Setup

local appName = "db"
local appVersion = "1.0a"

local function doScreen(txt)
  term.clear()
  term.setCursorPos(1,1)
  print("DropBox Downloader (v"..appVersion..")")
  print("------------------------------")
  print(txt)
end

args = {...}

-- Download a program from Dropbox
local function Download(link)
  -- Ensure direct download link
  addr = string.gsub(link,"(//www.)","//dl.",1)

  -- Open the file
  handle = http.get(addr)
  if handle == nil then
    print("Invalid link")
    return nil, nil, nil
  end

  code = handle.readAll()

  -- First take name from address, then try from code
  for word in string.gmatch(addr, "/(%w+)") do
    name = word
  end
  for word in string.gmatch(code, "appName = \"(.-)\"") do
    name = word
  end

  -- Try to take version from code, default to N/A
  version = "N/A"
  for word in string.gmatch(code, "appVersion = \"(.-)\"") do
    version = word
  end

  -- If no label on computer, set label to program name
  if not os.getComputerLabel() then
    os.setComputerLabel(name)
  end

  file = fs.open(name, "w")
  file.write(code)
  file.close()
  return name, version, addr

end

if args[1] == "update" then
  if (not fs.exists("db-data")) then
    print("No existing db data.  Must run db get first.")
  else
    doScreen("Updating:")
    local handle = fs.open("db-data","r")
    local data = handle.readAll()
    for program,version,addr in string.gmatch(data, "\"(.-)\"|\"(.-)\"|\"(.-)\"") do
      name, ver, addr = Download(addr)
      print("- Program: "..name.." (v"..ver..")")
    end
  end
elseif (args[1] == "get") and (#args == 2) then
  name, version, addr = Download(args[2])
  if name == nil then
    doScreen("Problem installing program.")
  else
    doScreen("Installed: "..name.." (v"..version..")")
    local handle = fs.open("db-data","a")
    handle.writeLine("\""..name.."\"|\""..version.."\"|\""..addr.."\"\n")
    handle.close()
  end
else
  print("Usage:")
  print(appName.." update")
  print(appName.." get [address]")
end