require "tempfile"

module Buildr

  # Create a task that will download a file from a URL.
  #
  # Takes a single argument, a hash with one pair. The key is the file being
  # created, the value if the URL to download. The task executes only if the
  # file does not exist; the URL is not checked for updates.
  #
  # The task will show download progress on the console; if there are MD5/SHA1
  # checksums on the server it will verify the download before saving it.
  #
  # For example:
  #   download "image.jpg"=>"http://example.com/theme/image.jpg"
  def download(args)
    if String === args || URI === args
      # Given only a download URL, download into a temporary file.
      # You can infer the file from task name.
      temp = Tempfile.new(File.basename(args.to_s))
      task = file_create(temp.path) do |task|
        Transports.download task.source, task.name
      end
      task.sources << args
    else
      # Download to a file created by the task.
      fail unless args.keys.size == 1
      url = args.values.first
      task = file_create(args.keys.first) do |task|
        mkpath File.dirname(task.name), :verbose=>false
        Transports.download task.source, task.name
      end
      task.sources << url
    end
    task
  end

end