todo

local color1 = colors.lime
local color2 = colors.white

local taskFile = "/.tasks"
local page = 1

local function getTasks()
 if not fs.exists(taskFile) then
  local A = fs.open(taskFile, "w")
  A.write("{}")
  A.close()
  return {}
 else
  local A = fs.open(taskFile, "r")
  local tmp = textutils.unserialize(A.readAll())
  A.close()
  return tmp
 end
end

local function redraw(page)
 local tasks = getTasks()
 local maxX, maxY = term.getSize()
 local nMaxY = maxY - 2

 term.clear()
 term.setCursorPos(1,1)
 term.setBackgroundColour(color1)
 term.setTextColour(color2)
 term.clearLine()
 print(" + / -  |  HD's Todo list  ")

 for i=1, nMaxY do
  if i%2 == 1 then
   term.setBackgroundColour(color2)
   term.setTextColour(color1)
  else
   term.setBackgroundColour(color1)
   term.setTextColour(color2)
  end

  term.setCursorPos(1,1+i)
  term.clearLine()

  local num = i+(nMaxY*(page-1))

  if tasks[num] ~= nil then
   write(num..": "..tasks[num])
  else
   write(num..": ")
  end
 end

 term.setBackgroundColour(color2)
 term.setTextColour(color1)
 term.setCursorPos(2,maxY)
 term.clearLine()
 write("<")
 term.setCursorPos((maxX/2-#tostring(page)/2)+1,maxY)
 write(page)
 term.setCursorPos(maxX-1,maxY)
 write(">")
end

local function saveTasks(tbl)
 local A = fs.open(taskFile, "w")
 A.write(textutils.serialize(tbl))
 A.close()
end

local function addTask()
 local tasks = getTasks()
 term.setBackgroundColour(colors.black)
 term.setTextColour(colors.white)
 term.clear()
 term.setCursorPos(1,1)
 write("Task: ")
 local tsk = read()
 table.insert(tasks, tsk)
 saveTasks(tasks)
end

local function delTask()
 local tasks = getTasks()
 term.setBackgroundColour(colors.black)
 term.setTextColour(colors.white)
 term.clear()
 term.setCursorPos(1,1)
 write("Task number: ")
 local tsknmbr = tonumber(read())
 table.remove(tasks, tsknmbr)
 saveTasks(tasks)
end

local function showTask(pg, pos, h, w)
 local tasks = getTasks()
 local step1 = (h-2)*(pg-1)
 local step2 = (pos-1)+step1
 term.setBackgroundColour(color2)
 term.setTextColour(color1)
 term.clear()
 term.setCursorPos(1,1)
 if tasks[step2] ~= nil then
  write("Task #"..step2..":")
  local text = tasks[step2]
  local k = 1
  for i=1, h-1 do
   term.setCursorPos(1,i+1)
   for j=1,w do
    write(string.sub(text, k, k))
    k = k + 1
   end
  end
 term.setCursorPos(1,h)
 write("Press any key to continue")
 os.pullEvent("key")
 end
end

redraw(page)
local maxX, maxY = term.getSize()
while true do
 sleep(0)
 ev, b, xPos, yPos = os.pullEvent("mouse_click")
 if xPos == 2 and yPos == 1 then
  addTask()
 elseif xPos == 6 and yPos == 1 then
  delTask()
 elseif xPos == 2 and yPos == maxY then
  if page > 1 then
   page = page - 1
  end
 elseif xPos == maxX-1 and yPos == maxY then
  page = page + 1
 elseif xPos > 1 and yPos < maxY then
  showTask(page, yPos, maxY, maxX)
 end
 redraw(page)
end