paulfioravanti / resume

require "socket"

require "tmpdir"

require "pathname"

require_relative "exceptions"

require_relative "file_system"

module Resume

  module CLI

    # The module concerned with fetching an asset file to be used in the

    # generation of a resume.

    #

    # @author Paul Fioravanti

    module FileFetcher

      REMOTE_REPO =

        "https://raw.githubusercontent.com/paulfioravanti/resume/master".freeze

      private_constant :REMOTE_REPO

      module_function

      # Fetches an asset file.

      #

      # File is fetched by making lookups in the following order:

      #

      # - Search in immediate local directory

      # - Search in the machine `/tmp` directory

      # - Search at the remote asset repository

      #

      # @param path [String] The path to look up to fetch an asset file.

      # @raise [NetworkConnectionError] if a remote asset cannot be reached.

      # @return [File] The fetched file.

      def fetch(path)

        pathname = Pathname.new(path)

        fetch_file(pathname)

      end

      def fetch_file(pathname)

        filename = pathname.basename.to_path

        local_file(pathname) ||

          tmpfile(filename) ||

          remote_file(pathname, filename)

      end

      private_class_method :fetch_file

      def local_file(pathname)

        File.open(pathname) if pathname.file?

      end

      private_class_method :local_file

      def remote_file(pathname, filename)

        tmpfile = tmpfile_path(filename)

        File.open(tmpfile, "wb") do |file|

          write_file(file, pathname)

        end

        tmpfile

      rescue SocketError, OpenURI::HTTPError, Errno::ECONNREFUSED

        raise NetworkConnectionError

      end

      private_class_method :remote_file

      def tmpfile_path(filename)

        FileSystem.tmpfile_path(filename)

      end

      private_class_method :tmpfile_path

      def write_file(file, pathname)

        Kernel.open(remote_file_path(pathname)) do |uri|

          file.write(uri.read)

        end

      end

      private_class_method :write_file

      def remote_file_path(pathname)

        path = pathname.to_path

        uri?(pathname) ? path : File.join(REMOTE_REPO, path)

      end

      private_class_method :remote_file_path

      def uri?(pathname)

        uri = URI.parse(pathname.to_path)

        %w[http https].include?(uri.scheme)

      rescue URI::BadURIError, URI::InvalidURIError

        false

      end

      private_class_method :uri?

    end

  end

end