game.go

package main

import "github.com/qjuanp/gameoflife/board"

type GameOfLife struct {
	board.Board
}

const ALIVE bool = true
const DEAD bool = false

func NewGameOfSize(rows uint, columns uint) GameOfLife {
	return GameOfLife{board.NewRandomBoard(rows, columns, 1)}
}

func (game *GameOfLife) next() GameOfLife {
	newBoardState := board.NewEmptyBoardAsBigAs(&game.Board)

	for rowIndex, row := range game.Board {
		for columnIndex, cell := range row {
			aliveNeighbors := game.checkAliveNeighboars(rowIndex, columnIndex)
			newBoardState[rowIndex][columnIndex] = newCellState(cell, aliveNeighbors)
		}
	}

	return GameOfLife{newBoardState}
}

func (game *GameOfLife) checkAliveNeighboars(rowIdx int, columnIdx int) uint8 {
	var aliveNeighbors uint8 = 0

	for row, hasNextRow, currentRowIndex, itRows := game.Board.IterateNeighborsOfRow(rowIdx); hasNextRow; row, hasNextRow, currentRowIndex = itRows() {
		for cell, hasNextColumns, currentColumnIndex, itColumns := game.Board.IterateNightborsOf(row, columnIdx); hasNextColumns; cell, hasNextColumns, currentColumnIndex = itColumns() {
			if (rowIdx != currentRowIndex || columnIdx != currentColumnIndex) && cell == ALIVE {
				aliveNeighbors++
			}
		}
	}
	return aliveNeighbors
}

func newCellState(cell bool, quantityOfAliveNeighbors uint8) bool {
	// Overpopulation
	if quantityOfAliveNeighbors > 3 {
		return DEAD
	}

	// Revive
	if quantityOfAliveNeighbors == 3 {
		return ALIVE
	}

	// Right conditions
	if cell == ALIVE && quantityOfAliveNeighbors >= 2 && quantityOfAliveNeighbors <= 3 {
		return ALIVE
	}

	if quantityOfAliveNeighbors <= 1 {
		return DEAD
	}

	// no rule applied
	return cell
}