pry--pry/lib/pry/commands/wtf.rb

class Pry
  class Command::Wtf < Pry::ClassCommand
    match(/wtf([?!]*)/)
    group 'Context'
    description 'Show the backtrace of the most recent exception.'
    options listing: 'wtf?'

    banner <<-'BANNER'
      Usage: wtf[?|!]

      Show's a few lines of the backtrace of the most recent exception (also available
      as `_ex_.backtrace`). If you want to see more lines, add more question marks or
      exclamation marks.

      wtf?
      wtf?!???!?!?

      # To see the entire backtrace, pass the `-v` or `--verbose` flag.
      wtf -v
    BANNER

    def options(opt)
      opt.on :v, :verbose, "Show the full backtrace"
    end

    def process
      raise Pry::CommandError, "No most-recent exception" unless exception

      output.puts "#{bold('Exception:')} #{exception.class}: #{exception}\n--"
      if opts.verbose?
        output.puts with_line_numbers(backtrace)
      else
        output.puts with_line_numbers(backtrace.first(size_of_backtrace))
      end

      if exception.respond_to? :cause
        cause = exception.cause
        while cause
          output.puts "#{bold('Caused by:')} #{cause.class}: #{cause}\n--"
          if opts.verbose?
            output.puts with_line_numbers(cause.backtrace)
          else
            output.puts with_line_numbers(cause.backtrace.first(size_of_backtrace))
          end
          cause = cause.cause
        end
      end
    end

    private

    def exception
      _pry_.last_exception
    end

    def with_line_numbers(bt)
      Pry::Code.new(bt, 0, :text).with_line_numbers.to_s
    end

    def backtrace
      exception.backtrace
    end

    def size_of_backtrace
      [captures[0].size, 0.5].max * 10
    end
  end

  Pry::Commands.add_command(Pry::Command::Wtf)
end