require 'repertoire/media/exceptions/unknown_media'

module Repertoire
  module Media
    #
    # All registered media types.
    #
    # @return [Hash]
    #   The media types.
    #
    def Media.types
      @@media_types ||= {}
    end

    #
    # Determines if a media type has been registered.
    #
    # @param [Symbol, String] name
    #   The name of the media type to check for.
    #
    # @return [Boolean]
    #   Specifies whether there is a Media type registered with the
    #   matching  name.
    #
    def Media.supports?(name)
      Media.types.has_key?(name.to_sym)
    end

    #
    # Finds a media type by name.
    #
    # @param [Symbol, String] name
    #   The name of the media type to search for.
    #
    # @return [Type]
    #   The Media type with the matching name.
    #
    def Media.get(name)
      name = name.to_sym

      unless Media.supports?(name)
        raise(UnknownMedia,"media type #{name} is not registered",caller)
      end

      return Media.types[name]
    end

    #
    # The media types associated to various URI schemes.
    #
    # @return [Hash]
    #   All registered Media types and their associated URI schemes.
    #
    def Media.schemes
      @@media_schemes ||= {}
    end

    #
    # URI schemes associated to media types.
    #
    # @return [Array]
    #   All registered URI schemes.
    #
    def Media.registered_schemes
      Media.schemes.keys
    end

    #
    # Determines whether a given URI scheme is supported.
    #
    # @param [String, Symbol] scheme
    #   The URI scheme to check for.
    #
    # @return [Boolean]
    #   Specifies whether a Media type was registered for the specified
    #   scheme.
    #
    def Media.supports_scheme?(scheme)
      Media.schemes.has_key?(scheme.to_s)
    end

    #
    # Finds the media type that supports a given URI scheme.
    #
    # @param [String, Symbol] name
    #   The URI scheme to search for.
    #
    # @return [Type]
    #   The Media type that was registered for the specified scheme.
    #
    def Media.supports_scheme(name)
      name = name.to_s

      unless Media.supports_scheme?(name)
        raise(UnknownMedia,"media type for scheme #{name.dump} is not registered",caller)
      end

      return Media.schemes[name]
    end

    #
    # Media types associated to media storage directories.
    #
    # @return [Hash]
    #   All registered Media types and their associated media storage
    #   directories.
    #
    def Media.directories
      @@media_directories ||= {}
    end

    #
    # Media storage directories associated with media types.
    #
    # @return [Array]
    #   All registered media storage directories.
    #
    def Media.registered_directories
      Media.directories.keys
    end

    #
    # Determines if the media storage directory is recognized by any
    # media type.
    #
    # @param [String, Symbol] name
    #   The media storage directory to search for.
    #
    # @return [Boolean]
    #   Specifies whether a Media type was registered with the specified
    #   media storage directory.
    #
    def Media.recognizes_directory?(name)
      Media.directories.has_key?(name.to_s)
    end

    #
    # Finds the media type which uses a given media storage directory.
    #
    # @param [String, Symbol] name
    #   The media storage directory to search for.
    #
    # @return [Type]
    #   The Media type that was registered for the specified media storage
    #   directory.
    #
    def Media.recognizes_directory(name)
      name = name.to_s

      unless Media.recognizes_directory?(name)
        raise(UnknownMedia,"media type for directory #{name.dump} is not registered",caller)
      end

      return Media.directories[name]
    end

    #
    # Get the Media type that was registered for the scheme of the given
    # URI.
    #
    # @param [String, URI::HTTP] uri
    #   The URI to infer the media type from.
    #
    # @return [Type]
    #   The media type which handles the specified URI.
    #
    def Media.guess_from_uri(uri)
      Media.supports_scheme(uri.to_s.scan(/^[^:\/@]+:/).first.chop)
    end

    #
    # Attempts to determine the correct Media type for a given path.
    #
    # @param [String] path
    #   The path to infer the media type from.
    #
    # @return [Type]
    #   The media type which handles the repository at the specified path.
    #
    def Media.guess_from_path(path)
      path = File.expand_path(path)

      Media.directories.each do |directory,media|
        if File.directory?(File.join(path,directory))
          return media
        end
      end

      raise(UnknownMedia,"the media type for #{path.dump} is unknown",caller)
    end
  end
end