pry/pry

# frozen_string_literal: true

class Pry
  class Command
    class Hist < Pry::ClassCommand
      match 'hist'
      group 'Editing'
      description 'Show and replay Readline history.'

      banner <<-'BANNER'
        Usage:   hist [--head|--tail]
                 hist --all
                 hist --head N
                 hist --tail N
                 hist --show START..END
                 hist --grep PATTERN
                 hist --clear
                 hist --replay START..END
                 hist --save [START..END] FILE
        Aliases: history

        Show and replay Readline history.
      BANNER

      def options(opt)
        opt.on :a, :all, "Display all history"
        opt.on :H, :head, "Display the first N items",
               optional_argument: true, as: Integer
        opt.on :T, :tail, "Display the last N items",
               optional_argument: true, as: Integer
        opt.on :s, :show, "Show the given range of lines",
               optional_argument: true, as: Range
        opt.on :G, :grep, "Show lines matching the given pattern",
               argument: true, as: String
        opt.on :c, :clear, "Clear the current session's history"
        opt.on :r, :replay, "Replay a line or range of lines",
               argument: true, as: Range
        opt.on :save, "Save history to a file", argument: true, as: Range
        opt.on :e, :'exclude-pry', "Exclude Pry commands from the history"
        opt.on :n, :'no-numbers',  "Omit line numbers"
      end

      def process
        @history = find_history

        @history = @history.between(opts[:show]) if opts.present?(:show)

        @history = @history.grep(opts[:grep]) if opts.present?(:grep)

        @history =
          if opts.present?(:head)
            @history.take_lines(1, opts[:head] || 10)
          elsif opts.present?(:tail)
            @history.take_lines(-(opts[:tail] || 10), opts[:tail] || 10)
          else
            @history
          end

        if opts.present?(:'exclude-pry')
          @history = @history.reject do |loc|
            command_set.valid_command?(loc.line)
          end
        end

        if opts.present?(:save)
          process_save
        elsif opts.present?(:clear)
          process_clear
        elsif opts.present?(:replay)
          process_replay
        else
          process_display
        end
      end

      private

      def process_display
        @history = @history.with_line_numbers unless opts.present?(:'no-numbers')

        pry_instance.pager.open do |pager|
          @history.print_to_output(pager, true)
        end
      end

      def process_save
        case opts[:save]
        when Range
          @history = @history.between(opts[:save])

          raise CommandError, "Must provide a file name." unless args.first

          file_name = File.expand_path(args.first)
        when String
          file_name = File.expand_path(opts[:save])
        end

        output.puts "Saving history in #{file_name}..."

        File.open(file_name, 'w') { |f| f.write(@history.raw) }

        output.puts "History saved."
      end

      def process_clear
        Pry.history.clear
        output.puts "History cleared."
      end

      def process_replay
        @history = @history.between(opts[:r])
        replay_sequence = @history.raw

        # If we met follow-up "hist" call, check for the "--replay" option
        # presence. If "hist" command is called with other options, proceed
        # further.
        check_for_juxtaposed_replay(replay_sequence)

        replay_sequence.lines.each do |line|
          pry_instance.eval line, generated: true
        end
      end

      # Checks +replay_sequence+ for the presence of neighboring replay calls.
      # @example
      #   [1] pry(main)> hist --show 46894
      #   46894: hist --replay 46675..46677
      #   [2] pry(main)> hist --show 46675..46677
      #   46675: 1+1
      #   46676: a = 100
      #   46677: hist --tail
      #   [3] pry(main)> hist --replay 46894
      #   Error: Replay index 46894 points out to another replay call:
      #   `hist -r 46675..46677`
      #   [4] pry(main)>
      #
      # @raise [Pry::CommandError] If +replay_sequence+ contains another
      #   "hist --replay" call
      # @param [String] replay_sequence The sequence of commands to be replayed
      #   (per saltum)
      # @return [Boolean] `false` if +replay_sequence+ does not contain another
      #   "hist --replay" call
      def check_for_juxtaposed_replay(replay_sequence)
        if replay_sequence =~ /\Ahist(?:ory)?\b/
          # Create *fresh* instance of Options for parsing of "hist" command.
          slop_instance = slop
          slop_instance.parse(replay_sequence.split(' ')[1..-1])

          if slop_instance.present?(:r)
            replay_sequence = replay_sequence.split("\n").join('; ')
            index = opts[:r]
            index = index.min if index.min == index.max || index.max.nil?

            raise CommandError,
                  "Replay index #{index} points out to another replay call: " \
                  "`#{replay_sequence}`"
          end
        else
          false
        end
      end

      # Finds history depending on the given switch.
      #
      # @return [Pry::Code] if it finds `--all` (or `-a`) switch, returns all
      #   entries in history. Without the switch returns only the entries from the
      #   current Pry session.
      def find_history
        h = if opts.present?(:all)
              Pry.history.to_a
            else
              Pry.history.to_a.last(Pry.history.session_line_count)
            end

        Pry::Code(Pry.history.filter(h[0..-2]))
      end
    end

    Pry::Commands.add_command(Pry::Command::Hist)
    Pry::Commands.alias_command 'history', 'hist'
  end
end