src/derails/action_controller/metal/data_streaming.rb
# frozen_string_literal: true

# :markup: markdown

require "action_controller/metal/exceptions"
require "action_dispatch/http/content_disposition"

module ActionController # :nodoc:
  # # Action Controller Data Streaming
  #
  # Methods for sending arbitrary data and for streaming files to the browser,
  # instead of rendering.
  module DataStreaming
    extend ActiveSupport::Concern

    include ActionController::Rendering

    DEFAULT_SEND_FILE_TYPE        = "application/octet-stream" # :nodoc:
    DEFAULT_SEND_FILE_DISPOSITION = "attachment" # :nodoc:

    private
      # Sends the file. This uses a server-appropriate method (such as `X-Sendfile`)
      # via the `Rack::Sendfile` middleware. The header to use is set via
      # `config.action_dispatch.x_sendfile_header`. Your server can also configure
      # this for you by setting the `X-Sendfile-Type` header.
      #
      # Be careful to sanitize the path parameter if it is coming from a web page.
      # `send_file(params[:path])` allows a malicious user to download any file on
      # your server.
      #
      # #### Options:
      #
      # *   `:filename` - suggests a filename for the browser to use. Defaults to
      #     `File.basename(path)`.
      # *   `:type` - specifies an HTTP content type. You can specify either a string
      #     or a symbol for a registered type with `Mime::Type.register`, for example
      #     `:json`. If omitted, the type will be inferred from the file extension
      #     specified in `:filename`. If no content type is registered for the
      #     extension, the default type `application/octet-stream` will be used.
      # *   `:disposition` - specifies whether the file will be shown inline or
      #     downloaded. Valid values are `"inline"` and `"attachment"` (default).
      # *   `:status` - specifies the status code to send with the response. Defaults
      #     to 200.
      # *   `:url_based_filename` - set to `true` if you want the browser to guess the
      #     filename from the URL, which is necessary for i18n filenames on certain
      #     browsers (setting `:filename` overrides this option).
      #
      #
      # The default `Content-Type` and `Content-Disposition` headers are set to
      # download arbitrary binary files in as many browsers as possible. IE versions
      # 4, 5, 5.5, and 6 are all known to have a variety of quirks (especially when
      # downloading over SSL).
      #
      # Simple download:
      #
      #     send_file '/path/to.zip'
      #
      # Show a JPEG in the browser:
      #
      #     send_file '/path/to.jpeg', type: 'image/jpeg', disposition: 'inline'
      #
      # Show a 404 page in the browser:
      #
      #     send_file '/path/to/404.html', type: 'text/html; charset=utf-8', disposition: 'inline', status: 404
      #
      # You can use other `Content-*` HTTP headers to provide additional information
      # to the client. See MDN for a [list of HTTP
      # headers](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers).
      #
      # Also be aware that the document may be cached by proxies and browsers. The
      # `Pragma` and `Cache-Control` headers declare how the file may be cached by
      # intermediaries. They default to require clients to validate with the server
      # before releasing cached responses. See https://www.mnot.net/cache_docs/ for an
      # overview of web caching and [RFC
      # 9111](https://www.rfc-editor.org/rfc/rfc9111.html#name-cache-control) for the
      # `Cache-Control` header spec.
      def send_file(path, options = {}) # :doc:
        raise MissingFile, "Cannot read file #{path}" unless File.file?(path) && File.readable?(path)

        options[:filename] ||= File.basename(path) unless options[:url_based_filename]
        send_file_headers! options

        self.status = options[:status] || 200
        self.content_type = options[:content_type] if options.key?(:content_type)
        response.send_file path
      end

      # Sends the given binary data to the browser. This method is similar to `render
      # plain: data`, but also allows you to specify whether the browser should
      # display the response as a file attachment (i.e. in a download dialog) or as
      # inline data. You may also set the content type, the file name, and other
      # things.
      #
      # #### Options:
      #
      # *   `:filename` - suggests a filename for the browser to use.
      # *   `:type` - specifies an HTTP content type. Defaults to
      #     `application/octet-stream`. You can specify either a string or a symbol
      #     for a registered type with `Mime::Type.register`, for example `:json`. If
      #     omitted, type will be inferred from the file extension specified in
      #     `:filename`. If no content type is registered for the extension, the
      #     default type `application/octet-stream` will be used.
      # *   `:disposition` - specifies whether the file will be shown inline or
      #     downloaded. Valid values are `"inline"` and `"attachment"` (default).
      # *   `:status` - specifies the status code to send with the response. Defaults
      #     to 200.
      #
      #
      # Generic data download:
      #
      #     send_data buffer
      #
      # Download a dynamically-generated tarball:
      #
      #     send_data generate_tgz('dir'), filename: 'dir.tgz'
      #
      # Display an image Active Record in the browser:
      #
      #     send_data image.data, type: image.content_type, disposition: 'inline'
      #
      # See `send_file` for more information on HTTP `Content-*` headers and caching.
      def send_data(data, options = {}) # :doc:
        send_file_headers! options
        render options.slice(:status, :content_type).merge(body: data)
      end

      def send_file_headers!(options)
        type_provided = options.has_key?(:type)

        content_type = options.fetch(:type, DEFAULT_SEND_FILE_TYPE)
        self.content_type = content_type
        response.sending_file = true

        raise ArgumentError, ":type option required" if content_type.nil?

        if content_type.is_a?(Symbol)
          self.content_type = content_type
        else
          if !type_provided && options[:filename]
            # If type wasn't provided, try guessing from file extension.
            content_type = Mime::Type.lookup_by_extension(File.extname(options[:filename]).downcase.delete(".")) || content_type
          end
          self.content_type = content_type
        end

        disposition = options.fetch(:disposition, DEFAULT_SEND_FILE_DISPOSITION)
        if disposition
          headers["Content-Disposition"] = ActionDispatch::Http::ContentDisposition.format(disposition: disposition, filename: options[:filename])
        end

        headers["Content-Transfer-Encoding"] = "binary"
      end
  end
end
