module "file"

local MAXBLOCKSIZE = 16384 -- 16 K

-- existence ------------------------
function exists(filename)
  local f = io.open(filename, "r")
  if f==nil then 
  	return false 
  else
    f:close()
    return true  
  end	
end

-- size -------------------------
function size (filename)
  local f = io.open(filename, "r+b")
  if f==nil then return nil end  
  local current = f:seek()      -- get current position
  local size = f:seek("end")    -- get file size
  f:seek("set", current)        -- restore position
  f:close()  
  return size
end

-- save -------------------------
function save(filename, rbuf)
  if rbuf==nil then return false end
  local f = io.open(filename, "w+b")
  if f==nil then return false end
  f:write(rbuf)
  f:flush()
  f:close()
  return true
end

-- load ------------------------
function load(filename)
  local f = io.open(filename, "r")
  if f==nil then return nil end  
  local cmdbuf = f:read("*all")
  f:close()
  return(cmdbuf)
end

function loadastable(filename)
  local f = io.open(filename, "r")
  if f==nil then return nil end
  local cmdbuf  = {}
  table.insert(cmdbuf,f:read("*l"))
  f:close()
  return(cmdbuf)
end

function loadasbinary(filename)
  local f = io.open(filename, "r+b")
  if f==nil then return nil end
  local bytes = ""
  while true do
	  local rbytes = f:read(MAXBLOCKSIZE)
	  if rbytes then
	  	bytes = bytes .. rbytes
	  else
	  	break
	  end
  end
  f:close()
  return(bytes)
end

-- extension ---------------------
function getext(filename)
    local file_ext = nil
    for w in string.gfind(filename,"(%.%a*)") do
   		file_ext = string.lower(string.sub(w,2,10))
	end 
	return file_ext
end