pry--pry/lib/pry/commands/help.rb

class Pry
  Pry::Commands.create_command "help" do |cmd|
    group 'Help'
    description "Show a list of commands. Type `help <foo>` for information about <foo>."

    banner <<-BANNER
      Usage: help [ COMMAND ]

      With no arguments, help lists all the available commands in the current
      command-set along with their description.

      When given a command name as an argument, shows the help for that command.
    BANNER

    # We only want to show commands that have descriptions, so that the
    # easter eggs don't show up.
    def visible_commands
      visible = {}
      commands.each do |key, command|
        visible[key] = command if command.description && !command.description.empty?
      end
      visible
    end

    # Get a hash of available commands grouped by the "group" name.
    def command_groups
      visible_commands.values.group_by(&:group)
    end

    def process
      if args.empty?
        display_index(command_groups)
      else
        display_search(args.first)
      end
    end

    # Display the index view, with headings and short descriptions per command.
    #
    # @param Hash[String => Array[Commands]]
    def display_index(groups)
      help_text = []

      groups.keys.sort_by(&method(:group_sort_key)).each do |key|
        commands = groups[key].sort_by{ |command| command.options[:listing].to_s }

        unless commands.empty?
          help_text << "#{text.bold(key)}\n" + commands.map do |command|
            "  #{command.options[:listing].to_s.ljust(18)} #{command.description}"
          end.join("\n")
        end
      end

      stagger_output(help_text.join("\n\n"))
    end

    # Display help for an individual command or group.
    #
    # @param String  The string to search for.
    def display_search(search)
      if command = command_set.find_command_for_help(search)
        display_command(command)
      else
        groups = search_hash(search, command_groups)

        if groups.size > 0
          display_index(groups)
          return
        end

        filtered = search_hash(search, visible_commands)
        raise CommandError, "No help found for '#{args.first}'" if filtered.empty?

        if filtered.size == 1
          display_command(filtered.values.first)
        else
          display_index({"'#{search}' commands" => filtered.values})
        end
      end
    end

    # Display help for an individual command.
    #
    # @param [Pry::Command]
    def display_command(command)
      stagger_output command.new.help
    end

    # Find a subset of a hash that matches the user's search term.
    #
    # If there's an exact match a Hash of one element will be returned,
    # otherwise a sub-Hash with every key that matches the search will
    # be returned.
    #
    # @param [String]  the search term
    # @param [Hash]  the hash to search
    def search_hash(search, hash)
      matching = {}

      hash.each_pair do |key, value|
        next unless key.is_a?(String)
        if normalize(key) == normalize(search)
          return {key => value}
        elsif normalize(key).start_with?(normalize(search))
          matching[key] = value
        end
      end

      matching
    end

    # Clean search terms to make it easier to search group names
    #
    # @param String
    # @return String
    def normalize(key)
      key.downcase.gsub(/pry\W+/, '')
    end

    def group_sort_key(group_name)
      [%w(Help Context Editing Introspection Input_and_output Navigating_pry Gems Basic Commands).index(group_name.gsub(' ', '_')) || 99, group_name]
    end
  end
end