os.unloadAPI("buffer")
os.loadAPI("buffer")

local width,height = 51,19

local buf = buffer.new(width,height,1,1,term.current())
local oldTerm = term.redirect(buf:redirect())

local args = {...}
local programPath = args[1]
local func = loadfile(programPath)

local programCoroutine = coroutine.create(func)
local bufferMoveCoroutine = coroutine.create(function()
  while true do
    local evt = {coroutine.yield()}
    if(evt[2] == keys.up) then
      buf.y = buf.y-1
    elseif(evt[2] == keys.down) then
      buf.y = buf.y+1
    elseif(evt[2] == keys.left) then
      buf.x = buf.x-1
    elseif(evt[2] == keys.right) then
      buf.x = buf.x+1
    end
  end
end)

local function translate(evt)
  local e = evt
  if(evt[1] == "mouse_click" or evt[1] == "mouse_drag") then
    e[3] = e[3]+(buf.x-1)
    e[4] = e[4]+(buf.y-1)
  end
  return e
end

--manage the coroutines
local expectedFromProgram = nil
local keepRunning = true
while keepRunning do
  buf:render()
  local evt = {os.pullEvent()}
  local t = evt[1]
  if(expectedFromProgram == nil or expectedFromProgram == t) then
    _,expectedFromProgram = coroutine.resume(programCoroutine,unpack(translate(evt)))
  end
  if(t=="key") then
    coroutine.resume(bufferMoveCoroutine,unpack(evt))
  end
  keepRunning = coroutine.status(programCoroutine) ~= "dead"
end

--get back to old term
term.redirect(oldTerm)