To Do List

local version = "1.3"
local todos = { }
local h = true
local mon = peripheral.wrap("right")
function load(name)
  local file = fs.open(name,"r")
  local data = file.readAll()
  file.close()
  return textutils.unserialize(data)
end
function save(table,name)
  local file = fs.open(name,"w")
  file.write(textutils.serialize(table))
  file.close()
end
function tablelength(T)
  local count = 0
  for _ in pairs(T) do count = count + 1 end
  return count
end
local function centerText(text, object)
    if object == nil then
        object = term
    end
        local x,y = object.getSize()
        local x2,y2 = object.getCursorPos()
        object.setCursorPos(math.floor((x / 2) - (string.len(text) / 2)), y2)
        object.write(text)
end
function create(x,y,width,height,color,mon)
        mon.setCursorPos(x,y)
        for j = 0, height do
                mon.setCursorPos(x,y+j)
                for i = 0,width do
                        mon.setBackgroundColor(color)
                        mon.write(" ")
                end
        end
end
function clearAll(mon, color)
        local w,h = mon.getSize()
        for i = 0,h do
                for j = 0, w do
                        mon.setCursorPos(1+j,1+i)
                        mon.setBackgroundColor(color)
                        mon.write(" ")
                end
        end
end
function reload(object)
    if object == nil then
        object = term
    end
    if fs.exists("saves/todos") then
        todos = load("saves/todos")
        background(object)
        for i = 1, tablelength(todos) do
        object.setCursorPos(1,3+i)
        centerText(i..". "..todos[i], object)
        end
    end

end
function background(object)
    if object == nil then
        object = term
    end
    local x,y = object.getSize()
    create(x/2-20,3,40,tablelength(todos)+1,colors.black,object)
end
    clearAll(term, colors.blue)
    clearAll(mon, colors.blue)
    mon.clear()
    term.clear()
    background(mon)
    background(term)
reload(term)
reload(mon)

while true do
    mon.setBackgroundColor(colors.blue)
    term.setBackgroundColor(colors.blue)
    mon.setCursorPos(1,1)
    term.setCursorPos(1,1)
    centerText("To Do list v.".. version)
    centerText("To Do list v.".. version, mon)
    term.setCursorPos(1,2)
    centerText("To Do:")
    message = read()
    if message == "delete" then
        clearAll(term, colors.blue)
    clearAll(mon, colors.blue)
    mon.clear()
    term.clear()
    background(mon)
    background(term)
    reload(term)
    reload(mon)
        while h do
            mon.setBackgroundColor(colors.blue)
            term.setBackgroundColor(colors.blue)
            mon.setCursorPos(1,1)
            term.setCursorPos(1,1)
            centerText("To Do list v.".. version)
            centerText("To Do list v.".. version, mon)
            term.setCursorPos(1,2)
            term.clearLine()
            term.setTextColor(colors.red)
            centerText("Delete:")
            delete = read()
            if delete == "" then
                h = false
                term.clearLine()
            else
                h = true
                todos = load("saves/todos")
                table.remove(todos, tonumber(delete))
                save(todos, "saves/todos")
            end
            term.setTextColor(colors.white)
            term.clear()
            mon.clear()
            reload(term)
            reload(mon)
        end

    elseif message == "change" then
        clearAll(term, colors.blue)
        clearAll(mon, colors.blue)
        mon.clear()
        term.clear()
        background(mon)
        background(term)
        reload(term)
        reload(mon)
        mon.setBackgroundColor(colors.blue)
        term.setBackgroundColor(colors.blue)
        mon.setCursorPos(1,1)
        term.setCursorPos(1,1)
        centerText("To Do list v.".. version)
        centerText("To Do list v.".. version, mon)
        term.setCursorPos(1,2)
        term.clearLine()
        term.setTextColor(colors.orange)
        centerText("Change:")
        changenum = tonumber(read())
        if change == "" then
            term.setCursorPos(1,2)
            term.clearLine()
        else
            term.setCursorPos(1,2)
            term.clearLine()
            centerText("To:")
            tonum = tonumber(read())
        end
        todos = load("saves/todos")
        to = todos[tonum]
        change = todos[changenum]
        todos[tonum] = change
        todos[changenum] = to
        save(todos, "saves/todos")
        term.setTextColor(colors.white)
        term.clear()
        mon.clear()
        reload(term)
        reload(mon)
    else
    clearAll(term, colors.blue)
    clearAll(mon, colors.blue)
    table.insert(todos, message)
    fs.makeDir("saves")
    save(todos, "saves/todos")
    term.clear()
    mon.clear()
    reload(term)
    reload(mon)
    end
end