-- Matrix screensaver v0.7
-- (C) 2012 User 'Advert' at http://www.computercraft.info/forums2/
-- X11/mit licence (use/modify at your will, but please, leave credit where due)
-- Spacebar to quit cleanly!
local term = peripheral.wrap("left")
local mobj = {}
do -- Standart variables.
mobj.x = 0
mobj.y = 0 -- Offscreen
mobj.lingerMin = 3 -- Minimum time to linger (frames)
mobj.lingerMax = 10 -- Maximum time to linger
mobj.linger = 10 -- How long this object will linger
mobj.tailLenMin = 3 -- Minimum tail length
mobj.tailLenMax = 10 -- Maximum tail length
mobj.tailLen = 10
mobj.chars = "1234567890-=!@#$%^&*()_+qwertyuiop[]QWERTYUIOP{}asdfghjkl;'\\ASDFGHJKL:\"|zxcvbnm,./ZXCVBNM<>?"
mobj.charsLen = mobj.chars:len()
mobj.currentTail = {"a", "a", "a", "a", "a", "a", "a", "a", "a", "a"}
end

function mobj:new(o, ...)
local o = o or {}
setmetatable(o, self)
self.__index = self
o:__init(...)
return o
end


function mobj:__init(x)
self.linger = math.random(self.lingerMin, self.lingerMax)
self.tailLen = math.random(self.tailLenMin, self.tailLenMax)
self.x = x
self.y = 1
self.nFrame = 1
self.currentTail = {}
end
function mobj:randomLinger()
self.linger = math.random(self.lingerMin, self.lingerMax)
end

local function printPos(x, y, sText)
term.setCursorPos(x, y)
term.write(sText)
end
function mobj:randomChar()
local r = math.random(1, self.charsLen)
return string.sub(self.chars, r, r)
end
function mobj:printTail()
for i = 1, self.tailLen do
if not self.currentTail[i] then break end
printPos(self.x, self.y - i, self.currentTail[i])
end
end

local termX, termY = term.getSize()

function mobj:render()
self:printTail()
self.nFrame = self.nFrame + 1
if self.nFrame == self.linger then
table.insert(self.currentTail, 1, self:randomChar())
printPos(self.x, self.y, self.currentTail[1])
self.y = self.y + 1
self.nFrame = 1
if self.y > termY + self.tailLen then
self:__init(self.x)
end
else
printPos(self.x, self.y, self:randomChar())
end
end

local objects = {}
local eventT
function init()
for i = 1, termX do
objects[i] = mobj:new({}, i)
end
eventT = os.startTimer(0)
end


function render()
term.clear()
for _, k in pairs(objects) do
k:render()
end
end



init()

while true do
local e, p1, p2 = os.pullEvent()
if e == "timer" and p1 == eventT then
eventT = os.startTimer(0.05) -- 20 fps
render()
elseif e == "key" and p1 == 57 then
term.clear()
term.setCursorPos(1,1)
break
end
end