ComputerCraft - Screensaver

-- Constants
local colorList = {colors.blue, colors.green, colors.lime, colors.yellow, colors.orange, colors.red}
local timerLength = 0.1
local corneredCountPercent = 0.05

-- Variables
local grid = {}
local lastPixel = {}
local currentColorCount = 1
local timer = nil
local restartTimer = nil
local corneredCount = 1
local width, height = 0
local rangeBetweenColors = 50

--931

-- Load tools API
if os.loadAPI("tools")==false then error("Failed to load Tools API!") end

-- Init monitor
local monitor = peripheral.find("monitor")
if monitor==nil then error("Monitor not found!") end
term.redirect(monitor)
width, height = term.getSize()
corneredCount = width*height*corneredCountPercent
rangeBetweenColors = (width*height)/(table.getn(colorList)*2)

-- Draw functions
local function getCurrentColor()
    local colorIndex = math.ceil(currentColorCount/rangeBetweenColors)
    if colorIndex > table.getn(colorList) then
        return colorList[table.getn(colorList)]
    else
        return colorList[colorIndex]
    end
end

-- Logic functions
local function isPositionValid(x, y)
    return grid[x]~=nil and grid[x][y]==false
end
local function checkForCorneredIsValidPosition(x, y, checkedPositions)
    return isPositionValid(x, y) and checkedPositions[x]~=nil and checkedPositions[x][y]==false
end
local function recursiveCheckForCornered(x, y, checkedPositions, count)
    if count[1]>=corneredCount then return false end
    count[1]=count[1]+1
    checkedPositions[x][y] = true
    if checkForCorneredIsValidPosition(x+1, y, checkedPositions) and not recursiveCheckForCornered(x+1, y, checkedPositions, count) then return false end
    if checkForCorneredIsValidPosition(x-1, y, checkedPositions) and not recursiveCheckForCornered(x-1, y, checkedPositions, count) then return false end
    if checkForCorneredIsValidPosition(x, y+1, checkedPositions) and not recursiveCheckForCornered(x, y+1, checkedPositions, count) then return false end
    if checkForCorneredIsValidPosition(x, y-1, checkedPositions) and not recursiveCheckForCornered(x, y-1, checkedPositions, count) then return false end
    return true
end
local function isPositionCornered(x, y)
    local checkedPositions = {}
    for i = 1, width do
        checkedPositions[i] = {}
        for j = 1, height do
            checkedPositions[i][j] = false
        end
    end

    local count = {0}
    local isCornered = recursiveCheckForCornered(x, y, checkedPositions, count)
    return isCornered, count[1]


    --if isPositionValid(x+1, y) then return false end
    --if isPositionValid(x-1, y) then return false end
    --if isPositionValid(x, y+1) then return false end
    --if isPositionValid(x, y-1) then return false end
    --return true
end
local function update()
    currentColorCount = currentColorCount + 1
    local directions = {1,2,3,4}
    local corneredPosition = nil
    local corneredCount = 0

    while table.getn(directions) > 0 do
        local direction = table.remove(directions, math.random(1,table.getn(directions)))

        local x = lastPixel[1]
        local y = lastPixel[2]

        if direction==1 then x=x+1
        elseif direction==2 then x=x-1
        elseif direction==3 then y=y+1
        else y=y-1 end

        if isPositionValid(x, y) then
            local isCornered, cCorneredCount = isPositionCornered(x, y)
            if isCornered then
                if cCorneredCount >= corneredCount then
                    corneredPosition = {x, y}
                    corneredCount = cCorneredCount
                end
            else
                lastPixel = {x, y}
                paintutils.drawPixel(x, y, getCurrentColor())
                grid[x][y] = true
                return true
            end
        end
    end

    if corneredPosition~=nil then
        lastPixel = {corneredPosition[1], corneredPosition[2]}
        paintutils.drawPixel(corneredPosition[1], corneredPosition[2], getCurrentColor())
        grid[corneredPosition[1]][corneredPosition[2]] = true
        return true
    end

    restartTimer = os.startTimer(3)
    return false
end

-- Loop
os.queueEvent("restart")
while true do
    local event, a, b, c = os.pullEvent()

    if event=="restart" then
        tools.gui.reset()
        grid = {}
        for i = 1, width do
            grid[i] = {}
            for j = 1, height do
                grid[i][j] = false
            end
        end
        lastPixel = {math.random(1, width), math.random(1, height)}
        currentColorCount = 1
        paintutils.drawPixel(lastPixel[1], lastPixel[2], getCurrentColor())
        grid[lastPixel[1]][lastPixel[2]] = true
        timer = os.startTimer(timerLength)
    elseif event=="timer" then
        if a==timer then
            if update() then
                timer = os.startTimer(timerLength)
            end
        elseif a==restartTimer then
            os.queueEvent("restart")
        end
    elseif event=="char" then
        os.queueEvent(event, a)
        tools.gui.reset()
        break
    elseif event=="monitor_touch" or event=="key" then
        tools.gui.reset()
        break
    end
end

term.restore()