clbin client for OpenComputers

clbin.lua

local com = require("component")
local comp = require("computer")
local fs = require("filesystem")
local shell = require("shell")

local inet = com.internet

local function generateBorder(str)
  local longestOccurence = nil

  for match in str:gmatch("%-*cldata") do
    if not longestOccurence or #match > #longestOccurence then
      longestOccurence = match
    end
  end

  return longestOccurence and ("-" .. longestOccurence) or "cldata"
end

local function asFormData(str, fieldName)
  local border = generateBorder(str)

  local contentType = "multipart/form-data; boundary=" .. border

  return ([[
--%s
Content-Disposition: form-data; name="%s"

%s
--%s--]]):format(
    border,
    fieldName,
    str,
    border
  ), contentType
end

local function request(url, body, headers, timeout)
  local handle, err = inet.request(url, body, headers) -- ①

  if not handle then
    return nil, ("request failed: %s"):format(err or "unknown error")
  end

  local start = comp.uptime() -- ②

  while true do
    local status, err = handle.finishConnect() -- ③

    if status then -- ④
      break
    end

    if status == nil then -- ⑤
      return nil, ("request failed: %s"):format(err or "unknown error")
    end

    if comp.uptime() >= start + timeout then -- ⑥
      handle.close()

      return nil, "request failed: connection timed out"
    end

    os.sleep(0.05) -- ⑦
  end

  return handle -- ⑧
end

local function sendFile(path)
  local f, err = io.open(path, "r") -- ①

  if not f then
    return nil, ("could not open file for reading: %s"):format(err or "unknown error")
  end

  local contents = f:read("*a") -- ②
  f:close()

  local data, contentType = asFormData(contents, "clbin") -- ③
  local headers = {["Content-Type"] = contentType}

  local handle, err = request("https://clbin.com", data, headers, 10) -- ④

  if not handle then
    return nil, err
  end

  local url = {} -- ⑤
  local read = 0

  local _, _, responseHeaders = handle.response() -- ⑥
  local length

  for k, v in pairs(responseHeaders) do -- ⑦
    if k:lower() == "content-length" then
      length = tonumber(v)
    end
  end

  while not length or read < length do -- ⑧
    local chunk, err = handle.read()

    if not chunk then
      if length then -- ⑨
        return nil, ("error occured while reading response: %s"):format(err or "unknown error") -- ⑩
      end

      break -- ⑩
    end

    read = read + #chunk -- ⑪

    if length and read > length then
      chunk = chunk:sub(1, length - read - 1) -- ⑫
    end

    table.insert(url, chunk)
  end

  handle.close() -- ⑬

  return table.concat(url) -- ⑭
end

local function getFile(url, path)
  local f, err = io.open(path, "w") -- ①

  if not f then
    return nil, ("could not open file for writing: %s"):format(err or "unknown error")
  end

  local handle, err = request(url, nil, nil, 10) -- ②

  if not handle then
    return nil, err
  end

  local read = 0

  local _, _, responseHeaders = handle.response()
  local length

  for k, v in pairs(responseHeaders) do
    if k:lower() == "content-length" then
      length = tonumber(v)
    end
  end

  while not length or read < length do
    local chunk, err = handle.read()

    if not chunk then
      if length then
        f:close() -- ③

        return nil, ("error occured while reading response: %s"):format(err or "unknown error")
      end

      break
    end

    read = read + #chunk

    if length and read > length then
      chunk = chunk:sub(1, length - read - 1)
    end

    f:write(chunk)
  end

  f:close() -- ④
  handle.close()

  return true
end

local args, opts = shell.parse(...)

local function printHelp()
  io.stderr:write([[
Usage: clbin { get [-f] <code> <path> | put <path> }
  clbin get [-f] <code> <path>
    Download a file from clbin to <path>.
    If the target file exists, -f overwrites it.
  clbin put <path>
    Upload a file to clbin.
]])
  os.exit(1)
end

if args[1] == "get" then
  if #args < 3 then
    printHelp()
  end

  local code = args[2]
  local path = args[3]
  local url = ("https://clbin.com/%s"):format(code)
  path = fs.concat(shell.getWorkingDirectory(), path)

  if not (opts.f or opts.force) and fs.exists(path) then
    io.stderr:write("file already exists, pass -f to overwrite\n")
    os.exit(2)
  end

  local status, err = getFile(url, path)

  if status then
    print("Success! The file is written to " .. path)
    os.exit(0)
  else
    io.stderr:write(err .. "\n")
    os.exit(3)
  end
elseif args[1] == "put" then
  if #args < 2 then
    printHelp()
  end

  local path = args[2]
  local url, err = sendFile(path)

  if url then
    url = url:gsub("[\r\n]", "")
    print("Success! The file is posted to " .. url)
    os.exit(0)
  else
    io.stderr:write(err .. "\n")
    os.exit(4)
  end
else
  printHelp()
end