paintcan

local tHex = {[0]="0",[1]="1",[2]="2",[3]="3",[4]="4",[5]="5",[6]="6",[7]="7",[8]="8",[9]="9",[10]="a",[11]="b",[12]="c",[13]="d",[14]="e",[15]="f",}

local function fDecToBin(iNum)
    local tBinary = {}
    while iNum > 0 do
        table.insert(tBinary,1,iNum%2)
        iNum=math.floor(iNum/2)
    end
    return #tBinary > 0 and table.concat(tBinary) or "0"
end

local function fRepeats(tFirst,tSec,iIndex,iStart)
    local iNum = 1
    while tFirst[iIndex][iStart+iNum] and tFirst[iIndex][iStart+iNum-1]==tFirst[iIndex][iStart+iNum] and tSec[iIndex][iStart+iNum-1]==tSec[iIndex][iStart+iNum] do
        iNum = iNum + 1
    end
    return iNum
end

local function fTextReps(tText,iIndex,iStart)
    local iNum = 1
    while tText[iIndex][iStart+iNum] and tText[iIndex][iStart+iNum-1]==tText[iIndex][iStart+iNum] do
        iNum = iNum + 1
    end
    return iNum
end

local tBinToDec = {}
local tHexToDec = {}
local tDecToHex = {}

for i=0,255 do
    tBinToDec[tonumber(fDecToBin(i))] = i
end

local sBinary
for iBackground=0,15 do
    tHexToDec[tHex[iBackground]] = {}
    for iText=0,15 do
        sBinary = fDecToBin(iBackground)..fDecToBin(iText)
        tHexToDec[tHex[iBackground]][tHex[iText]] = tBinToDec[tonumber(sBinary)]
        tDecToHex[tBinToDec[tonumber(sBinary)]] = {tHex[iBackground],tHex[iText]}
    end
end



function encode(tText,tForeground,tBackground,sFile)
    local tTemp
    if type(tText)=="string" then
        tTemp = {}
        for word in tText:gmatch("[^\n]+") do
            table.insert(tTemp,{})
            for char in word:gmatch(".") do
                table.insert(tTemp[#tTemp],char)
            end
        end
        tText = tTemp
    end
    if type(tForeground)=="string" then
        tTemp = {}
        for word in tForeground:gmatch("[^\n]+") do
            table.insert(tTemp,{})
            for char in word:gmatch(".") do
                table.insert(tTemp[#tTemp],char)
            end
        end
        tForeground = tTemp
    end
    if type(tBackground)=="string" then
        tTemp = {}
        for word in tBackground:gmatch("[^\n]+") do
            table.insert(tTemp,{})
            for char in word:gmatch(".") do
                table.insert(tTemp[#tTemp],char)
            end
        end
        tBackground = tTemp
    end
    local continue = 0
    local tFile = fs.open(sFile,"wb")
    if #tBackground~=#tForeground or (tText and #tBackground~=#tText) then
        error("size of tables must match. \n#("..tostring(#tForeground)..","..tostring(#tBackground)..","..tostring(tText and #tText or nil)..")")
    end
    for i=1,#tForeground do
        for t=1,#tForeground[i] do
            if continue > 0 then
                continue = continue - 1
            else
                if fRepeats(tForeground,tBackground,i,t) > 1 then
                    continue = fRepeats(tForeground,tBackground,i,t)-1
                    tFile.write(1)
                    tFile.write(1)
                    tFile.write(continue+1)
                end
                tFile.write( tHexToDec[tBackground[i][t]][tForeground[i][t]] )
            end
        end
        if i~=#tForeground then
            tFile.write(10)
            tFile.write(10)
        end
    end
    if #tText > 0 then
        tFile.write(255)
        tFile.write(255)
        for i=1,#tText do
            for t=1,#tText[i] do
                if continue > 0 then
                    continue = continue - 1
                else
                    if fTextReps(tText,i,t) > 1 then
                        continue = fTextReps(tText,i,t) - 1
                        tFile.write(1)
                        tFile.write(continue+1)
                    end
                    tFile.write(string.byte(tText[i][t]))
                end
            end
            tFile.write(10)
        end
    end
    tFile.close()
end

function decode(sFile)
    local tFile = fs.open(sFile,"rb")
    tTemp = {}
    sFore = ""
    sBack = ""
    sText = ""
    for iByte in tFile.read do
        table.insert(tTemp,iByte)
    end
    while #tTemp > 0 do
        if tTemp[2]==tTemp[1] then
            table.remove(tTemp,1)
            local iCon = table.remove(tTemp,1)
            if iCon==1 then
                local tClone = tDecToHex[table.remove(tTemp,2)]
                local reps = table.remove(tTemp,1)
                for i=1,reps do
                    sBack = sBack..tClone[1]
                    sFore = sFore..tClone[2]
                end
            elseif iCon==10 then
                sFore = sFore.."\n"
                sBack = sBack.."\n"
            elseif iCon==255 then
                break
            end
        else
            local tHandle = tDecToHex[table.remove(tTemp,1)]
            sBack = sBack..tHandle[1]
            sFore = sFore..tHandle[2]
        end
    end
    while #tTemp > 0 do
        local iCon = table.remove(tTemp,1)
        if iCon==1 then
            local iClone = tTemp[2]
            for i=2,table.remove(tTemp,1) do
                table.insert(tTemp,1,iClone)
            end
        else
            sText = sText..string.char(iCon)
        end
    end
    return sFore,sBack,sText
end

function draw(iX,iY,sText,sFore,sBack)
    local fTextFunc = sText:gmatch("[^\n]+")
    local fBackFunc = sBack:gmatch("[^\n]+")
    local sTextSplit
    local sBackSplit
    local iRep = 0
    for sForeSplit in sFore:gmatch("[^\n]+") do
        sTextSplit = fTextFunc()
        sBackSplit = fBackFunc()
        term.setCursorPos(iX,iY+iRep)
        term.blit(sTextSplit,sForeSplit,sBackSplit)
        iRep = iRep + 1
    end
end