--- Attempts to guess the pastebin ID from the given code or URL
local function extractId(paste)
  local patterns = {
      "^([%a%d]+)$",
      "^https?://pastebin.com/([%a%d]+)$",
      "^pastebin.com/([%a%d]+)$",
      "^https?://pastebin.com/raw/([%a%d]+)$",
      "^pastebin.com/raw/([%a%d]+)$",
  }

  for i = 1, #patterns do
      local code = paste:match( patterns[i] )
      if code then return code end
  end

  return nil
end

function download(url)
  if not http then
    return false, "Pastebin requires http API"
  end

  if type( url ) ~= "string" then
    error( "bad argument #1 (expected string, got " .. type( url ) .. ")", 2 )
  end

  local paste = extractId( url )
  if not paste then
      return false, "Invalid pastebin code."
  end

  -- Add a cache buster so that spam protection is re-checked
  local cacheBuster = ("%x"):format(math.random(0, 2^30))
  local response, err = http.get(
      "https://pastebin.com/raw/"..textutils.urlEncode( paste ).."?cb="..cacheBuster
  )

  if response then
      -- If spam protection is activated, we get redirected to /paste with Content-Type: text/html
      local headers = response.getResponseHeaders()
      if not headers["Content-Type"] or not headers["Content-Type"]:find( "^text/plain" ) then
          return false, "Pastebin blocked the download due to spam protection. Please complete the captcha in a web browser: https://pastebin.com/" .. textutils.urlEncode( paste )
      end

      local sResponse = response.readAll()
      response.close()
      return true, sResponse
  end

  return false, err
end

function put(sPath)
  if not http then
    return false, "Pastebin requires http API"
  end

  if type( sPath ) ~= "string" then
    error( "bad argument #1 (expected string, got " .. type( sPath ) .. ")", 2 )
  end

  -- Upload a file to pastebin.com
  -- Determine file to upload
  if not fs.exists( sPath ) or fs.isDir( sPath ) then
      return false, "No such file"
  end

  -- Read in the file
  local sName = fs.getName( sPath )
  local file = fs.open( sPath, "r" )
  local sText = file.readAll()
  file.close()

  -- POST the contents to pastebin
  local key = "0ec2eb25b6166c0c27a394ae118ad829"
  local response = http.post(
      "https://pastebin.com/api/api_post.php",
      "api_option=paste&"..
      "api_dev_key="..key.."&"..
      "api_paste_format=lua&"..
      "api_paste_name="..textutils.urlEncode(sName).."&"..
      "api_paste_code="..textutils.urlEncode(sText)
  )

  if response then
      local sResponse = response.readAll()
      response.close()

      local sCode = string.match( sResponse, "[^/]+$" )

      return true, sCode
  end
  return false, "Failed."
end

function get(sCode, sPath)
  if not http then
    return false, "Pastebin requires http API"
  end

  if type( sCode ) ~= "string" then
    error( "bad argument #1 (expected string, got " .. type( sCode ) .. ")", 2 )
  end

  if type( sPath ) ~= "string" then
    error( "bad argument #2 (expected string, got " .. type( sPath ) .. ")", 2 )
  end

  if fs.exists( sPath ) then
      return false, "File already exists"
  end

  -- GET the contents from pastebin
  local res, msg = download(sCode)
  if not res then
    return res, msg
  end

  local file = fs.open( sPath, "w" )
  file.write( msg )
  file.close()

  return true
end

function run(sCode, ...)
  if not http then
    return false, "Pastebin requires http API"
  end

  if type( sCode ) ~= "string" then
    error( "bad argument #1 (expected string, got " .. type( sCode ) .. ")", 2 )
  end

  local res, msg = download(sCode)
  if not res then
    return res, msg
  end
  local func, err = load(msg, sCode, "t", _ENV)
  if not func then
      return func, err
  end
  return pcall(func, ...)
end