CONWAYS-GAME-OF-LIFE.ps1

param(
    $Alive = 'O',
    $Dead = ' ',
    $SleepInSeconds = .5
)

<#
    Conway's Game of Life
    The classic cellular automata simulation. Press Ctrl-C to stop.
    More info at: https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life
#>

$WIDTH = 79   # The width of the cell grid.
$HEIGHT = 20  # The height of the cell grid.

# $null = Get-Random -SetSeed ([Environment]::TickCount) # not needed - Get-Random is cryptographically random by default

$nextCells = @{}

foreach ($x in 0..($WIDTH - 1)) {
    foreach ($y in 0..($HEIGHT - 1)) {
        if ((Get-Random -Minimum 0 -Maximum 8) -eq 0) {
            $nextCells.$x += @{$y = $Alive }            
        }
        else {
            $nextCells.$x += @{$y = $Dead }
        }
    }
}

while ($true) { 
    "`n" * ($HEIGHT - 7)
    $Host.UI.RawUI.CursorSize = 0
    $cells = $nextCells.Clone()

    foreach ($y in 1..($HEIGHT - 1)) {
        foreach ($x in 0..($WIDTH - 1)) {
            $Host.UI.RawUI.CursorPosition = [System.Management.Automation.Host.Coordinates]::new($x, $y)
            $Host.UI.Write($cells.$x.$y)
        }
    }
    ''
    'Press Ctrl+C to quit.'

    foreach ($x in 0..($WIDTH - 1)) {
        foreach ($y in 0..($HEIGHT - 1)) {
            $left = ($x - 1) % $WIDTH
            $right = ($x + 1) % $WIDTH
            $above = ($y - 1) % $HEIGHT
            $below = ($y + 1) % $HEIGHT
            
            $numNeighbors = 0

            if ($cells.$left.$above -eq $Alive) {
                $numNeighbors += 1
            }

            if ($cells.$x.$above -eq $Alive) {
                $numNeighbors += 1
            }

            if ($cells.$right.$above -eq $Alive) {
                $numNeighbors += 1
            }

            if ($cells.$left.$y -eq $Alive) {
                $numNeighbors += 1
            }

            if ($cells.$right.$y -eq $Alive) {
                $numNeighbors += 1
            }

            if ($cells.$left.$below -eq $Alive) {
                $numNeighbors += 1
            }

            if ($cells.$x.$below -eq $Alive) {
                $numNeighbors += 1
            }

            if ($cells.$right.$below -eq $Alive) {
                $numNeighbors += 1
            }

            # Set cell based on Conway's Game of Life rules
            if ($cells.$x.$y -eq $Alive -and ($numNeighbors -eq 2 -or $numNeighbors -eq 3)) {
                # Living cells with 2 or 3 neighbors stay alive
                $nextCells.$x.$y = $Alive
            } 
            elseif ($cells.$x.$y -eq $Dead -and $numNeighbors -eq 3) {
                # Dead cells with 3 neighbors come to life

                $nextCells.$x.$y = $Alive
            }
            else {
                # All other cells die
                $nextCells.$x.$y = $Dead
            }
        }
    }

    Start-Sleep -Seconds $SleepInSeconds
}