class Pry
  module Helpers

    module BaseHelpers

      module_function

      def silence_warnings
        old_verbose = $VERBOSE
        $VERBOSE = nil
        begin
          yield
        ensure
          $VERBOSE = old_verbose
        end
      end

      def find_command(name)
        command_match = commands.find { |_, command| command.options[:listing] == name }

        return command_match.last if command_match
        nil
      end

      def gem_installed?(gem_name)
        require 'rubygems'
        Gem::Specification.respond_to?(:find_all_by_name) ? !Gem::Specification.find_all_by_name(gem_name).empty? : Gem.source_index.find_name(gem_name).first
      end

      def command_dependencies_met?(options)
        return true if !options[:requires_gem]
        Array(options[:requires_gem]).all? do |g|
          gem_installed?(g)
        end
      end

      def set_file_and_dir_locals(file_name)
        return if !target or !file_name
        _pry_.last_file = File.expand_path(file_name)
        _pry_.inject_local("_file_", _pry_.last_file, target)

        _pry_.last_dir = File.dirname(_pry_.last_file)
        _pry_.inject_local("_dir_", _pry_.last_dir, target)
      end

      def stub_proc(name, options)
        gems_needed = Array(options[:requires_gem])
        gems_not_installed = gems_needed.select { |g| !gem_installed?(g) }
        proc do
          output.puts "\nThe command '#{name}' requires the following gems to be installed: #{(gems_needed.join(", "))}"
          output.puts "-"
          output.puts "Command not available due to dependency on gems: `#{gems_not_installed.join(", ")}` not being met."
          output.puts "-"
          output.puts "Type `install #{name}` to install the required gems and activate this command."
        end
      end

      def create_command_stub(names, description, options, block)
        Array(names).each do |name|
          commands[name] = {
            :description => "Not available. Execute #{(name)} command for more information.",
            :action => stub_proc(name, options),
            :stub_info => options
          }
        end
      end

      def colorize_code(code)
        if Pry.color
          CodeRay.scan(code, :ruby).term
        else
          code
        end
      end

      def highlight(string, regexp, highlight_color=:bright_yellow)
        string.gsub(regexp) { |match| "<#{highlight_color}>#{match}</#{highlight_color}>" }
      end

      # formatting
      def heading(text)
        text = "#{text}\n--"
        Pry.color ? "\e[1m#{text}\e[0m": text
      end

      def page_size
        27
      end

      # are we on Jruby platform?
      def jruby?
        defined?(RUBY_ENGINE) && RUBY_ENGINE =~ /jruby/
      end

      # are we on rbx platform?
      def rbx?
       defined?(RUBY_ENGINE) && RUBY_ENGINE =~ /rbx/
      end

      # a simple pager for systems without `less`. A la windows.
      def simple_pager(text, output=output())
        text_array = text.lines.to_a
        text_array.each_slice(page_size) do |chunk|
          output.puts chunk.join
          break if chunk.size < page_size
          if text_array.size > page_size
            output.puts "\n<page break> --- Press enter to continue ( q<enter> to break ) --- <page break>"
            break if $stdin.gets.chomp == "q"
          end
        end
      end

      # Try to use `less` for paging, if it fails then use
      # simple_pager. Also do not page if Pry.pager is falsey
      # FIXME! Another JRuby hack
      def stagger_output(text, output=output())
        if text.lines.count < page_size || !Pry.pager
          output.puts text
          return
        end

        # FIXME! Another JRuby hack
        if jruby?
          simple_pager(text, output)
        else
          lesspipe { |less| less.puts text }
        end
      rescue Errno::ENOENT
        simple_pager(text, output)
      rescue Errno::EPIPE
      end

      #
      # Create scrollable output via less!
      #
      # This command runs `less` in a subprocess, and gives you the IO to its STDIN pipe
      # so that you can communicate with it.
      #
      # Example:
      #
      #   lesspipe do |less|
      #     50.times { less.puts "Hi mom!" }
      #   end
      #
      # The default less parameters are:
      # * Allow colour
      # * Don't wrap lines longer than the screen
      # * Quit immediately (without paging) if there's less than one screen of text.
      #
      # You can change these options by passing a hash to `lesspipe`, like so:
      #
      #   lesspipe(:wrap=>false) { |less| less.puts essay.to_s }
      #
      # It accepts the following boolean options:
      #    :color  => Allow ANSI colour codes?
      #    :wrap   => Wrap long lines?
      #    :always => Always page, even if there's less than one page of text?
      #
      def lesspipe(*args)
        if args.any? and args.last.is_a?(Hash)
          options = args.pop
        else
          options = {}
        end

        output = args.first if args.any?

        params = []
        params << "-R" unless options[:color] == false
        params << "-S" unless options[:wrap] == true
        params << "-F" unless options[:always] == true
        if options[:tail] == true
          params << "+\\>"
          $stderr.puts "Seeking to end of stream..."
        end
        params << "-X"

        IO.popen("less #{params * ' '}", "w") do |less|
          if output
            less.puts output
          else
            yield less
          end
        end
      end

    end
  end
end