Game of Life [1.0.0]

--(c) 2013 Felix Maxwell
--License: CC BY-SA 3.0

local fps = 8 --Determines how long the program will wait between each tick
local char = "#" --Live cells will look like this

function getMonitors()
    local monitors = {}
    if checkMonitorSide( "top" ) then table.insert( monitors, "top" ) end
    if checkMonitorSide( "bottom" ) then table.insert( monitors, "bottom" ) end
    if checkMonitorSide( "left" ) then table.insert( monitors, "left" ) end
    if checkMonitorSide( "right" ) then table.insert( monitors, "right" ) end
    if checkMonitorSide( "front" ) then table.insert( monitors, "front" ) end
    if checkMonitorSide( "back" ) then table.insert( monitors, "back" ) end
    return monitors
end
function checkMonitorSide( side )
    if peripheral.isPresent( side ) then
        if peripheral.getType(side) == "monitor" then
            return true
        end
    end
    return false
end
function printMonitorStats( side )
    local x, y = peripheral.call(side, "getSize")
    local color = "No"
    if peripheral.call(side, "isColor") then
        color = "Yes"
    end
    print("Side:"..side.." Size:("..x..", "..y..") Color?"..color)
end
function askMonitor()
    local monitors = getMonitors()
    if #monitors == 0 then
        print("No monitors found, add more!")
        return nill
    elseif #monitors == 1 then
        return monitors[1]
    else
        while true do
            print("Multiple monitors found, please pick one.")
            for i,v in ipairs(monitors) do
                write("["..(i).."] ")
                printMonitorStats( v )
            end
            write("Selection: ")
            local sel = tonumber(io.read())
            if sel < 1 or sel > #monitors then
                print("")
                print("Invalid number.")
            else
                return monitors[sel]
            end
        end
    end
end

function printCharAt( monitor, x, y, char )
    monitor.setCursorPos( x, y )
    monitor.write( char )
end
function printGrid( monitor, grid )
    monitor.clear()
    for i=1,#grid do
        for o=1,#grid[i] do
            printCharAt( monitor, i, o, grid[i][o] )
        end
    end
end

function getNumNeighborhood( grid, x, y )
    local neighbors = 0
    if x > 1 then
        if y > 1 then
            if grid[x-1][y-1] == char then neighbors = neighbors + 1 end
        end
        if grid[x-1][y] == char then neighbors = neighbors + 1 end
        if y < #grid[x] then
            if grid[x-1][y+1] == char then neighbors = neighbors + 1 end
        end
    end

    if y > 1 then
        if grid[x][y-1] == char then neighbors = neighbors + 1 end
    end
    if y < #grid[x] then
        if grid[x][y+1] == char then neighbors = neighbors + 1 end
    end

    if x < #grid then
        if y > 1 then
            if grid[x+1][y-1] == char then neighbors = neighbors + 1 end
        end
        if grid[x+1][y] == char then neighbors = neighbors + 1 end
        if y < #grid then
            if grid[x+1][y+1] == char then neighbors = neighbors + 1 end
        end
    end

    return neighbors
end
function lifeOrDeath( cur, neighbors )
    if neighbors < 2 then
        return " "
    elseif neighbors > 3 then
        return " "
    elseif neighbors == 3 then
        return char
    else
        return cur
    end
end
function tick( grid )
    local retGrid = {}
    for x=1,#grid do
        retGrid[x] = {}
        for y=1,#grid[x] do
            local num = getNumNeighborhood( grid, x, y )
            retGrid[x][y] = lifeOrDeath( grid[x][y], num )
        end
    end
    return retGrid
end

function setup( w, h )
    local grid = {}
    for i=1,w do
        grid[i] = {}
        for o=1,h do
            if math.random(1, 5) == 1 then
                grid[i][o] = char
            else
                grid[i][o] = " "
            end
        end
    end
    return grid
end
function run()
    local monitor = peripheral.wrap( askMonitor() )
    if monitor.isColor() then
        monitor.setTextColor(colors.lime)
        monitor.setBackgroundColor(colors.black)
    end
    local w, h = monitor.getSize()
    local grid = setup( w, h )
    while true do
        printGrid( monitor, grid )
        grid = tick( grid )
        os.sleep(1/fps)
    end
end

run()

--This one looks kind of cool
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