> {
        let mut new_render_grid = vec![vec![Cell{color: BLACK}; self.grid.len()]; self.grid.len()];
        let mut new_life_grid = vec![vec![false; self.grid.len()]; self.grid.len()];

        for y in 0..self.grid.len() {
            for x in 0..self.grid[y].len() {
                let mut nalive = 0;

                let mut ylow = 0;
                if y > 1 {
                    ylow = y-1;
                }
                let yhigh = cmp::min(self.grid.len()-1, y+1);

                let mut xlow = 0;
                if x > 1 {
                    xlow = x-1;
                }
                let xhigh =  cmp::min(self.grid.len()-1, x+1);

                for i in ylow..yhigh+1 {
                    for j in xlow..xhigh+1 {
                        if i == y && j == x {
                            continue;
                        }
                        if self.grid[i][j] {
                            nalive += 1;
                        }
                    }
                }

                if self.grid[y][x] {
                    if nalive == 2 || nalive == 3 {
                        new_render_grid[y][x] = Cell{color: WHITE};
                        new_life_grid[y][x] = true;
                    }
                } else if nalive == 3 {
                    new_render_grid[y][x] = Cell{color: WHITE};
                    new_life_grid[y][x] = true;
                }
            }
        }

        self.grid = new_life_grid;
        new_render_grid
    }
}