class Pry
  module DefaultCommands

    NavigatingPry = Pry::CommandSet.new do
      command "switch-to", "Start a new sub-session on a binding in the current stack (numbered by nesting)." do |selection|
        selection = selection.to_i

        if selection < 0 || selection > _pry_.binding_stack.size - 1
          raise CommandError, "Invalid binding index #{selection} - use `nesting` command to view valid indices."
        else
          Pry.start(_pry_.binding_stack[selection])
        end
      end

      command "nesting", "Show nesting information." do
        output.puts "Nesting status:"
        output.puts "--"
        _pry_.binding_stack.each_with_index do |obj, level|
          if level == 0
            output.puts "#{level}. #{Pry.view_clip(obj.eval('self'))} (Pry top level)"
          else
            output.puts "#{level}. #{Pry.view_clip(obj.eval('self'))}"
          end
        end
      end

      command "jump-to", "Jump to a binding further up the stack, popping all bindings below." do |break_level|
        break_level = break_level.to_i
        nesting_level = _pry_.binding_stack.size - 1

        case break_level
        when nesting_level
          output.puts "Already at nesting level #{nesting_level}"
        when (0...nesting_level)
          _pry_.binding_stack.slice!(break_level + 1, _pry_.binding_stack.size)

        else
          max_nest_level = nesting_level - 1
          output.puts "Invalid nest level. Must be between 0 and #{max_nest_level}. Got #{break_level}."
        end
      end

      command "exit-all", "End the current Pry session (popping all bindings) and returning to caller. Accepts optional return value. Aliases: !!@" do
        # calculate user-given value
        exit_value = target.eval(arg_string)

        # clear the binding stack
        _pry_.binding_stack.clear

        # break out of the repl loop
        throw(:breakout, exit_value)
      end

      alias_command "!!@", "exit-all"

      create_command "exit" do
        description "Pop the previous binding (does NOT exit program). Aliases: quit"

        banner <<-BANNER
          Usage:   exit [OPTIONS] [--help]
          Aliases: quit

          It can be useful to exit a context with a user-provided value. For
          instance an exit value can be used to determine program flow.

          e.g: `exit "pry this"`
          e.g: `exit`

          https://github.com/pry/pry/wiki/State-navigation#wiki-Exit_with_value
        BANNER

        command_options(
                        :keep_retval => true
                        )

        def process
          if _pry_.binding_stack.one?
            _pry_.run_command "exit-all #{arg_string}"
          else
            # otherwise just pop a binding and return user supplied value
            process_pop_and_return
          end
        end

        def process_pop_and_return
          popped_object = _pry_.binding_stack.pop.eval('self')

          # return a user-specified value if given otherwise return the object
          return target.eval(arg_string) unless arg_string.empty?
          popped_object
        end
      end

      alias_command "quit", "exit"

      command "exit-program", "End the current program. Aliases: quit-program, !!!" do
        Pry.save_history if Pry.config.history.should_save
        Kernel.exit target.eval(arg_string).to_i
      end

      alias_command "quit-program", "exit-program"
      alias_command "!!!", "exit-program"

      command "!pry", "Start a Pry session on current self; this even works mid multi-line expression." do
        target.pry
      end

    end
  end
end