local width, height = term.getSize()

local programs = {}

local userEvents = {"mouse_click", "mouse_up", "mouse_drag", "char", "key", "monitor_touch", "key_up", "paste", "terminate"}

programs.new = function(func, x, y, w, h)

  local x = x or 1

  local y = y or 1

  local w = w or widht

  local h = h or height

  local program = {

    x = x, y = y, w = w, h = h,

    term = window.create(

      term.current(), x, y, w, h

    ),

    selected = false,

    coroutine = coroutine.create(func),

    reposition = function(self, x, y)

      self.x, self.y = x, y

      self.term.reposition(x, y)

    end,

    resize = function(self, w, h)

      oldX, oldY = self.term.getPosition()

      self.term.reposition(oldX, oldY, w, h)

      os.queueEvent("term_resize")

    end,

    reset = function(self, x, y, w, h)

      self.x, self.y, self.w, self.h = x, y, w, h

      self.term.reposition(x, y, w, h)

      os.queueEvent("term_resize")

    end

  }

  return program

end

local updateProgram = function(programs, programNum, event, var1, var2, var3, isUserEvent)

  local program = programs[programNum]

  local event, var1, var2, var3 = event, var1, var2, var3

  -- redirect to programs terminal

  local oldTerm = term.redirect(program.term)

  -- give the mouse click as seen from the program window

  if string.sub(event, 1, #"mouse") == "mouse" then

    var2 = var2-program.x+1

    var3 = var3-program.y+1

  end

  -- find out if the program window is clicked

  if event == "mouse_click" and var2>=0 and var3>=0 and var2<=program.w and var3<=program.h then

    -- select this program and deselect every other one

    for programNum = 1, #programs do

      programs[programNum].selected = false

    end

    program.selected = true

    if var3 == 0 then

      program.barSelected = true

      program.barSelectedX = var2

      if var2 == 1 then

        program.resizeIconSelected = true

      end

      if var2 == program.w then

        table.remove(programs, programNum)

        term.redirect(oldTerm)

        return

      end

    end

    -- resort program table

    local selectedProgram

    for i = 1, #programs do

      if programs[i].selected then

        selectedProgram = programs[i]

        table.remove(programs, i)

        break

      end

    end

    table.insert(programs, selectedProgram)

  end

  -- move window when mouse is dragged

  if event == "mouse_drag" and program.barSelected then

    if program.resizeIconSelected then

      program:reset(program.x + var2-program.barSelectedX, program.y+var3, program.w-var2+1, program.h-var3)

    else

      program:reposition(program.x + var2-program.barSelectedX, program.y+var3)

    end

  end

  -- deselect bar if mouse is released

  if event == "mouse_up" then

    program.barSelected = false

    program.resizeIconSelected = false

  end

  -- only give program user events if selected

  if isUserEvent and not program.selected then

    event, var1, var2, var3 = ""

  end

  -- resume program

  coroutine.resume(program.coroutine, event, var1, var2, var3)

  -- delete program if it is finished

  if coroutine.status(program.coroutine) == "dead" then

    table.remove(programs, programNum)

    term.redirect(oldTerm)

    return true

  end

  program.term.redraw()

  term.redirect(oldTerm)

  -- draw line above program

  if program.selected then

    term.setBackgroundColor(colors.lightGray)

    term.setTextColor(colors.gray)

  else

    term.setBackgroundColor(colors.gray)

    term.setTextColor(colors.lightGray)

  end

  paintutils.drawLine(program.x, program.y-1, program.x+program.w-1, program.y-1)

  -- draw resize icon

  term.setCursorPos(program.x, program.y-1)

  term.write("/")

  -- draw close icon

  term.setCursorPos(program.x+program.w-1, program.y-1)

  term.setTextColor(colors.orange)

  term.write("x")

end

programs.update = function(programs, event, var1, var2, var3)

  -- check if event is made from the user

  local isUserEvent = false

  for userEventNum = 1, #userEvents do

    local userEvent = userEvents[userEventNum]

    if event == userEvent then

      isUserEvent = true

      break

    end

  end

  -- update every program

  for programNum = 1, #programs do

    if updateProgram(programs, programNum, event, var1, var2, var3, isUserEvent) then break end

  end

end

return programs