local lineBreak = string.byte("\n")

local function log2(num)
    return math.log(num)/math.log(2)
end

-------------------------------------------
-- Thanks for this, Lignum :)            --
-------------------------------------------
local function unify(bgColour, fgColour)
  local bg = log2(bgColour)
  local fg = log2(fgColour)

  local field = bit.bor(bg, bit.blshift(fg, 4))
  return field
end

local function extractColors(bitfield)
  local bg = 2^(bit.band(bitfield, 0xF))
  local fg = 2^(bit.brshift(bitfield, 4))
  return bg, fg
end
-------------------------------------------


-------------------------------------------
-- Intended for conversion and stuff.    --
-------------------------------------------
local colorChars = "0123456789abcdef"

local function getCharForColor(col)
    local c = log2(col)+1
    return colorChars:sub(c,c)
end

local function getColorForChar(ch)
    for i = 1,16 do
        if(colorChars:sub(i,i) == ch) then
            return 2^(i-1)
        end
    end
end
-------------------------------------------


function load(path)
    local content = {}
    local handle = fs.open(path,"rb")
    local currentLine = {}
    local isChar = false
    for byte in handle.read do
        if(byte == lineBreak) then
            table.insert(content,currentLine)
            currentLine = {}
            isChar = false
        else
            if(isChar) then
                print(#currentLine)
                currentLine[#currentLine][3] = string.char(byte)
                isChar = false
            else
                currentLine[#currentLine+1] = {extractColors(byte)}
                isChar = true
            end
        end
    end
    return content
end

function draw(img)
    for y,line in pairs(img) do
        for x,char in pairs(line) do
            term.setCursorPos(x,y)
            term.setBackgroundColor(char[1])
            term.setTextColor(char[2])
            term.write(char[3])
        end
    end
end

function save(data,file)
    local handle = fs.open(file,"wb")
    for _y,y in pairs(data) do
        for _x,x in pairs(y) do
            handle.write(unify(x[1],x[2]))
            handle.write(x[3] ~= nil and string.byte(x[3]) or string.byte(" "))
        end
        handle.write(lineBreak)
    end
end