dld

-- dld
-- Simple download program for Computercraft
-- ============================================
-- == config
-- ============================================
URL = "http://zzz.yyy.example.com/ulddld.php"
PASSWORD = "xxxxxx"
-- ============================================
-- == utilities
-- ============================================
local function fileOverwrite(fileName, text)
  local hFile = fs.open(fileName, "w")
  hFile.writeLine(text)
  hFile.close()
end
local function makePostText(tbl)
  local rslt = ""
  for key, val in pairs(tbl) do
    if ("" ~= rslt) then
      rslt = rslt .. "&"
    end
    rslt = rslt ..
      textutils.urlEncode(tostring(key)) ..
      "=" ..
      textutils.urlEncode(tostring(val))
  end
  return rslt
end
local function httpPost(url, data)
  local file = http.post(url, makePostText(data))
  local rslt
  if file ~= nil then
    rslt = file.readAll()
    file.close()
  else
    rslt = ""
  end
  return rslt
end
local function getOneLine(src, start)
  local nl = string.find(src, "\n", start)
  if nil == nl then
    return string.sub(src, start), nil
  else
    local next_pos = nl + 1
    if string.len(src) < next_pos then
      next_pos = nil
          end
          return string.sub(src, start, nl - 1), next_pos
  end
end
-- ============================================
-- == main
-- ============================================
data = {}
data.command = "dld"
data.password = PASSWORD
response = httpPost(URL, data)
-- line 1 : OK or NG
-- line 2 : when OK -> file name
--          when NG -> error message
-- line 3 : when OK -> file data
line1, nxt = getOneLine(response, 1)
line2, nxt = getOneLine(response, nxt)
if ("NG" == line1) then
  print(line2)
  return
elseif ("OK" == line1) then
  fileOverwrite(line2, string.sub(response, nxt))
  print("downloaded " .. line2)
end