Framebuffer API

function new(_sizeX, _sizeY, _color)
    local redirect = {buffer = {text = {}, textColor = {}, backColor = {}, cursorX = 1, cursorY = 1, cursorBlink = false, curTextColor = "0", curBackColor = "f", sizeX = _sizeX or 51, sizeY = _sizeY or 19, color = _color}}
    redirect.write = function(text)
        text = tostring(text)
        local pos = redirect.buffer.cursorX
        if redirect.buffer.cursorY > redirect.buffer.sizeY or redirect.buffer.cursorY < 1 then
            redirect.buffer.cursorX = pos + #text
            return
        end
        local writeText
        if pos + #text <= 1 then
            --skip entirely.
            redirect.buffer.cursorX = pos + #text
            return
        elseif pos < 1 then
            --adjust text to fit on screen starting at one.
            writeText = string.sub(text, math.abs(redirect.buffer.cursorX) + 2)
            redirect.buffer.cursorX = 1
        elseif pos > redirect.buffer.sizeX then
            --if we're off the edge to the right, skip entirely.
            redirect.buffer.cursorX = pos + #text
            return
        else
            writeText = text
        end
        local lineText = redirect.buffer.text[redirect.buffer.cursorY]
        local lineColor = redirect.buffer.textColor[redirect.buffer.cursorY]
        local lineBack = redirect.buffer.backColor[redirect.buffer.cursorY]
        local preStop = redirect.buffer.cursorX - 1
        local preStart = math.min(1, preStop)
        local postStart = redirect.buffer.cursorX + string.len(writeText)
        local postStop = redirect.buffer.sizeX
        redirect.buffer.text[redirect.buffer.cursorY] = string.sub(lineText, preStart, preStop)..writeText..string.sub(lineText, postStart, postStop)
        redirect.buffer.textColor[redirect.buffer.cursorY] = string.sub(lineColor, preStart, preStop)..string.rep(redirect.buffer.curTextColor, #writeText)..string.sub(lineColor, postStart, postStop)
        redirect.buffer.backColor[redirect.buffer.cursorY] = string.sub(lineBack, preStart, preStop)..string.rep(redirect.buffer.curBackColor, #writeText)..string.sub(lineBack, postStart, postStop)
        redirect.buffer.cursorX = pos + string.len(text)
    end
    redirect.clear = function()
        for i=1, redirect.buffer.sizeY do
            redirect.buffer.text[i] = string.rep(" ", redirect.buffer.sizeX)
            redirect.buffer.textColor[i] = string.rep(redirect.buffer.curTextColor, redirect.buffer.sizeX)
            redirect.buffer.backColor[i] = string.rep(redirect.buffer.curBackColor, redirect.buffer.sizeX)
        end
    end
    redirect.clearLine = function()
        redirect.buffer.text[redirect.buffer.cursorY] = string.rep(" ", redirect.buffer.sizeX)
        redirect.buffer.textColor[redirect.buffer.cursorY] = string.rep(redirect.buffer.curTextColor, redirect.buffer.sizeX)
        redirect.buffer.backColor[redirect.buffer.cursorY] = string.rep(redirect.buffer.curBackColor, redirect.buffer.sizeX)
    end
    redirect.getCursorPos = function()
        return redirect.buffer.cursorX, redirect.buffer.cursorY
    end
    redirect.setCursorPos = function(x, y)
        redirect.buffer.cursorX = math.floor(tonumber(x)) or redirect.buffer.cursorX
        redirect.buffer.cursorY = math.floor(tonumber(y)) or redirect.buffer.cursorY
    end
    redirect.setCursorBlink = function(b)
        redirect.buffer.cursorBlink = b
    end
    redirect.getSize = function()
        return redirect.buffer.sizeX, redirect.buffer.sizeY
    end
    redirect.scroll = function(n)
        n = tonumber(n) or 1
        if n > 0 then
            for i = 1, redirect.buffer.sizeY - n do
                if redirect.buffer.text[i + n] then
                    redirect.buffer.text[i] = redirect.buffer.text[i + n]
                    redirect.buffer.textColor[i] = redirect.buffer.textColor[i + n]
                    redirect.buffer.backColor[i] = redirect.buffer.backColor[i + n]
                end
            end
            for i = redirect.buffer.sizeY, redirect.buffer.sizeY - n + 1, -1 do
                redirect.buffer.text[i] = string.rep(" ", redirect.buffer.sizeX)
                redirect.buffer.textColor[i] = string.rep(redirect.buffer.curTextColor, redirect.buffer.sizeX)
                redirect.buffer.backColor[i] = string.rep(redirect.buffer.curBackColor, redirect.buffer.sizeX)
            end
        elseif n < 0 then
            for i = redirect.buffer.sizeY, math.abs(n) + 1, -1 do
                if redirect.buffer.text[i + n] then
                    redirect.buffer.text[i] = redirect.buffer.text[i + n]
                    redirect.buffer.textColor[i] = redirect.buffer.textColor[i + n]
                    redirect.buffer.backColor[i] = redirect.buffer.backColor[i + n]
                end
            end
            for i = 1, math.abs(n) do
                redirect.buffer.text[i] = string.rep(" ", redirect.buffer.sizeX)
                redirect.buffer.textColor[i] = string.rep(redirect.buffer.curTextColor, redirect.buffer.sizeX)
                redirect.buffer.backColor[i] = string.rep(redirect.buffer.curBackColor, redirect.buffer.sizeX)
            end
        end
    end
    redirect.setTextColor = function(clr)
        if clr and clr <= 32768 and clr >= 1 then
            if redirect.buffer.color then
                redirect.buffer.curTextColor = string.format("%x", math.floor(math.log(clr) / math.log(2)))
            elseif clr == 1 or clr == 32768 then
                redirect.buffer.curTextColor = string.format("%x", math.floor(math.log(clr) / math.log(2)))
            else
                return nil, "Colour not supported"
            end
        end
    end
    redirect.setTextColour = redirect.setTextColor
    redirect.setBackgroundColor = function(clr)
        if clr and clr <= 32768 and clr >= 1 then
            if redirect.buffer.color then
                redirect.buffer.curBackColor = string.format("%x", math.floor(math.log(clr) / math.log(2)))
            elseif clr == 32768 or clr == 1 then
                redirect.buffer.curBackColor = string.format("%x", math.floor(math.log(clr) / math.log(2)))
            else
                return nil, "Colour not supported"
            end
        end
    end
    redirect.setBackgroundColour = redirect.setBackgroundColor
    redirect.isColor = function()
        return redirect.buffer.color == true
    end
    redirect.isColour = redirect.isColor
    redirect.render = function(inputBuffer)
        for i = 1, redirect.buffer.sizeY do
            redirect.buffer.text[i] = inputBuffer.text[i]
            redirect.buffer.textColor[i] = inputBuffer.textColor[i]
            redirect.buffer.backColor[i] = inputBuffer.backColor[i]
        end
    end
    redirect.clear()
    return redirect
end

function draw(buffer, current)
    for i=1, buffer.sizeY do
        term.setCursorPos(1,i)
        if (current and (buffer.text[i] ~= current.text[i] or buffer.textColor[i] ~= current.textColor[i] or buffer.backColor[i] ~= current.backColor[i])) or not current then
            local lineEnd = false
            local offset = 1
            while not lineEnd do
                local textColorString = string.match(string.sub(buffer.textColor[i], offset), string.sub(buffer.textColor[i], offset, offset).."*")
                local backColorString = string.match(string.sub(buffer.backColor[i], offset), string.sub(buffer.backColor[i], offset, offset).."*")
                term.setTextColor(2 ^ tonumber(string.sub(textColorString, 1, 1), 16))
                term.setBackgroundColor(2 ^ tonumber(string.sub(backColorString, 1, 1), 16))
                term.write(string.sub(buffer.text[i], offset, offset + math.min(#textColorString, #backColorString) - 1))
                offset = offset + math.min(#textColorString, #backColorString)
                if offset > buffer.sizeX then lineEnd = true end
            end
            if current then
                current.text[i] = buffer.text[i]
                current.textColor[i] = buffer.textColor[i]
                current.backColor[i] = buffer.backColor[i]
            end
        end
    end
    term.setCursorPos(buffer.cursorX, buffer.cursorY)
    term.setTextColor(2 ^ tonumber(buffer.curTextColor, 16))
    term.setBackgroundColor(2 ^ tonumber(buffer.curBackColor, 16))
    term.setCursorBlink(buffer.cursorBlink)
    return current
end